American Dryer Corp. AD-385 - Manual (Page 28)

2. TECHNICAL GAS DATA
a. Gas Specifications
The natural gas supply pressure to the dryer must be between 6 and 12 inches water column.
If the pressure is too low, ignition failure and/or slow drying times may result. Excessively
high supply pressure will result in erratic operation of the gas valve's internal pressure
regulator. The pressure measured at the pressure tap on the body of the gas valve must be
4-inches water column.
b. Liquid Petroleum TL-P.^ Gas
Dryers made for use with L.P. gas have the gas valve pressure regulator blocked open, so that
the gas pressure
must be regulated upstream of the dryer. The pressure measured at the gas
valve body pressure tap must be 11-inches water column. There is no regulator provided on
an L.P. dryer. The water column pressure must be regulated at the source (L.P. tank), or an
external regulator must be added to each dryer.
3. Piping/Connections
The dryer is provided with a 3/4" N.P.T. inlet pipe connection extending out the rear or
through the top of the dryer. For ease of servicing, the gas supply line of each dryer should
have its own shut-off valve.
IMPORTANT; The gas pipe supply line to each dryer must be a minimum of 3/4". DO NOT
REDUCE THIS PIPE SIZE REQUIREMENT.
The size of the gas supply line (header) will vary depending on the distance this supply line
travels from the gas meter or, in the case of L.P. gas, the supply tank, the number of tees,
other gas-operated appliances, etc. Specific information regarding supply line size
should be
determined by the gas supplier.
NOTE: Undersized gas supply piping can create a low or inconsistent gas pressure which will
_____ result in erratic operation of the burner ignition system.
Consistent gas pressure is essential at ALL gas connections. It is recommended that a 2-inch
pipe gas loop be installed in the supply line serving a bank of dryers. An in-line pressure
regulator must be installed in the gas supply line (header) if the (natural) gas pressure
exceeds 12.0 inches of water column pressure.
24