Groth 1200A User Manual
Page 7
Page 7 of 17
Figure 4 - Valve Cross Section
VI. MAINTENANCE
Groth Corporation recommends
that all service performed on a
pressure/vacuum relief valve is
done at a Groth Authorized Repair
Dealer. Contact Groth Corporation
for your local authorized repair
dealer. Trained mechanics with
specialized test equipment will
ensure that the valve is accurately
set.
It is important to regularly inspect
the diaphragm, guides and seating
surfaces to ensure the valve can
open freely. Refer to Figure 4
which illustrates a typical
Pressure/Vacuum relief valve
when disassembling the unit.
WARNING: Before disassembling valve carefully read and understand the Safety Warnings listed
on page 5.
Refer to the Figure 4 for Part References
1. Loosen and remove all nuts (#2) and washers.
2. Lift off the vacuum cover (#17) and weatherhood (#9). The weatherhood and weatherhood
posts (#7) have a snug fit. Loosen the hex nuts (#2) that retain the weatherhood posts in the
body a few turns; this will allow the weatherhood to be removed easily.
3. Remove the vacuum and pressure pallet assemblies by firmly grasping the stems (#10 & #18)
and lifting up. Depending on the pressure/vacuum settings of the particular valve, weight
plates may have been added to the pallet assemblies. The weights and pallets must be
reinstalled in their original locations. Make sure that all weight plates stay with the appropriate
pallet assembly. Tag the assemblies "Pressure" and "Vacuum" as they are removed from the
valve. Take proper precaution as lead weights may have been used.
4. Carefully inspect all guides (#7 & #16) for corrosion, damage or product build up. Also inspect
the guide hole in the vacuum cover (#17). Check the metal seating surfaces for pitting,
corrosion or product build up. It is recommended to replace all soft goods including
diaphragms (#12 & #22), O-Ring (#26) and cover gasket (#20).
NOTE: If the metal seating surfaces are damaged, they must be lapped using a flat ground
metal disc, flatness better than 0.005", and fine grit emery cloth attached to the disc. Wipe the
seating surface clean before proceeding.
5. If the stems are being replaced, check Table 3 to ensure that the correct length is being used
in both the pressure and vacuum ports.
6. Verify that the pallets and weights are back in their proper location. Assemble in reverse
order, observing the maximum dimensions for the weight blocks as listed in Table 8 on Page
10. Make sure that pallet assemblies sit flat on the seat and that the stem is not cocked when
the weatherhood (#9) and vacuum cover (#17) are installed. Tighten all nuts firmly.