Graco Merkur A Series Use and care manual

Repair/Parts
Merkur®
Displacement Pump 312792F
ENG
For use with high-performance finishing and coating pumps in hazardous and
non-hazardous locations. For professional use only.
See page 3 for model information, including maximum working pressures.
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.
TI11643a TI11645
LW025A LW150A

Related Manuals
2312792F
Contents
Related Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Component Identification . . . . . . . . . . . . . . . . . . . . 4
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
General Information . . . . . . . . . . . . . . . . . . . . . . 5
Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Repair Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Optional Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Graco Standard Warranty . . . . . . . . . . . . . . . . . . . 14
Graco Information . . . . . . . . . . . . . . . . . . . . . . . . . 14
Related Manuals
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

Models
312792F 3
Models
Check your displacement pump’s identification marking for the 6-digit part
number. Use the following matrix to define the construction of your displace-
ment 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.
* Cycle refers to combination of one upstroke and one downstroke.
ti12415a
LW 025 A
First Digit
Second Digit
(Description)
Third, Fourth, and Fifth
Digits
(Displacement Pump
Volume Per Cycle* in cc)
Sixth Digit
(Packings; Displacement Rod Coating)
L
(Lower)
WWet-cup style,
stainless steel
025 A 3 UHMWPE, 2 PTFE; Chromex™
050
075
100
125
150
Model, Series
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

Component Identification
4312792F
Component Identification
Key:
A Piston/Rod Assembly
BWetCup
C Fluid Outlet
D Fluid Inlet
E Lower Cylinder
F Upper Cylinder
G Intake Valve
FIG. 1. Component Identification
A
B
D
E
G
F
ti11645a
C

Repair
312792F 5
Repair
General Information
Preparation
Follow all warnings and instructions in your pump man-
ual 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.
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◆).
3. Remove the seat (22†) and use an o-ring pick to
remove the seal (26†) from the intake housing. See
FIG. 7.
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.
10. Remove the spring (4*) from the top of the upper
cylinder (1).
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.
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 ◆.
Threads are very sharp. Use a rag to protect hands.
NOTICE
The jam nut can remain attached to the upper cylin-
der.
ti12918a

Repair
6312792F
11. Remove the wet cup seal (27*) and the upper cylin-
der 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
13. Remove the o-ring (18†), seat (15†) and ball (16◆).
See FIG. 5.
Reassembly
1. Clean and inspect all parts.
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).
4. Install the spring (4*) in the top of the upper cylinder.
5. Lubricate the threads and screw the wet cup (5) into
the upper cylinder (1), hand tight.
FIG. 2. Remove Flow-Through Nut
ti12782a
NOTICE
Replace all o-rings removed from the pump. Com-
pressed o-rings may cause the pump to leak.
FIG. 3. Replace Throat Packings
NOTICE
All threads, packings, and seals must be well lubri-
cated. Use Lubriplate (Graco Part Number 285791)
or a similar product.
*28
*9
*7
*8
*7
*8
*7
*6
5
ti11691a
Lips must
face down.
*27

Repair
312792F 7
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).
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).
8. Place piston in vice and torque flow-through nut
(17†) as specified in the following table.
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).
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).
FIG. 4. Replace piston packings.
ti11693a
10*
11*
12*
13*
12*
13*
14*
12*
5
4*
1
Lips must
face up
Displacement Pump Torque
LW025A–LW050A 58-62 ft-lb (78-84 N•m)
LW075A–LW150A 78-82 ft-lb (105-111 N•m)
FIG. 5. Replace piston ball and seat.
3
◆16
†15
†18
†17 ti11692a

Repair
8312792F
12. Lubricate and install the seal (25*†) on the bottom of
the lower cylinder (2).
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.
14. Lubricate the seal (25*†) and threads of the lower
cylinder (2). Place the ball (24◆) on the seat (22†).
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.
16. Torque wet cup (5) to 58-62 ft-lb (78-84 N•m).
FIG. 6. Assemble piston/rod assembly and cylinders.
1
3
21*
2
ti12414a
25*†
FIG. 7. Replace intake ball and seat.
Displacement Pump Torque
LW025A–LW050A 58-62 ft-lb (78-84 N•m)
LW075A–LW150A 78-82 ft-lb (105-111 N•m)
25✓
24✓
22✓
26✓
23
ti11694a

Parts
312792F 9
Parts
5
27*
28*
9*
7*
8*
7*
8*
7*
6*
1
16◆
15†
18*†
17 †
10*
11*
12*
13*
12*
13*
12*
14*
21* †
25*†
24◆
22†
26*†
23
2
3
Lubricate.
Torque to 95-105 ft-lb (128-142 N•m)
3
Torque to 58-62 ft-lb (78-84 N•m)
Torque varies by lower size.
LW025A-LW050A: 58-62 ft-lb (78-84 N•m)
LW075A-LW150A: 78-82 ft-lb (105-111 N•m)
3
35
36
37
ti11644a
4*
32
Apply thread lubricant.
4
1
2
1
1
1
1
1
1
5
5
5
5
5
2
4
4
1
33*
5
2
1

Parts
10 312792F
----- Not sold separately.
* Included in Seal Repair Kit. See page 11.
† Included in Seat Repair Kit. Stainless steel seats also
are available. See page 11.
◆Included in Check Ball Kit. Tungsten carbide check
balls also are available. See page 11.
Ref. Description Part Qty.
1CYLINDER KIT, upper; includes
21, 28, 32, and 33 (qty. 1)
1
LW025A 24A813
LW050A 24A814
LW075A 24A815
LW100A 24A816
LW125A 24A817
LW150A 24A818
2CYLINDER KIT, lower; includes
21 and 25
1
LW025A 24A822
LW050A 24A823
LW075A 24A824
LW100A 24A825
LW125A 24A826
LW150A 24A827
3PISTON/ROD, assembly;
includes 15-18, 36, and
37 (qty. 1)
1
LW025A 24A643
LW050A 24A644
LW075A 24A645
LW100A 24A646
LW125A 24A647
LW150A 24A648
4* SPRING, throat ----- 1
5WET CUP; includes 27 and 28
(qty. 1 each)
1
LW025A 24A807
LW050A 24A808
LW075A 24A809
LW100A 24A810
LW125A 24A811
LW150A 24A812
6* GLAND, male, throat ----- 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
15† SEAT, piston valve, tungsten
carbide
----- 1
16◆BALL, piston valve, stainless
steel
----- 1
17† NUT, flow through ----- 1
18*† O-RING, piston ----- 1
21*† O-RING, lower cylinder ----- 1
22† SEAT, intake valve, tungsten
carbide
----- 1
23 INTAKE VALVE KIT; includes 26 1
LW025A 24A834
LW050A 24A835
LW075A 24A836
LW100A 24A837
LW125A 24A838
LW150A 24A839
24◆BALL, intake valve, stainless
steel
----- 1
25*† O-RING, lower cylinder ----- 2
26*† O-RING, intake valve ----- 1
27* O-RING, wet cup; package of 10 1
LW025A 24A630
LW050A-LW075A 24A631
LW100A 24A632
LW125A-LW150A 24A633
28* O-RING, wet cup ----- 1
32 FITTING, outlet, 3/8-18 npt X
3/4-16 unf; includes 33 (qty. 1)
1
LW025A-LW100A 24A840
LW125A 24A841
LW150A 24A842
33* O-RING, outlet; package of 10 1
LW025A-LW100A 24E457
LW125A 24E458
LW150A 24E459
35 JAM NUT 1
LW025A 24A634
LW050A 24A635
LW075A 24A636
LW100A 24A637
LW125A 24A638
LW150A 24A639
36 NUT, coupling 1
LW025A 15M758
LW050A-LW150A 15T311
37 COLLAR, coupling; pkg. of 10 1
LW025A 24A618
LW050A-LW150A 24A619
Ref. Description Part Qty.