2.3.1
Gas Main Regulators
Pressure regulators for main distribution lines, supplied from a source of
gas which is at a higher pressure than the maximum allowable operating
pressure for the system, and shall be equipped with pressure regulating
devices of adequate capacity. In addition to the pressure regulating
devices, a suitable method shall be provided to prevent overpressuring of
the system in accordance with ASME B31.8. Suitable protective devices are
as follows:
a. Spring-loaded relief valve meeting the provisions of ASME BPVC SEC
VIII D1.
b. Pilot-loaded back pressure regulator used as relief valve, so
designed that failure of the pilot system will cause the regulator to open.
c.
Weight-loaded relief valves.
d. Monitoring regulator installed in series with the primary pressure
regulator.
e. Series regulator installed upstream from the primary regulator,
set to limit the pressure on the inlet of the primary regulator
continuously to the maximum allowable operating pressure of the system, or
less.
f. Automatic shutoff device installed in series with the primary
regulator, set to shut off when the pressure on the distribution system
reaches the maximum allowable operating pressure of the system, or less.
This device shall remain closed until manually reset.
g.
Spring-loaded, diaphragm type relief valves.
2.3.2
Service Line Regulators
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NOTE: If service regulator does not have all the
characteristics listed, or if gas contains materials
which would interfere with operation of the
regulator, protective devices will be installed to
prevent overpressuring of the user's system should
the regulator fail. The following devices should be
considered to be installed as an integral part of
the regulator or as separate devices operating in
conjunction with the regulator.
a.
Monitoring regulator
b.
Relief valve
c. Automatic shutoff device
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Pressure regulators for individual service lines shall have ferrous bodies.
Regulator shall be capable of reducing distribution line pressure to
pressures required for users. Regulators shall be provided where gas will
be distributed at pressures in excess of 2.5 kPa (10 inches of water
column). 10 inches of water column. Pressure relief shall be set at a
lower pressure than would cause unsafe operation of any connected user.
SECTION 02556A
Page 15
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