Emerson ANDERSON GREENWOOD 727 Installation And Maintenance Instructions Manual page 22

ANDERSON GREENWOOD TYPE 727 DUAL PILOT MANIFOLD
INSTALLATION AND MAINTENANCE INSTRUCTIONS
Pilot performance
1. Increase the pressure at the inlet port
slowly until leakage is detected at the
pilot exhaust port. Check for leakage with
a bubble tester. This pressure shall be
recorded as the cracking pressure.
2. Increase the pressure at the inlet port
further until the pilot actuates or 'pops'.
This pressure should be recorded as
the set pressure.
3. Shut off the inlet pressure to the test
accumulator and bleed inlet pressure to
allow the pilot to reseat. This pressure
should be recorded as the reseat pressure.
Check the valve for leakage at the exhaust
port with a bubble tester.
4. Repeat steps 1 through 3 a minimum of
three times. The cracking pressure, set
pressure and reseat pressure must be
within the limits specified in the applicable
performance requirements for three
consecutive cycles. The valve action must
be consistent.
5. Slowly increase the inlet pressure until
the crack test pressure specified in the
applicable valve specification sheet is
reached. Maintain this pressure for one
minute and check for leakage at the
exhaust port with a bubble tester.
6. Tighten locknut (525) and bend tabs of
blowdown locking seal (526) as shown in
Figure 6. Replace cap (512) and tighten.
Performance requirements
Cold differential test pressure is the increase in
specified set to compensate for the change in
spring force with increased temperature. Cold
differential test is the air test bench setting
pressure. Specified set is the nameplate set
pressure used to determine relief capacity.
1. Cold differential test pressure
Operating temperature Cold differential set
Below 295°F 100% of specified set
296°F to 400°F 101% of specified set
401°F and above 103% of specified set
2. Set pressure tolerance
[1]
Above 70 psig ± 3% of specified cold
differential test
70 psig and below ± 2 psig of specified
cold differential test
3. Crack pressure
50 psig to 1200 psig 90% +10%/-0%
of specified cold
differential test
4. Reseat pressure
Steam service
50 psig to 1200 psig 94% ± 2% of specified
cold differential test
Vapor service
50 psig to 1200 psig 90% ± 1% of specified
cold differential test
5. Leakage test
Steam service
- Air on pilot test stand: not to exceed 60
bubbles per minute at 90% of set pressure.
- Steam test: no visible condensate on metal
rod at pilot outlet for 10 seconds when
tested 3 minutes after reseat.
Vapor service
- Air on pilot test stand: zero leakage
below cracking pressure.
NOTE
1. ± 3% or 2 psig is ASME specified performance
tolerance.
Anderson Greenwood setting tolerance is:
Above 70 psig Set 0% to 2% above specified
cold differential test
70 psig and below 0 to 1 psig above specified
cold differential test
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