Home Fire Protection

9 Oct 2017 - Redwood
        Valley & Potter Valley Fires Just over hill from my house.

© Brooke Clarke 2017
Background
Applicability
Protection Steps
Fire Hydrant
Hoses
Hose Nozzles
Home Water Supply
    Local Water District
    Head
    Flow Rate
    Meter
    Mains Pressure Water
    Flow from New Hose Bib
    Pressure Reducing Valve
    Meter to House supply pipe
    3 Valve Stations on Fire Pipe
Smith Indian - Fedco Fire Pump - Moved to its own web page
Hot Embers
    Vents
Exterior Sprinklers
    Rain Rate
    Testing impact Sprinklers
    Nozzles
    Commercial Outdoor Fire Sprinklers
Fire Insurance
Shelter in Place
Mass Notification
     Ham Radio
Fire Weather
Map Your Neighborhood
Suppliers
References
    FireWise
    House Numbers
California Codes
Related
Links

Background

After getting an fire evacuation call at 1 am early Monday morning 9 October 2017.  It turned out that I did not need to evacuate, but the Mendocino lake complex fire was lighting up the sky.  Here are photos of fire attack helicopters and aircraft flying over my house fighting the fire.  Since then I've been studying what I can do to reduce the chance that my house will burn.  The three elements of fire (Wiki) are: fuel + air + heat.

Applicability

When I started this page I thought it would only apply someone living in a jungle or forest.  I also thought fire spread like a water wave where the fire front moves and ignites all the flammable material in it's path.  Now I know both of these ideas were wrong.

How Fire Spreads

Fire can spread like a wave with direct flame contact if it has fuel.  Fire can spread by radiant heat, but that requires both a large fire and long exposure.  Most trees burn too quickly to ignite houses at one hundred feet away, but can ignite nearby trees.  Fire also spreads by means of firebrands or hot embers (Wiki).  But these embers are small and can only ignite tinder (Wiki: Tinder) such as dry leaves, pine needles, fir bark, &Etc. which in turn lights kindling (Wiki) such as small plants with dead branches or plants/bushes that are dry, or dry wood like wood shingles or wood fencing.  Kindling can in turn light larger pieces of wood, like wood siding on a house, 4x4 posts &Etc..

Some scenarios are:

  •  A crown fire is advancing on your property. - A defensible space fire break is needed to keep the fire from you house.
  • A crown fire is within a mile. - The house needs to be ember safe AND the defensible space fire break is needed to keep vegetation from igniting.
The key factors in the spreading of fire are: Weather (mainly humidity and wind), topology (fire tends to move up hill if there's no wind) and Fuel (fire can not spread if there's nothing to burn).

The above ideas are codified in the Notice of Defensible Space Inspection.  In the upper left corner on the back side: "Hardening Your Home - Flying embers can destroy homes up to a mile ahead of a wildfire.  Prepare (harden) your home now before a fire starts."
Cal Fire Property Inspection Guide - 65 pages

How fire spreads has nothing to do with the location of a house.  That is to say houses in a city or suburb need defensible space just as do houses in the jungle or forest. But there's a problem in that the spaces involved are:
  • Remove all branches within 10 feet of a chinney or stove-pipe.
  • Zone 1 (within 30 feet of the house) remove all tinder and kindling, no wood piles
  • Zone 2 (between 30 and 100 feet of the house) rules about removing plants, shrubs and trees
The problem for city lots is they are too small to meet the zone sizes, hence these rules are not applicable.  But, fire does not recognize this limitation.

Protection Steps

Remove Fuel

The first thing is to remove a lot of the undergrowth that is potential fuel.  The street was not visible in either of these views a couple of months ago.  More needs to be removed in these views and in adjacent areas.  When I first moved here you could not even walk in these spaces.  Notice that the vegetation is so dense across the street that you can not walk there.

Fig 1 Click photo to see larger version,
then look just to the left of the foreground tree
 (at the street) to see fire hydrant.
Wildland Fire
                      Defensible Space
Fig 2
Wildland Fire
                      Defensible Space
2 April 2018 CAL Fire clearing brush in the right of way
in front of my house:  https://youtu.be/PhVr-hTdiFk

Fire Fighting Equipment

As part of the second step I'm investigating getting some wildfire fighting equipment.  A number of people in the recent fire saved their houses or the houses of a neighbor/friend/relative by fighting it themselves.  Note that there's no way the local fire departments could respond to all the calls for help.

My son who lives in Santa Barbara says there's almost a fire engine in everyone's driveway to protect houses from the Thomas Fire (Wiki).

Areas that were evacuated and they had police road blocks, with the rule once you leave the area you can not return.  But they would not force anyone to leave.  So those who stayed had a neighbor/friend/relative who could meet them bringing needed supplies.
Fire Apparatus (Wiki) "any vehicle that has been customized for use during firefighting operations."

Fire Hydrant

It happens that there's a fire hydrant in front of my property.  It's made by Clow and is a wet barrel type.

Note the stem on fire hydrents is a pentagon (5-sided) that's to say it is NOT like a hexagon (6-sided) bolt so normal tools will not fit, nor will adjustable wrenches work.  Do not use any tool other than a purpose built hydrant wrench.

Wet vs. Dry Barrel Fire Hydrants
In areas where it freezes in winter the dry barrel type hydrant is used.  These have the valve located below the freeze depth and in addition have "slop" in the connection between the valve and the actuating mechanism.  This allows for a bleed valve to be opened to drain the hydrant into the nearby ground so that no water is inside after it's turned fully off.  The valve should be either fully opened or fully closed.  If in an intermediate position water will be forced out of the drain and might erode the ground nearby.

In warmer climates, like here in California, the valves are directly in line with the outlet fittings and so can be used for flow control as well as on/off.  

Note that the outlets are 2-1/2" and 4-1/2".  The nuts are pentagon shaped, not the hexagon shape that's commonly used on nuts and bolts, so standard tools will not work.  Also vice grips, pliers &Etc. will fail and damage the pentagon shape.

Fig 1
Clow Wet
                      Barrel Fire Hydrant 
Fig 2
Clow Wet
                      Barrel Fire Hydrant
I'm trying to learn why this and other hydrants on my street are painted white.
As of 2 Jan 2018 I have not had a return call from the local fire department (I think they are in S. California on mutual aid - Wiki).




Hoses

The wiki page on fire hoses misses some the functional differences in fire hoses (Wiki). 

Wall Stiffness
I would say the most important hose parameter is wall flexibility.
Flexible wall tubing will collapse when a vacuum is applied.  The lower radiator hose in a car (feeds the water pump) has a metal helix inside to prevent collapse which would have the effect of blocking water flow.

Note that the tubing connected to a vacuum pump has flattened.
Gomco
                      M180 Aspirator
Note that the stiff wall tubing does not collapse.
Gomco
                      M180 Aspirator

Common garden hoses (Wiki) have stiff walls and are easy to use.  For example if a common garden hose is lying on the ground and the faucet is turned full on, the hose will not move. You can hold a garden hose nozzle in one hand and point it left or right without resistance from the hose. 

Cloth fire hoses (Wiki) have very weak walls which makes them much lighter in weight and store in a much smaller volume
 than stiff wall hoses.  But the price paid is that flexible wall hoses can not be used for suction applications, like on the input to a water pump.  Also flexible wall hoses want to straighten out when pressurized and so require more effort to aim a nozzle that stiff wall hoses.  A pressurized 3" fire hose is very difficult to work and may require more than one person at the nozzle.  Monitors (Wiki) are water nozzles that are anchored to avoid problems with the pressurized hose.

Flexible wall hoses will not flow water when folded, for example when in a pin rack (Wiki photo) inside a building or when on a reel.  These hoses need to be pulled out so there are no kinks before the water is turned on. 

Stiff wall "Booster" fire hoses are typically mounted on a reel with a swivel fitting allowing them to be pressurized all the time.  Just pull out and open nozzle when at the fire.  These are very similar to garden hoses, except slightly larger in diameter.

The key advantages of flexible wall (fire) hoses is that they are lighter in weight, lower in cost and take much less storage space than stiff wall hoses.  The early fire hoses were made only from fabric and so would degrade if left wet.  This is why most fire stations have a tall hose drying tower.  More modern fire hoses have linings that are not effected by long exposure to water and so don't need to be dried prior to being stored. 
Sizes
Hose Size
Wall
Comment
Area
Wt/10'
3/4"
Stiff
Booster
used on pressurized reels
0.44

1"
Stiff
0.79

1.5"
Stiff
1.77

3"
Stiff Suction (pump inlet)
7.1

4"
Stiff Suction (pump inlet) 12.6

5"
Stiff Suction (pump inlet) 19.6

6"
Stiff Suction (pump inlet) 28.3

5/8" & 3/4"
Flex
3/4" Garden hose Fitting
<= 0.44

1"
Flex Forestry 0.79
1.5"
Flex Forestry 1.77
2"
Flex
Forestry
3.14

2.5" Note 1
Flex Attack
Matches hydrant
4.9

3"
Flex Heavy Duty - Supply line
7.1
4"
Flex
Heavy Duty - Supply line 12.6
5"
Flex Heavy Duty - Supply line 19.6
Note 1: This is the classic handline and requires training and strength to keep under control.  Larger diameter lines are refereed to as supply lines, i.e. lines are are not moved once in place.

Construction

The early fire hoses were made of leather made much the same way that leather boots were made.  Then came hemp fabric hoses that would leak water when first wet but after the fibers swelled would be water tight.  These fabric hoses would be damaged if left wet and to fire houses needed drying racks to dry hoses.

More modern hoses have liners so that the fabric does not see water and so do not need drying racks.  This also means these hoses are more suitable for home protection since they can be used for practice.

Water Pump (Wiki)

There are many types of pump, but a key property for a fire pump is self priming capability.  This requires a positive displacement type pump that can generate a good vacuum on the input so as to suck water into it.  (This really is just creating a vacuum so that the atmospheric air pressure can push the water into the pump.  For fresh water with a density of 62 pounds per cubic foot or 0.43 PSI per foot of head and an atmospheric pressure of 14.7 PSI the maximum depth a pump can pull up water is about 34 feet.)

Hose Nozzles

There is a plethora of nozzle types, sizes where there is a special application where the excel.

I got this United Fire Safety model 1030 nozzle because there are a family of them is sizes from 3/4" garden hose (my unit) and larger fire hose sizes.  It can be adjusted from off to wide and narrow streams.  But . . .
I only have 7.5 Gallons per minute at the strongest hose bib (probably due to the combination of 150+ feet of 1" pipe from the meter to my house and the Pressure Reducing Valve that's set for over 60 PSI pressure drop, so is also greatly restricting the flow.  The nozzle is rated for 8 to 22 GPM so performs poorly with 7.5 GPM input.
Fig 1 UFS 1030 3/4" Garden Hose Nozzle
with 25 GPM input at 116 PSI it works well.
UFS 1030
                      3/4" Garden Hose Nozzle
Fig 2 Granger 572-0711 Nozzle _ Everbilt LFA-679 3/4" FH x 3/4" MIP
This adapter also has an internal 1/2"FIP thread that's no being used here.
The idea is to change the 3/4" female pipe thread in the nozzle into
3/4"Garden Hose female threads.
Granger
                      572-0711 Nozzle _ Everbilt LFA-679 3/4" FH x
                      3/4" MIP
This nozzle, like the UFS nozzle to the left, is anemic when used on the house hose
bib with 60 PSI and about 10 GPH max flow.  But on the new hose bib with 106 PSI and 25+ GPM it throws over 50'.  The nozzle orifice is 0.261"

GPM = 29.72 * D2*SQRT(PSI)
= 29.72 * 0.261 * 0.261 * SQRT(106) = 21 GPH just under the available water flow of 25+ GPM.
There's a noticeable reaction force pushing back from the nozzle.

Nozzle Reaction = 1.57 * D * D * NozzlePSI = 1.57 * 0.261 * 0.261 * 106 = 11 pounds
This is not enough to be a problem while holding, but would be if not holding.

Home Water Supply

Also see Water Pressure.

Local Water District

There are two tanks above me operated by the local water district.  Many years ago there was a multi-day power failure and the water company brought in a big generator.  I asked then why the generator and the answer was that they needed to keep the tank full in case of fire, i.e. not about supplying domestic water to houses.

Both of the local water tanks are much higher in elevation than me so there's plenty of pressure.

Tank on ridge & Pump house
about 80,000 Gallons
Brooke's Guide
                      to Utility Poles
Tank on hill, no pump
about 200,000 Gallons
Water tank on
                      hill

Head

If my pressure at the meter is 106 PSI then the water level in the supply tank is at 106 (P/sq in) * 144 sq in / 62.5 Lb/cu ft = 244 feet above my meter.
My meter is at about 1,000 elevation so the water level in the tank is at about 1,244 ft.  The pressure at any other meter fed from this tank can be calculated from knowing their altitude.

Flow Rate

The flow rate is determined by a number of things:

The size of the meter
The size and adjustment of the pressure regulating valve
The size of the piping between the meter and the nozzle where the water enters the atmosphere
Elevation difference between the meter and outlet.
 . . . .

In order to use exterior sprinklers where you can not use a line powered timer (the power probably will go out), it's necessary to have an adequate flow for all the sprinklers to run at the same time.  At my house the water pressure at the street (fire hydrant) is 106 PSI and it's less than 10 feet of elevation below the house foundation elevation.

Meter (Wiki)

The size of the water meter limits the flow.  Most houses have a 5/8" - 1/2" meter and the maximum flow is about 22 gallons per minute.

Table of flow rates for water meter size.

Size
GPM
5/8" - 1/2"
common house meter
22
3/4"
32
1"
50
1-1/4"
67
1-1/2"
79
2"
94

Mains Pressure Water

By adding a hose bib between the water meter and the pressure regulator there will be access to the full pressure and flow from the meter.  This will be very close to water meter so pipe loss will be negligible.  Separate 1" pipe will be laid for the new sprinkler-hose bibs.  1" is good for 12 Gallons per Minute, so maybe will up the pipe size depending on the final flow rate for all of the sprinklers. The existing 1" pipe feeding the house, sprinkler system and hose bibs attached to the house will remain.

DO NOT USE METAL FITTING INSIDE PVC FITTING!
See Fig 5


First System - with Fatal Flaw
Mains water
                      pressure hose bib - prior to house pressure
                      regulator
Mains water
                      pressure hose bib - prior to house pressure
                      regulator From bottom to top, as water will flow:
1" compression "T" with threaded side outlet.  This will be inserted into the existing 1" line from water meter.
1" thread to slip PVC fitting
1" PVC pipe
1" PVC 45 deg
1" PVC pipe
1" PVC "T" with threaded side outlet.  The in line fitting has a short 1" pipe and cap for extending this line.
The threaded side outlet has:
 2 each Galvanized street "ells" which feed a couple of 1" galvanized nipples topped with a standard hose bib with 1" NPT inlet and 3/4" Garden hose outlet.
The metal stake is commonly used for concrete forms.
Note the two street ells are arranged so that if the pipe holding the hose bib is pushed in any direction it will not break the below ground PVC.  That's to say the two street ells act as a universal joint.  For this to work the male threads on the bottom/first street ell must be horizontal.
Note: All the PVC joints were made after light sanding and application of PVC primer.  Then left to cure overnight.
To be installed the next morning so there will be minimal time without water.
Note:  all threaded joints made with white Teflon tape applied so that no tape can come loos inside pipe. That may cause a problem with a sprinkler nozzle.

Fig 4 Leaking - meter turned off - no water in house.
Note leak at riser, not at compression fitting.
Mains water
                      pressure hose bib - prior to house pressure
                      regulator
Fig 5 Crack in PVC "T"

"Female plastic threads on male metal threads are the most vulnerable to over-torqueing, so avoid them if possible."

"Do not use a plastic female threaded connector with a metal male connector! The joint will almost always leak or break."
Mains water
                      pressure hose bib - prior to house pressure
                      regulator


Fig 6  Second System
Now that I know there's plenty of water flow available,
the system is upgraded to 1-1/2" pipe and the first
hose bib located in the correct spot.
The existing 1" compression T left in place, then step up to 1-1/2" and valve.

Note: 1-1/2" PVC is good for 30 GPM with a pressure loss of  2.28 PSI per 100'.
Mains wate
                      pressure hose bib - prior to house pressure
                      regulator
Fig 7  1-1/2" pipe on the wat ot first Hose Bib.
Mains wate
                      pressure hose bib - prior to house pressure
                      regulator
Fig 8 After 1-1/2" T, a reducer to 1".
Waiting for cement to dry overnight, then will install 1" Hose Bib riser.
Valve prior to 1" line.
Both 1" and 1-1/2" pipes end with threads so easy to extend either one without shutting off house.
Mains water
                      pressure hose bib - prior to house pressure
                      regulator
Fig 9 RainBird 29J (5/32") two valves
(third main line valve in box just to the left)
The sprinkler does not work when higher because of the
leaves on nearby plants.
Mains water
                      pressure hose bib - prior to house pressure
                      regulator


Flow from New Hose Bib 1st try

The hope is the flow will be near 22 GPM, or about 14 seconds to fill a 5 gallon bucket.

Fig 3 New hose bib installed near water meter.
Mains water
                      pressure hose bib - prior to house pressure
                      regulator

New hose bib near water meter - Pressure 116 PSI
at end of short garden hose.
New hose
                      bib near water meter - Pressure 116 PSI
Video of filling 5 Gallon bucket
(filmed using GoPro Hero 5 Black)

Time to fill:  12 seconds
GPM = (60 sec * 5 gal)/12 sec = 25 GPM
The flow is probably more because I filled the bucket to the brim.
The 5 Gallon fill line is just below the top ridge not the brim.
5 Gallon Bucket
                      Calibrated

Video of Rainbird 14VH running at 116 PSI.  (normal speed)
Rated for 20 to 60 PSI.
The distance is slightly less than at 45 PSI.



WeatherTec 10-10 1/2" Full Circle Sprinkler 3/32"FC Nozzle (240 fps)

This 25 GPM flow is the total flow for all sprinklers that are running at the same time.

Pressure Reducing Valve (Wiki)

The hose bib just after the pressure regulator tests at 44 PSI static with a Rain Bird P2A pressure gauge.
This hose bib will fill a 5 gallon bucket in 40 seconds.  5 * 40/60 = 7.5 Gallons Per Minute, and the pressure on the other bib is 20 PSI.
The difference between the static pressure (44 PSI) and the dynamic pressure (20 PSI) is the "Fall Off" (24 PSI) in pressure regulator speak.

The water district says my water meter should flow 25 GPM at the meter.  So the flow limitation is caused either by the 1" pipe between meter and regulator and/or the pressure regulator.  The meter does flow 25 GPM see Flow from new hose bib above.

12 April 2018 - Increased the house pressure to 60 PSI and the flow is now about 10 GPM, up from 7.5 GPM.   This means a couple of 29JH sprinklers with the maximum 5/32 nozzles would work for the roof when fed from the house plumbing.  This greatly simplifies getting pipes to where they need to be.  A slight pressure decrease will result from the 30+ foot elevation rise above the ground.  A 1" pipe will save a couple of PSI in pressure loss at 5 CFM.

There may be sprinklers that are tapped off the line between the meter and pressure regulator, need to test to see if that's the case.  Not the case the pressure at the sprinkler is 45 PSI, so they are after the house pressure regulator valve.
This would also explain why I've had so many problems with the irrigation system leaking.  Two or three valves have failed in such a way that water leaks, in one case slow, and in another case the meter reader knocked on my door because the fast dial on my water meter was spinning very fast and had been for less than a month.

House Water
                      Pressure Regulator & Hose Bib

1" Water line coming from meter goes to pressure regulating valve then a "T" to the house and a hose bib.  The hose bib has a "Y" with a battery powered timer and another hose bib (rather than use the "Y" ball valve).

PS I've had problems with leaking faucets inside and leaks at the unions here at the entrance.  Here the plumber needed to redo some of the PVC fittings to (attempt) fixing the leak. 

After waiting the normal time for the PVC glue to set up they opened the meter valve and the PVC fittings blew apart.  The plumber said my water pressure was much higher than he expected (maybe 150 to 200 PSI).

I now think the pressure reducing valve is cutting down the flow from 25 GPM to 7.5 GPM, that's a lot!
For my case were there's a large pressure drop required to keep the pressure inside the house low enough that the appliances and fittings can handle it, more than one reducing valve may be needed.  Note that the hose bibs are plumed from inside the house and to get good flow the whole house needs good flow.  Also, if the hose bibs were connected before the pressure reducing valve then burst hoses would be the likely result.

Zurn-Wilkins 70XL water Pressure Reducing Valve (PRV).  - 34-NR3XLDU (3/4") - 1-NR3XL (1") -

There might be a relationship between the PRV size the the maximum flow you can get (based on Watts LF25AUB-Z3, LF is Lead Free, not Low Flow).  But this is a function of the specific PRV.

Idea: "Reduced Pressure Drop", on the data sheet plot, varies from 0 PSI to 25 PSI for the Watts LF25AUB-Z3 and is the Y-axis scale on the Capacity plot.  Flow (GPM) is the X-axis scale.
Reduced pressure drop probably is the same as "Fall Off", i.e the difference between static and flowing pressure on the output of the valve.

1651237 Pressure regulator, Wilkins James M, Adolph Mueller, Nov 29, 1927, 137/327, 137/464, 137/328 -
2519805 Pressure regulator valve, Wilkins James M, Aug 22, 1950, 137/505, 70/151.00R, 137/505.44, 210/432, 251/357, 137/549, 137/543.19 - adds strainer and removable mechanism without removing body from pipes.
2704551 Valve Mechanism , E.K. Ralston, Mar 22, 1955, 137/494, 200/83.00B, 137/505.44, 92/95, 251/337, 200/83.00P - uses Belleville washer (Wiki) in addition to the coil spring to get greatly improved GPM as pressure varies.  In the PRVs that only use a coil spring the flow rate depends on the pressure drop.

Meter to House supply pipe

The flow through a pipe should be under 5 feet per second according to the two following references.  At higher flow rates the friction loss goes way up, see Engineering Tool Box, RainBird Sch 40 PVC.pdf. This means I probably will need a new much larger pipe from the meter to my house.  The pipe needs to be sized to flow what the meter can deliver.

Indoor Fire Sprinklers
A friend that lives in Los Altos did a remodel on his house that required installing indoor fire sprinklers.  As part of that a new pipe was run from the water main, bypassing the house meter, to the sprinkler system.  The idea is that even if the homeowner does not pay their water bill and the water utility shuts of and locks the meter, the sprinkler system will still function.  Another aspect of this is that the new pipe will be sized for proper water flow, i.e. much larger than the normal house feed.

5 feet per second is the same as (5 * 60) = 300 feet per minute.  The RainBird PVC sch 40 table does not show flows above 20 feet/min and uses 5 feet/min as the limit for use.
The area of a 3/4" pipe is 0.4417 sq in or 0.4417 / 12 / 12) = 3.0679E-3 sq ft.
25 cu ft of water will fill a 3/4" pipe that's 8149 feet long and it takes one minute for it to move through the pipe, much faster than 300 Feet in a minute.

What size should be pipe be between the water meter and the pressure reducing valve?
25 cu ft / 300 ft/min = 8.3333E-2 sq ft or ( 8.3333E-2 *144) = 12 sq in. or  1.95" ID or a 2" pipe.  This is very different from the 1" line that's now there.

If I get a 1" water meter that can flow 50 Gal/min then:
50/300 = 0.166666 sq ft or 24 sq in or 2.76" ID pipe so a 2-1/2" or 3" pipe may be a better choice for a retrofit (the RainBird pdf shows 2" as the minimum size pipe for 50 Gal/min)

Filling a boiling pot in the kitchen.
While flow restricting faucets will save water when they flow into the drain they also waste time when filling a pot.  When the whole house has restricted flow rates even filling the bath tub takes much longer than it used to.  It might make sense to have a high flow rate (>>2 Gal/min) faucet in the kitchen for filling pots.
It may be that adding a fire water line from the meter is a better idea than replacing the 3/4" pipe to the house.  the new line would feed sprinklers and also new high flow standard 3/4" garden hose bibs located maybe 50' from the house.  That way they would have the same coverage as a 100' garden hose connected to the house, but with much higher flow rates and pressure so better for use by fireman.

Note that in the 9 October Mendocino lake complex fire many households turned on sprinklers and left them on almost draining the water tank which was needed for the fireman.  So water needs to be conserved.  I'm looking into what size of impulse sprinkler makes the most sense.  If the flow rate is very low then there might not be enough time to put down enough water and turn off the sprinkler.  If the flow rate is high enough to put down a couple of inches in a short amount of time then it might not generate as much humidity as would a lower volume sprinkler.

3 Valve Stations on Fire Pipe

April 2018 - my current idea is to leave the existing pipe feeding the house and add a new pipe just for the new hose bibs and outdoor fire sprinklers.  There will be a number of stations on this pipe where each station has a hose bib and a 1/2" sprinkler.  Three valves: 1. the hose bib, 2. a main inlet valve and 3. a sprinkler valve.  A master valve near the water meter on the new supply pipe can turn on or off all the stations.  The station nearest the underground main valve is shown in Fig 9.

Station Valve Positions
Mode
Main Valve
Sprinkler Valve
Hose Bib
Comment
Gardening
Open
Off
as needed
Normal gardening hose bib
Winter
Closed
Open
Open
air in sprinkler and hose bib = Freeze protection
Fire
Open
Open
Closed
Sprinkler on
Dual
Open
Open
Open
both station sprinkler & sprinkler on garden hose

Note that the valve near the meter will turn on or off all the stations which might be connected just as a sprinkler, just as a garden hose feed sprinkler or both.
The station will include freeze protection for the pipes and main valve in the form of a very small building.

April 2018 - this can be reduced to 2 valves if there is a main shutoff valve in the pipe supplying the sprinklers.  See Fig 9 for the current (May 2018) setup.
The Main Valve is in the underground box.
The hose bib and sprinkler valves are visible at each station.
Station to station distance is 70 feet.

Hot Embers

It turns out that contrary to popular belief a key factor in the spread of fire is a storm of hot embers landing on something that acts as kindling.  The hot embers will not start solid wood on fire.  This explains the sight of a housing tract in the recent (October 2017) Santa Rosa fire where many houses, but not all of them, where burned to the ground.  Yet this was a suburban housing tract, not a forest.  That's to say it was not contact with fire that started the houses on fire but rather hot embers falling on dry leaves, pine needles or other kindling the flame from this then set something on fire, like a wood fence, which acted as a wick to the house.  I say a storm because there's going to be thousands of these embers coming from the main fire and landing like rain down wind.  If a house has nothing connected to the wood siding, like foundation planting, then even after the owners leave it may survive the ember storm without any outside help.  Watch the videos in the box below so see how this works.  There are many problems that need to be addressed, but a lot can be done to protect your house and out buildings.

The web pages of  CCI (below) differentiate "Defensible Space" and the effect of embers.  They are saying the "Defensible Space" on it's own is not adequate.  I would agree.  "Defensible Space" might be thought of a part of a plan to prevent ember fires and minimize flame front fires.

YouTube videos featuring Jack Cohen.

NFPA: Wildfire: Prevent Home Ignition: Part 1, Part 2 - firebrands (small hot embers) are the dangerous things, not the crown fire.  The embers start things that act as kindling which in turn can start the house on fire.  So, eliminating the kindling is key to preventing house ignitions.
NFPA: Your Home Can Survive a Wildfire (13:19)
NFPA: Firewise Virtual Workshop - Power of Embers (1:00:26) - http://firewise.org/ - Wind tunnel that can hold a full size house. Steve Quarles
Radiant Heat Versus Firebrands (embers) (3.33)
Protecting Your Home From Wildfire (28:51) Jack Cohen - examples of homes that burned and evaluation of homes that did not - details
Wildfire! Preventing Home Ignitions (19:26)
Fire Behavior in the Wildland/Urban Interface (21:07)
Fire dynamics (4:57) - smoke from heated wood is flammable
IBHS - IBHS Research Center Ember Storm Test Highlights (4:18)  - Today Show - IBHS Research Center Ember Testing (2:55)- Insurance Institute for Business & Home Safety (IBHS) - has a wind tunnel with a bunch of NIST firebrand generators - "embers" Play List - Gable End Vents (louver type) and 1/4" screens let the firebrands through (YouTube)
NIST: Standard Firebrand Generator - used in wind tunnels for fire related testing - NIST Publications relating to Wildfires
Considerations For The Built Environment-Steve Quarles, PhD - The Landscape Industry's Role - Ed Smith - Ed's talk is about plants & embers - Living With Fire and Defensible Space - Ed Smith - Things that control wildfire behavior: Weather, Topography & Fuels
Living with Fire - the full version of the USGS film (22:44) -  many scenes showing ember storms - "think from the house out"
PS the Oakland Hills-Berkeley fire of 1991 (Wiki) was made much worse by wood shingle roofs.  The fire "jumped" the freeway, but what really happened is hot embers were blown over the freeway, not a wall of flame.
NIST Special Publication 1198 Summary of Workshop on Structure Ignition in Wildland-Urban Interface (WUI) Fires - pdf - slides emphasizing embers rather than wall of flame is the key factor.  Report on 12 papers @ Workshop:  Structure Ignition in Wildland-Urban Interface (WUI) Fires Manzello, S.L. & Quarles, S.L. Fire Technol (2017) 53: 425. https://doi.org/10.1007/s10694-016-0639-6 (pdf)
Pathways for Building Fire Spread at the Wildland Urban Interface, March 2015 - 163 pages lots of good info
Lessons Learned from Waldo Canyon, Quarles et al, " This field survey has confirmed findings of other post-fire surveys in terms of the basic mechanisms whereby buildings can ignite, particularly by exposure to wind-blown embers."
http://fireadapted.org/ -
Be Ember Aware (1/2) & Be Ember Aware (2/2) - Excellent videos
UC pub 8393: Home Survival in Wildfire-Prone Areas: Building Materials and Design Considerations.pdf  (22 pages) - emphasis on embers
Disaster Safety Org: Vulnerability-of-Vents-to-Wind-Blown-Embers_IBHS.pdf - Cover shows many NIST Fire Dragon ember generators working.  good info but also depends on what kindling is there

Characterizing firebrand exposure during wildland urban interface fires, Ethan I.D. Foote (CalFire), 2011 - 90% of firebrands were less than 3/16".  this is less than the common 1/4" (4/16") screen used to protect houses from rodents and pests.  Updating to 1/8" metal screen would be good.

External Sprinkler Systems and Defensible Space: Lessons Learned from the Ham Lake Fire and Gunflint Trail.pdf
Conclusion
Experience with the Ham Lake Fire in northeastern Minnesota demonstrated that external wildfire sprinkler systems can be highly effective at protecting structures and their surrounding vegetation from wildfire damage and destruction under certain conditions. Sprinkler systems are not a panacea however; they must be regularly tested and maintained, and even then, are not guaranteed to be 100% effective. When effective, there are several management challenges during wildfire events that still need to be addressed (e.g., getting property owners to evacuate when warranted and supplying propane to run the systems). Finally, Firewise principles and practices must be emphasized, with sprinkler systems as another tool on the Firewise list.

Note: the above comments are mainly about the propane powered water pumps which needed to be refueled and some did not start.
PublicResource.Org - Using Water Effectively in the Wildland/Urban Interface - Portable Sprinklers - 9:59 -
Portable
                      Sprinkler
Portable
                      Sprinkler Garden Hose fitting to left.
Stake and foot step may be re-bar.
4' or 5' 1/2" iron water pipe and full circle 1/2" sprinkler.

10:36 "Home owners can play a role here too by using their own sprinklers to raise the moisture level in the area long before the fire arrives."

Note in this YouTube video that the burning house is surrounded by green trees, i.e. is was not a wave of fire that ignited the house.

Vents

My house has open eves rather than soffits.  The screen in Fig 1 appears to be 1/8" mesh rather than 1/4" mesh.  But the Social Wasp (Wiki) nests might be a fire hazard.  Need to test one.  The inside baffle was put there to keep blown in place insulation (Class 1 fire rating) from blocking the vent.  But it also will bounce any hot embers up to the bottom side of the roof (2 bounces total) which may put them out?  Has this been tested with the NIST Fire Dragon?

Fig 1 Outside view of eve vents
Outside
                        view of eve vents
Fig 2 Inside view of eve vent with baffle
Inside
                        view of eve vent with baffle
Fig 3 Building plans for eve vents with insulation baffle
Building
                        plans for eve vents with insulation baffle

Exterior Sprinklers

The above information on hot embers suggests that 2" or 3" of rain fall has the effect of preventing ignition.  It's not clear how since tall trees that were not directly whetted by the sprinklers did not burn.  Maybe something to do with humidity.  In the above references the exterior sprinkler systems used 3/4" impulse type sprinklers with a 3/16" nozzle.  But these use a lot of water.

1/2" Brass Full Circle Impulse sprinkler Head

I'm looking into the Rain Bird 20JH 1/2" full circle sprinkler head (also 20A, 29JH?).  It's a very simple design (reliable) and is used in high volumes for irrigation.  It's also all metal construction which may be important for fire use in the case where the system is turned on after the heat/fire is nearby.  They list for about $25 each, but supposed equivalents are made by other manufacturers for less than half the price, but it remains to be determined if they are as good for this application. Any plastic part would disqualify a sprinkler for this application if it's melting would in any way degrade the performance.


1997901 Water
                      sprinkler, Orton H Englehart, Apr 16, 1935
1997901 Water sprinkler, Orton H Englehart, Apr 16, 1935, 239/230, 239/259 -

This is the classic Rainbird impact sprinkler. 
Wiki - "
The name Rain Bird was taken from the Native American legend of a bird that brought rain, in reference to the "bird-like" appearance of the impact sprinkler in action"

3022012 Partial circle water sprinklers, Carl R Sharp, John E Streeter, 1959-05-18 - uses "S-tube" to keep water off walkway.
3309025
                      Self-cleaning spray deflector wedge for
                      sprinklers, William R Malcolm, 1965-07-06 - Wobble
                      Wedge
3309025 Self-cleaning spray deflector wedge for sprinklers, William R Malcolm, 1965-07-06 - Wobble Wedge - self cleaning including the bearing between wedge and its shaft. If main arm jams there will still be some dispersion of water jet so as not to erode the soil.

4330087 Impulse sprinkler deflector spoon, William A. Wood, Frank J. D'Amore, Rain Bird Corp, 1980-03-24 - allows for nozzle hole aimed a little off in angle or for a nozzle drilled on purpose at a different angle.

65PJADJ-TNT - Brass Impact Sprinkler - this has a 1" inlet, 57' to 65' radius, 50 to 80 PSI line pressure, up to 1" per hour (I will need regulator just for these).
35ADJTNTB – ¾” Inlet Brass Impact Sprinkler - 3/4" inlet, maybe 30' radius
20JH 1/2" Inlet Full Circle Brass Impact Sprinklers - 1/2" inlet, 35 - 80 PSI, 35' to 44' radius (Full circle is much simpler, less to go wrong).
Underhill Product Code: SI100F Impact sprinkler - 1" Full Circle -
Manual valve and galvanized iron plumbing.  Minimal plastic parts.  Birds sitting on swing arm???? Freeze protection =  drain valve
Report examines effectiveness of outdoor sprinkler systems during wildfires - External Sprinkler Systems and Defensible Space: Lessons Learned from the Ham Lake Fire and Gunflint Trail - "Experience was that with the cooler, moister environment created by the sprinklers, embers were suppressed before they were able to ignite the fuels, whether structures or vegetation. "
Recommendations:
3/4" inlet heads with 3/6" nozzle
Pipe
Size"
GPM
3/4
8
1
15
2
60
3
>60

At least one 1-1/2" NH (National Hose) threaded Fire Department standpipe.
There is a question about "shelter in place".
Wildfire Sprinklers Inc. - full big $ systems
Rainbird Sprinkler Heads   
Nelson Sprinkler Heads   - Catalog (7 MB) - 1" & 1-1/4" inlets & much larger Big Guns - Brochure - 2", 3" or 4" inlets.
Nelson F33 (full circle) impact sprinkler head, 3/16 & 1/8" nozzles at 80 PSI: 13.25 GPM & 106' diameter.  [The F33V the same except 113' diameter)
FEMA Fire Sprinklers - Interior & Exterior

FlameGuard® CPVC Fire Sprinkler Products - some compatibility issues with non CPVC parts of the water system.  Iron pipe may have a number of advantages for this application.

RainBird: Impact Sprinklers, Pressure Regulators, 20JH.pdf, 20JHparts.pdf, L20H.pdf, 20ADBJ.pdf, 20VH.pdf, Sprinkler Irrigation Uniformity (14VH, 808A, 14070)

Rain Rate

Sprinklers are specified to generate some radius circle and flow rate given the input pressure.  The area of the circle and the flow rate can be converted into a rain rate expressed in inches per minute, hour or day.  One of the papers suggests that 2" of rain will offer protection.  But another suggests that it's the change in humidity that may be the key while yet another suggests that all that's needed is to wet the surface.  The Fine Dead Fuel Moisture YouTube talks by the U. of Montana suggest that 0.2" of rain will lower the Probability of Ignition to it's minimum, so I'll try putting down 1/4" of rain and see what happens to the PIG.
Inlet pressure 45 PSI

Light rain might be 0.08 inches per hour, heavy rain might be 1 inch/hour.

Model
Angle
deg
Inlet
Inches
Nozzle
NPT
Nozzle dia
inches
Radius
Ft.
Area
Sq In
Area
acres
Flow
GPM
Flow
Cu In/Min
Rain Rate
In/Hour
10-10
23
1/2
1/8
3/32 (1/16 to 1/8)
36 (30.5 to 41)
586,296 0.093
1.73 (0.58 to 3.71)
399
0.040
14VH
23
1/2
1/8 1/16 to 5/32
29 to 38


0.56 to 2.68


20JH
23
1/2
1/8 1/16 to 5/32
38' to 44'


2 to 5.5


29JH
23
1/2
1/8
7/64 to 5/32
35' to 46'


1.56 to 6.35


L20H
10
1/2
1/8
9/64 (7/64 to 9/64)
34 (28 to 35)
522,962
0.083
3.84 (1.73 to 4.05)
887
0.102
30H
27
3/4
1/4 & 1/8
3/16 x 0.125
49
1,086,186
0.173
9.90
2287
0.126
70CH
21
1
3/8 & 3/8
13/32 x 0.125
72
2,345,166
0.374
30.4
7022
0.180
80EHD
27
1-1/4
? & ?
11/16 x 7/32
82
3,041,865
0.485
49.2
11365
1.16

A given size impact sprinkler (Wiki) there are a limited number of nozzle sizes that will work and those only will work over some range of pressures.  But it's not clear what the real limits are.

Time to reduce PIG

The experimental setup uses 3 each 29JH sprinklers with 5/32" nozzles.  When all 3 are operating the line pressure is80 PSI.
That means each nozzle is flowing: 

Based on measured 80 PSI while all three 29JH sprinklers are operating.
GPM = 29.72 * D2*SQRT(PSI) = 29.72 * 0.15625 * 0.15625 * SQRT(80) = 6.49 GPM
The data sheet says at 80 PSI the radius is 46 feet -> area of 6648 Sq Ft.
6648 * 0.25/12 = 138.5 Cu Ft
6.49 GPM = 0.868 CuFt/min
138.5 / 0.868 = 159 minutes = 2 hours 40 minutes.
and so to get 1/4" of rain they need to be running for 3 hours.
The test on 20 July 2018 for 2 hours was less than it should have been, but it still lowered the PIG from 50 to 40%.

An approximation (so I don't need to get wet making the above pressure measurement) Assume 5 GPM and 40 foot radius, then:
Area = PI * R * R = 5026 Sq Ft.
A cylinder of water 40' in diameter by 1/4" thick will therefore have a volume of 5026 Sq Ft * 0.25/12 Cu Ft = 104 Cu Ft.
5 Gal/Min / 7.48 Gal/Cu Ft = 0.668 Cu Ft/Min flow rate
104 Cu Ft / 0.668 Cu Ft/Min = 156 minutes = 2 hours 37 minutes.
If the radius is shorter then there will be more than 1/4" of rain.

Testing impact Sprinklers

The local Ag supply stores only stock the RainBird 14VH (or the equivalent WeatherTec 10-10) 1/2" impact sprinkler heads since these are popular with local vintners.  They are designed to work with nozzles as small as 1/16" or up to 7/64".  I think the key design parameter is the rotational inertia of the moving arm and the design of the vane that the water strikes located at the end of the moving arm.  As the flow (gallons/minute) gets higher the inertia of the arm must increase.  In order to work with low flow rates, like the 14VH, the mass of the moving arm needs to be small.

First test 14VH and 10-10 1/2" sprinkler heads.

Both of these sprinkler heads have a double sided plastic spoon that pivots into one of two positions.  In one position it tries to push the moving are into the frame and so no movement results, but that position is unstable since the force also causes the spoon to move to its other position where it causes the moving arm to swing.

3563465 Water sprinkler, MARTIN FOREMAN, 1968-03-26 - maybe this spoon design?
Fig 1 Parts for first test.  $69.46 for parts shown in photo.
3/4" x 5' iron pipe (matches 3/4" male garden hose fitting) 3/4"-1/2 coupling for sprinkler head.  5/8" x 2' re-bar for stake. 
1-1/2" hose clamp is too small for 3/4" pipe AND 5/8" rebar.
RainBird 14VH
                      and WatherTec 10-10 1/2" sprinkler heads
RainBird 14VH, 20JH & 29J are all 1/2" inlet Impact Sprinklers
Note the frame on the 14VH and 20JH are the same, they differ in the swing arm.
The 29J is a much larger sprinkler.
RainBire
                      14VH - 20JH - 29 Impact Sprinklers
Fig 2 RainBird 14VH 1/2" sprinkler head with 3/32" nozzle
Wobble Wedge
RainBird 14VH 1/2" sprinkle head
                              with 3/32" nozzle
Fig 1 WeatherTec 10-10 1/2" sprinkler head with 3/32" FC2 nozzle.  Wobble Wedge
WeatherTec 10-10 1/2" sprinkler
                              head with 3/32" FC2 nozzle
RainBird 20JH
Ratings: 5/32"max  (comes w/o nozzle) <= 60 PSI
Fixed spoon instead of Wobble Wedge.
RainBird 20JH impulse
                                      sprinkler
RainBird 20JH impulse
                                      sprinkler

RainBird 29JH
5/32" <+80 PSI
@ 45 PSA & 3/32": 70' dia & 1.71 GPM

Nozzle

 is 1/8" pipe thread (0.405 OD from theory).
measures 0.345 at exposed dia.
 3/8" across flats
@ 45 PSI & 3/32": 72' diameter & 1.73 GPM (100 Gal/hr,  2491 Gal/day)
1.73 GPM = (x231) 399 cu in./min
72' dia = 4071.5 sq ft = 586296 sq in
Rain rate = 0.04" hour or about 1" per 24 hour day

Nozzle

measures 0.400 at exposed dia.
Thread Size: 3/8-24NF and 1/8 NPT
 7/16" across flats




YouTube: WeatherTec 10-10 1/2" Full Circle Sprinkler 3/32"FC Nozzle


RainBird P2A Pressure Gauge
40 PSI at end of hose.
RainBird P2A Pressure Gauge


Fig 2 Mounted on 1/2" Orbit Metal Ring Base, Model 58030
Arm has just started to move or is just finishing movement.
WeatherTec 10-10 1/2" Full
                              Circle Sprinkler 3/32"FC Nozzle


Fig 2:  36' radius.
Rubber band holding moving arm so nozzle open.
RainBird 14VH 1/2" sprinkle head
                              with 3/32" nozzle
Fig 3:   35' radius.
Rubber band holding moving arm so nozzle open.
WeatherTec 10-10 1/2" Full
                              Circle Sprinkler 3/32"FC Nozzle


Video of 14VH operating at 116 PSI
Note that 1. it works with extreme over pressure and
2. the wobble wedge directs the water both to the
left and right of the nozzle direction.





Nozzles

The impulse sprinklers typically use removable nozzles to allow changing the opening size.

Theory

The pressure and nozzle size determine the water flow rate (gallons per minute or cubic feet per minute).  The velocity of the water leaving the nozzle (feet per minute) depends on the pressure. The distance that the water travels (throw radius) depends on the nozzle angle above horizontal and the height of the nozzle above the ground in addition to the velocity.  There is wind resistance so the actual throw distance will be less than the calculated distance.  The swing arm both powers the rotation of the frame and nozzle and also breaks up the nozzle water stream so that some water falls at distances shorter than the main nozzle stream.  Ideally the water falls equally over the full circle.  Practically the sprinkler manufacturers recommend some overlap in coverage to even out the rain rate.

The flow rate is closely related to the rotational inertia of the swinging arm.  If the mass of water hitting the swing is too small it will not have enough energy to turn the main body.  If the mass of water hitting the swing are is too great the swing are will never be able to hit the main body and it will not turn.  So there is a range of pressures for a given nozzle size and sprinkler arm inertia where it will work.

WeatherTec FC2 Nozzle - between 30 PSI and 80 PSI the flow varies between 1.70 GPM and 1.80 GPM, the diameter varies between 69' and 77' over that pressure range.

The RainBird 14VH operates between 20 and 60 PSI with flow rates ranging between 1.14 and 1.97 GPM (i.e. a straight, non compensating, nozzle)
4492339 Flow control nozzle,  Nelson Irrigation Corp, 1983-03-02, B05B3/0472 - pressure compensating
------  laminar nozzle patents ----
4730786 Low noise, flow limiting, laminar stream spout, Walter R. Nelson , CHRONOMITE LABORATORIES Inc - flow restricter  for home  faucets
5169065 Low noise, flow limiting, laminar stream spout, Walter R. Nelson , CHRONOMITE LABORATORIES Inc -
5472145 Straight Stream Nozzle, Timothy C. Shannon, Steven L. Honeycutt, , Delavan Inc,1994-04-14 - anti swirl - anti turbulence features
5779099 Nozzle with turbulence control member for water gun laminar flow ejection,Bruce M. D'Andrade, (Super Soaker), 1996-06-28 - contains walls to stop water swirl that causes stream to separate.  A laminar stream goes farther than a turbulent one.

The nozzles have 1/8" NPT (11/32" tap drill).
 
Nozzles: 14VH, 20JH, and 25BPJ
 (from Harmony Farm Supply)
Note last 2 digits of model number is size in /64 of an inch.
RainBird
                      Nozzlesv for 1/2" impact sprinklers: 14VH,
                      20JH, and 25BPJ
p/n
Size
in 64ths
dia"
SBN104
4/64
1/16
SBN105 5/64
5/64
SBN106 6/64
3/32
SBN107 7/64
7/64
SBN108 8/64
1/8
SBN109 9/64
9/64
SBN110 10/64
5/32
SBN111
11/64?
available?

The Flow rate (GPM) depends on the hole area & water pressure (WSU)
GPM = 29.72 * D2*SQRT(PSI)
Hole    \ PSI
20
40
60
80
100
1/16
0.5
0.7
0.9
1.0
1.2
5/64 0.8
1.1
1.4
1.6
1.8
3/32 1.1
1.6
2.0
2.3
2.6
7/64 1.5
2.2
2.7
3.1
3.6
1/8 2.0
2.9
3.5
4.0
4.6
9/64 2.6
3.6
4.4
5.1
5.9
5/32 3.2
4.5
5.5
6.3
7.3


There are 7.48 Gallons in a cubic foot.  This can be used to convert the
flow rate in Gallons per minute to Cubic Feet per minute.
0.133681 * GPM = CFPM
If the CFPM value is divided by the area of the nozzle in sq ft (PI*D*D/4) the result is the velocity of the water leaving the nozzle in Feet per Minute.

The GPM can be calculated for a water nozzle based on the pressure and orifice diameter.  Based on the GPM and orifice diameter the nozzle velocity can be calculated, but the trajectory can NOT be calculated because it's too complicated so the values shown in the data sheets are based on empirical measurements.
An idea for testing nozzles using just a garden hose.
Tap drill depends on application.
A drill press is handy.
Tap backed out and thread tested with nozzle, then a little more
tapped, until nozzle tightened half way.

Tap
size
Threads
per inch
Drill size w/ taper
pipe reamer
Drill size w/out
taper pipe reamer
Straight pipe
threads

1/8

27

21/64
0.328125

Q
0.332

11/32
0.34375


Garden Hose
                      Adapter for 1/8" NPT sprinkler nozzles
 SGN104 (4/64 = 1/16") Nozzle.
Maximum range at 106 PSI input just under 30', but breaking up a lot.
Maybe more range at 45 PSI input.
Garden Hose
                      Brass Cap Tapped 1/8" NPT for testing Nozzles
                      used on 1/2" input Impulse sprinklers

The range a calculated the same as for a cannon, for example see: Calculate the Range of a Projectile Fired at an Angle.

Shooting a cannon at a particular angle with respect to
            the ground.
Shooting a cannon at a particular angle with respect to the ground.

image6.png
Where S is the range, g is the acceleration of gravity, theta is the elevation angle.  But this does not work for cannons or for water sprinklers because of air resistance.  For cannon balls and bullets there are calculations that can be made that more or less work for practical purposes (see Ballistics).

It's interesting that for the case above, where there is no air resistance the angle (theta) for maximum range is 45 deg.  But the actual sprinklers have an angle that's half of 45 deg, ie  22.5 deg rounded to 23 deg.  The 20JH, with a 23 deg angle gets much more range than the L20H, with a 10 deg angle, when using the same nozzle at the same pressure.  The 29JH is rated for higher pressures and hence the longest throw distance of all the 1/2" sprinklers I've looked at.

Commercial Outdoor Fire Sprinklers

Company
Size
Comments
One Stop Fire Products 3/4"
Pumps and related outdoor fire suppression products
WaveGUARD
varies
Tank & Pump system with flame detector(s?)(ember detector being worked on)
20140338930 Fire Mitigation System, waveGUARD, 2014-05-15
20160175633 Hydo Fire Mitigation System, waveGUARD Corp, 2013-05-15
Steadfast Safety Services ?
no details started 2016
FlameSniffer misters?
they make 360 degree flame sensor US13041679 Fire& ember Detection (4300nm)
Wildfire Automated Sprinkler Protection
Custom
Gutter mounted - garden hose feed to each one.
Roof Saver Sprinklers 1/2"
"V" bracket for roof ridge - garden hose feed.
Spiedr 1" kit This uses a huge amount of water: where's it going to come from?
DIY
3/4"
Ham Lake Fire and Gunflint Trail.pdf - propane powered pumps fed from lake
Platypus
US9403175 Sprinkler - shrub type sprinkler head

6167971 Fire Protection system, Paul Van Lingen, 1998-10-06, - under eve sprinklers
Calls:
Publication number Priority date Publication date Assignee Title
US1489A *    1840-10-16 Rendering Building Fireproof
US218100A *  1879-07-29 Improvement in fire-extinguishers
US647875A *  1900-02-09 1900-04-17 Ernest Piepenbrink Fire-extinguishing apparatus.
US1507350A * 1922-06-28 1924-09-02 Eric T Franzen (Wall washer) Sprinkler head
US1620142A * 1925-04-24 1927-03-08 Albert T Walraven Fire extinguisher
US3576212A * 1969-03-10 1971-04-27 James H Siler Fire-shielding device (tower for wetting roof)
US3583490A * 1969-01-24 1971-06-08 Arloa Bunnell Fire protection system(recirculates roof and wall water)
US3858618A * 1973-01-10 1975-01-07 Factory Mutual Res Corp Piping for fire protection systems(small holes to cool pipe)
US4330040A * 1980-05-12 1982-05-18 Ence Gerald R Fire prevention and cooling system
US5083618A * 1990-09-24 1992-01-28 Hayes Gary D Bush fire protection of building(above-roof & below gutter spray)
US5165482A * 1991-06-10 1992-11-24 Smagac Dennis E, Intelagard Inc Fire deterrent system for structures in a wildfire hazard arean (water management, but using what sensors?)
US5692571A * 1996-11-21 1997-12-02 Jackson; Willie C. Building exterior fire prevention system
US5732511A * 1996-10-18 1998-03-31 Scott; Jackie May Roof mounted fire protection system

Fire Insurance

After over 20 years with the same company I received a "will not be renewed" notice on my homeowners policy.  This was based on the Verisk Insurance Solutions (Fireline Overview, ISO Risk Analyzer, Wildfire Risk) computer program that "scores" you house based on its location.  The problem is there is no option to mitigate the risk.
Google search: California wildfire insurance score -

The information on hot embers (above) says there's a lot that can be done to mitigate the danger of living in a brush area, but that Verisk computer program makes not provision for mitigation measures so in my opinion is very flawed.  Note that in after fire photos you will see some houses burned to the ground and next door other houses that are still standing.  The Verisk program makes no provision for the standing houses.  Also note that being in a brush or Wildland Urban Interface (WUI) area has nothing to do with hot embers.  Hot embers are generated whenever wood burns and it does not matter if a tree or house is burning.  That's to say houses located in urban areas are just as susceptible to hot embers as houses in WUI areas.  A case in point is the housing development in Rohnert Park (Santa Rosa, CA) where some houses burned while neighboring houses did not.  The same thing happened in the 9 Oct 2017 Redwood Valley fire.

Shelter in Place

This is a generic phrase (Wiki) commonly used in active shooter situations, chemical spills &Etc.  There is some talk of it's use in relation to Wildland Urban Interface (WUI) fires.

NFPA: WILDFIRE + EVACUATION: Stay or Go?

2001 Australasian Fire Authorities Council - Appendix H: Australasian Fire Authorities Council Paper - the beginning of the Shelter in Place idea.

"Houses protect people and people protect houses. Research conducted following major bushfires in Australia has concluded that the most buildings lost in bushfire situations are the result of initially small fires started by sparks and embers. A building will generally survive the initial passage of a fire front providing adequate preparations have been made. People who are well prepared and take shelter in their homes have an excellent chance of surviving a bushfire. Also, houses will survive if people remain to extinguish small fires started in and around them. "

2004 Preventing Wildland/Urban Interface Fire Disasters, Santa Rosa, CA, Ethan Foote -

2005 Homeland Security paper: Sheltering-In-Place During Wildfire, Is it a Viable Option? 2005

2008 Fire Center UC Berkeley - Living with Fire in Chaparral Ecosystems - Lessons Learned (Australian bibliography with links) -

California Chaparral Institute - An Appeal to California’s Fire Agencies - "While creating defensible space is a critical component of fire risk reduction, it fails to address the main reason homes burn - embers landing on flammable materials in, on, or around the home, igniting the most dangerous concentration of fuel available, the house itself." ".... many homeowners have complied with defensible space regulations only to see their homes burn in a wildfire." - PROTECTING YOUR HOME FROM FIRE "Nearby vegetation was not a big factor in home destruction." - Fire Safe Techniques  -

Mass Notification

The idea is to let people know there's danger and they need to take action.  There's not a single system that will do this, it takes a number of parallel actions.

Siren, Horn, Whistle

The idea here is to let people know there's an emergency and maybe what type of emergency.  How loud the device is depends on the input power and its efficiency.  So, a hand cranked siren will put out much less sound than other devices that have larger power inputs.  Devices that will work without electricity are desirable since that's likely to happen in a forest fire by the time the alarm is needed.  I like the idea of using compressed air to sound the alarm.  I also don't like sirens since it takes some time for the motor to spin up and spin down so they can not be used to send Morse code.  Horns and Whistles can be turned on and off using a manual valve and so may be the best option.
Wolo Manufacturing Corp: Mass Notification SystemsK4-1 Four Horns air alarm, Model 119 Whistle, Model 122 Whistle, they also have horns for aircraft carriers and other very loud devices.

Telephone Tree

A neighborhood phone tree is also in place as well as an email list.  There might be a night time fire lookout associated with this.  Some people have DSL internet service on top of their home land line phone.  They are fed from a DSLAM box which in turn is fed by fiber optic cable.  The DSLAM box has some batteries about the size used in motorcycles and so only work for maybe a day.  After that those households will no longer have land line phone service.  So they probably can receive the initial notification, but after a day may not have phone service of any kind.

There is a county wide emergency notification system that calls people effected by some emergency.  I've received calls when the local bridge was flooded, meaning I could not get to town using the shortest path, and maybe not at all if the adjacent bridge is also flooded (a common occurrence). On 9 Oct 2017 I got an evacuation call, but was not in the immediate area of the fire.  So this system still has some bugs. 

A neighborhood phone tree is also in place as well as an email list.  But the land line phones may or may not be working.  Cell phones don't work at my house and so not a reliable way to communicate.

There is a state wide CAL Fire notification system that depends on cell phones, but my cell does not work when I'm at home.

Commercial Radio Stations

The local FM station KXYZ - was the best source of fire information during the fire that started 9 Aug 2017.  They carried live the press meetings (although there were technical problems).

I think something people wanted to know was the boundary of the fire.

Ham Radio

We are also looking into using ham radios to communicate an alarm to our neighborhood and for neighbor to neighbor communications.  This can not be done radio to radio because of the mountains and valleys, but might work with VHF/UHF radios through a repeater.  This probably require an outside antenna on a house or on a car.
Yaesu VX-7 or BaoFeng hand held2 meter - 440 MHz radios.

Note that people without ham radio licenses can still buy radios and listen in.  These are around $100 including a good antenna for the house and car.

Fig 1 J-Pole Antenna for 2 meters & 440 MHz (Arrow Antennas: OSJ - Model OSJ 146/440 Dual Band J-Pole)

J-Pole Antenna
                      for 2 meters & 440 MHz
Mounted on Premier stainless steel 6' - 12' telescoping painters pole (Home Depot sells them one at a time ~$20)
The idea is to see the effect an outdoor antenna in house to house and house to repeater coms.
PS the elements are parallel, distortion due to camera looking up at angle.

On the Wednesday 7 pm simplex net the antenna worked well with the paint pole standing on the ground, i.e. with the antenna below the first floor gutter elevation.  It will work much better when roof mounted.

Fire Weather (See Kestrel 5500FW meter)

I've moved this from a reference to a main topic since it's going to be part of the strategy related to sprinklers.  The idea is that when the Probability of Ignition (PIG) is high the sprinklers can be operated for about 3 hours to add humidity and to wet the kindling on the ground.  Then the PIG can be measured again.  I'm hoping that the effect will last a day or more, but need to try it out.

Major wildfires seem to occur in October.  This is after one or more years of drought at a time when there has not been any rain all year and there is wind.  These conditions are part of the fire weather forecast.

Test 1
July 29 2018 - ran for 2 hours.  The PIG was peaking at 50% on prior days and staying at 50% for a few hours.  The sprinklers seemed to knock down the PIG to 40%.  Have changed the logging interval to 30 minutes.

Test 2
3 August 2018 - Evacuation warning - on about 4:40 pm plan for 3 Hours (about 1/4" rain equivalent).

Northern California Geographic Area Coordination Center - The initial map shows Northern California fire areas.  If you mouse over Day1 through Day7 you can see the projected fire weather color coded on the map.
Fire Weather Zones - Mendocino county is CAZ276. If the map shows brown or red there is high fire danger.
Talking with Steve at the NCGACC the effect of sprinklers on the local humidity would be very small since wind would easily bring in new air with it's own humidity.  BUT . . . any moisture would put out an ember that landed in it.
California Fire Weather Page - Click Map for counties

Probability of Ignition (Incident Response Pocket Guide pg 82)
Reference Fuel Moisture (%) depends on Temperature & Relative Humidity.
Then shade, slope and corrections for dead fuel moisture content.

The Kestrel 5500FW hand held weather instrument has PIG built in so might be an easy way to keep track of this at a local level and to monitor the effect of using the sprinklers.  As of 11 April 2018 the lower cost Kestrel weather instruments do not have PIG built-in.  There is an option that adds a wind vane so that the instrument knows the direction of the wind and adds LiNK which is their name for BlueTooth connectivity to Apple and Android phone apps or a desktop dongle.

YouTube: SFE Webinar: Simple FFMC - New Fine Dead Fuel Moisture Estimation Tool - Fine Dead FMC (on line hour to hour calculator explained in video) - much more modern than the Probability of Ignition Tables in the Pocket Guide.  It looks like 0.2" of rain will saturate the wood.  The rate it moves out of the wood depends on the fuel surface temperature and humidity, but typically it takes longer for the water to leave.  This may mean outdoor sprinklers will work with a small amount of water in fire prevention mode (not fire fighting mode).
U of Montana - Weather App -
There are three codes (fire danger ratings): 1. the Fine Fuel Moisture Code relates to the surface, 2. the Duff Moisture Code (DMC) is for the organic layer below the surface (maybe up to 4" deep), 3. the Deep Duff Code (DC) applies to the ground below the Duff layer.
YouTube: Duff Moisture Code - works in a way very similar to the FFMC but with longer time constants.

YouTube: Fine Fuel Moisture Code - % Fuel Moisture = 147.2 * (101-FFMC) / (59.5 + FFMC)
FFMC
0 - 79.9
80 - 85.9
86 - 88.9
89 - 91.9
92+
The FFMC can be changed using outdoor sprinklers prior to a fire to lower the fire danger.
Initial Spread Index (ISI) - combines the FFMC & Wind (but wind is not under our control).

Map Your Neighborhood

As part of the FireWise community program we are making a map of our immediate area.
Map Your Neighborhood - a generic program that can be tailored for specific needs.

Some FireWise map features are:

- Fire Hydrants
- Water Tanks
- Ponds/pools
- Roads: primary roads (labeled) and secondary roads/driveways
- Watercourses/Streams (if you can, identify whether seasonal and perennial streams - label with names)
- Contour layer (40' contours should be good)
- Gates - Homes
- Potential safety zones (see: References Incident Response Pocket Guide pg 6)
- Township/Range and Sections
- Boundary of your Fire Safe Area

Suppliers

Akron Brass - Booster Reels - Nozzles - YouTube -
Continental (Goodyear) - Water Hoses - Water Hoses -
eDarley - Darley - Wildland -
Eley / Rapid Reel Wall Mount Garden Hose Reel Model 1041 - Amazon - p/n 1044 Extra-Capacity Kit - 5/8"id X 175' Garden Hose -
Elkhart Brass - YouTube - Nozzles
Firequip - YouTube (installing fittings on hose, kink resistance)
Hannay - Booster Reels -
Honda - Water Pumps - WX (light weight), WT (trash), WH (High pressure), WMP (Multi Purpose), WSP (submersible)
Key Hose -
Kochek - Hoses -
Reelcraft - General Water Reels - 601044-150 3/4" x 150' Hose Assembly w/ Garden Hose Fittings, 300 psi - Amazon - GCCA33118 L 175' x 3/4" Reel - S601026-200 200'x3/4" hose -
1. Can the reel be mounted on the side of a house either directly or using an optional bracket?
2. Are the hose assemblies available with the correct male thread for connection to the reel and with a standard Garden Hose Thread male outside end?
3. On the motorized reels can the hose be pulled out by hand when there is a power failure?

R&R Fabrications - bags for many uses - Fire Hose -
Fyre-Tec™ Fire Rated Windows -
Steel Sliding Fire Windows -
Bandguard Vents -
Barricade Fire Blocking Gel - this has some problems: It must be applied immediately prior to the fire, i.e. you can not apply it a day or week ahead since once it dries out it's no longer effective. It is difficult to apply to all exposed faces, i.e. any surface irregularity will shadow a surface which is not protected. "Depending on weather conditions such as sunlight, wind and humidity, Barricade can be expected to last from a minimum of 6-8 hours to a maximum of 24-36 hours." Shelf life of concentrate is 4 Years if kept from freezing or getting above 120 deg F.  If there's not a fire you have to remove it, not easy.
Spiedr - 1" impact sprinkler kit - This uses a huge amount of water: where's it going to come from?
Wildlife Inventory Systems - Willits, CA - custom mapping
Firezat™ inc. - similar to space blanket, comes in a roll for wrapping houses.

References

National Wildfire Coordinating Group
Lessons Learned
Advances in Fire Practice
Handy pocket reference

Incident Response Pocket Guide
PMS461
NFES 1077
5-1/2" x 3-1/4" pocket guide
Table of Contents
Operational Leadership
Color codes sections:
Green: Risk Management
Gold: How to Properly Refuse Risk
Yellow: Vehicle Accident Operations
Pink: First Aid
Blue: Aviation User Checklist
White: Other References


National
                        Wildfire Coordinating Group - Incident Response
                        Guide

Safety Zone
= 8 to 40 times vegetation height (different from IRPG which says 4 times flame height.) in all directions.
YouTube:
Latest Research on Estimating Safety Zones - 8x for flat and no wind (note radiant and convection related to camp fire).
If people and vehicles are in center of safe zone then the more room they take up the larger the safe zone needs to be.
Helicopter landing has additional requirements.
YouTube: The How, What, and Where of Safety Zones: Recent Findings -

Probability of Ignition (Incident Response Pocket Guide pg 82)
Reference Fuel Moisture (%) depends on Temperature & Relative Humidity.
Then shade, slope and corrections for dead fuel moisture content.
The Kestrel 5500FW has PIG built in along with Fine Dead Fuel Moisture (FPFM).

FireWise

FireWise is part of the National Fire Protection Association Wildfire branch.
Fire Safe Mendocino is our local branch.
Ready for Wildfire  - Hardening Your Home  -
Creating a safety zone for use in a wildfire emergency
Australia August 20, 2017: Where to take refuge in your home during a bushfire -
Cal Fire - Ready for Wildfire - Hardening Your Home - 32 Questions about your home and online assessment - Building Materials Listings - Search Listing Services: -
While they say 1/4 to 1/8" metal vent screening - the testing I've seen says 1/8" metal is much better since it stops embers that might ignite some attic items.
It's interesting that the problem with embers escaping from a fireplace have been known for many years and my house came with screens on all chimneys.

US Berkeley: Fire Information Engine - Homeowner Wildfire Assessment - an online report (but it has problems) - Center for Fire Research and Outreach at UC Berkeley - Homeowner's Wildfire Mitigation Guide: This web page has many sub pages each addressing ember problem areas and has excellent suggestions & Videos:
Be Ember Aware (1/2) & Be Ember Aware (2/2) - Excellent videos
Living With Fire - Fire Adapted Communities - Community Wildfire Protection Plans (CWPPs) -
http://disastersafety.org/wildfire/ 
National Fire Protection Association/Wildfire - The ember threat and the home ignition zone (does not include the detached garage?)
National Wildfire Coordinating Group -
Incident Response Pocket Guide, PMS 461, NFES 1077, January 2010 - not the current version but still lots of good info.
PMS 447-1 Water Handling Equipment Guide, June 2013, pg 122 Hose Flow Rate Determination by the Splash Method - simple to do.
A 3' long pipe with known inside area (A) and known distance above flat ground (h) and the distance along ground from a point directly below pipe opening (D) has the following flow in Gallons per minute:
GPM = (3.61 * A * D) / SQRT(h)
Table C3 gives recommended values for various pipe sizes and flow rates.  Here are values for sizes applicable to homeowners:
Pipe
Size
"
Flow
 range
GPM
Suggested
height
"
GPM
per inch (D)
1/2
2 - 10
18-3/4
0.25
3/4
5 - 20
29-7/8
0.35
1
10 - 40
38-9/16
0.5
1-1/4
20 - 100
45-13-16
0.8
The GPM per inch of horizontal distance can be used to mark the ground in GPM if you have a permanent setup.
The 2 1/2 Inch Handline - article about use of classic fire hose and effectiveness of smaller lines.
California Fire Safe Council - Reducing Wildland Risk brochure
Mendocino County Fire Safe Council - Fire Prep Resources -
YouTube: National Fire Protection Association - Making Your Home Firewise -
National Fire Fighter - Hose Packs
Handle for fire hose HANDLE-X™
YouTube: Self locking twin donut roll - Single Donut Roll - no carry bag needed
Insurance Institute for Business & Home Safety (IBHS) - has a wind tunnel with a bunch of NIST firebrand generators
Wildland fire spot ignition by sparks and firebrands, Fire Safety Journal 91 (2017) 2–10,  - "After ignition the wild fire can propagate as a combination of a surface fire and a firebrand spotting assisted fire." . . "Moisture content of the fuel is one of the most important parameter (sic) of the problem, if not the most important, because it determines the limiting condition for ignition of a fuel in terms of its natural state."  -> suggests to me that outdoor sprinklers should be very effective.
Combustion and Fire Processes Laboratories U.C. Berkeley - Ignition by Embers and Hot Particles - Defensible space -
 Community Wildfire Hazard Assessment and Ranking -
Community Wildfire Hazard Assessment form.pdf 
User Guide.pdf
Builders Wildfire Mitigation Guide - tabs at top of page for various fire critical components
Under Codes & Standards:
California Building Code Chapter 7A
ASTM Committee E05
NFPA -NFPA - 1141 Fire Protection Infrastructure, 1143 Wildland Fire Management, 1144 Reducing Structure Ignition Hazards from Wildland Fire
ICCWildland-Urban Interface Code.pdf  - the pdf is just the front pages ending with the table of contents
Homeland Security papers with "Wildfire" in title - search results -
Art and Science of Wildfire (Training): 1. Fire Orders, 2. Fire Operations Doctrine, 3. Crew Cohesion, 4.Aviation Resources, 5. Sky (Weather) Watching, 6. Indians Fire, 7. Predicting Fire Behavior, 8. Man Against Fire, 9. Fire Weather Forecast
National Fuel Geyser Awareness - if the cap is opened on a vaper locked chain saw (or other gas powered tool) the fuel may squirt out and douse the operator, and if flame is nearby set the operator on fire. YouTube: Fuel Geysering: Predictable? ans: No. - Videos -
Video - Using Hand Tools to Suppress TN Forest Fires - Personnel Protective Equipment (PPE) & hand tools

House Numbers

It's important that houses and the streets that lead to them are clearly marked.  Remember that a fire truck may be approaching your house from either direction along the street. 
A problem in the recent fire was that there were duplicate street names in the county and that was a huge problem for mutual aid fire fighters who didn't know that fact.
There also may be a problem with identical house numbers where it's not clear if the number applies to the main or cross street.

Photos of reflective house numbers mounted to be in the headlight beam of fire truck.
Driving down street
FireWise House Number
Driving up street
Even in daytime you can see the reflective effect from camera flash
FireWise House Number

Contact Info for street signs:
Mary Mayeda, Mendocino Co Firesafe Council
410 Jones St.  C-3
Ukiah, CA 95482
462-3662 or 272-4513

California Codes

14 CA ADC § 1299.03 Requirements - Ref Link Cal Fire list of links 
Zone 1: from the building structure out 30 feet.
Zone 2: from 30 feet to 100 feet but not beyond the property line.

Related

Forest Gardening - Irrigation
Kestrel 5500FW Fire Weather Instrument
Smith Indian - Fedco Fire Pump
Smart Meters - water & electric

Links

Forest Gardening -

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
Page Created 14 November 2017