Tightness Test; Tightness Test Of Shaft Seal Housing; Tightness Test Of Stator Housing (Submerged) - Grundfos S Series Service Instructions Manual

10. Tightness test

Maintenance and service work on explosion-proof
pumps must be carried out by Grundfos or a service
workshop authorised by Grundfos.
The tightness test always has to be carried out if the motor has
been opened, and before refilling of oil.
Use nitrogen gas to test the tightness. If moisture enters the
stator chamber with compressed air, the moisture switch will trip.
Make sure that the pressure never exceeds 1 bar.
This could displace the seal.
Do not immerse the free end of the cable.

10.1 Tightness test of shaft seal housing

Make sure that there is tight seal between the seal housing (58)
and the stator housing (55). Make sure that no water gets into the
stator housing via the hose.
N or pressurised air
2
Fig. 22 Checking the shaft seal housing
1. Place the motor in horizontal position with a hoist.
2. Remove one oil plug (193) including the O-ring (194) from the
shaft seal housing (58).
Step 3 applies only to Ex pumps.
3. Fit the gas hoses (N or dry pressurised air) to the test plug
2
and pressurize the seal housing to 0.8 bar.
4. Remove the locking screw (25a) from the motor top cover
(164a).
5. Remove the screw (25) and O-ring (100) from the motor top
cover (164a).
6. Fit the test plugs () instead of the oil plug (193) and the screw
(25).
7. Submerge the hose end fitted to the motor top cover under
water in a test basin.
In order to detect possible leaks, let the hose end be
submerged for 15 minutes.
8. If air emerges (water bubbles) from the end of the hose, the
joint must be dismantled and the cause of the leak found and
corrected.
9. Lift the hose end out of the test basin.
10. Disconnect the gas hoses and the test plugs.
11. Fit the oil plug (193) including the O-ring (194) on the shaft
seal housing (58).
Step 12 applies only to Ex pumps.
12. Fit the screw (25) including the O-ring (100).
13. Fit the locking screw (25a).

10.2 Tightness test of stator housing (submerged)

N
2
1. Place the motor in horizontal position with a hoist.
2. Remove one oil plug (193) including the O-ring (194) from the
shaft seal housing (58).
Step 3 applies only to Ex pumps.
3. Remove the locking screw (25a) from the motor top cover
(164a).
4. Remove the screw (25) and O-ring (100) from the motor top
cover (164a).
5. Fit the test plugs () instead of the oil plug (193) and the screw
(25).
6. Fit the gas hoses (N or dry pressurised air) to the test plug
2
and pressurize the motor to 0.8 bar.
7. Submerge the motor under water in a test basin.
In order to detect possible leaks, let the hose end be
submerged for 15 minutes.
8. If air emerges (water bubbles) from the joints, the joints must
be dismantled and the cause of the leak must be found and
corrected.
9. Lift the motor out of the test basin.
10. Disconnect the gas hoses and the test plugs.
11. Fit the oil plug (193) including the O-ring (194) on the shaft
seal housing (58).
Step 12 applies only to Ex pumps.
12. Fit the screw (25) including the O-ring (100).
13. Fit the locking screw (25a).
or pressurised air
23