Desmi NSLV Instruction Manual

OPERATION AND MAINTENANCE INSTRUCTIONS
DESMI end suction centrifugal pump
NSLV and NSLH Monobloc
DESMI Pumping Technology A/S
Tagholm 1 –DK-9400 Nørresundby –Denmark
Tel.:
[phone]
Fax:
[phone]
E-mail:
[email protected]
Internet:
www.desmi.com
Manual:
T1524
Language:
English
Revision:
L(12/22)
Special pump No. ...............................................

DESMI Pumping Technology A/S 2
Tagholm 1
9400 Nørresundby - Denmark
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Fax [phone]
E-mail: [e-mail] www.desmi.com
TABLE OF CONTENTS: PAGE
1. PRODUCT DESCRIPTION ........................................................................................................................... 4
1.1 DELIVERY............................................................................................................................................ 4
2. TECHNICAL DATA....................................................................................................................................... 4
2.1 EXPLANATION OF THE TYPE NUMBER ............................................................................................. 4
2.2 TECHNICAL DESCRIPTION.................................................................................................................. 6
3. INSTALLATION ............................................................................................................................................ 7
3.1 MOUNTING/FASTENING ...................................................................................................................... 7
3.2 WIRING................................................................................................................................................... 7
4. TRANSPORT/STORAGE ............................................................................................................................. 8
5. DISMANTLING.............................................................................................................................................. 9
5.1 ACCESS TO IMPELLER........................................................................................................................ 9
5.2 DISMANTLING SHAFT SEAL.............................................................................................................. 10
5.3 DISMANTLING SEAT .......................................................................................................................... 10
5.4 DISMANTLING BEARING (ONLY 02-COMBINATION)...................................................................... 10
5.5 INSPECTION........................................................................................................................................ 11
5.6 DISMANTLING COUPLING (02-COMBINATION) /SHAFT (12-COMBINATION) ............................. 12
6. ASSEMBLING............................................................................................................................................. 12
6.1 TIGHTENING TORQUES..................................................................................................................... 12
6.2 FITTING SEALING RINGS................................................................................................................... 13
6.3 FITTING BEARING (ONLY 02-COMBINATION) ................................................................................. 13
6.4 FITTING WATER DEFLECTOR (ONLY 02-COMBINATION).............................................................. 13
6.5 FITTING SHAFT SEAL......................................................................................................................... 13
6.6 FITTING IMPELLER............................................................................................................................. 14
6.7 FITTING SHAFT SEAL COVER OR MOTOR BRACKET (12-COMBINATION) ................................. 14
6.9 FITTING COUPLING (ONLY 02-COMBINATION)............................................................................... 15
7. FROST PROTECTION................................................................................................................................ 15
8. DISMANTLING............................................................................................................................................ 16
9. START-UP................................................................................................................................................... 16
9.1 START-UP............................................................................................................................................ 16
10. SYSTEM BALANCING ............................................................................................................................. 16
10.1 MECHNICAL SEAL FAILURE ANALYSIS ............................................................................................ 17
11. INSPECTION AND MAINTENANCE ........................................................................................................ 22
11.1 DRAINING THE PUMP....................................................................................................................... 23
11.2 BEARING ........................................................................................................................................... 23
12. REPAIRS................................................................................................................................................... 25
12.1 ORDERING SPARE PARTS.............................................................................................................. 25
13. OPERATING DATA .................................................................................................................................. 25
13.1ALLOWED MAXIMUM MOTOR FRAME SIZE .................................................................................. 25
13.2 MAXIMUM WORKING PRESSURE................................................................................................... 26
14. EU & UK DECLARATION OF CONFORMITY ......................................................................................... 27
15. ATEX DECLARATION OF CONFORMITY............................................................................................... 28
15.1 PRODUCT DESCRIPTION................................................................................................................. 28
15.2 PRECAUTIONS.................................................................................................................................. 28
16. INFORMATION RELEVANT FOR DISASSEMBLY OR DISPOSAL AT END-OF-LIFE ......................... 29

DESMI Pumping Technology A/S 3
Tagholm 1
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17. ASSEMBLY DRAWING Ø215/265/ 02-COMB......................................................................................... 30
18. SPARE PARTS LIST Ø215/265 ............................................................................................................... 30
19. ASSEMBLY DRAWING Ø330/415/465/525 02-COMB............................................................................ 31
20. SPARE PARTS LIST Ø330/415/465/525 WITH HEAVY BEARING HOUSING...................................... 31
21. ASSEMBLY DRAWING 300-418 02-COMB. ........................................................................................... 32
22. SPARE PARTS LIST 300-418 02-COMB................................................................................................. 32
23. ASSEMBLY DRAWING Ø215/265 12-COMB.......................................................................................... 33
24. SPARE PARTS LIST Ø215/265 12-COMB.............................................................................................. 33
25. ASSEMBLY DRAWING STAINLESS STEEL PUMP Ø215/265 12-COMB. ........................................... 34
26. SPARE PARTS LIST STAINLESS STEEL PUMP Ø215/265 12-COMB................................................. 34
27. ASSEMBLY DRAWING Ø330/415/525 12-COMB................................................................................... 35
28. SPARE PARTS LIST Ø330/415/525 12-COMB....................................................................................... 35
29. ASSEMBLY DRAWING 300-418 AND 350-525 12-COMB. .................................................................... 36
30. SPARE PARTS LIST 300-418 AND 350-525 12-COMB.......................................................................... 36
31. ASSEMBLY DRAWING 65-265/-02 WITH INDUCER.............................................................................. 37
32. SPARE PARTS LIST 65-265/-02 WITH INDUCER.................................................................................. 37
33. ASSEMBLY DRAWING 100-265/-02 WITH INDUCER............................................................................ 38
34. SPARE PARTS LIST 100-265/-02 WITH INDUCER................................................................................ 38
35. ASSEMBLY DRAWING 100-330/-02 AND 100-465/-02 WITH INDUCER. ............................................. 39
36. SPARE PARTS LIST 100-330/-02 AND 100-465/-02 WITH INDUCER................................................... 39
37. ASSEMBLY DRAWING 125-330/-02 WITH INDUCER............................................................................ 40
38. SPARE PARTS LIST 125-330/-02 WITH INDUCER................................................................................ 40
39.ASSEMBLY DRAWING 150-465/-02 WITH INDUCER............................................................................. 41
40. SPARE PARTS LIST 150-465/-02 WITH INDUCER............................................................................... 41
41.ASSEMBLY DRAWING 300-415/-02 WITH INDUCER............................................................................. 42
42. SPARE PARTS LIST 300-415/-02 WITH INDUCER............................................................................... 42
43. ASSEMBLY DRAWING NSLH 250-210/300-250/350-310/400-390/500-500/600-630. .......................... 43
44. SPARE PARTS LIST NSLH 250-210/300-250/350-310/400-390/500-500/600-630................................ 43
45. ASSEMBLY DRAWING NSLV 250-210/300-250/350-310/400-390/500-500/600-630............................ 44
46. NSLV 250-210/300-250/350-310/400-390/500-500/600-630 ................................................................... 44
47. DIMENSIONAL SKETCH.......................................................................................................................... 45
48. DESMI SUBSIDIARY................................................................................................................................ 46
49. SERVICE CENTER-DENMARK ............................................................................................................... 47
APPENDIX A................................................................................................................................................... 48
APPENDIX B................................................................................................................................................... 49

DESMI Pumping Technology A/S 4
Tagholm 1
9400 Nørresundby - Denmark
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1. PRODUCT DESCRIPTION
These operation andmaintenance instructions apply to the DESMI NSLV and NSLH Monobloc pump.
The NSLV pump is designed for vertical mounting (with suction flange downwards) and the NSLH
pump for horizontal mounting.
The pump is a single-stage end suction centrifugal pump equipped with stainless steel shaft,
mechanical shaft seal, and closed impeller.
The pump is suitable for the pumping of liquids with temperatures up to 80oC. With special shaft seal
up to 100oC in Monobloc pumps with bearing (/-02 design) and up to 140oC in Monobloc pumps
without bearing (/-12 design). For pumping of liquids with temperatures above 100oC DESMI
recommends using noting but ductile iron (for instance GGG40) for pump casing and rear cover.
Max. working pressure and number of revolutions are indicated under Operating Data.
The pump is particularly suitable for the pumping of water in connection with cooling systems, cooling
of diesel engines, as bilge pumps, ballast pumps, fire pumps, brine pumps, pumps for irrigation, fish
farms, water works, district heating, salvage corps, army and navy, etc.
The descriptions in the operation and maintenance instructions are divided into three parts covering
the groups ø215/265 and ø330/415/465/525 and ø210/250/310/390/500/630 as the designs of these
three groups are different. The numbers refer to the standard impeller diameter of the pump. E.g.:
ø215/265: Pumps with ø215 or ø265 impellers:
The back of the impeller is equipped with relief blades to reduce the load on the bearings.
ø330/415/465/525: Pumps with ø330, ø415, ø465 and ø525 impellers:
The back and the front of the impeller are equipped with sealing rings and relief holes to reduce the
load on the bearings.
ø210/250/310/390/500/630: Mixed flow pumps with ø210, ø250, ø310, ø390, ø500 and ø630
impellers: The front of the impeller is equipped with sealing rings.
1.1 DELIVERY
- Check on delivery that the shipment is complete and undamaged.
- Defects and damages, if any, to be reported to the carrier and the supplier
immediately in order that a claim can be advanced.
2. TECHNICAL DATA
The pumps are manufactured in various material combinations which appear from the type number
on the name plate. See below.
2.1 EXPLANATION OF THE TYPE NUMBER
All the NSLV and NSLH pumps are provided with a name plate. The type number indicated on the
name plate is built up as follows:
NSLVXXX-YYY/MR-Z or NSLHXXX-YYY/MR-Z
XXX: Pressure branch diameter, YYY: Nominal impeller diameter
M: The material combination of the pump.
R: The assembly combination of the pump.

DESMI Pumping Technology A/S 5
Tagholm 1
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Z: Other variants
M may be the following:
A: Casing and shaft seal cover : Cast iron + cast iron alloy. Impeller and sealing rings: Bronze
B: Casing and shaft seal cover : Cast iron + cast iron alloy. Impeller and sealing rings: Stainless.
C: All cast iron
D: Casing and shaft seal cover: Bronze or NiAlBz. Impeller and sealing rings: NiAlBz or stainless
steel
E: Special materials
S: Casing, shaft seal cover, impeller and sealing rings: SAF2507 and stainless steel alloy.
U: Nonmagnetic material
The pumps can be delivered in other material combinations accordingto agreement with the supplier.
R may be the following:
02: Monobloc, with bearing in the pump
07: Mounted on base plate with electric motor
09: Pump with bare shaft end
12: Monobloc, without bearing in the pump
13: Spacer, light bearing housing
14: Spacer, heavy bearing housing
15: Spacer, heavy bearing housing and heavy motor bracket (special motor bracket)
16: Compact spacer (i.e. pumps shown in this manual)
Z may be the following:
h : PN6 flanges
i : PN16 flanges
j : PN25 flanges
k : Special flange
l : Other shaft seal
m : BS flanges
n : ANSI flanges
o : Shockproof design
p : Other design
q : JIS flanges
r : With inducer
Any use of the pump is to be evaluated on the basis of the materials used in the pump. In case of
doubt, contact the supplier.
Pumps in material combinations A and C are primarily used for fresh water.
Pumps in material combination D and S are primarily used for seawater.
If the pumps are designed for special purposes the following is to be indicated:
Pump No. :
Pump type :
Application :
Comment :

DESMI Pumping Technology A/S 6
Tagholm 1
9400 Nørresundby - Denmark
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2.2 TECHNICAL DESCRIPTION
The noise level indicated is the airborne noise including the motor. The noise depends on the motor
type supplied, as the noise from the pump can be calculated as the noise level of the motor + 2dB(A).
The noise level is for pumps with electric motors.
The capacity of the pump appears from the name plate on the pump. If the pump has been delivered
without motor, the pump capacity is to be indicated on the plate when mounting the motor.
The permissible loads on the flanges appear from the following table. The values apply to standard
pumps in bronze (Rg5) and cast iron (GG20). As to pumps in SG iron (GGG40), NiAlBz or
stainless steel the values are to be increased by a factor 1.5.
Pump size
Fy
N
Fz
N
Fx
N
∑F
My
Nm
Mz
Nm
Mx
Nm
∑Mt
65-215
65-265
650
840
750
1340
510
310
380
700
80-215
80-265
80-330
800
950
850
1500
550
350
400
750
100-215
100-265
100-330
100-415
100-465
1000
1250
1150
2000
650
400
500
900
125-215
125-265
125-330
125-415
1250
1600
1430
2500
830
520
650
1160
150-265
150-330
150-415
150-465
1500
1900
1700
2950
1000
650
800
1400
200-265
200-330
200-415
200-525
2000
2520
2260
3920
1330
860
1060
1860
250-210
250-330
2500
3150
2820
4900
1770
1140
1400
2470

DESMI Pumping Technology A/S 7
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Pump size
Fy
N
Fz
N
Fx
N
∑F
My
Nm
Mz
Nm
Mx
Nm
∑ Mt
250-415
250-525
2500
3150
2820
4900
1770
1140
1400
2470
300-250
300-415
300-418
300-525
3000
3750
3350
5860
2750
1900
2200
4000
350-310
350-525
3500
4370
3920
6840
3630
2500
2930
5300
400-390
4000
5000
4480
7820
4600
3200
3700
6720
500-500
4500
5625
5040
8800
6090
4200
5040
8950
600-630
5000
6250
5600
9770
9800
6760
8100
14400
In connection with the permissible loads on the flanges the following is to be observed:
2
M
calc
M
+
F
calc
F
t
2 2





















where index "calc" is the values calculated by the user.
At the same time none of the forces or moments may exceed the indicated figure multiplied by 1.4.
3. INSTALLATION
See also: DESMI Guidelines for pump installations at:
www.desmi.com/media/sd5ltlox/guidelines_uk.pdf
3.1 MOUNTING/FASTENING
The pump should be mounted and fastened on a solid base plate or wall mounted frame so distortion
is avoided. The pumpshould be installed so that the motor can be pulled away from the pump during
maintenance work –i.e. any bolts mounted through the motor feet should be made so they are
possible to remove before the motor shall be pulled away from the pump.
The max. permissible loads on the flanges stated in paragraph 2.2 are to be observed.
At installations pumping hot or very cold liquids, the operator must be aware that it is
dangerous to touch the pump surface and, consequently, he must take the necessary
safety measures.
3.2 WIRING Wiring to be carried out by authorised skilled workmen according to the rules and
regulations in force.

DESMI Pumping Technology A/S 8
Tagholm 1
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4. TRANSPORT/STORAGE
See also: DESMI Pump Storage and Preservation at: www.desmi.com/media/vqkjqh54/t1534uk.pdf
The weights of the pumps in A(GG20&GGG40), D(RG5) and S(1.4436&1.4410) combination
(without motor or common baseplate) are stated in the following table, and the pumps are to be
lifted as shown below.
Pump size
Weight (Kg)
Pump size
Weight (Kg)
A/D/S-02
A/D/S-12
A/D/S-02
A/D/S-12
65-215
88/98/100
62/72/99
200-330
302/272/407
252/222/335
65-265
93/105/125
67/89/117
200-415
421/426/558
371/376/420
80-215
104/118/123
78/92/110
200-525
597/673/762
527/603/613
80-265
115/137/140
89/103/130
250-210
230/-/-
-
80-330
213/212/246
163/162/186
250-330
389/366/477
339/316/405
100-215
103/112/131
77/86/114
250-415
501/491/626
451/441/490
100-265
115/131/156
89/105/145
250-525
677/773/814
607/703/695
100-330
218/219/268
168/169/203
300-250
254/-/-
-
100-415
337/352/482
287/302/391
300-415
597/578/680
547/528/545
100-465
350/363/370
-
300-418
696/627/711
641/-/575
125-215
117/135/129
91/109/134
300-525
709/819/943
639/749/823
125-265
150/174/199
124/138/188
350-310
430/-/-
-
125-330
213/213/285
163/163/213
350-525
1060/-/-
1095/-/-
125-415
335/346/345
285/296/255
400-390
593/-/-
-
150-265
142/169/200
116/133/190
500-500
970/-/-
-
150-330
288/275/340
238/225/269
600-630
1820/-/-
-
150-415
353/360/392
303/310/299
150-465
-/403/-
-
200-265
247/283/260
221/247/235
The weight of the motor is given in motor operation manual. It can be found in
- Shipping documents together with the cargo
- Shipping mark on cargo box
- Other documents for the shipment, contracts or orders, etc.
The pump is to be stored in a dry area.
Before shipment the pump is to be fastened securely on pallets or the like.
The pumps are to be lifted in the following way:

DESMI Pumping Technology A/S 9
Tagholm 1
9400 Nørresundby - Denmark
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NSLV: NSLH:
The lifting straps must not bear against sharp edges and corners.
5. DISMANTLING
5.1 ACCESS TO IMPELLER
The numbers in brackets refer to the position numbers on the assembly drawing.
ø215/265 02-combination
Remove guards (28). Remove Allen screws (22) which hold the shaft seal cover (18) and the motor
bracket (20) to the pump casing (1). Dismantle copper pipe (58). Remove motor bracket and motor.
Loosen shaft seal cover (18) from pump casing by means of the two M12 bolts in the threaded holes
in the shaft seal cover. The shaft seal cover with shaft and impeller can now be lifted up allowing
inspection of the impeller.
ø215/265 12-combination
Remove guards (28). Remove Allen screws (22) which hold the motor bracket (20) to the pump
casing (1) (stainless steel pumps have separate rear cover (18) and motor bracket (20), and use
Allen screw (40) to connect). Dismantle copper pipe (58). The top piece can now be lifted up allowing
inspection of the impeller.
ø330/415/465/525 02-combination
Remove guards (28). Remove set screws (64) which hold the motor bracket (20) to the pump casing
(1). Dismantle copper pipe (58) (for NSLV). Remove motor bracket and motor. Remove set screws
(22) with washers (23), which hold the shaft seal cover (18) to the pump casing. Loosen the shaft
seal cover from the pump casing by means of the pointed screws (86). The shaft seal cover with
shaft and impeller can now be lifted up allowing inspection of the impeller.

DESMI Pumping Technology A/S 10
Tagholm 1
9400 Nørresundby - Denmark
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ø330/415/525 12-combination
Remove guards (28). Remove set screws (64) which hold the motor bracket (20) to the pump casing
(1). Dismantle copper pipe (58) (for NSLV). Remove set screws (22) with washers (23), which hold
the shaft seal cover (18) to the pump casing. Loosen the shaft seal cover from the pump casing by
means of the pointed screws (86). The motor and motor bracket with shaft seal cover and shaft with
impeller can now be lifted up allowing inspection of the impeller.
ø210/250/310/390/500/630 02-combination
Remove guards (28). Remove set screws (64) which hold the motor bracket (20) to the pump casing
(1). Dismantle copper pipe (58) (for NSLV). Remove motor bracket and motor. Remove set screws
(22) with washers (23), which hold the shaft seal cover (18) to the pump casing. Loosen the shaft
seal cover from the pump casing by means of the pointed screws (86). The shaft seal cover with
shaft and impeller can now be lifted up allowing inspection of the impeller.
5.2 DISMANTLING SHAFT SEAL
ø215/265 02-combination
Pull the shaft seal cover off the motor bracket, bywhich the coupling (19) is pulled off themotor shaft.
Remove nut (6). Pull off the impeller (5) and remove sunk key (9). Remove Allen screws (16), which
hold the bearing cover (15) to the shaft seal cover, pull shaft seal cover and bearing cover apart, by
which shaft seal (10) and water deflector (11) are pulled off the shaft.
ø215/265 12-combination
Remove nut (6). Pull off the impeller (5), and remove sunk key (9). Remove set screws (71) and pull
motor bracket and electric motor with shaft (17) apart, by which the shaft seal is pulled off the shaft.
ø330/415/465/525 02-combination
Remove set screw (6). Pull off the impeller, and remove sunk key (9). Remove set screws (16),
which hold the bearing cover (15) to the shaft seal cover, pull shaft seal cover and bearing cover
apart, by which the shaft seal (10) is pulled off the shaft.
ø330/415/525 12-combination
Remove set screw (6). Pull off the impeller, and remove sunk key (9). Pull shaft seal cover out of
motor bracket, by which the shaft seal (10) is pulled off the shaft.
ø210/250/310/390/500/630 02-combination
Remove set screw (6). Pull off the impeller, and remove sunk key (9). Remove set screws (16),
which hold the bearing cover (15) to the shaft seal cover, pull shaft seal cover and bearing cover
apart, by which the shaft seal (10) is pulled off the shaft.
5.3 DISMANTLING SEAT
Press out the seat from behind the shaft seal cover or motor bracket (ø215/265 in 12-combination)
5.4 DISMANTLING BEARING (ONLY 02-COMBINATION)
Before dismantling bearing, remove ring lock (12). Pull the shaft/coupling out of the bearing cover
and press the bearing out of the bearing cover.

DESMI Pumping Technology A/S 11
Tagholm 1
9400 Nørresundby - Denmark
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5.5 INSPECTION
When the pump has been dismantled, check the following parts for wear and damage:
- Sealing ring/impeller:
Pump Type
Impeller material
Max. clearance
measured in radius/mm
-215/265/330/415/465/525
NiAlBz/CC333G
0.4-0.5
Stainless steel
0.6-0.7
-210/250/310/390/500/630
NiAlBz/CC333G
0.6-0.7
Stainless steel
0.8-0.9
- Shaft seal/shaft seal cover: Check the seat for flatness and cracks.
Check the rubber parts for elasticity.
- Bearings: Replace in case of wear and noise.
- Sliding bearing/shaft: Wear=max. 0.7 mm diameter difference (only for NSLV mixed flow)

DESMI Pumping Technology A/S 12
Tagholm 1
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5.6 DISMANTLING COUPLING (02-COMBINATION) /SHAFT (12-COMBINATION)
It is not necessary to remove the coupling in the 02-combination or the shaft in the 12-combination
during normal maintenance. However, in the 12-combination the shaft must be removed when the
lower bearing in the electric motor is replaced.
02-combination:
Dismantle the coupling by removing the pointed screw (73) and pull off the coupling. If the coupling
is removed on the assembled pump, take care that the bearing is not damaged by pulling too hard
on the coupling. If the coupling is removed after dismantling the pump, fix the shaft at the thread at
the opposite shaft end, while the coupling is pulled off. The coupling might be heated to facilitate
dismantling.
12-combination:
Remove pointed screws (73). Pull off the shaft. The coupling might beheated to facilitate dismantling.
6. ASSEMBLING
The type of accessories used during assembling work including oil and grease shall meet the
requirement from application, food-approved if required.
6.1 TIGHTENING TORQUES
Part. No.
Thread
Size (mm)
Tightening Torque (Nm)
Pump Casing/Rear
Cover in GG20/Rg5
material
Pump Casing/Rear Cover
in GGG40/NiAlBz/SS
material
64
M8
8
16
M12
27
54
M16
65
130
22
M8
8
16
M12
27
54
M16
65
130
16
M12
27
54
M16
65
130
6
M16
65
M20
130
M24
220
71
M12
54
M16
130
M20
240
M24
400

DESMI Pumping Technology A/S 13
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6.2 FITTING SEALING RINGS
When fitted, the sealing ring (4) has to bear against the shoulder of the pump casing.
ø330/415/465/525
When fitted the sealing ring (27) has to bear against the shoulder of the shaft seal cover (20).
6.3FITTING BEARING (ONLY 02-COMBINATION)
Place the support disc (14) (grease valve ring in ø330/415/525 & ø210/250/310/390/500/630 with
angular ball bearings) in the bearing cover and press the bearing into place in the bearing cover.
Lead the shaft through the bearing cover, support disc and bearing, and press the bearing into
place up against the support disc. Fit ring lock (12).
ø330/415/465/525 & ø210/250/310/390/500/630
Fit cover under bearing (26). For pumps with Lip seal in cover under bearing please read appendix
B.
If shim(s) are mounted between cover under bearing (26) and bearing then also mount shim(s)
when bearings are replaced.
DESMI spare part numbers for 0.1 mm thick shims:
705057 (SHIM Ø110/140), 707214 (SHIM Ø130/160), 722876 (SHIM Ø160/190)
6.4FITTING WATER DEFLECTOR (ONLY 02-COMBINATION)
ø215/265
Assemble bearing cover and shaft seal cover. Lead the water deflector (11) over the shaft until it
touches the shaft seal cover and then further 1-1.5 mm into the shaft seal cover. Do not fasten
bearing cover and electric motor until motor and coupling have been mounted and the shaft can
rotate freely without noise.
ø330/415/465/525
Lead the water deflector (11) over the shaft until it touches the cover under bearing (26) and then
further 1-1.5 mm towards the cover under bearing. Assemble bearing cover and shaft seal cover.
Do not fasten bearing cover and electric motor until motor and coupling have been mounted and
the shaft can rotate freely without noise.
ø210/250/310/390/500/630
Lead the water deflector (11) over the shaft until it touches the cover under bearing (26) and then
further 1-1.5 mm towards the cover under bearing. Assemble bearing cover and shaft seal cover.
Do not fasten bearing cover and electric motor until motor and coupling have been mounted and
the shaft can rotate freely without noise.
6.5FITTING SHAFT SEAL
For pumps with balanced shaft seal type ELK (=”-L” included in pump code on name plate) please
read appendix A
Before fitting the seat, clean the recess in the shaft seal cover or the motor bracket (ø215/265 in
12-combination). When fitting the seat, remove the protective coating without scratching the lapped
surface and lubricate the outer rubber L-ring of the seat with a thin layer of silicone grease. Use a
brush and ensure that no silicone grease ends up at the slide surface. Now press the seat into
place with the fingers and check that all parts are correctly imbedded.

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If it is necessary to use tools for assembling, then protect the sliding surface of the seat to prevent
it from being scratched or cut. Lubricate the inner surface of the slide ring rubber bellows with a
thin layer of silicone grease (ensure that no silicone grease ends up at the slide surfaces) and push
it over the shaft. The use of a conical fitting bush as shown on the assembly drawing is
recommended to avoid that the rubber bellows is cut.
Push the slide ring over the shaft with the hand. If the rubber bellows is tight, use a fitting tool and
take care that the slide ring is not damaged. If the carbon ring is not fixed, it is important to check
that it is fitted correctly, i.e. the chamfered/lapped side is to face the seat. The carbon ring can be
held by a little grease.
When using silicone grease on the shaft, the bellows will settle and seat in abt. 15 minutes, and
until then tightness should not be expected. After start, check by viewing the leak hole that there
are no leaks.
6.6FITTING IMPELLER
Fit the sunk key in the shaft and lead the impeller towards the shoulder of the shaft. Take care that
the ring at the end of the shaft seal spring locates in the recess of the impeller. Secure the impeller
with washers (7 and 8) and a nut (ø215/265) or a set screw (ø330/415/465/525). Secure set screw
(6) or nut (6) with a removable screw locking agent, e.g. Loctite 243 or Omnifit 40M. Tighten
according to below table.
6.7FITTING SHAFT SEAL COVER OR MOTOR BRACKET (12-COMBINATION)
Place the O-ring (21) between pump casing and shaft seal cover (or motor bracket in ø215/265 12
combination) in the O-ring groove and hold it with a little grease. However, check the material of
the O-ring first. As standard the material is nitrile, but it might be EPDM which will be damaged by
mineral grease. Use soft soap or silicone grease for EPDM. Fit and fasten shaft seal cover or
motor bracket, mounted with the electric motor, in the pump casing. Screw the pointed screws (86)
back into the shaft seal cover before tightening. Fit copper pipe (58).
6.8 SHAFT
When the pump has been assembled, check that the shaft rotates freely. In case the shaft has
been dismantled in the 12-combination, tap the shaft towards the shaft end of the electric motor by
means of a plastic hammer, and fasten the pointed screws (first the middle screw) according to the
below table. Check that the wobble, measured as close to the shaft end as possible, is within the
limits indicated in the table.
Motor size
Dimension Pointed
screws
Torque Pointed
screws
Max. wobble
100/112
M6
10 Nm
70 μm
132
M8
24 Nm
70 μm
160
M10
40 Nm
70 μm
180
M12
55 Nm
70 μm
200
M12
75 Nm
70 μm
225
M16
160 Nm
70 μm

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Motor size
Dimension Pointed
screws
Torque Pointed
screws
Max. wobble
250
M16
160 Nm
70 μm
280
M16
160 Nm
70 μm
315
M16
160 Nm
70 μm
315 / 355
M20
320 Nm
70 μm
6.9FITTING COUPLING (ONLY 02-COMBINATION)
Fit sunk key (76). If the coupling is fitted on the assembled pump, take care that you do not
damage the bearing by pressing the coupling too hard. The coupling might be heated to facilitate
the fitting. If the coupling is fitted before assembling the pump, the shaft must be supported at the
opposite shaft end while the coupling is pressed into place. When the coupling bears against the
shoulder of the pump shaft, fit the pointed screw.
7. FROST PROTECTION
Pumps which are not in operation during frost periods are to be drained to avoid frost damage.
Remove the plug (3) at the bottom to empty the pump. Alternatively, it is possible to use anti-freeze
liquids in normal constructions.

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8. DISMANTLING
Before dismantling the pump make sure that it has stopped. Empty the pump of liquid before it
is dismantled from the piping system. If the pump has been pumping dangerous liquids you are
to be aware of this and take the necessary safety measures.
If the pump has been pumping hot liquids, take great care that it is drained
before it is removed from the piping system.
9. START-UP
A centrifugal pump will not function until it has been filled with liquid between the foot valve and
somewhat above the impeller of the pump.
The liquid also serves as coolant for the shaft seal. In order to protect the
shaft seal the pump must not run dry.
For safety reasons the pump is only allowed to operate against closed discharge valve for a short
time (max. 5 minutes and at a max. temperature of 80°C for standard pumps). Otherwise there is a
risk of damage to the pump and, at worst, of a steam explosion. If the pump is not monitored, the
installation of a safety device is recommended.
9.1 START-UP
Before starting the pump check that:
- the shaft rotates freely without jarring sounds.
- the pump casing and the suction line are filled with liquid.
Start the pump for a moment to check the direction of rotation. If the direction is correct (i.e. in the
direction of the arrow) the pump may be started.
10. SYSTEM BALANCING
It is often difficult to calculate a manometric delivery head in advance. It is, however, decisively
important to the quantity of liquid delivered.
A considerably smaller delivery head than expected will increase the quantity of liquid delivered,
causing increased power consumption and perhaps cavitation in pump and piping. In the pump the
impeller may show signs of heavy erosion caused by cavitation (corrosion) which may at times
render an impeller unfit for use in a very short time. Not unusually do similar erosions occur in pipe
bends and valves elsewhere in the piping system.
Therefore, after start-up, it is necessary to check either the quantity of liquid delivered or the power
consumption of the pump e.g. by measuring the current intensity of the connected motor. Together
with a reading of the differential pressure the quantity of water delivered can be determined against
the characteristics of the pump.
Should the pump not function as intended, please proceed according to the fault-finding list. Bear
in mind, though, that the pump was carefully checked and tested at the factory and that the
ATTENTION

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majority of faults stem from the piping system.
FAULT
CAUSE
REMEDY
The pump has no or
too low capacity
1. Wrong direction of rotation
Change direction of rotation to
clockwise when viewed from shaft
end (the direction of the arrow)
2. Piping system is choked
Clean or replace the piping
system
3. The pump is choked
Clean the pump
4. Suction line leaks
Find the leakage, repair the fault,
non-return valve not submerged
5. Pump takes air
6. Suction lift is too high
Check data sheet Q/H curve and
NPSH or contact DESMI
7. Pump and piping system
wrongly dimensioned
As 5
The pump uses too
much power
1. Counter-pressure is too low
Insert orifice plate or check valve
/ Contact DESMI
2. The liquid is heavier than
water
Contact DESMI
3. Foreign body in pump
Dismantle the pump, remove the
cause
4. Electric motor is running on
2 phases
Check fuses, cable connections,
and cables
The pump makes
noise
1. Cavitation in pump
Suction lift is too high / Suction
line wrongly dimensioned / Liquid
temperature is too high
10.1 MECHNICAL SEAL FAILURE ANALYSIS
Description of
possible failure
Impacts on the
pump/system
Indications of
failure
How to avoid
Pump settled (due to
seizing sliding rings
in mechanical shaft
seal) due to standstill
after storage
Mechanical seal
failure/leaking after
short time
1. Initial leaking
after first start up
that does not
stop after short
time
1. Ensure correct
storage of pumps
2. Preventive
maintenance to
be followed for
long term
storage
3. Rotate pump
carefully by hand
prior to first start
up, to ensure
integrity of mech.
shaft seal

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Description of
possible failure
Impacts on the
pump/system
Indications of
failure
How to avoid
Pump settled (due to
seizing sliding rings
in mechanical shaft
seal) due to standstill
in system / stored
with water inside for
longer duration of
time
Medium could
change properties
when standstill in
pump based on the
environment and
type of medium
1. Higher power
consumption
than calculated
short time after
startup
2. Leakage from
mech. shaft seal
after start up
1. Rotate the pump
regularly, to
avoid seizing
2. If not possible,
pumps should be
drained
Lack of NPSH
available vs. NPSH
required
Cavitation duty,
creating vibration
and mechanical
damage
1. Vibration and
noise from the
pump
2. Wear on
impeller/seal
ring, and
possible leaking
mec. seal
1. Make sure to
have sufficient
NPSHa at all
times
Bad piping and fitting
arrangement
Turbulent flow and
vibrations in the
system
1. Vibration, and
noises from the
piping system.
2. Possible
premature
leakage from
mec. seal
1. Check piping and
fitting
arrangement is in
accordance with
CEN standards.
2. Should be
reviewed and
approved in
design phase
Starvation / lack of
inlet flow
Pump not receiving
enough liquid to give
a stable operation,
pump not giving
sufficient flow. Could
cause insufficient
liquid film in seal and
cause dry running
1. Vibrations in the
pump and
unstable
operational
readings
2. Flow not
increasing at
higher pump
speed.
3. Possible leaking
mechanical seal
1. Make sure all
valves are open,
and no filters are
clogged etc.
2. Check piping and
fittings
3. Other consumers
on the same
suction line might
cause problems

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Description of
possible failure
Impacts on the
pump/system
Indications of
failure
How to avoid
High liquid velocities
Vibrations and
turbulent flow in the
system
1. Noise, vibration
and lack of pump
performance.
2. Possible leaking
mech. shaft seal
1. Make sure to
have piping
dimensioned for
specified flow
rating
2. In general liquid
velocity should
increase from
piping inlet
trough the pump
to the outlet
External excited
vibrations from the
vessel or piping
system
If above
recommended levels
(7mm/s) it can lead
to premature
mechanical failures
1. Visual and
measured
vibration levels.
2. Leaking mech.
shaft seal
1. Install vibration
reducing
components
such as flexible
bellows at
inlet/outlet,
vibration pads on
base plate,
horizontal lateral
support on motor
Dry running of the
pump –closed
inlet/discharge valve
Pump should never
be run dry, this will
damage the
mechanical seal in
very short time, and
will cause bearing
failure and total
pump breakdown
1. Valves closed,
quickly
generating heat
in the pump, high
noises,
increased power
consumption
before total
breakdown
1. Always make
sure pump is
never operated
dry (check
regularly that any
priming systems
are working)
and/or with
closed suction
valves.
2. Can operate for
a short time
towards shut
discharge valve,
refer to the
chapter 9

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Description of
possible failure
Impacts on the
pump/system
Indications of
failure
How to avoid
Operating outside
recommended QH
area (70-120% of
BEP)
Can lead to
premature
mechanical failure
and further damage
1. Readings of
operational/log
data.
2. At least diff.
pressure, power
and pump speed.
Compare with
design
specification
1. Continuously
monitoring the
operation.
2. Use limitations
and alarms in the
control system –
min/max rpm,
flow, pressure
Medium and/or
pressure and/or
liquid temperature
not according to
specification
Depends on
specification and
actual difference in
this
1. Abnormal wear
and corrosion in
the pump.
2. Leaking
mechanical seal
1. Mechanical seal
material and
properties are
specified based
on medium and
conditions.
2. Difference in
spec. might
require a
different
mechanical seal /
pump material
Water hammer /
hydraulic shocks
Cause a tremendous
pressure shock to
the pump and
system that could
cause serious
damage
1. Shutting down
and closing
valves creates
noise and give
hydraulic shocks
to the whole
system
2. Will cause
mechanical
damage, not only
to mechanical
seals
1. Have sufficient
ramp down time
and avoid closing
valves too fast.
2. Correct usage of
non-return valves
Pump parts (e.g.
vent/flush piping) in
pump clogged up
Missing supply of
liquid for
cooling/lubrication of
mechanical shaft
seal and/or missing
automatic air venting
of shaft seal
chamber
1. Seal leakage
after short time
1. Ensure proper
filters / mesh size
on suction side
of pump.
2. If solids sediment
inside pump
parts (e.g.
piping) they must
be disassembled
and cleaned
inside regularly