SAFETY PRECAUTIONS
Read and understand this instruction manual
before installing, operating or performing
maintenance on a 121FSV pressure and vacuum
relief valve. Follow all precautions and warnings
noted herein when installing, operating or
performing maintenance on this equipment.
Safety precaution definitions
CAUTION
Damage to equipment may result if this
precaution is disregarded.
WARNING
Direct injury to personnel or damage to
equipment that can cause injury to personnel may
result if this precaution is not followed.
NOTE
This manual is issued for guidance only and does not
affect our standard terms and conditions and our
product limited warranty, all of which are available
upon request.
Read Anderson Greenwood Marvac general instructions before continuing
ANDERSON GREENWOOD
MARVAC FIGURE 121FSV PRESSURE AND VACUUM RELIEF VALVES
INSTALLATION AND MAINTENANCE INSTRUCTIONS
Emerson.com/FinalControl
© 2017 Emerson. All rights reserved.
VCIOM-04095-EN 18/01
1 INSTALLATION
121FSV pressure and vacuum relief valves
must be mated with the appropriate flange.
1. These valves must be gasketed and bolted
to a flat machined horizontal flange. Bolts
must be tightened uniformly to ensure a
good seal.
2. The exhaust pipework which is to be
gasketed and bolted to the horizontal flange
must not be supported by the valve, i.e.
these valves are not designed to carry any
external loads.
3. This valve does not contain any internal
packing. Therefore, internal checks should
not be necessary.
4. It is recommended that carbon steel valves
be given a coat of paint immediately after
installation is complete. Apply paint to
external surfaces only.
2 MAINTENANCE (DURING ATMOSPHERIC
VENTING PERIOD)
WARNING
The relief valve must be isolated from tank
pressure before servicing. All gas must be
blocked and pressure vented safely.
Wear appropriate gloves and/or breathing
apparatus if hazardous vapors are present.
Pressure relief (refer to Figure 1)
1. Remove pressure cover (item 15), inspect
O-ring for damage and replace if necessary.
2. Remove pallet assembly to inspect pallet
seating for wear and replace if necessary.
3. To replace damaged/worn items from pallet
assembly (see recommended spares):
a. remove nut from pallet stem, remove
support disc, diaphragm & backing disc
b. clean pallet surface and threads
c. replace with new parts
d. reassemble in reverse order
4. Inspect valve seats (item 3) for wear and
regrind or replace where necessary.
5. Clean seating surface thoroughly with
suitable solvent.
6. Generally clean inside of valve, remove all
foreign matter and repaint exterior where
possible to prevent corrosion.
7. Replace pressure pallet on pressure seat
(with lead disc if fitted).
8. Replace pressure cover & replace sealing
washers if necessary, secure with screws.
