Graco 312792G Merkur Displacement Pump Users Manual 312792G, Pump, Repair/Parts, English

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Repair/Parts

Merkur®
Displacement Pump

312792G
EN

For use with high-performance finishing and coating pumps in hazardous and
non-hazardous locations. For professional use only.
Important Safety Instructions
Read all warnings and instructions in this manual.
For complete warnings and instructions see your
pump or package manual. Hazard symbols refer to
specific procedure risks. Save all instructions.
See page 3 for model information, including maximum working pressures.

LW025A

LW150A

TI11643a

TI11645

Related Manuals

Contents
Related Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . .
Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Identification . . . . . . . . . . . . . . . . . . . .
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information . . . . . . . . . . . . . . . . . . . . . .
Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2
3
4
5
5
5
5
6

Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Standard Repair Kits . . . . . . . . . . . . . . . . . . . . . . . 11
Optional Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Graco Standard Warranty . . . . . . . . . . . . . . . . . . . 14
Graco Information . . . . . . . . . . . . . . . . . . . . . . . . . 14

Related Manuals

2

Manual

Description

312796

NXT™ Air Motor

312794

Merkur Pump Assembly

312797

Merkur Spray Packages, ambient, AA
and Airless

312798

Merkur Electrostatic Spray Packages

313255

Merkur Heated Spray Packages

312792G

Models

Models
Check your displacement pump’s identification marking for the 6-digit part
number. Use the following matrix to define the construction of your displacement pump. For example, displacement pump model LW025A represents a
wet-cup style stainless steel displacement pump, 25 cc, with a Chromex
coated rod and 3 UHMWPE, 2 PTFE packings.
To order replacement parts, see Parts section starting on page 9. The digits in
the matrix do not correspond to the reference numbers in the Parts drawings
and lists.

L

First Digit

L

ti12415a

W

025

A

Second Digit
(Description)

Third, Fourth, and Fifth
Digits
(Displacement Pump
Volume Per Cycle* in cc)

Sixth Digit
(Packings; Displacement Rod Coating)

W

(Lower)

Wet-cup style,
stainless steel

025

A

3 UHMWPE, 2 PTFE; Chromex™

050
075
100
125
150
* Cycle refers to combination of one upstroke and one downstroke.

Maximum Working
Pressure
psi (MPa, bar)

Fluid Inlet

Fluid Outlet

LW025A, Series A

3000 (20.7, 207)

1/2 in. npt

3/8 in. npt

LW050A, Series A

4500 (31.0, 310)

3/4 in. npt

3/8 in. npt

LW075A, Series A

4800 (33.1, 331)

3/4 in. npt

3/8 in. npt

LW100A, Series A

3600 (24.8, 248)

3/4 in. npt

3/8 in. npt

LW125A, Series A

2900 (20.0, 200)

1 in. npt

1/2 in. npt

LW150A, Series A

2400 (16.5, 165)

1 in. npt

3/4 in. npt

Model, Series

312792G

3

Component Identification

Component Identification
A
B

F
C

E
G

D
ti11645a

FIG. 1. Component Identification
Key:
A
B
C
D
E
F
G

4

Piston/Rod Assembly
Wet Cup
Fluid Outlet
Fluid Inlet
Lower Cylinder
Upper Cylinder
Intake Valve

312792G

Repair

Repair

Threads are very sharp. Use a rag to protect hands.

General Information
NOTICE
Reference numbers and letters in parentheses in the
text refer to the callouts in the figures and the parts
drawing.
Always use Genuine Graco Parts and Accessories,
available from your Graco distributor. If you supply
your own accessories, be sure they are adequately
sized and pressure rated for your system.

Preparation

1. Place cylinder (1)
sideways in a vise
with soft jaws.
2. Use an adjustable
wrench on hex of
intake housing
(23) to unscrew it
from the lower
cylinder (2).
Loosen vice
briefly and tip out
the ball (24◆).

ti12918a

3. Remove the seat (22†) and use an o-ring pick to
remove the seal (26†) from the intake housing. See
FIG. 7.
Follow all warnings and instructions in your pump manual for the following preliminary steps:
1. Flush the equipment.
2. Relieve the pressure.
3. Remove the displacement pump from the pump
assembly.

Disassembly
Lay out all removed parts in sequence to ease
reassembly. Clean all parts with a compatible solvent
and inspect them for wear or damage.
NOTICE
Repair Kits are available. See the chart on page 11
to order the correct kit(s) for your pump.
•
•
•

Parts included in the Seal Repair Kit are marked
with an *, for example 8*.
Parts included in the Seat Repair Kit are marked
with a †.
Parts included in the Check Ball Kit are marked
with a ◆.

312792G

4. Use an adjustable wrench on hex of lower cylinder
(2) to remove it from the upper cylinder (1) and slide
it straight off the pump. Be careful not to damage
the piston/rod assembly (3).
5. Remove the o-ring (21*†) from the top of the lower
cylinder.
6. Loosen the wet cup (5).
7. Pull the piston/rod assembly out the bottom of the
upper cylinder. Remove the spring (10*), piston
packings (12* and 13*) and glands (11* and 14*).
8. Remove the wet cup (5).
9. Remove the throat packings (7*, 8*) and glands (6*,
9*) from the bottom of the wet cup.
NOTICE
The jam nut can remain attached to the upper cylinder.
10. Remove the spring (4*) from the top of the upper
cylinder (1).

5

Repair

11. Remove the wet cup seal (27*) and the upper cylinder seal (28*).
12. Clamp the piston in a vice. Use a hex wrench to
remove the nut (17†) from end of piston.
•
•

LW025A–LW050A: 7 mm (1/4 in.) hex
LW075A–LW150A: 13 mm (1/2 in.) hex

Reassembly
1. Clean and inspect all parts.
NOTICE
Replace all o-rings removed from the pump. Compressed o-rings may cause the pump to leak.
2. Lubricate and install new wet cup seal (27*) and
upper cylinder seal (28*).
3. Assemble the female gland (9*), v-packings (7*, 8*),
and male gland (6*), as shown. Alternate the
v-packings with the lips facing down. Lubricate the
packings. Install the packing stack into the wet
cup (5).

*27
5
ti12782a

FIG. 2. Remove Flow-Through Nut

*9
*7

13. Remove the o-ring (18†), seat (15†) and ball (16◆).
See FIG. 5.

*8
*7
*8

Lips must
face down.

*7
*6
*28
ti11691a

FIG. 3. Replace Throat Packings
4. Install the spring (4*) in the top of the upper cylinder.
NOTICE
All threads, packings, and seals must be well lubricated. Use Lubriplate (Graco Part Number 285791)
or a similar product.
5. Lubricate the threads and screw the wet cup (5) into
the upper cylinder (1), hand tight.

6

312792G

Repair

6. Assemble the male gland (11*), v-packings (12*,
13*), and female gland (14*), as shown. Alternate
the v-packings, with the lips facing up. Lubricate the
packings. Install the spring (10*) and packing stack
into the bottom of the upper cylinder (1).

5

8. Place piston in vice and torque flow-through nut
(17†) as specified in the following table.
Displacement Pump

Torque

LW025A–LW050A

58-62 ft-lb (78-84 N•m)

LW075A–LW150A

78-82 ft-lb (105-111 N•m)

4*

1

3

◆16

10*

†15
†18
ti11692a
†17
FIG. 5. Replace piston ball and seat.

11*
12*
13*
12*
13*
12*
14*

Lips must
face up

9. Push the piston/rod assembly (3) into the upper
cylinder (1).
10. Lubricate and install the seal (21*) on the top of the
lower cylinder (2).

ti11693a

FIG. 4. Replace piston packings.

11. Lubricate the threads and screw the lower cylinder
(2) onto the upper cylinder (1). Torque to 95-105
ft-lb (128-142 N•m).

7. Place the ball (16◆) in the piston body. Install the
seat (15†) and o-ring (18†). Lubricate the o-ring and
the threads of the flow-through nut (17†). Screw the
flow-through nut (17†) into the piston/rod
assembly (3).

312792G

7

Repair

14. Lubricate the seal (25*†) and threads of the lower
cylinder (2). Place the ball (24◆) on the seat (22†).

25✓
1

24✓
22✓
26✓
23

3
ti11694a

FIG. 7. Replace intake ball and seat.
15. Keep upright to screw the housing (23) into the
lower cylinder (2) hand tight, so the seat remains
firmly in place. Then clamp the cylinder in a vice and
torque as specified in the following table.

21*
2
25*†
ti12414a

FIG. 6. Assemble piston/rod assembly and cylinders.
12. Lubricate and install the seal (25*†) on the bottom of
the lower cylinder (2).

Displacement Pump

Torque

LW025A–LW050A

58-62 ft-lb (78-84 N•m)

LW075A–LW150A

78-82 ft-lb (105-111 N•m)

16. Torque wet cup (5) to 58-62 ft-lb (78-84 N•m).

13. Install the o-ring (26†) and intake seat (22†) into the
top of the inlet housing. Lubricate the o-ring. The
seat (22†) is reversible. Turn over or replace as
needed.

8

312792G

Parts

Parts
37
36

Lubricate.

1
2
3

35
1 27*
5

2 5

Torque to 95-105 ft-lb (128-142 N•m)
Torque varies by lower size.

4 LW025A-LW050A: 58-62 ft-lb (78-84 N•m)

LW075A-LW150A: 78-82 ft-lb (105-111 N•m)

5

9*
7*
8*
7*
8*
7*
6*

1

Torque to 58-62 ft-lb (78-84 N•m)

Apply thread lubricant.

3

28*
4*

2

16◆
15†
18*† 1
17† 4 5

1 33*
5 32

21*† 1
3 5

1

2

10*

4 5

25*† 1
24◆
22†
26*† 1

11*
12*
13*
1 12*
13*
12*
14*

23

ti11644a

312792G

9

Parts

Ref.

Description
21*† O-RING, lower cylinder
22† SEAT, intake valve, tungsten
carbide
INTAKE VALVE KIT; includes 26
23
LW025A
LW050A
LW075A
LW100A
LW125A
LW150A
24◆ BALL, intake valve, 440 stainless
steel
25*† O-RING, lower cylinder

Part
-----

Qty.
1

-----

1

26*† O-RING, intake valve
27* O-RING, wet cup; package of 10
LW025A
LW050A-LW075A
LW100A
LW125A-LW150A
28* O-RING, wet cup

6*

1

7*

PACKING, throat, UHMWPE

-----

3

8*

PACKING, throat, PTFE

-----

2

9*

GLAND, female, throat

-----

1

10*

SPRING, piston

-----

1

11*

GLAND, male, piston

-----

1

12*

PACKING, piston, UHMWPE

-----

3

13*

PACKING, piston, PTFE

-----

2

14*

GLAND, female, piston

-----

1

----- Not sold separately.

15†

SEAT, piston valve, tungsten
carbide
BALL, piston valve, 440 stainless steel
NUT, flow through

-----

1

* Included in Seal Repair Kit. See page 11.

-----

1

† Included in Seat Repair Kit. 316 stainless steel seats
also are available. See page 11.

-----

1

-----

1

1

2

3

4*
5

16◆
17†

18*† O-RING, piston

10

Qty.
1

Ref.

Description
Part
CYLINDER KIT, upper; includes
21, 28, 32, and 33 (qty. 1)
LW025A
24A813
LW050A
24A814
LW075A
24A815
LW100A
24A816
LW125A
24A817
LW150A
24A818
CYLINDER KIT, lower; includes
21 and 25
LW025A
24A822
LW050A
24A823
LW075A
24A824
LW100A
24A825
LW125A
24A826
LW150A
24A827
PISTON/ROD, assembly;
includes 15-18, 36, and
37 (qty. 1)
LW025A
24A643
LW050A
24A644
LW075A
24A645
LW100A
24A646
LW125A
24A647
LW150A
24A648
SPRING, throat
----WET CUP; includes 27 and 28
(qty. 1 each)
LW025A
24A807
LW050A
24A808
LW075A
24A809
LW100A
24A810
LW125A
24A811
LW150A
24A812
GLAND, male, throat
-----

1

1

32

1
1

33*

35

36

37

FITTING, outlet, 3/8-18 npt X
3/4-16 unf; includes 33 (qty. 1)
LW025A-LW100A
LW125A
LW150A
O-RING, outlet; package of 10
LW025A-LW100A
LW125A
LW150A
JAM NUT
LW025A
LW050A
LW075A
LW100A
LW125A
LW150A
NUT, coupling
LW025A
LW050A-LW150A
COLLAR, coupling; pkg. of 10
LW025A
LW050A-LW150A

1
24A834
24A835
24A836
24A837
24A838
24A839
-----

1

-----

2

-----

1
1

24A630
24A631
24A632
24A633
-----

1
1

24A840
24A841
24A842
1
24E457
24E458
24E459
1
24A634
24A635
24A636
24A637
24A638
24A639
1
15M758
15T311
1
24A618
24A619

◆ Included in Check Ball Kit. Tungsten carbide and 316
stainless steel check balls also are available. See
page 11.

312792G

Standard Repair Kits

Standard Repair Kits
Kit Description

LW025A

LW050A LW075A LW100A LW125A

LW150A

* Seal Repair Kit
Throat v-packings (7* and 8*) and glands (6*
and 9*), piston v-packings (12* and 13*) and
glands (11* and 14*), o-rings (18*, 21*, 25*, 26*
27*, 28*, and 33*), and springs (4*and 10*)

24A251

24A252

24A253

24A254

24A255

24A256

V-Packing Repair Kit
Throat v-packings (7* and 8*), piston v-packings
(12* and 13*, and o-rings (18*, 21*, 25*, 26*
27*, 28*, and 33*)

---

---

24R167

24R168

---

† Tungsten Carbide Seat Repair Kit
Seats (15† and 22†), o-rings (18†, 21†, 25†,
and 26†), and flow-through nut (17†)

24A781

24A782

24A783

24A784

24A785

24A786

◆ 440 Stainless Steel Check Ball Kit
Piston ball (16◆) and intake ball (24◆)

24A261

24A261

24A263

24A264

24A264

24A264

Wet-Cup O-Ring (27)
Package of 10

24A630

24A631

24A631

24A632

24A633

24A633

Coupling Collars (37)
Package of 10

24A618

24A619

24A619

24A619

24A619

24A619

Kit Description

LW025A

LW050A LW075A LW100A LW125A

LW150A

Reinforced PTFE V-Packing Kit**
Reinforced PTFE throat packings and glands,
reinforced PTFE piston packings and glands,
o-rings, and springs

24J852

24J853

24J854

24J855

24J856

24J857

†316 Stainless Steel Seat Repair Kit***
Seats (15† and 22†), o-rings (18†, 21†, 25†,
and 26†), and flow-through nut (17†)

24A794

24A795

24A796

24A797

24A798

24A799

316 Stainless Steel***

24P612

24P612

24P613

24P614

24P614

24P614

Tungsten Carbide

24A667

24A667

24A669

24A670

24A670

24A670

---

Optional Kits

◆Check Ball Kit
Piston ball (16◆) and intake ball (24◆)

** Use with materials that cause chemical compatibility concerns with UHMWPE, such as acid catalyst materials.
*** Replaces standard kits for high corrosive applications.

312792G

11

Dimensions

Dimensions
Model LW025A

Model LW150A

A

A

C

C

B

B
ti11643a

ti11645a

FIG. 8

Displacement Pump Dimensions
Displacement
Pump

A
(Height*)

B
(Inlet Size)

C
(Outlet Size)

Weight

in. (mm)

in. npt

in. npt

lbs (kg)

LWO25A

14.9 (378)

1/2 in.

3/8 in.

9.0 (4.1)

LW050A

14.8 (376)

3/4 in.

3/8 in.

13.2 (6)

LW075A

15.4 (391)

3/4 in.

3/8 in.

15.3 (6.9)

LW100A

15.4 (391)

3/4 in.

3/8 in.

18.6 (8.4)

LW125A

15.6 (396)

1 in.

1/2 in.

21.2 (9.6)

LW150A

15.6 (396)

1 in.

3/4 in.

22.0 (10)

* Height measured at mid-stroke.

12

312792G

Technical Data

Technical Data
Maximum fluid working pressure
LW025A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW050A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW075A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW100A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW125A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW150A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum operating temperature . . . . . . . . . . . . . . . . . . .
Fluid inlet size
LW025A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW050A– LW100A . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW125A–LW150A . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid outlet size
LW025A–LW100A . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW125A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LW150A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stroke length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wetted parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

312792G

3000 psi (20.7 MPa, 207 bar)
4500 psi (33.1 MPa, 310 bar)
4800 psi (33.1 MPa, 331 bar)
3600 psi (24.8 MPa, 248 bar)
2900 psi (20.0 MPa, 200 bar)
2400 psi (16.5 MPa, 165 bar)
160°F (71°C)
1/2 in. npt
3/4 in. npt
1 in. npt
3/8 in. npt
1/2 in. npt
3/4 in. npt
2.5 in.
stainless steel, tungsten carbide, UHMWPE, PTFE

13

Graco Standard Warranty
Graco warrants all equipment referenced in this document which is manufactured by Graco and bearing its name to be free from defects in
material and workmanship on the date of sale to the original purchaser for use. With the exception of any special, extended, or limited warranty
published by Graco, Graco will, for a period of twelve months from the date of sale, repair or replace any part of the equipment determined by
Graco to be defective. This warranty applies only when the equipment is installed, operated and maintained in accordance with Graco’s written
recommendations.
This warranty does not cover, and Graco shall not be liable for general wear and tear, or any malfunction, damage or wear caused by faulty
installation, misapplication, abrasion, corrosion, inadequate or improper maintenance, negligence, accident, tampering, or substitution of
non-Graco component parts. Nor shall Graco be liable for malfunction, damage or wear caused by the incompatibility of Graco equipment with
structures, accessories, equipment or materials not supplied by Graco, or the improper design, manufacture, installation, operation or
maintenance of structures, accessories, equipment or materials not supplied by Graco.
This warranty is conditioned upon the prepaid return of the equipment claimed to be defective to an authorized Graco distributor for verification of
the claimed defect. If the claimed defect is verified, Graco will repair or replace free of charge any defective parts. The equipment will be returned
to the original purchaser transportation prepaid. If inspection of the equipment does not disclose any defect in material or workmanship, repairs will
be made at a reasonable charge, which charges may include the costs of parts, labor, and transportation.
THIS WARRANTY IS EXCLUSIVE, AND IS IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO WARRANTY OF MERCHANTABILITY OR WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE.
Graco’s sole obligation and buyer’s sole remedy for any breach of warranty shall be as set forth above. The buyer agrees that no other remedy
(including, but not limited to, incidental or consequential damages for lost profits, lost sales, injury to person or property, or any other incidental or
consequential loss) shall be available. Any action for breach of warranty must be brought within two (2) years of the date of sale.
GRACO MAKES NO WARRANTY, AND DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE, IN CONNECTION WITH ACCESSORIES, EQUIPMENT, MATERIALS OR COMPONENTS SOLD BUT NOT
MANUFACTURED BY GRACO. These items sold, but not manufactured by Graco (such as electric motors, switches, hose, etc.), are subject to
the warranty, if any, of their manufacturer. Graco will provide purchaser with reasonable assistance in making any claim for breach of these
warranties.
In no event will Graco be liable for indirect, incidental, special or consequential damages resulting from Graco supplying equipment hereunder, or
the furnishing, performance, or use of any products or other goods sold hereto, whether due to a breach of contract, breach of warranty, the
negligence of Graco, or otherwise.
FOR GRACO CANADA CUSTOMERS
The Parties acknowledge that they have required that the present document, as well as all documents, notices and legal proceedings entered into,
given or instituted pursuant hereto or relating directly or indirectly hereto, be drawn up in English. Les parties reconnaissent avoir convenu que la
rédaction du présente document sera en Anglais, ainsi que tous documents, avis et procédures judiciaires exécutés, donnés ou intentés, à la suite
de ou en rapport, directement ou indirectement, avec les procédures concernées.

Graco Information
For the latest information about Graco products, visit www.graco.com.
For patent information, see www.graco.com/patents.
TO PLACE AN ORDER, contact your Graco distributor or call to identify the nearest distributor.
Phone: 612-623-6921 or Toll Free: 1-800-328-0211 Fax: 612-378-3505

All written and visual data contained in this document reflects the latest product information available at the time of publication.
Graco reserves the right to make changes at any time without notice.
Original instructions. This manual contains English. MM 312792

Graco Headquarters: Minneapolis
International Offices: Belgium, China, Japan, Korea
GRACO INC. AND SUBSIDIARIES • P.O. BOX 1441 • MINNEAPOLIS MN 55440-1441 • USA
Copyright 2008, Graco Inc. All Graco manufacturing locations are registered to ISO 9001.
www.graco.com
Revision G - May 2013



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Linearized                      : Yes
Page Mode                       : UseOutlines
XMP Toolkit                     : 3.1-701
Create Date                     : 2008:05:15 12:56:52Z
Modify Date                     : 2013:06:10 12:54:47-05:00
Creator Tool                    : FrameMaker 9.0
Metadata Date                   : 2013:06:10 12:54:47-05:00
Format                          : application/pdf
Description                     : 312792, Merkur Displacement Pump, Repair/Parts
Title                           : 312792G, Merkur Displacement Pump, Repair/Parts, English
Creator                         : Shelly Saunders
Producer                        : Acrobat Elements 10.0.0 (Windows)
Keywords                        : 312792, Merkur Displacement Pump, LW025A, LW050A, LW075A, LW100A, LW125A, LW150A, nopct
Marked                          : True
Copyright                       : 2008, Rev. F 12/2012
Job Ref                         : Z081420
Web Statement                   : 312792, Merkur Displacement Pump
Document ID                     : uuid:54ce359d-8f9f-491c-90fb-a7c78810280a
Instance ID                     : uuid:8bf85a83-95e1-4ccf-93fb-ac340a14c941
Page Count                      : 14
Subject                         : 312792, Merkur Displacement Pump, Repair/Parts
Author                          : Shelly Saunders

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