Type 289P
5
pressures according to the shutdown
procedure. Use gauges to monitor inlet,
loading, and outlet pressures while
releasing these pressures.
NPS 1 Type 289P Main Valve
This procedure is to be performed if inspecting
or replacing main valve parts. Key numbers are
referenced in Figure 4.
Note
The main valve body (key 1) may remain
in the line during maintenance. Lightly
lubricate O-rings before assembly.
Disassembly
1. Loosen the set screw (key 6) to remove
spring compression.
2. Remove the screws (key 8) and remove the spring
case (key 2), spring (key 7), and spring seat (key 4).
3. Remove the screws (key 29) from the stem guide
assembly (key 31). Lift out the diaphragm (key 5)
and trim assembly.
4. Unscrew the hex nut (key 24) and remove the lower
spring guide (key 17), diaphragm head (key 3), and
inspect diaphragm (key 5).
5. Slide the washer (key 27), gasket (key 19), stem
guide assembly (key 31), and bushing (key 23) from
the pitot tube (key 18).
6. Remove the upper O-ring (key 30), O-ring holder
(key 21), O-ring (key 20), O-ring washer (key 22),
and lower O-ring (key 30) from around the pitot tube
(key 18).
7. Inspect and replace parts as necessary.
Table 2. NPS 1 Main Valve Capacities and Type 6358B Pilot Information
MAIN VALVE SPRING,
PART NUMBER, AND
COLOR, PSIG (bar)
SET PRESSURE
RANGE,
PSIG (bar)
SET PRESSURE
(1)
,
PSIG (bar)
BUILD-UP OVER
SET PRESSURE TO
BEGIN OPENING MAIN
VALVE
(2)
, PSIG (bar)
BUILD-UP OVER
SET PRESSURE
TO FULLY OPEN MAIN
VALVE
(3)
, PSIG (bar)
PRESSURE DROP
BELOW SET PRESSURE
TO RESEAT PILOT,
PSIG (bar)
For set pressures up to
30 (2,1)
1F826927052
Pink
10 to 18
(0,69 to 1,2)
10
15
18
(0,69)
(1,0)
(1,2)
0.8
0.8
0.8
(0,05)
(0,05)
(0,05)
1.0
1.0
1.0
(0,07)
(0,07)
(0,07)
1.0
1.0
1.0
(0,07)
(0,07)
(0,07)
18 to 30
(1,2 to 2,1)
18
25
30
(1,2)
(1,7)
(2,1)
0.9
0.9
0.9
(0,06)
(0,06)
(0,06)
1.2
1.2
1.2
(0,08)
(0,08)
(0,08)
1.0
1.0
1.0
(0,07)
(0,07)
(0,07)
For set pressures over
30 (2,1)
1D892327022
Red
30 to 100
(2,1 to 6,9)
30
40
50
60
(2,1)
(2,8)
(3,4)
(4,1)
1.4
1.4
1.4
1.4
(0,10)
(0,10)
(0,10)
(0,10)
1.9
1.9
1.9
1.9
(0,13)
(0,13)
(0,13)
(0,13)
1.0
1.0
1.0
1.0
(0,07)
(0,07)
(0,07)
(0,07)
70
80
90
100
(4,8)
(5,5)
(6,2)
(6,9)
1.6
1.6
1.6
1.6
(0,11)
(0,11)
(0,11)
(0,11)
2.1
2.1
2.1
2.1
(0,14)
(0,14)
(0,14)
(0,14)
1.0
1.0
1.0
1.0
(0,07)
(0,07)
(0,07)
(0,07)
1. Set pressure is dened as the pressure at which the pilot exhaust starts to bubble (discharge).
2. Crack pressure is the inlet pressure at which the main valve starts audible ow.
3. Inlet pressure build-up over the set pressure to achieve wide-open capacity.
Table 3. NPS 2 Main Valve Capacities and Types 6365 and 6358B Pilot Information
PILOT
TYPE
RELIEF SET PRESSURE
RANGE, SPRING PART
NUMBER, AND COLOR
SET PRESSURE
(1)
,
PSIG (bar)
BUILD-UP OVER SET
PRESSURE TO FULLY OPEN
MAIN VALVE
(3)
, PSIG (bar)
PRESSURE DROP BELOW SET
PRESSURE TO RESEAT PILOT,
PSIG (bar)
6365
14-inches w.c. to 2 psig
(35 mbar to 0,14 bar)
14A9672X012
Yellow
0.5
1.0
1.5
2.0
(0,03)
(0,07)
(0,10)
(0,14)
0.25
0.25
0.25
0.25
(0,017)
(0,017)
(0,017)
(0,017)
0.25
0.25
0.25
0.25
(0,017)
(0,017)
(0,017)
(0,017)
6358B
2 to 10 psig
(0,14 to 0,69 bar)
14A9673X012
Black
2.0
4.0
6.0
8.0
10.0
(0,14)
(0,28)
(0,41)
(0,55)
(0,69)
0.30
0.30
0.30
0.30
0.30
(0,021)
(0,021)
(0,021)
(0,021)
(0,021)
0.30
0.30
0.30
0.30
0.30
(0,021)
(0,021)
(0,021)
(0,021)
(0,021)
1. Set pressure is dened as the pressure at which the pilot exhaust starts to bubble (discharge).
2. Crack pressure is the inlet pressure at which the main valve starts audible ow.
3. Inlet pressure build-up over the set pressure to achieve wide-open capacity.
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