374A Relief Valves
Watts Series 374A Boiler
Pressure Relief Valves are used
in hot water boiler applications
to protect against excessive
pressure on all types of hot
water heating boiler equipment.
It consists of an iron body
construction with forged bronze
inlet connections, non-metallic
disc-to-metal seating, stainless
steel spring, and test lever.
374A resists corrosive water
conditions, sticking and
freezing, and prevents water and
sediment from being trapped in
the seat. It is designed for
emergency safety relief and
shall not be used as an
operating control. Standard
Pressure Setting: 30psi (206.9
kPa), Pressure range: rated up
to 550,000 BTU/hr at a 30psi (2
bar) setting only.
3/4" x 3/4"
thermal expansion conditions develop,
pressure builds up to the setting of the
relief valve. This will cause
discharging of small quantity of water.
Should operating controls fail,
permitting runaway firing, the boiler
water may reach steam temperatures. The
valve will then open to discharge steam
at the rate or faster than the boiler
can generate it, thus restoring system
pressure to a safer level.
Important: The discharge
line must be the same size as the valve
outlet, and must pitch downward from the
valve to a safe place for disposal.
Valve lever must be tripped at least
once a year to ensure that waterways are
clear. This device is designed for
emergency safety relief and shall not be
used as an operating control.
• Seat located above drain; water can’t
be trapped and sediment can’t foul seat.
• Non-mechanical seat-to-disc alignment
will not stick or freeze.
• Water seal of high temperature
resisting material isolates spring
working parts from water during relief.
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