HP 8-UB-1 User Manual download pdf (Page 24)

UB USER INSTRUCTIONS ENGLISH 71569247 07-04

Page 24 of 32

q) Remove impellers, casing rings, diaphragm plate

complete with its bush together with the impeller

key.

If impellers prove difficult to remove, the

use of heat is permissible. Refer to Section 1.6,

Safety, APPLYING HEAT TO REMOVE

IMPELLER, for more details.

r) If it is required to remove the diaphragm plate

bush then remove the 4 countersunk screws and

push out the bush.

s) If impeller rings are also fitted, they are shrunk

onto the impeller and fixed with locking screws

between their diametric mating surfaces.

t) To remove the impeller rings, remove the locking

screws and heat up the ring until it slides off easily.

6.9 Examination of parts

Used parts must be inspected before

assembly to ensure the pump will subsequently run

properly.

In particular, fault diagnosis is essential to enhance

pump and plant reliability.

6.9.1 Casing, seal housing and impeller

a) Inspect for excessive wear, pitting, corrosion,

erosion or damage and any sealing surface

irregularities.

b) Replace as necessary.

6.9.2 Shaft and sleeve (if fitted)

Replace if grooved, pitted or worn.

6.9.3 Gaskets and O-rings

After dismantling, discard and replace.

6.9.4 Bearings

It is recommended that bearings are not re-used after

any removal from the shaft.

6.9.5 Bearing isolators, labyrinths or lip seals

(if fitted)

a) The lubricant, bearings and bearing housing

seals are to be inspected for contamination and

damage.

b) If bearing damage is not due to normal wear and

the lubricant contains adverse contaminants, the

cause should be corrected before the pump is

returned to service.

c) Labyrinth seals and bearing isolators should be

inspected for damage but are normally non-

wearing parts and can be re-used.

d) Bearing seals are not totally leak free devices.

Oil from these may cause staining adjacent to the

bearings.

6.10 Assembly

To assemble the pump consult the sectional

drawings, see section 8, Parts list and drawings.

Ensure threads, gasket and O-ring mating faces are

clean. Apply thread sealant to non-face sealing pipe

thread fittings. Coat the outside diameter of the dowel

bushings with pipe compound prior to installation.

6.10.1 Impeller wear rings

a) Impeller rings (when fitted) should be heated up

to approximately 100 ºC (212 ºF) using a hotplate

or hot oil bath and then slipped onto the impeller

and pressed down to the shoulder. (Do NOT use

a steel hammer to knock them into position.)

b) Drill and tap 3 holes approximately 120 degrees

apart into the diametral mating faces of the ring

and impeller and insert socket head screws.

(The existing half tapped holes from the removed

impeller ring cannot be re-used.)

6.10.2 Pre-assembly of casing gasket

a) Fit casing gasket to the bottom half horizontal

flange using a small amount of contact adhesive

to prevent movement when the top half is fitted.

Do not apply adhesive to the top surface of the

gasket.

b) It is important that the external corner of the

casing gasket face and the stuffing box face is as

sharp as possible.

Do not chamfer with a file.

c) If necessary trim gasket to match volute profile.

Do not trim to stuffing box face at this stage.

6.10.3 Rotating element and bearing bracket

a) Ensure all gaskets and O-rings are renewed and

replaced in the correct position during assembly.

b) Assemble the impellers on the shaft. It is

important to mount the impellers so that the vane

tips point away from the apparent flow direction.

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HP 8-UB-1 User Manual Page 24

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