PRESSURE RELIEF VALVES
The main function of a Pressure Relief Valve is to protect against
accidental over-pressure of a pressure vessel due to system
malfunction or fire.
Henry Technologies’ Relief Valves are designed to be used in refrigeration
systems to prevent over-pressure due to system malfunction or excessive
external heat. They are to be used only with refrigerant vapor or gas, where
they are typically installed on the top section of a pressure vessel, i.e. liquid
receiver or suction accumulator.
Most states and municipalities which have refrigeration safety codes conform
to the “American Standard Safety Code for Mechanical Refrigeration
(ANSI/ASHRAE 15)”. This code and ASME states that the Relief Valve
setting is not to exceed the design working pressure of the vessel on which
the Relief Valve is installed. The discharge capacity of relief valves varies
with pressure setting. The discharge capacity required is based on the size
of the vessel and the refrigerant used. See “Determining Minimum Required
Discharge Capacity” section for more information, or contact Technical
Support at 1-800-627-5148.
Whenever conditions permit, it is highly advisable to have the Relief Valve
pressure setting (which must not exceed the design working pressure of the
vessel) at least 25% higher than the normal operating pressure for the
52 series Pressure Relief Valves are suitable for use with HCFC and HFC
refrigerants and their associated oils, as well as other industrial fluids non-
corrosive to brass, steel and Teflon.
53 and 56 series Pressure Relief Valves are suitable for use with ammonia,
HCFC and HFC refrigerants and their associated oils, as well as other
industrial fluids non-corrosive to steel, iron and Teflon.
NPT and SAE flare connections
High pressure line available (500-675 PSI) suitable for R410A & CO . See
model numbers 5233AX, 5234AX and 5235AX
Valves fully open before 10% overpressure when taken from the average
Reset pressure ranges typically 10-40% (blowdown) from pop pressure
Valves bear individual serial numbers
UV-1 pressure test reports available upon request
All Henry Technologies PRV’s have a set pressure range +/- 3% of the
Set pressure range = see tables
Allowable operating temperature = -20°F to +225°F (-29°C to +107°C)
Henry Technologies’ Relief Valves are stamped with the ASME UV symbol
and NB to indicate National Board certification as to capacities. Additionally,
Pressure Relief Valves are designed and registered for use in Canada.
Please contact Technical Support at 1-800-627-5148 for CRN details and list
of approved provinces and territories.
How it works
All Henry Technology Relief Valves are 100% tested and manufactured to
guidelines as indicated in ASME Section VIII Division I. Every Relief Valve is
calibrated to indicate a pre-determined set pressure, where the valve begins
to allow gas or vapor to pass through. The valve will open to a full discharge
within 10% over set pressure. After discharge Pressure Relief Valves will
blow down and reseat once the pressure falls below the valves set pressure.
Materials of Construction
The 52 series Relief Valves have brass valve bodies. The internal parts are
made of brass and carbon steel. The 53 series valves have stainless steel
valve bodies. Internal parts are made from stainless steel and carbon steel.
The 56 series valves have cast or ductile iron valve bodies. The internal
parts are made from stainless steel and carbon steel. All valves have Teflon
Relief Valve Capacity Ratings
Henry Technology Relief Valves are marked with a discharge capacity in unit
lbs-air/min, and marked in accordance with the requirements of the ASME
(Boiler and Pressure Vessel Code Section VIII, Division 1). These valves are
also approved by many local refrigeration and air conditioning codes in the
USA and Canada for relief of excess pressure.