14
GAGE- 3.5 kPa) SUPPLY GAS PRESSURE. EXPOSURE TO
HIGHER SUPPLY PRESSURE MAY CAUSE DAMAGE TO THE
GAS VALVE WHICH COULD RESULT IN FIRE OR EXPLOSION.
IF OVERPRESSURE HAS OCCURRED SUCH AS THROUGH
IMPROPER TESTING OF GAS LINES OR EMERGENCY
MALFUNCTION OF THE SUPPLY SYSTEM, THE GAS VALVE
MUST BE CHECKED FOR SAFE OPERATION. MAKE SURE
THAT THE OUTSIDE VENTS ON THE SUPPLY REGULATORS
AND THE SAFETY VENT VALVES ARE PROTECTED AGAINST
BLOCKAGE. THESE ARE PARTS OF THE GAS SUPPLY
SYSTEM, NOT THE HEATER. VENT BLOCKAGE MAY OCCUR
DURING ICE STORMS.
IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING
FROM CONTAMINANTS IN THE GAS WAYS. SUCH FOULING
MAY CAUSE IMPROPER OPERATION, FIRE OR EXPLOSION.
IF COPPER SUPPLY LINES ARE USED THEY MUST BE
INTERNALLY TINNED AND CERTIFIED FOR GAS SERVICE.
BEFORE ATTACHING THE GAS LINE, BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.
TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS
SUPPLY LINE, A DIRT LEG (SOMETIMES CALLED SEDIMENT
TRAP OR DRIP LEG) MUST BE INCORPORATED IN THE PIPING
(SEE FIG. 11). THE DIRT LEG MUST BE READILY ACCESSIBLE
AND NOT SUBJECT TO FREEZING CONDITIONS. INSTALL IN
ACCORDANCE WITH RECOMMENDATIONS OF SERVING GAS
FIGURE 12
SUPPLIERS. REFER TO THE CURRENT EDITION OF THE
NATIONAL FUEL GAS CODE. For Canadian installations consult
Natural Gas and Propane Installation Code CAN/CSA-B149.1.
To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to gas valve inlet.
Apply joint compounds (pipe dope) sparingly and only to the male
threads of pipe joints. Do not apply compounds to the first two
threads. Use compounds resistant to the action of liquefied
petroleum gases.
GAS PIPING AND DIRT LEG INSTALLATION
FIGURE 11
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