W:\ELECTRICAL\INSTRUCT\FURNACE\FURNACE GENERAL INSTRUCTIONS 2011.DOC
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01/2014
3-6.3
All gas heated equipment shall be provided with an individual gas pressure
regulator properly sized to supply the pressure and volume required. The furnace
nameplate lists the gas pressure and the burner capacity. Gas pressure regulator
should have the following characteristics:
a.
The regulator must be of the full lock-up type; gas pressure must be regulated
even under no flow condition.
b.
Incoming pipe size should not exceed 2" diameter.
c.
Self contained with no external static or control piping.
d.
Single port with correctly sized orifice for the maximum gas pressure at the
regulator inlet.
e.
Valve seat is of resilient material designed to withstand abrasion of gas,
impurity in gas, cutting by the valve and to resist permanent deformation by
the valve port.
f. Capable of regulating downstream pressure under no flow conditions to not more
than 150 percent of the discharge pressure under flow conditions.
If these criteria are not met, a pressure relieving or limiting device is required as
outlined in the NFPA 54 National Fuel Gas Code.
3-6.4
A remotely located emergency manual shutoff valve shall be provided to allow the
fuel to be turned off in an emergency and shall be located so that fire or explosion
at the furnace does not prevent access to this valve. Operators should be
instructed on the location of this valve and allowed access to shut off fuel flow in an
emergency. Valve shall have permanently affixed visual indication of position and
be operable without tools.
3-6.5
An equipment isolation shutoff valve must be provided at each piece of equipment.
Valve shall be quarter turn with stop, permanently affixed visual indication of
position, and operable without tools. Valve handle must remain affixed and be
parallel to pipe when open and perpendicular to pipe when closed.
3-6.6
Regulators and high or low gas pressure switch vent lines shall be piped to a safe
location outside the building according to local codes. Protect outlet from water
entry and provide bug screen.
3-6.7
Vent lines from regulator and switches of a single furnace may be manifolded
together in such a manner that diaphragm rupture of one regulator or switch does
not back load others. The cross section of the vent manifold should be not less
than the area of the largest vent line plus 50% of additional lines.
3-6.8
Vent lines from multiple furnaces shall not be manifolded together.
3-6.9
A normally open vent valve between safety valves shall not be combined with other
vents. Care must be taken to terminate a vent valve line in a safe approved
location.
