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CROSBY STYLE JQ 4 IN. PRESSURE RELIEF VALVE
INSTALLATION AND MAINTENANCE INSTRUCTIONS
2 INTRODUCTION
2.1 Purpose
The purpose of this manual is to provide
a complete source of information and
recommended instructions on the Style JQ
Safety Valve.
2.2 Scope
This manual provides a detailed physical and
functional description of the Style JQ Safety
Valve. Information is presented to enable
properly trained personnel to inspect, test,
maintain, disassemble, repair and reassemble
the safety valve.
2 .3 Definitions
In this manual, the following meanings apply
unless otherwise noted:
Abbreviation
Definition
cfm
cubic feet per minute (air)
CFR
Code of Federal Regulations
chlorine
dry chlorine (either gas or liquid)
DOL
U.S. Department of Labor
DOT
U.S. Department of Transportation
EPA
Environmental Protection Agency
OSHA
Occupational Safety and Health
Administration (DOL)
psig
pounds per square inch gauge
psia
pounds per square inch absolute
Viton
a registered trademark of E.I. du
®
Pont de Nemours and Co.
TC
Transport Canada
USCG
United States Coast Guard
The numbers in parentheses throughout this
manual refer to items on Emerson Drawings,
Tables 6.1 and 6.2 of this manual, or Institute
Drawings 127, 128 and 132. Part numbers
cited are those of Emerson. Shop numbers are
Emerson identification numbers for complete
valve assemblies.
2.4 Disclaimer
The user should be aware that changing
technology or regulations may require a change
in the recommendations herein. Appropriate
steps should be taken to insure that the
information is current when used. These
recommendations should not be confused with
federal, state, provincial, municipal or insurance
requirements or with national safety codes.
2.5 Approvals
2.5.1 Valves
The USCG has approved various drawings
of the Style JQ 4 in. valves for chlorine
barges dating back to 1956. The most
recent approval (June 16, 2023) was under
Certificate No. 162.018/35/0.
The Style JQ 4 in. valves modified to meet ASME
requirements have application in chlorine
stationary storage service. They are available
in both metal-to-metal and elastomeric seat
seal designs.
2.6 Revisions
Suggestions for revision should be directed
to Emerson.
2.7 Reproduction
The contents of this manual are not to be copied
for publication, in whole or in part, without
Institute permission.
3
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