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2) Liquid Propane (L.P.) Gas
Dryers made for use with L.P. gas have the gas valves internal pressure regulator blocked open so
that the gas pressure must be regulated upstream of the dryer. The pressure measured at each gas
valve pressure tap must be a consistent 10.5 inches water column (W.C.) - 26.1 mb. There is no
regulator or regulation provided in 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
ALL components/materials must conform to National Gas Code Specifications, or in Canada, the Canadian
Installation Codes (for General Installation and Plumbing). It is important that gas pressure regulators meet
applicable pressure requirements and that gas meters be rated for the total amount of ALL the appliance
BTUs being supplied.
The dryer is provided with a 1-inch N.P.T. inlet pipe connection extending out the back area of the burner
box. The minimum pipe size (supply line) to the dryer is 1-inch N.P.T. For ease servicing, the gas supply line
of each dryer must have its own shut-off valve.
The size of the main gas supply line (header) will vary depending on the distance this line travels from the
gas meter or, in the case of L.P. (liquid propane) gas, the supply tank, other gas-operated appliances on the
same line, 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 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 1-inch (2.54 cm)
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 10.5 inches of water column
(W.C.) - 26.1 mb - pressure.
NOTE: A water column (W.C.) test pressure of 3.5 inches (8.7 mb) for natural gas and 10.5 inches
(26.1 mb) for L.P. (liquid propane) dryers is required at the gas valve pressure tap of each
dryer for proper and safe operation.
A 1/8 N.P.T. plugged tap, accessible for a test gauge connection, must be installed in the main gas supply
line immediately upstream of each dryer.
IMPORTANT: Pipe joint compounds that resist the action of natural gas and L.P. gas must be used.
Type of Gas
L.P.
Conversion
Kit
Part Number
MODEL
NUMBER
BTU
Per Hour
Rating
kcal/hr
Rating
Natural Liquid Propane
Qty. D.M.S.*
Part
Number
Qty. D.M.S.*
Part
Number
ML-130DR 300,000
75,600 3
#1
2
140863 3 #33 140855 882626
Shaded area is stated in metric equivalent
* D.M.S. (Drill Material Size) equivalents are as follows:
Natural Gas ............... #12 = .1890” (4.8006 mm)
Liquid Propane Gas .. #33 = .1130” (2.8702 mm)