Graham Corporation
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5.5 Mechanical Seals
The Series 2 pumps are fitted with single acting mechanical shaft seals. They should be
replaced when worn, scratched, or cracked, or when the rotating segment no longer grips the
shaft. There is a weep hole on the underside of each bearing seal housing. If a mechanical seal
has failed, leakage will occur at this location.
Series 1 pumps may be fitted with mechanical seals when a specific type of seal will not fit into
the stuffing box of a Series 2 pump.
The Series 1 pumps are also used when double mechanical seals are required. This arrangement
is used when handling gases that are volatile, toxic, or corrosive. The shaft seal coolant is
normally circulated through the seal chamber at a pressure slightly above the pump discharge
pressure or as recommended by the mechanical seal manufacturer. This creates a barrier and
prevents the pumped gasses or liquid from escaping to the atmosphere. The barrier fluid also
dissipates heat, lubricates both sealing faces, and monitors the condition of the mechanical seals.
When replacing the mechanical seals, clean the shaft thoroughly. The seal faces must be
protected during installation from particles which may scratch the surfaces.
CAUTION:
DO NOT RUN THE PUMP WITHOUT SERVICE LIQUID AND
SHAFT SEAL FLUID.
5.6 Storage
If a pump is to be out of service, it should be protected internally from rusting by using a rust
inhibitor. The pump should be drained completely by removing all the lower plugs. Install the
plugs and fill with Oakite HPO (or equal) preservative solution. Remove the manifold(s) and
spray the insides with preservative. Rotate the pump manually to circulate the solution. Drain
the pump to below the shaft centerline and replace the manifold(s). This procedure may be
disregarded for pumps made of stainless steel, bronze, Monel, or other corrosion resistant
materials.
Seal the flanged openings to prevent foreign material from entering the pump.
The pump shaft should be rotated each week to distribute the preservative and to prevent flat
spots on the bearings. Document the time, date, and by whom this procedure was performed.
The manifold(s) should be re-sprayed monthly and the pump checked to see that the
preservative is maintained. This will protect the pump for up to twelve months.
Pumps stored at low temperatures may need to be protected from freezing either by draining
completely or by using an anti-freeze solution.
Pumps with V-belt drives should have the belts loosened to relieve the belt tension during
storage. Do not store near running electric motors as ozone produced is detrimental to the
rubber in the belts.
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