Anderson Greenwood fig. 910 Low pressure pilot operated relief valve, Anderson Greenwood-EN Manuals & Guides
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ANDERSON GREENWOOD MARVAC FIG. 910 LOW PRESSURE PILOT OPERATED RELIEF VALVE
InstallatIon and MaIntenance InstructIons
Before installation these instructions must be read fully and understood
1 INSTALLATION
Refer to Figures 1 and 2
1. This equipment will be supplied in a packing
case and should be kept in the case for
protection until the engineer is ready to
install it.
2. Prior to installation the engineer should
check that the equipment is not damaged,
particularly the total pressure sensing tube
(item 17).
3. Visually check inside the casting via the
outlet port and remove any packing or
foreign matter if present.
4. When lifting the equipment care should
be taken not to damage the stainless steel
tubing (item 17), the protruding studs and
the actual pilot valve itself (item 16).
5.
Sizes 2” x 3”, 3” x 4” and 4” x 6” can be lifted
manually or by slings. Care should be taken
not to hold the stainless steel tubing and
actual pilot valve whilst lifting. All other sizes
have three tapped bosses for lifting bolts.
6. The valve inlet should be gasketed and
bolted to a flat machined horizontal flange.
7. The valve outlet should be gasketed and
bolted to a flat machined vertical flange.
NOTE
On no account should the exhaust pipework be
supported by the valve. These valves are not designed
to carry external loads.
3. Remove the complete piston / pressure
pallet assembly, taking care not to damage
the dome seal (item 15) on the elastomer
diaphragm. The PTFE seal tape on the PFA
diaphragm will need replacing and the
spinning will need cleaning.
4. Check the pilot diaphragm (item 11) and the
PFA diaphragm under the pressure pallet
for damage. Replace as necessary.
5. Release the bolts from the pressure seat
(item 20) and remove the seat. Replace the
expanded PTFE seal (item 19).
6. Clean the inside of the casting, removing
any dust or grit.
7. If necessary, replace pressure seat with new
seal.
8. Clean the seating surfaces thoroughly with a
suitable solvent.
9. If installed, remove the casing from the
non-return valves, check the 2 x O-rings and
replace if necessary.
10. Re-assemble the unit in reverse order.
11. If damaged or scratched, the exterior of
the valve should be painted to prevent
corrosion.
12. The efficiency of the valve depends on
maintaining good seating surfaces and on
the condition of the main valve diaphragm.
Maintenance periods should be adjusted to
suit service conditions.
2 MAIN VALVE MAINTENANCE
Refer to Figures 1 and 2
1. Remove pilot valve (Item 16) by releasing the
upper nut (Item 25) and unscrew pilot valve
from dome spinning (Item 10)
2. Release the cover screws (item 2) from the
dome spinning (item 10) and remove the
dome spinning without damaging the pilot
diaphragm (item 11). Mark dome spinning
before reassembly to ensure correct hole
alignment on reassembly.
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ANDERSON GREENWOOD MARVAC FIG. 910 LOW PRESSURE PILOT OPERATED RELIEF VALVE
InstallatIon and MaIntenance InstructIons
3 SPARES
When spare parts are required the customer
should quote the valve size, the serial number
and the item number and material of the parts
required.
The valve size and serial number can be
obtained from the valve identification label.
The item number and description of the part
can be obtained from the general arrangement
drawing.
Care should be taken to quote the correct
material as the materials quoted in the general
arrangements are not for hazardous conditions.
The following items may require to be replaced
periodically:
Main valve
Item 3 Pallet diaphragm (PFA)
Item 11 Main valve diaphragm (Elastomer)
or (PFA)
Item 15 PTFE seal
Item 19 PTFE seal
Item 27 Sealing washers
If non-return valves installed:
O-ring seals (2 off)
FIGURE 1
Main valve with fluoropolymer diaphragm
(suitableforcryogenic and light loaded applications)
FIGURE 2
Main valve with rolling diaphragm
Maximum set pressure 1 bar
Pilot valve
See Figures 3 and 4.
Items, 7, 8, 9, 10, 11, 21, 27, 37, 49, 50
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ANDERSON GREENWOOD MARVAC FIG. 910 LOW PRESSURE PILOT OPERATED RELIEF VALVE
InstallatIon and MaIntenance InstructIons
FIGURE 3
MWP Pilot valve
See
detail B
FIGURE 4
MWP Pilot valve
See detail C
Detail A
See detail A
PARTS LIST
Item Description Qty.
1 Body 1
2 Case - lower 1
3 Case - upper 1
4 Bonnet 1
5 Sense plate 1
6 Spring 1
7 Gasket - sense diaphragm 3
8 Gasket - body 3
9 Gasket - seat 1
10 Diaphragm - spindle 1
11 Diaphragm - sense 1
12 Adjusting screw 1
13 Spring plate - upper 1
16 Locknut - adjusting screw 1
17 Nut - bonnet 4
18 Bolt - bonnet 4
Detail B
Detail C
Item Description Qty. Item Description Qty.
19 Seat 1
20 Cap 1
21 Bug screen 1
23 Spacer - hex 1
25 Nut - casing 12
27 Screen - body inlet 1
28 Spindle 1
29 Nut - spindle 1
30 Spring washer - spindle 1
31 Spring plate - lower 1
32 Insert - bonnet 1
33 Check plate 1
34 Spacer - sense 1
35 Spacer - spindle 1
36 Ball 1
37 Disc 1
38 Disc holder base 1
39 Gasket - spacer 4
40 Nameplate 1
41 Hammer drive screw 2
42 Support plate 1
43 Washer - spacer 1
44 Lead and wire seal 1
45 Bushing - blowdown 1
46 Needle - blowdown 1
47 Retaining clip 1
48 Locknut - blowdown 1
49 O-ring 1
50 Seal - blowdown 1
51 Bolt - body 4
52 Bolt - case 12
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ANDERSON GREENWOOD MARVAC FIG. 910 LOW PRESSURE PILOT OPERATED RELIEF VALVE
InstallatIon and MaIntenance InstructIons
4 PILOT VALVE MAINTENANCE
Stripdown
During strip down, check each component
carefully for wear, particularly the diaphragms
and seals. The filter needs to be washed with
cleaning solvent and blow shop air through the
filter to ensure that the orifice behind is clear.
Inspect the seat surfaces, minor scratches can
be removed with 500 grit paper. The seat can
be removed if damage is severe. If machining
is carried out, ensure that the original profile is
maintained. To facilitate assembly place all parts
in an orderly arrangement so the correct parts
are assembled in the proper sequence. Refer
to Figures 3 and 4.
Assembly
1. Prior to assembly, all components must be
inspected visually, cleaned and de-burred
as necessary. Ensure that all pressure
transmission holes are clear.
2. Assemble the screwed fittings into both the
body (1) and bonnet (4) using PTFE tape as
a thread seal.
3. If the seat (19) has been removed, fit the
gasket (9) under the seat (19) and screw
into the body (1), tighten down securely.
4. Fit the spindle (78) / disc holder (38),
ensure that the disc holder is free to pivot
and that there is adequate movement.
Fit the PTFE disc (37) into the holder (38).
Lightly polish the disc to remove any sharp
edges, the seating face profile should be
hemispherical.
5. Fit the spacing washer (43), spacer (35) and
spacer gasket (39) onto the spindle. Lightly
lubricate both sides of the gasket (39).
6. Place disc assembly inside the body (1) and
onto the seat (19).
7. Assemble onto the body (1) carefully, in the
following order, ensuring that all the holes
are in line: body gasket (8) support plate (42)
and the second body gasket (8). Placing a
straight edge across the body, there should
be a 0.010”/0.015” gap above the spacer (35),
shim as appropriate.
8. Fit spindle diaphragm (10), body gasket (8)
ensuring that all the holes are in line.
9. Fit the lower case (2) and carefully tighten
down onto the body (1) with 4 x bolts.
10. Fit onto the disc/spindle assembly in
the following order: a gasket spacer
(39) sense spacer (34). Fit the check
plate (33) over the sense spacer (34),
fit gasket spacer (39). Fit the sense
diaphragm gasket (7) and diaphragm (11);
fit another sense diaphragm gasket (7).
Fit the sense plate (5) gasket spacer (39) hex
spacer (23), fit the lower spring plate (31),
spring washer (30) and spindle nut (29) and,
making sure that all the bolt holes through
the gasket and diaphragm are in line,
tighten down the spindle assembly with the
spindle nut (29) until lock washer becomes
flat, do not over tighten.
Caution: do not distort the diaphragm when
tightening the spindle nut.
11. Fit bonnet nuts (17) into the upper case (3).
12. Fit the upper case (3) and tighten securely
with the 12 x bolts and nuts.
13. Assemble the spring (6) over the plate (31)
and fit the upper spring plate (13).
14. Fit the bonnet insert into the bonnet.
15. Fit the bonnet (4) and securely tighten down
with the 4 x bolts.
16. Fit the adjusting screw (12) and locknut (16).
Apply 2/3 turns to the adjusting screw.
17. Assemble the blowdown adjustment screw
assembly, parts 45/46/47/48/49 and 50.
Screw this assembly into the body (1) until
the blowdown needle (46) is screwed home
fully, turn back 1-full turn and lock in
position with the locknut (48).
Pilot set pressure adjustment
1.
Install pilot on test stand, this should consist
of a pressure vessel of approximately 3liter
capacity with pressure gauge, see figure5.
Turn set pressure adjustment screw
clockwise until screw is near the end of its
travel.
2. Increase supply pressure to desired set
pressure and turn adjustment screw slowly
counter clockwise until flow through pilot
exhaust begins.
3. Continue to turn adjustment screw slowly
counter clockwise until dome pressure
gauge records a pressure equal to values
shown in Table 1. As flow increases through
pilot exhaust it is important to maintain
supply pressure at a value equal to the set
pressure.
4. Reduce supply pressure to 50% or less and
tighten locknut on the adjustment screw.
5. Check set pressure 3 times to ensure
consistency. Set pressure is defined as that
supply pressure where dome pressure is
equal to the values shown in Table 1.
6. Increase supply pressure to 90% of set
pressure and check seat leakage, using a
bubble tester as per API 527, there should
be no leakage.
7.
Check all gaskets and connections with soap
solution to ensure that there is NO leakage.
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ANDERSON GREENWOOD MARVAC FIG. 910 LOW PRESSURE PILOT OPERATED RELIEF VALVE
InstallatIon and MaIntenance InstructIons
NOTES
Final set pressure should be checked when the pilot
is fitted onto the main valve and any necessary final
adjustments to the pilot setting to achieve nameplate
setting can then be made. Maximum difference
between pilot and main valve set pressure is shown
in Table 1. This should be checked when the pilot is
assembled onto the main valve.
Main valve set pressure adjustment
Fit the pilot to the main valve ensuring that
the pitot pick up pipe is clear and the pitot is
in direct line with the inlet flow stream.
Pressurize the inlet slowly. Gas will escape
from the pilot exhaust when the pilot set
pressure is reached. Continue to increase the
inlet pressure until the main valve starts to
open. Adjust the pilot setting as appropriate to
achieve main valve nameplate set pressure.
Note the maximum allowable difference
between pilot and main valve set pressure in
Table 1. Do not exceed this value. If the value is
exceeded, adjust blowdown screw (part number
46) clockwise, DO NOT SCREW IN FULLY,
MINIMUM SCREW SETTING:
- ¼ TURN.
After test is complete, lead wire seal the cap to
the bonnet bolt, lead wire seal the blow down
adjusting screw to the body.
TABLE 1
Main valve set pressure
Less than 1.0 psig
(68.9 mbar)
1.0 psig through 15.0 psig
(68.9 -1035 mbar)
FIGURE 5
Optional test set-up
Supply
pressure
Vent
Dome pressure as a % of supply
pressure to achieve set pressure
35 - 45% 7%
55 - 65% 5%
Supply port
Supply
pipe
Accumulator
Maximum difference between pilot
and main valve set pressure
Pressure
adjustment
¼
Blowdown
adjustment
Dome
pressure
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