LPG Mechanicl ON/OFF Acturated Valve

BCC Forum
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I just posted six photos of a mechanical LPG actuator which turns the gas ON or OFF. The photos are in the Gallery New Upload section but will eventually be moved to the BCC gallery under IDUNA.

The actuator is a push/pull control rod connected to a yoke. A pin through the yoke runs in a slot cut into the bellcrank. The bellcrank is connected to the valve by 5 machine screws that thread into a C-pressure plate on the backside of the valve handle. When the screws are tightened the bellcrank and C-pressure plate clamp to the valve handle by friction.

The actuator rod is pushed or pulled to close or open the valve 1/4 turn. The actuator rod remains straight as the yoke pin slides in the bellcrank slot. I made sideview drawings of the actuator and bellcrack when the valve was closed, half open and fully open to determine the length of the bellcrank and the slot in the bellcrank.

The actuator through the cabin bulkhead is sealed by two compression fittings packed with greased flax packing string. A grease zerk threaded into the outside compression fitting provides a means to fill the pipe nipple passing through the bulkhead with grease.

Material:

Bellcrank - Garolite (mcmasters.com)
C-pressure plate - Garolite
Yoke - Naval Brass (mcmasters.com)
Yoke pin - bronze cotter pin (jamestowndistributors.com)
Actuator rod - 5/16" diameter bronze rod (had available)
Compression fittings - brass (hardware store)
Pipe nipple - leaded red brass (hardware store)
Flax Packing string - made my un-weaving 1/4"X 1/4" flax packing (had available)
Zerk - auto parts store,
Grease - Shell marine grease,
Pull Knob - Kitchen Cabinets, Lowes

This type of system can also be adapted for a rotating ON/OFF handle inside the cabin. Two bellcranks connected by a actuator rod with a yoke on each end is employed.

This topic will also be posted at the BCC forum. Please direct any questions on this topic in the BCC forum.

Thanks,

Rod

Correction: the pressure plate is a garolite disc on the outside of the valve handle and the bellcrank end is fitted to the backside of the valve handle. The bellcrank has the C-end to fit around the valve stem.

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Huh. I wouldn’t have thought a 1/4 turn would be enough to open/close that kind of valve. Were I doing it, I would be tempted to use a 1/4 turn ball valve. Neat install!

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Rod,

Nice bit of work. Thanks for the clear photos and description. From the photos it appears that the LPG tank is resting on its side. I have been looking for a horizontal aluminum tank and have not found one. Do you have a source or did it come with the boat?

Drew

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Drew: The two 20 lb horizontal tanks came with the boat. Try Weld World in Brooklyn (Baltimore) MD. http://www.weldworld.us/ I purchased the regulator there for $15. The pressure gauge is SS from McMaster.com. The system pictured will also work for a vertical mounted tank.

Hypothetical: Gas has a very low viscosity, hence on a small differential pressure between the high side and low is side of a valve is required to move a large volume gas. The LPG system pictures leads to a 9,000 BTU heater. I thought of using a ball valve but did not have the space. The system pictured is based a friends system that uses two bellcranks to open the tank valve 1/4 turn. By utilizing a push-pull actuator, the system pictured is simpler and fit within the space I had available.

Rod

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Ahoy Rod , It is V important that you also state just why you went to all this work , to be able to “shut off or turn on” , the outside gas supply, from inside the cabin .

You must have already discovered that a 1/4 turn on the tank valve was enough to allow a full supply of gas , but I would like to know why I have always been opening the valve fully, for so many years ?

Was it just habit or poor instruction from gas suppliers ?

What ever, it is still important that you bring this subject to the attention of all owners .

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IDUNA is fitted with two 20 lb horizontal mounted LPG tanks (came with boat).

The starboard tank is connected to the galley stove. This system is fitted with a Blue Seas solenoid shutoff valve. ABYC specifies a LPG shutoff valve must be mounted outside the cabin and the shutoff control must be within arms reach of the service. Considering the galley is located by the companionway and the LPG tank is forward of the cabin house, we opted to using a solenoid shutoff valve instead of designing and building a complex mechanical shutoff. The control switch for the solenoid in located by the stove, i.e. within arms reach of the service.

The port tank supplies the Dickinson P-9000 heater. This is located on the port side of the cabin and is mounted on the bulkhead separating the fo’c’s’le from the main saloon. We choose to use a mechanical actuated shutoff valve for this service for the following reasons:

  1. Required no amps,
  2. Could be located within arms reach of the service,
  3. Was failure proof compared to a solenoid shutoff valve
  4. I like to design and build mechanical “stuff”
  5. Because of where the LPG tank and heater were located, it was practical to install a mechanical shutoff.

The amount of work to build the system was less than you may imagine. Designing the system probably took more time than building and install the system. I also have a friend who had access to a machine shop. He offered to make the yoke for me. I could have made the yoke out of brass, garolit, delrin, etc. using a drill, hacksaw, files and taps. I receive great joy from solving engineering problems and building solutions. It’s just my makeup. The system is not complicated and is not difficult to build.

Valve opening:

The valve on an LPG tank is not a throttling valve, i.e. it’s either “open” or closed. In the chemical business, the standard for these valves is to open them all the way then close the valve 1/4 to 1/3 turn. This practice allows “back and forth play” on the valve should it become stuck. I recommend this practice for LPG valves. I suspect, the recommendation to always open a LPG valve fully, came into practice to ensure the valve was open.

As I stated before, gasses have very low viscosity and require only a small differential pressure across a valve or restricted opening to achieve a high volume of flow. The amount of fuel a galley stove or cabin heater requires is minimal. You can demonstrate this by lighting a stove burner then turning off the solenoid valve. It take awhile before the burner goes out. Considering the volume of the gas line from the solenoid valve to the stove is small, the burner requires very little fuel. This also holds true for the P-9000 heater. The P-9000 burns 20 lb of fuel per 100 hours when set on high or 0.05 oz of fuel per minute. At standard temperature and pressure, the volume occupied by 0.05 oz of propane is 0.7 l (700 ml) about the volume of 1 wine bottle. This is the reason 1/4 turn open works - low volume demand.

Thought about LPG systems:

When we purchased the boat, the stove shutoff valve was located in the cabin near the stove - simple, cost effective and almost failure proof. The only reason we installed a ABYC system was for insurance purpose.

We always turn off the shutoff valve to a service and burn the fuel in the supply line up. The practice also tests if the shutoff valve is operational or has failed.

Should we every go cruising, I plan to have a spare gas regulator and solenoid valve on the boat.

When we purchased our Blue Seas LPG solenoid valve and breaker switch, The breaker switch was fitted with a 5 amp breaker. LPG solenoid valves require less than 1 amp to open. It takes about 10 to 20 seconds for a breaker to open. Should a short occur in the solenoid, the solenoid will “burn up” before the breaker opens. I discussed this with Blues Seas They sent me a 2 amp breaker.

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Addendum:

The push-pull actuator rod is 5/16" diameter and the cabin knob is tapped for a 1/4" X 20 tpi machine screw. Instead of drilling the knob and tapping to 5/16" X 18 tpi, an odd size, I turned the 5/16" rod down to 1/4" and threaded it with a 20 tpi die.

Because I do not have a lathe, I “strapped” my hand drill to the workbench, fitted a 5/16" drill bit in the drill then pressed a block of wood to the work bench surface and drilled a 5/16" hole in the block by pushing the wood into the turning bit.

Once I had the pillow bearing (block bearing) made, I fitted the 5/16" bronze rod into the drill chuck then threaded the pillow bearing onto the rod. The pillow bearing was clamped to the workbench near the end of the rod that would be machined. IF necessary, drill the wood bearing to 11/32" diameter.

To machine the rod, turn the drill on and use a mill file to turn the end down to 1/4" diameter, measure the diameter as you work.

“Necessity if the mother of invention.”