BJM Pumps LWA75H-575T - Manual (Page 15)

14
CHANGING SEAL OIL
Checking the seal chamber by following step one of the disassembly/assembly
procedures listed below. To change the seal chamber oil, drain the oil by removing drain
plug (55). Replace with the proper amount of ISO 32 NSF Food Grade Mineral Oil. Note
that a 10-15% air gap should be maintained in the seal chamber to allow for heat
expansion.
DISASSEMBLY/ASSEMBLY PROCEDURE FOR LWA TO REVIEW/REPLACE THE
MECHANICAL SEAL
1. Remove drain plug (55) from the seal housing (26) and take a sample of the oil. If
the oil is clear and shows no signs of water, then replace the drain plug. No
further inspection or disassembly is necessary until the next service period is
reached.
2. If the oil is milky and shows signs of water and/or other contaminants, then the
mechanical seal should be replaced. Proceed with draining the oil into a catch
basin for proper disposal.
3. Remove the suction strainer/stand (31) from the bottom of the pump by removing
the four retaining cap screws.
4. Remove the suction/wear plate (28) and O-Ring (47) by removing the four cap
screws that retain this.
5. Remove the agitator (39) by turning the agitator counter clockwise to the shaft. If
the agitator is difficult to turn, a plastic mallet or hammer and block of wood can
be used to strike against the agitator blades to break it loose from the shaft.
6. Remove the retaining nut by holding the impeller or shaft. Not do not damage the
shaft.
7. Remove the impeller (27) by sliding it off of the shaft with the shaft key (46). Take
note of any shims that are placed behind the impeller, these will need to be
reinstalled during assembly.
8. Remove the seal housing (26) by removing the four retaining cap screws. Note
that some residual oil will be found in the chamber.
9. Once the seal housing has been removed, remove all of the old seal parts. This
will require the removal of the stationary seal clamping ring and retaining screws.
10. Clean all parts and inspect for any damage. It is recommended that O-Rings and
lip seals be replaced when replacing the mechanical seal assembly (21).
11. Lubricate the cup of the stationary seal with a light amount of the Shell FM32 oil.
Using a pushing tool (PVC pipe), press the stationary seal into the pocket.
Repeat this step for both the upper and lower stationary seal.