2
ANDERSON GREENWOOD
MARVAC FIGURE 121FSV PRESSURE AND VACUUM RELIEF VALVES
INSTALLATION AND MAINTENANCE INSTRUCTIONS
3 SPARES
When spare parts are required, the customer
should quote the valve size, serial number,
the item number and the material of the parts
required.
The valve size and serial number can be obtained
from the valve identification label. The item
number and description can be obtained from
the arrangement on page 3.
Care should be taken to quote the correct
material as the materials quoted are for non
hazardous conditions.
Vacuum relief (refer to Figure 1)
1. Remove bonnet cap (item 6) and note exact
position (height) of adjustment screw (item 7)
inspect O-ring for damage and replace if
necessary.
2. Remove locknut (item 8) and unscrew
adjustment screw.
3. Remove spring bonnet (item 5) and spring
assembly, inspect O-ring for damage and
replace if necessary.
4. Remove pallet assembly to inspect pallet
seating for wear and replace if necessary.
5. To replace damaged/worn items from pallet
assembly (see recommended spares):
e. remove nut from pallet stem, remove
support disc, diaphragm & backing disc
f. clean pallet surface and threads
g. replace with new parts
h. reassemble in reverse order
6. Inspect valve seat (item 3) for wear and
regrind or replace where necessary.
7. Clean seating surface thoroughly with
suitable solvent.
8. Generally clean inside of valve, remove all
foreign matter and repaint exterior where
possible to prevent corrosion.
9. Replace in reverse order.
10. Reset adjustment screw to its original position
(height), tighten locknut and replace cap.
11. Check vacuum relief setting on test run and
adjust if necessary.
CAUTION
The end of the pallet stem must engage the stem
guide in the covers to ensure correct seating and
valve operation.
NOTE
The efficiency of the valve depends on maintaining
good seating surfaces. Therefore, maintenance
periods should be adjusted to suit service conditions.
Recommended spares
1. Item 14 Nitrile O-ring
2. Item 13 Sealing washers
3. Item 19 Spacer disc (non-asbestos fiber)
4. Item 20 Diaphragm backing disc (non-
asbestos fiber)
5. Item 21 Diaphragm (PTFE)
