Nordson RA-20 User manual

Instruction Sheet
Part 237431-03
E2018 Nordson Corporation
P/N 237431-03
RA-20 Paint/Solvent/Dump Valve
Description
The paint/solvent valve is a normally closed valve used to trigger coating
material. The valve may be used alone to actuate paint or solvent within the
rotary atomizer, or may be coupled with a dump valve for paint actuation
and dump.
1
2
Figure 1 Paint/Solvent/Dump Valve
1. Fluid Inlet 2. Air Inlet
Removal
Refer to the Repair section in the RA-20 Rotary Atomizer manual for a
detailed description of removing the valve from the rotary atomizer.
Installation
Based on the system they are used with, the paint/solvent/dump valves can
be installed in several possible configurations. Single-, dual-, and
three-valve installations allow the valves to function in a variety of ways.
Figures 2 and 3 show all four possible installations which may be used to
actuate paint from within the rotary atomizer. The dual-valve can be
installed as a paint/dump (installation B), or a paint/solvent valve
configuration (installation C). The three-valve installation (installation D),
can be used as a paint/solvent/dump valve configuration. For part numbers
of reference items, refer to the parts list at the end of this document.

RA-20 Paint/Solvent/Dump Valve
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Part 237431-03 E2018 Nordson Corporation
Single-Valve Installation
See Figure 2, Installation A. The single-valve installation is where the valve
is used as a paint valve. To install a single-valve, perform the following
steps:Cover the O-ring with O-ring lube.Insert valve (2) into the interface
plate.Tighten set screw.Install pneumatic line to air inlet (1).Connect fluid
tubing to fluid inlet (3).
Dual-Valve Installation
See Figures 2 and 3. Installations B and C show two alternate dual-valve
installations, a paint/dump valve configuration and a paint/solvent valve
configuration.
Paint/Dump Installation
See Figure 2. Installation B. The dual-valve installation shown is typical in
RA-20 rotary atomizers, where the two valves are used for paint and dump.
To install the two valves, perform the following steps:
1. Loosen the two cap screws (6) in the dual-port manifold (5).
2. Make sure the v-notch on the manifold is facing down.
3. Insert the paint valve (2) into the left-hand port of the manifold.
4. Place the O-ring (8) between the valves.
5. Use the two screws (4) to connect the dump valve (7) to the underside
of the paint valve (2), as shown.
6. Tighten the screws.
7. Insert the dummy valve plug (9) into the right port of the manifold.
8. Make sure the side of the dump valve fits tightly against the v-notch on
the manifold. The curved groove of the manifold should be facing up.
9. Tighten the cap screws (6) on the manifold to secure the valves during
operation.
10. Refer to the RA-20 Rotary Atomizer manual for procedures to reinstall
the manifold into the rotary atomizer.

RA-20 Paint/Solvent/Dump Valve 3
Part 237431-03
E2018 Nordson Corporation
Paint/Solvent Installation
See Figure 3, Installation C. The dual-valve installation shown is typical in
RA-20 rotary atomizers where the two valves are used for paint and solvent.
To install the two valves, perform the following steps:
1. Loosen the two cap screws (3) in the dual-port manifold (2).
2. Make sure the v-notch on the manifold is facing down.
3. Insert the paint valve (1) into the left port of the manifold. Make sure the
fluid inlet on the valve is facing down.
4. Insert the solvent valve (4) into the right port of the manifold. Make sure
the solvent inlet is facing up.
5. Tighten both cap screws on the manifold to secure the valves into the
ports.
6. Refer to the RA-20 Rotary Atomizer manual for procedures to reinstall
the manifold into the rotary atomizer.
Three-Valve Installation
See Figure 3, Installation D. The three-valve installation is used when a
paint/solvent/dump configuration is desired. To install the three valves,
perform the following steps:
1. Loosen the two cap screws (3) on the dual-port manifold (2).
2. Make sure the v-notch on the manifold is facing down. The curved
groove on the manifold should face up.
3. Insert the paint valve (1) into the port on the left-hand side of the
manifold. Make sure the fluid inlet is facing down.
4. Place the O-ring (7) between the two valves. Use the two screws (5) to
attach the dump valve (6) to the underside of the paint valve (1) as
shown.
5. Tighten the two screws (5).
6. Make sure that the side of the dump valve (6) fits tightly against the
v-notch on the manifold. The curved groove of the manifold should face
up.
7. Insert the solvent valve (4) into the right port on the manifold with the
solvent inlet facing up.
8. Tighten the two cap screws on the manifold to secure the valves during
operation.
9. Refer to the RA-20 Rotary Atomizer manual for procedures to reinstall
the manifold into the rotary atomizer.

RA-20 Paint/Solvent/Dump Valve
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Part 237431-03 E2018 Nordson Corporation
Rotary Atomizer Installations Diagram
A. Single Valve
B. 2−Valve (RA-20, typical)
2
5
6
7
4
9
2
8
4
1
3
6
Figure 2 Rotary Atomizer Installations A and B
1. Air inlet
2. Paint valve
3. Fluid inlet
4. Screws
5. Dual-port manifold
6. Cap screws
7. Dump valve
8. O-ring
9. Dummy valve plug

RA-20 Paint/Solvent/Dump Valve 5
Part 237431-03
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C. 2−Valve (RA-20)
D. 3−Valve (RA-20)
1
5
2
3
6
5
7
4
3
2
4
1
3
3
Figure 3 Rotary Atomizer Installations C and D
1. Paint valve
2. Dual-port manifold
3. Cap screws
4. Solvent valve
5. Screws
6. Dump valve
7. O-ring

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Part 237431-03 E2018 Nordson Corporation
Operation
The following information describes how paint/solvent/dump valves operate
in single-, dual-, and three-valve installations. All valve installations require
a minimum air pressure of 2.75 bar (40 psi).
Single-Valve
When air pressure is applied at the air inlet, the valve opens to dispense
coating material. Because of its spring-return closure, the valve closes
when air is removed.
Dual-Valve
See Figures 4 and 5. These figures show a dual-valve installation as it
dispenses coating material or solvent.
See Figure 4. In this figure, coating material or solvent from a low pressure
feed system enters at the fluid inlet (1). Since the lower valve is closed, the
coating material is dead-ended. When air is applied at the air inlet (3), the
valve opens and coating material or solvent flow through the fluid outlet (2)
to the rotary atomizer cup.
1
2
3
Figure 4 Dual-Valve Operation
1. Fluid Inlet
2. Fluid Outlet
3. Air Inlet
See Figure 5. If air is removed from the air inlet port of the upper valve, the
upper valve closes and blocks the coating material or solvent. When new
coating material or solvent flows through the fluid inlet (1), the material
passes into the second valve. When air is applied to the air inlet port of the
second valve (3), the lower valve opens and dumps material from the dump
port (2) into a waste container.

RA-20 Paint/Solvent/Dump Valve 7
Part 237431-03
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1
2
3
Figure 5 Dual Valve Operation
1. Fluid Inlet
2. Dump Port
3. Air Inlet Port of Secondary
Valve
Three-Valve
Three-valve installations are typically used in applications that require the
use of paint, solvent, and dump valves, such as quick color-change
applications. Each one of the three valves functions as a paint, solvent, or
dump valve. One valve is used as a paint valve to trigger paint. The
second valve is used as a solvent valve for cup flush. The third valve is
used as a dump valve for color-changing.

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Part 237431-03 E2018 Nordson Corporation
Repair
See Figure 6. If a visual inspection shows fluid in the weep hole or the
valve does not close, disassemble and rebuild as necessary.
Disassembly
To disassemble the valve, follow the procedures below.
1. When possible, flush the valve with a compatible cleaning solution
before removing the valve from the system.
2. Turn off both fluid and air pressure to the valve.
3. Remove the screws (1), lock washers (2), and air cylinder (3) from the
valve body (13, 14).
4. Remove and discard the O-ring (12) from the valve body (13, 14).
5. Using the Nordson wrenches provided, remove the lock nut (5) from the
piston lock nut assembly (6).
6. Remove the screws (23) that attach the valve seat (21, 22) to the valve
body (13, 14).
a. remove retaining ring (17)
b. push out seat (18) from bottom at valve seat (21, 22)
c. discard O-ring (16)
7. Remove the retaining ring (7).
8. Remove the packing cartridge (9) with ball tip (10) attached by pushing
at the seat end.
NOTE: The cartridge seat is reversible. If the valve has
been leaking, reinstall the cartridge seat with the end that had
been seated opposite the ball tip.
9. Check the ball tip (10) for wear or scoring. Replace if necessary.
10. Check the packing cartridge (9) and discard its O-ring (11). Replace the
packing cartridge, if necessary.

RA-20 Paint/Solvent/Dump Valve 9
Part 237431-03
E2018 Nordson Corporation
Assembly
To reassemble the valve, follow these procedures.
1. Coat the packing cartridge (9) and new O-rings (11) with a small amount
of non-detergent grease.
2. Install the O-rings into the valve body (13, 14).
3. Install the packing cartridge (9) into the valve body.
4. Insert retaining ring (8).
5. Install the valve seat (21, 22) by tightening the screws (23) evenly to
compress the packing cartridge spring (4).
6. Insert the lock nut (5) and new O-ring (16) into the piston locknut
assembly (6).
7. Screw the piston locknut assembly into the packing cartridge clockwise
until it comes to rest against the valve body. Turn the piston locknut
assembly counterclockwise 1-1/2turns.
8. Hold the piston locknut assembly (6) and lock it in place with the locknut
(5) and thread locking compound.
9. Install the air cylinder (3), lock washers (2), and screws (1) into the valve
body.
10. Install the air inlet elbow to the port of the valve, as shown.

RA-20 Paint/Solvent/Dump Valve
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Part 237431-03 E2018 Nordson Corporation
Parts
Paint/Solvent/Dump Valve
Item Part Part Description Quantity Note
— 302134 VALVE, paint, solvent 1
— 302135 VALVE, dump 1
1 981380 981380 SSCREW, fillister, 10-32 x 1.000 in., nylon 4
2 983120 983120 SWASHER, lock, E, spt, #10, stl, nickel 4
3- - - - - - - - - - - - SCYLINDER, air, valve 1
4 295347 295347 SSPRING, comp, 1.000 x 0.720 OD x
0.081 in.
1
5 984539 984539 SNUT, lock, #10-32, upper 1A, B
6 302136 302136 SPISTON, locknut, assembly 1 B
7 940090 940090 SS O-RING, Viton, 0.208 ID x 0.070 w, br 1 B
NS - - - - - - - - - - - - SS DISC, piston 2 B
NS - - - - - - - - - - - - SS SEAL, piston 1 B
NS - - - - - - - - - - - - SS NUT, seal lock 1 B
NS - - - - - - - - - - - - SS RETAINER, piston 1 B
8 986033 986033 SRETAINING RING, internal, 56, basic 1 C
9 295354 295354 SCARTRIDGE, packing 1
10 - - - - - - - - - - - - SBALL TIP 1 C
11 940155 940155 SO-RING, hotpnt, 0.562 x 0.688 x 0.063 in. 2 C
12 940240 940240 SO-RING, hotpnt, 1.125 x 1.250 x 0.063 in. 1 C
13 - - - - - - SBODY, valve, paint, solvent 1
14 - - - - - - SBODY, valve, dump 1
15 971407 971407 SELBOW, male, 1/4in. tube x 1/8in. npt, ny 1
16 940170 940170 SO-RING, hotpnt, 0.688 x 0.813 x 0.063 in. 1 C
17 986114 986114 SRETAINING RING, internal, 45, basic 1 C
18 - - - - - - - - - - - - SSEAT, cartridge 1 C
19 940105 940105 SS O-RING, PTFE, 0.250 x 0.375 x
0.060 in.
2
20 940118 940118 SS O-RING, hotpnt, 0.313 x 0.438 x
0.063 in.
1
21 - - - - - - SSEAT, valve, male O-ring seal 1
22 - - - - - - SSEAT, valve, male, tubing 1
23 982777 982777 SSCREW, skt, #10-32 x 0.50 in., nylon 4
24 941133 941133 SO-RING, Viton, 0.562 x 0.750 x 0.094 in. 1 C
NS 900424 900424 SCOMPOUND, thread lock, vc-3 AR
NS 1612251 1612251 SLUBRICANT, O-ring, Parker, 2 oz AR
NOTE A: This part is also included in Air Piston Kit, part 302136.
B: Refer to Air Piston Kit.
C: These parts are included in RA-20 Valve Repair Kit, part 295393.