Maintenance Guidelines--Centrifugal Pump Fits and Clearance Checklist

Elfer Inc. TM
Maintenance
Guidelines

Machinery Reliability
Programs

Luis F. Rizo, PE Phone:
518-371-0683

4
Mates Way Fax:
518-371-0683

Waterford,
New York 12188-1165 http://www.elfer.com

8.1 Centrifugal
pumps fits and clearance checklist. Basic data

No:

Measurement

Tolerance

1.

Ball bearing inside diameter (I.
D.) to shaft.

0.0001"
to 0.0007" (0.003mm to 0.018mm) interference.

2.

Ball bearing outside diameter
(O. D.) to housing.

0.0001"
to 0.001" (0.003mm to 0.03mm) clearance.

3.

Sleeve to shaft.

0.001"
to 0.0015" (0.03mm a 0.04mm) clearance.

4.

Impeller to shaft.

Metal
to metal fit to 0.0005" (0.13mm) clearance.

Note: there are pumps such as horizontal, axial split pumps and
multi-stage vertical pumps that have interference fits. Consult your OEM
manual

5.

Throat bushing

a)

Throat bushing to case.

0.002"
to 0.003" (0.05mm a 0.08mm) interference.

b)

Throat bushing to shaft.

0.015"
to 0.020" (0.40 a 0.51mm) clearance.

c)

The
throat bushings on some vertical in-line pumps act as clearances.

intermediate
bearings and require closer.

6.

Impeller

a)

Impeller ring to hub.

0.002"
to 0.003" (0.05mm a 0.08mm interference.

The impeller ring is normally doweled or spot welded in at least two places

b)

Impeller ring to case ring
clearance.

0.010"
to 0.012" (0.254mm a 0.3mm) plus 0.001" (0.03mm) per in. (25.4mm) of
impeller ring diameter up to a 12" (3,658mm) ring. Add 0.0005 (0.013mm)
per inch (25.4mm) of ring diameter over 12" (3,658mm). For temp. > or = 500 degrees (260 oC) add 0.10" (2.54mm). Also add 0.005 (0.127mm) for
galling materials (stainless steel).

c)

Renew impeller rings when
clearance reaches twice original clearance.

7.

Case rings

a)

Case rings are not to be bored
out larger than 3% of original diameter.

b)

Case ring to case.

0.002"
to 0.003" (0.05mm a 0.08mm) interference.

The case ring is normally doweled or spot welded in at
least two places.

8.

Oil deflector to shaft.

0.002"
to 0.003" (0.05mm a 0.08mm) clearance. Install "O" ring in the
ID if possible.

9.

Packing gland

a)

Packing gland to shaft.

1/32"
(0.8mm) clearance.

b)

Packing gland to stuffing box
bore.

1/64"
(0.016mm) clearance.

10.

Lantern ring

.

a)

Lantern ring to shaft.

0.015"
to 0.020" (0.40mm a 0.51mm) clearance.

b)

Lantern ring to stuffing box.

0.005"
to 0.010" (0.13mm a 0.25mm) clearance.

11.

Coupling to shaft.

Metal
to metal to 0.0005 (0.013mm) clearance.

12.

Seal gland

a)

Seal gland alignment boss to
stuffing box.

0.002" to 0.004"
(0.05mm a 0.10mm) clearance.

b)

Seal gland throttle bushing to
shaft.

0.018" to 0.020"
(0.5mm to 0.51mm) clearance, unless otherwise specified for hot pumps.

13.

Seal locking collar to shaft.

0.002" to 0.004"
(0.05mm a 0.10mm) clearance

14.

Seal spring compression.

7/8" (22.2mm) long springs
- 3/16"(4.8mm).

"

æ" (12.5mm) long springs -
5/32"(4.0mm)

Seal spring compression.

1/2"(12.7mm) short springs - 1/16" (1.6mm) unless otherwise
specified by the manufacturer.

15.

Rotating and stationary seal
rings.

Sealing surfaces to be flat
within 3 Helium light bands

16.

Heads, case, suction cover,
bearing housing to case alignments fits.

0.004"
(0.01mm) maximum clearance. Use dial indicator and feeler gauges to correct
fit-up and alignment.

Horizontal axial split case

1. Stationary
parts fit case metal to metal to
0.004" (0.01mm) clearance.

2. Measure
and inspect case fits for wear and
corrosion. Repair by building up
and re-machining.

3. All
other repairs same as vertical radial split case pumps except: Case
rings to be bored in a jig not chucked.

4. Align
element in case with feeler gauges and dial indicator. Dowel bearing housing in place after
alignment.

5. When cutting gaskets
for horizontal split pumps, cut bolt hole openings on head and split gasket
lengthwise. Cut the rest of the
gasket on the case with all the slack in the boltholes pulled to the outside
edges. Leave stuffing box gasket
length long and trim after head has been set in place and tightened.

OVERHUNG IMPELLER, SEPARATELY COUPLED, SINGLE STAGE,
FRAME MOUNTED [i]

1 Casing

18 Bearing, outboard

47 Seal, bearing cover,
inboard

2 Impeller

19 Frame

49
Seal, bearing, cover, outboard

6 Shaft, pump

22 Locknut, bearing

67 Shim, frame liner

11 Cover, stuffing box

29 Ring, lantern

69 Lockwasher

13 Packing

37 Cover, bearing

71 Adapter

16 Bearing, inboard

40 Deflector

73 Gasket

17 Gland

46 Key, coupling

[i] Courtesy of the Hydraulic Institute
Standards.

Copyright Elfer, inc. 1998, Waterford, New
York

HOME PAGE

Leave A Comment

  • Web page addresses and e-mail addresses turn into links automatically.
  • Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.

More information about formatting options

By submitting this form, you accept the Mollom privacy policy.