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SAFETY DEVICES

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.

Applications

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

refrigerant used.

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.

Main Features

Ÿ

NPT and SAE flare connections

Ÿ

High pressure line available (500-675 PSI) suitable for R410A & CO . See

2

model numbers 5233AX, 5234AX and 5235AX

Ÿ

Valves fully open before 10% overpressure when taken from the average

set pressure

Ÿ

Reset pressure ranges typically 10-40% (blowdown) from pop pressure

Ÿ

Valves bear individual serial numbers

Ÿ

UV-1 pressure test reports available upon request

Technical Specifications

All Henry Technologies PRV’s have a set pressure range +/- 3% of the

stamped pressure.

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

valve seats.

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.

CRN

31