WC in terms of pressure pipe systems stand for ‘water column’ and is a method & unit of measurement of pressure. 1psi equals 27.68 WC (inches of water column). So 10” Wc is only about 0.36 psi. … not much pressure …
The manifold described above is used for multiple connections at the tank or connecting two or more tanks together with one regulator. It can also be used if other temporary connects are needed outside of the truck. But, generally a ¾” black iron (gas) pipe is ran into and thought the truck and T-connections provided at each appliance location. The ¾” black pipe acts as a ‘manifold’. At each T-connection reduce the pipe size to that needed to supply the appliance. Generally, this is 3/8” copper or other gas flex pipe. Don’t forget to install a ‘shut-off’ value at each T-connection for equipment maintenance without shutting off the tank and all gas appliances.
A piping size reference can be found at http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d827.html
For one or two gas appliances it is very likely that you can work from a single tank regulator and set the line pressure as needed (10” WC). But, it you have more than two gas appliances or if an appliance requires low pressure per manufacturer (6 to 8 wc ???) then a secondary regulator is required to lower the ‘tank line’ pressure or manifold pressure at each appliance or t-connection.
In many Truck builds, the sum-total of BTUs required by ALL gas appliances exceed the ‘normal working’ capacity of the LPG tank. A good reference is at http://www.generatorjoe.net/html/PropaneNGUse.html
Look at the ‘vaporization’ tank rates table. At 30 deg F, the supply rate of a 40 lb tank is about ½ of the BTUs required by your frier. So without knowing all details of your gas & BTU requirements, I suggest considering two 40lb tanks manifold together (or 100 lb tank) to supply your needs.
When the LPG tank doesn’t have enough vapor capacity the line pressure can be increased (12 to 15 WC) to increase the available vapor within the pipe. Then regulators installed at each appliance to reduce the gas flow to less than the maximum required by the appliance (60% to 80% or 6 to 8 WC if the max. =10WC). While the appliance will heat up slower, in many cases once hot it doesn’t need to work at max. output anyway. This will allow several appliances to work together that would other wise overload the LPG tank and cause it to freeze up. This does not work in all cases or cure sever overload of the tank.
Another trick to help overloaded LPG tanks or cool weather freezing of the tank is to provide heat to the tank. Use a heat blanket or warm air exhausted from the kitchen to warm the tank. Think of LPG tanks as being a ‘steam boiler’. It is an operating peace of equipment producing steam (gas vapor). It is not a simple storage can.
So ¾” dia black pipe supply line with T-connections and 3/8” dia soft copper (or other flex pipe) connection to the appliance should be more than adequate for your needs. If any problems exist, then it would be vapor supply/tank capacity or regulator/pressure at the appliance.
Additional & general info can be found at http://rjmurray.com/serviceBulletins/LPGasServicemansHandbook.pdf http://www.larimer.org/building/liquid_propane.htm http://voices.yahoo.com/natural-gas-propane-pipes-codes-leaks-the-739045.html?cat=6
I hope this helps. This is the 10 minute tour for someone ‘out of his element’ as you stated.
post edited by edwmax - 2013/02/24 09:44:06