I live in an apartment complex where grilling has been recently questioned for its safety to the inhabitants. Most are of two minds either you're a griller and look over your copy of the constitution where the rights of grillers are firmly established or you become a member of the East German Stasi and follow the smell of burning meat to complain about your neighbors illicit habit. It used to be ok but the local fire laws now clearly state that balcony grilling is not ok, ever. The one exception is if your balcony is made of fireproof materials and is protected by a sprinkler system. These new enactments are done for a good reason: 10,000 home fires are started by grills each year, 20,000 people are seen in the ER each year for grill related injuries, 29 % of home barbecue fires started on balconies. Add to this mixture, drinking and the possibility that your neighbor in a multiunit apartment may not be very OCD and you have a adequate reason for these rules. There are a variety of regulations that attempt to clarify the use of these beloved machines and you must check your local ones for how or if they are allowed. Most of my neighbors have given up--selling their $1000 grills to more manly people that come by in pick-up trucks while you watch cable TV shows heavy on meat. I decided go the Instructable route and fireproof my grill. The Grill Abatement System (GAS) is a modified Weber Spirit two burner that features a standard fire sprinkler head connected to a water supply pressure switch which controls a propane gas solenoid. These readily available sprinkler heads ($10) work by having a fluid inside a glass tube that bursts when exposed to a specific heat level allowing a stream of water under pressure to spray over the fire. GAS requires connections to your outdoor tap and a 12v power supply to function. The switch to control propane flow is only activated when water is turned on to the water sprinkler system allowing grilling to take place only when the GAS system in ON. If a fire activates the sprinkler head, falling pressure in the water line switches off the propane supply and along with the sprinkler stops the fire. The system is easy to build, cheap and requires no maintenance.

Supplies

The supplies that you need for this project are all available on Amazon or a big box store.

5pc Fire Sprinkler Head 93?/199? Pendent Type 1/2" Thread Green High Temperature Sprinkler Heads 1/2" $10
KOOTANS 4pcs Heavy Duty 1/2 NPT Male Thread to 1/8 NPT Female Thread Brass Reducer Hex Bushing
SharkBite 1/2 x 1/2 Inch FNPT Adapter, Push To Connect Brass Plumbing Fitting, PEX Pipe, Copper, CPVC, PE-RT, HDPE $8
SharkBite 1/2 Inch x 3/4 Inch MHT Washing Machine Angle Valve, Push to Connect Brass Plumbing Fitting, PEX Pipe, Copper $8
SharkBite 1/2 inch FNPT Slip Adapter, Push To Connect Brass Plumbing Fitting, Copper, CPVC $10
YELUN Solid brass Garden Hose Fittings Connectors Adapter Heavy Duty Brass Repair Male to Male, Female faucet leader coupler dual water hose connector (3/4" GHT Double Male Double Female 4 Pcs) $10
Hose Fitting, SUNGATOR Brass Hose Barb Fitting, Adapter, 1/4" Barb x 1/4" NPT Male Pipe (4-Pack) $2
1/4" NPT Brass Electric Solenoid Valve 12VDC Normally Closed VITON (Standard USA Pipe Thread). Solid Brass, Direct Acting, Viton Gasket Solenoid Valve by U.S. Solid. $20
LEFOO LF08PS Air Pressure Switch Air Compressor Pressure Switch Oil Pressure Switch Low/High Pressure Switch 10-40psi Wire Terminal Normal Open air Water Pressure Control air Conditioner Condenser $15
SHINESTAR 5FT Propane Hose with Regulator for Gas Grill, Patio Heater, Fire Pit and More, Low Pressure $20
6 feet copper 1/2 inch pipe $16
or PEX pipe $ Cheaper than copper
1/2 inch U bolt $2
12 volt 2 amp power supply $4
Barrel Jack for above
Teflon tape
Optional ON/OFF switch
SharkBite 90 elbow x 2 $18

Step 1: Print Your Parts

The valve for the water connection is attached to the frame of the grill with a 3D printed stabilizer. It is printed in PLA with no supports.

GASvalveSupport.stl
Download View in 3D

Step 2: Build It--One

This is an fairly easy build. I will detail it so even if you are not experienced with plumbing you can get through it. I use Sharkbite brand connectors and copper piping. Code says you can use PEX tubing for fire sprinkler runs and some varieties of PVC. I tried using PEX at first but found its lack of rigidity for the build problematic. I imagined that if I completed the build I would have to use some structural support for the sprinkler head to stabilize it in the correct position. The advantages of PEX are that it is very light and you can bend it to any shape you want. The downside is proximity to heat would soften it and might make it leak if it got over 200F. The tube in my case passes close to the grilling surface which may get focally hot. The advantages of copper are its self supporting and very heat and exposure resistant. There are a variety of mounting positions available on the Weber grill. The side pillars are strong and I wanted to make sure the pressure switch was mounted in a location far from the heat. The right hinged table portion is removed from the grill to provide room to mount the unit. The 3D printed PLA part has two holes that take heat sink brass nuts M% x 10 mm. These are available as a set on Amazon. They are mounted using a soldering iron to heat them sufficiently so that they slide into their mounting holes. The valve is then mounted using two 5 mm bolts with lock washers. The Female-Female hose coupler is screwed on to the hose bib to enable the reverse connection to a garden hose. The 3D printed mount with attached valve is then bolted onto the rear lower frame member with 5mm bolts of appropriate length.

Step 3: Build It--Two

Cut a 6 inch section of straight copper pipe with a small pipe cutter. Make sure the ends are clean. You may light sandpaper the end and the mating surface to make sure it's smooth to go into the SharkBite connector. Sharkbite connectors are very easy to use. There are good instructions on the package.You just mark an inch length on the pipe going into the connector and slide it in until it stops on the mark. The greatest thing is the joint is totally rotatable after the connection is made maintaining its water seal. To mount the water pressure sensor switch you have to add the 1/2 NPT Male Thread to 1/8 NPT Female Thread Brass Reducer Hex Bushing to the SharkBite 1/2 inch FNPT Slip Adapter. Mount the latter in a vice and wrap the reducer with a good 6 turns of teflon tape and screw it in until its tight with a wrench. Wrap the sensor valve with 6 turns of tape and tighten it into the reducer. Attach the completed sensor unit to the 6 inch section of copper with its SharkBite connector. The hight of the next section of copper pipe requires a bit of measuring of your grill unit. You want enough space for the lid to clear the sprinkler head when it's lifted. Mine measured about 48 inches. Cut this length of copper and attach it to the sensor unit. Add a 90 degree SharkBite at the top to make the horizontal bend and 16 inches of copper to get it centered over the grill. Add another 90 SharkBite and a small section copper to the last SharkBite 1/2 x 1/2 Inch FNPT Adapter. To this you wrap the 1/2 inch fire sprinkler head and wrench it into the 1/2 inch adapter. Stabilize the setup by using a U Bolt screwed into the tab that originally supported the side table.

Step 4: Build It--Three

The propane solenoid is the last step in the plumbing of the unit. I bought a really long section of tank-propane-regulator connector to replace the short one that came with my unit to allow room for the insertion of the solenoid. You may be able to get by with what you have. Using sharp scissors cut the supply tube about 1/2 way from tank to connector. Wrap two SUNGATOR Brass Hose Barb Fittings, Adapter, 1/4" Barb x 1/4" NPT with about 6 wraps of teflon tape and screw them into opposite sides of the solenoid. Keeping mindful of the direction of flow arrow, attach the solenoid using 1/2 in stainless hose clamps to the supply hose on either side. Take out your old supply hose and replace with new one. Find a good attachment spot on the lower posterior side-wall of the weber that allows the hose to curl in a reasonable fashion to the tank. The lower the better in terms of staying away from heat and make sure it doesn't touch the tank as the solenoid itself can get warm from long duration current flows. The support holes in the solenoid take 4 mm screws to hold it in place.

Step 5: Wiring It

You will need a 12 v power supply (wall wart) with barrel jack in close proximity to your grill. If you get creative and want a wireless setup you could go with a small 12v battery sold at big box stores for security systems and a small solar panel that is designed for charging/maintaining 12 v systems. The wiring is very simple--the pressure switch is patched into one of the power wires that you run to the solenoid. You will need to extend the short two wires that came attached to the pressure switch--solder two 18 g wires to the ends of the the pressure switch wires ( or use butt connectors if its easier) to give you room to run these into grill housing. The barrel jack has two wire attachment holes with screw tighteners. Attach one solenoid wire to one side of it (polarity does not matter in this case) and attach the other screw mount to one of the wires from the pressure switch. Attach the other pressure switch wire to the other solenoid wire. Make sure you use heat shrink tubing to cover the wires or wrap with electrical tape to shield.

Step 6: Using It

The Sprinkler heads come in two different heat levels. The red go off at 150F and are used in residential construction. The blue go off at 200F and are used in Kitchen stove areas. Testing revealed that even with hot smoke/steam with lid open temps near the sprinkler head usually stayed below 100F. Side temps near the grilling area and where the copper conduit was closest never went above 120F--far less than hot water out of the tap. The area near the pressure sensor switch remained ambient. To use, plug in the 12 volts wall wart to the barrel jack in back. Connect a garden hose to the hose connector at the back of the unit. For practicality I use a hose splitter with individual valves on the outside tap with a dedicated hose to the unit. I use one of those contracting hoses that expands to full length when pressurized. When the valve is turned on at the connection point water will flow into the GAS system and pressurize the valve and you will hear the distinct thump of the solenoid being turned on. At that point if you turn on your valves propane will flow into the grill and you can light it. If the GAS system looses water pressure at any time the propane flow will be shut off and the fire will die. We have used the system for several weeks and have had no false alarms with flooded food. I have used the high temp head but with testing using the low temp sprinkler it takes a fair amount of heat to activate these devices. Once burst the water flow would easily douse the most common flare ups without difficulty especially with the loss of propane to the conflagration. Most grill fires result from not cleaning out the grease trap which can suddenly ignite when the grill is unattended resulting in engulfing the grill in a ball of flame that would easily trigger this unit. There are several improvements in the design including making it folding which can be done easily with SharkBite connections. You could also design a propane valve that opens with water pressure replacing the solenoid and its need for the 12 v connection. The solenoid is not rated for continuous operation and leaving the power and the water pressure accidentally connected will result in the solenoid being turned ON so you may want to add an extra on/off switch to prevent this occurrence (but you will probably forget to turn this failsafe off too...) This unit has not been inspected or condoned by any known local fire authority so I don't know if they would appreciate the elegant solution to fire safe grilling. WARNING: Everyone knows its not a good idea to throw water on a kitchen oil fire( it causes it to explode due to the production of steam) but this is the mandate for new construction for kitchen fires. Curious I contacted my friend a fire chief who indicated that water is essentially a heat eliminator and would work in this situation and that's why its code. If the grill is open and there is an oil pan that is on fire it may cause a temporary blast effect but the water will win that along with stopping propane flow to the burner heads. This device follows the Burning Man tradition of "safety third" and maybe wouldn't pass muster by the bureau of mutant vehicles (most of the propane canons use these solenoids..) so remember I am not a authority figure on anything and when building backyard projects that involve fire don't take advice from someone that knows nothing.