Goulds Pumps 3180-86 - IOM - Manual (Page 57)

The dynamic seal consists of two parts:
• A repeller seal that prevents leaks during operation
• A secondary seal that prevents leaks when unit is off
Table 5: Dynamic seal part function
Part Description and function
Repeller seal A repeller seal prevents liquid from entering the stuffing box during operation.
The repeller normally does not require a flush. Some services might require a
flush if solids have built up on the repeller. The unit contains a flush tap for
that purpose. The unit also contains a drain tap to drain the repeller chamber if
there is a danger that the unit might freeze.
Secondary seal The secondary seal prevents leaks during pump shutdown. The seal can be one
of these types:
• Graphic packing
• Diaphragm seal
Table 6: Secondary seal part function
Secondary seal type Description and operation
Graphic packing Graphite packing provides adequate life running dry but can provide longer
performance if lubricated with clean water or grease.
• If you lubricate with clean water, then the repeller reduces both the
quantity and pressure of seal water that is necessary. If the suction head is
less than the repeller capability, then the stuffing box pressure is the same
as the atmospheric pressure. Water pressure for the seal must be high
enough to overcome static head when the pump is not operating to keep
solids in the pumped fluid out of the packing. There must be enough flow
to cool the packing.
• If you lubricate with grease, then you must use spring-loaded grease
lubricators in order to maintain a constant supply of grease.
Diaphragm seal This is an elastomeric disk that seals against a follower when the pump is not
operating. The position of the follower is set at the factory but should be
checked prior to start-up. The step on the follower should line up with the face
of the gland plate. Some adjustment might be required.
This seal is non-contacting during operation so no flush is required.
NOTICE: Do not flush the box through the lantern ring connection. If the
box becomes pressurized during operation from a flush or excessive suction
pressures, this will cause the diaphragm to contact the follower and destroy the
diaphragm.
Use the repeller flush connection if you need to flush the repeller. Never use
more than 20 psig (1.4 kg/cm 2 ) with the diaphragm option.
Pump priming
WARNING:
These pumps are not self priming and must be fully primed at all times during operation. Loss of prime
can lead to excessive heat and severe damage to the pump and seal.
Prime the pump with the suction supply above the pump
1. Slowly open the suction isolation valve.
2. Open the air vents on the suction and discharge piping until the pumped fluid flows out.
3. Close the air vents.
Commissioning, Startup, Operation, and Shutdown
Models 3180, 3181, 3185, and 3186 Installation, Operation, and Maintenance Manual 55