PAGE 60 of 84 HU-SOUTHWEST-1480 GAS-FIRED HUMIDAIRE UNIT
© SAMUEL JACKSON, INCORPORATED 2005 ALL RIGHTS RESERVED
GAS PIPING
Size of pipe supplying gas to heaters and other appliances should be large enough to prevent
excessive pressure losses when all of them are in use. See the following Table of
RECOMMENDED MINIMUM PIPE SIZES
for heater capacities, pipe lengths, and pressures.
Where LPG (Liquefied Petroleum Gas, Propane, Butane) is used as fuel, see the following
Drawing:
LIQUEFIED PETROLEUM GAS TANK INSTALLATION FOR HUMIDAIRE UNITS
AND DRYING HEATERS
for recommended practices.
Emergency shut-off valves should be provided to permit turning off the fuel in an emergency.
They should be located so that they are accessible in an emergency situation.
IRI (Industrial Risk Insurers) and some state and local authorities require venting the gas
regulator and the normally open vent valve.
NFPA (National Fire Protection Association) 86* states:
3-3.4.3.2 Regulators shall be vented to a safe location, where vented gas cannot re-enter
the building without extreme dilution. The terminating end shall be protected against
water entry and bug-screened. Vent pipe shall be of adequate size so as to not lengthen
response time.
3-3.4.3.3 Vent lines from multiple regulators, where manifolded together, shall be piped
in such a manner that diaphragm rupture of one will not backload the others.
3-3.4.3.4 Vents from gas pressure switches, but from no other devices, may be vented
into the regulator lines provided that switch or regulator diaphragm failure will not
backload the regulator.
* Reprinted with permission from NFPA 86-1985, Standard for Ovens and Furnaces,
Copyright © 1985, National Fire Protection Association, Quincy, Mass. 02269. This reprint of
material is not the complete and official position of the NFPA on the referenced subject, which is
represented only by the standard in its entirety.
