NOTE: MSS SP-80 shows standard practice for check
valves. Of the check valves listed, only the metal
to metal lift check valve (Type 1) may be used.
However, spring loaded check valves (also called
"nonslam" check valves) are available and are
similar to the lift check valve referenced. These
spring loaded check valves are preferred and should
be used whenever practical.
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MSS SP-80, Type 1 (or nonslam, spring type), Class 125 or 150.
2.2.7
[MSS SP-72] [or] [MSS SP-110], Class 125 or 150.
2.2.8
Relief Valves, Pressure and Temperature
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NOTE: The system should be used with 862 kPa (125
psig) pressure relief and 99 degrees C (210 degree
F) temperature relief whenever possible. In the
event of overpressure, the pressure relief valves
located at the low points in the system (usually on
the expansion tank in the equipment room) should
open first due to the elevation head of the system.
This prevents fluid release at the collector level
and serves to alert maintenance personnel of a
problem.
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ANSI Z21.22. Pressure relief valves located on the solar collector array
upper manifold and on the expansion tank shall open and discharge the
collector fluid [into drain indicated] [into drain tank] when fluid
pressure rises above 862 kPa 125 psig. Pressure and temperature relief
valves located on the solar storage tank shall open and discharge water
[into drain indicated] [into drain tank] when fluid pressure rises above
[862] [_____] kPa [125] [_____] psig or when fluid temperature rises above
[99] [_____] degrees C [210] [_____] degrees F.
2.2.9
Calibrating Balancing Valves
Calibrated balancing valves shall be suitable for 862 kPa 125 psig and 121
degrees C 250 degrees F service. Calibrated balancing valves shall be of
bronze body/brass ball construction with seat rings compatible with system
fluid and shall have differential readout ports across valve seat area.
Readout ports shall be fitted with internal insert of compatible material
and check valve. Calibrated balancing valves shall have memory stop
feature to allow valve to be closed for service and reopened to set point
without disturbing balance position, and shall have calibrated nameplate to
assure specific valve settings.
2.2.10
Air Vents
Brass or bronze valves or cocks suitable for 862 kPa 125 psig service.
Air
vents shall be provided with threaded plugs or caps.
SECTION 13600A
Page 12
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