Instruction Manual
US9425739 (01-22)

425 4 Gallon Piston Backpack Sprayer

Operator’s Manual & Parts List
425, 425-101, 425-Prof, 475-B, 475-101, 475-Prof, 435, 485, 473-P, 473-D,
473-ECS, 425-Deluxe, 475-B-Deluxe, 425-HD, 475-B-HD, 315-A
If you are missing parts, instructions or have questions, DO NOT return this unit back to the store. Call 1-800-SOLO-INC (1-800-765-6462). Solo will send the missing parts/information to you promptly.
WARRANTY:
Solo backpack sprayers are covered by Solo’s 1-YEAR LIMITED WARRANTY. Solo manufactured parts which fail due to defective material or workmanship will be repaired or replaced without charge. See page 5 for full details and complete warranty information.
MAINTENANCE TIP: The cap gasket (#4061345 or #4061346) is prelubricated for improved sealing. Occasional lubrication with Solo Superior Grease (#9850-P) or petroleum jelly is recommended.

SAFETY PRECAUTIONS:

1. Before using sprayer with chemicals, fill sprayer with fresh water to assure that you have it properly assembled; pressurize and practice spraying.
   Also, check for any leaks at this time. When thoroughly familiar with the sprayer operation, follow normal operating procedures.

2. Ensure all pressure in the sprayer is relieved by locking the shut-off valve in the open position.

3. Avoid contact with chemicals.

4. Always wear rubber gloves, safety goggles and appropriate protective clothing.

5. Work in a well-ventilated area.

6. Individuals should be trained in the proper use of this sprayer, chemical handling procedures, and first aid/emergency care. Where training is not available, individuals should study and follow the procedures detailed in this manual.

WARNING:
Chemicals can be harmful to individuals and the environment if improperly used. In addition, some chemicals are caustic, corrosive or poisonous and should be avoided. Read warnings and chemical manufacturers’ instructions. Solo high density polyethylene sprayers are fitted with chemical resistant seals which are compatible to a wide variety of agricultural and household chemicals; however, care should be exercised to ensure that sprayer components are clean, functioning properly, and in a good state of repair before and during use.
If in doubt about a particular chemical, check the manufacturer’s instructions or call the manufacturer. If you suspect or observe indications that the material may be unsafe in a Solo sprayer…STOP. DO NOT USE OR APPLY CHEMICAL. ALWAYS WEAR
RUBBER GLOVES, GOGGLES, AND APPROPRIATE PROTECTIVE CLOTHING!

• Read and follow operating instructions.
• Do not fill with, use, or spray flammable materials, including Diesel Fuel.
• Do not modify sprayer.
• Never spray in the direction of humans, animals or property which might be injured or damaged by spray formula.
• Do not use disinfectants, solvents or impregnating agents unless first tested to ensure they are not harmful to the environment or sprayer.
• Do not use liquids with a temperature above 110°F (43°C).
• Wear appropriate protective clothing to prevent contact with chemical agents.
• Rinse and clean sprayer thoroughly after using. Disposal of contaminated rinse should be in accordance with applicable ordinances. Observe the precautionary instructions of the chemical manufacturer.
• Do not use any acid (including citrus) or caustic chemicals. For bleach solutions, try our Solo 475-B,
• 475-101, 475-Prof or 475-B Deluxe sprayers.
• Remember that a sprayer with liquid is a significant amount of weight (8 lbs. per gallon). Do not climb when wearing the sprayer. Use caution when bending, leaning or walking. Bend at the knees rather than the waist.
• During sprayer operation, the pressure cylinder (#4400240) contains compressed air and liquid. Compressed air and liquid under pressure are inherently dangerous. Before making adjustments on sprayers fitted with a pressure regulating valve assembly (#4800182) located on the pressure cylinder or any other repair or inspection of any sprayer, be sure to relieve pressure through the shut-off valve and wand.

CUSTOMER SERVICE COMMITMENT FROM SOLO’S SERVICE DEPARTMENT
In the event the sprayer you have purchased has missing or damaged parts, please call 1-800-765-6462, 9:00 AM – 5:00 PM EST.
In order to assist your service representative, please have the following information available: sprayer model number, part description and part number. A parts list is included in your operator’s manual.
Solo is committed to your satisfaction and is continuing its efforts to earn your future business.
Visit us on the web at us.solo.global
Troubleshooting and parts ordering available on-line.

REMOVING PLASTIC ADJUSTABLE NOZZLE
Unscrew the nozzle cap (1) from the nozzle body (3). This is best accomplished while the retaining nut (2) is fastened tightly to the elbow (5). Next, unscrew the retaining nut (2). Push the nozzle body (3) out of the retaining nut (2). The filter with gasket (4) will
come out with the body. To reinstall the nozzle, reverse the above instructions.

ASSEMBLY INSTRUCTIONS FOR WAND

1. Insert wand into shut-off valve as shown.
2. Tighten the screw cap clockwise onto the shut-off valve.

PUMP LEVER INSTALLATION: All hardware necessary for pump lever installation is included with the sprayer. The pump lever (C) should be installed as follows: place lever handle (C) onto the pump shaft (A). Align bolt holes and install the two bolts (E) and washers (F); then tighten. To install pump lever on the opposite side on a Diaphragm Pump sprayer, remove the stop plate (D) and washer. Install the pump lever as above. The stop plate (D) should then be mounted on the inner bolt hole with the closed end of the stop plate pointing downward on the opposite side of the pump shaft.

FOLD-AWAY PUMP HANDLE INSTALLATION (FOR SELECT MODELS ONLY):

1. Remove bolt and nut from pump handle.
2. Slide handle assembly over the pump shaft and align the holes so that the rear (elbow) portion of the handle points up and slightly forward (approximately 45 degrees) and away from the Solo logo. Reinstall bolt and locknut. Pump handle can be installed on the opposite side of the sprayer for right hand pumping. (For Diaphragm Pump Sprayer, stop plate will need to be relocated to the left side.)
3. The handle can be rotated to either down (pumping) or up (storage) positions. Note: The handle swings away from the sprayer, then up or down as desired. The spray wand attaches to the clamps on the handle assembly for storage (does not apply to the brass or stainless steel wands).

SHOULDER STRAP INSTALLATION:
The top of the shoulder straps are pre-attached to the sprayer by means of a buckle or pin. The lower end of the straps are attached by fastening the strap hooks to the metal frame between where frame exits the plastic tank and where the frame makes a bend.

REGULATING THE PRESSURE: (FOR DELUXE MODELS ONLY)
The Solo backpack sprayer is equipped with a built-in regulator to control output pressure. This regulator is operator adjustable. Make adjustments prior to filling tank. To adjust the regulator, remove the tank cap and the filter basket. Look inside the spray tank; you will see the top of the regulator. There are 4 fingers on the regulator knob. The finger farthest to the left is

1; to the right is #4. They are numbered 1, 2, 3, 4. 1 = 15 psi, 2 = 30 psi,

3 = 45 psi, 4 = 60 psi. The higher the pressure, the more chemical applied from the sprayer in a given amount of time, but the droplets will be smaller with more drift. If the spray pressure must be changed, excess pressure in the pressure cylinder must be released back into the tank through the spray tube.
To adjust, push down on the knob and rotate to align the desired number with the alignment pin. To operate the 425-Prof, 435, 425-Deluxe and 425-HD at higher than 60 psi, first release the excess pressure and then replace the pressure control valve with the optional plug (#4200215). Purchased separately. FILLING:
Mix the spray formula and the proper volume of water in a separate container. Pour the mix through the filter basket in the tank opening. This keeps debris from entering the sprayer. Pump the sprayer handle to prime the pump and pressurize the pressure cylinder. The volume of liquid in the sprayer tank will appear to decrease as the pressure cylinder is pressurized. Remember that it’s not necessary to completely fill the sprayer tank each time. Mix only the amount needed to get the job done. Chemicals should not be stored in the sprayer.
Always read and carefully follow the manufacturer’s instructions printed on the product label. This can save money and help prevent injury and crop and environmental damage.

OPERATING FEATURES:
Nozzles – Your Solo sprayer can provide a variety of spray patterns with the standard and optional nozzle arrangements.

*Brass adjustable nozzle and Speed Tip nozzle are not standard items on all Solo sprayers but each may be purchased as an accessory. Spray tips should be assembled as above for desired spray pattern.
WARNING: Handling the brass parts of this product will expose you to lead, a chemical known by the State ofCalifornia to cause cancer and birth defects or other reproductive harm. Wash hands after handling. For more information, go to www.P65Warnings.ca.gov.

SPRAYING:
Prime the pump with quick pump strokes. When you feel very firm resistance, the pressure chamber is filling with liquid. With repeated piston strokes, the air in the pressure chamber is slowly compressed. In a safe area, point the wand upward and press the shut-off valve lever spraying for 10 seconds or until no air and only liquid is com-ing out. This will bleed all of the air out of the hose and wand. By pressing the hand lever, the valve opens, and liquid is forced through the nozzle. The shut-off valve has a retaining clip which keeps the valve in the “OPEN” position for continuous operation. Pump using the end of the pump handle, as it is less fatiguing. The volume of liquid delivered varies with the working pressure which should be as high as needed to ensure an adequate spray pattern for each individual application.
NOTE: Should the pressure drop very quickly, drain the tank completely and pump without liquid. By this procedure, the air chamber is refilled with the required volume of air. It is advisable to pump the tank completely empty from time to time.
WETTABLE POWDERS:
Avoid use in piston pump sprayers models 425, 425-101 425-Prof, 425-HD, 315-A, 435, 473-P! The Solo models 475-B, 475-101, 475-Prof, 473-D, 473-ECS, 485 and 475-B-HD sprayers with a diaphragm pump are generally resistant to abrasive materials and are recommended for this purpose. Note: If you use a wettable powder in your 425, 425-101, 425-Prof, 425-HD, 315-A, 435 or 473-P sprayer, be sure that it is thoroughly mixed in the formula solution. Immediately after use, be sure to remove the piston and clean and lubricate the Viton collar with Solo Superior Grease* or petroleum jelly. Thorough® flushing of the sprayer will extend the life of its working parts. If you use wettable powders in the piston pump sprayer, be sure to inspect regularly for seepage around the piston, lubricate and/or repair accordingly.

CLEANING:

• After spraying, clean the tank thoroughly. If some spray liquid is left inside, drain tank completely.
• Pumping causes air to be taken in and the remaining liquid to be discharged. Pump until liquid and air are coming out through the nozzle.
• Refill tank with a few quarts of clean, soapy water and pump the water out as explained above (if necessary, repeat this procedure several times).
• If the shut-off valve is removed, the pump can be flushed quickly. Improper spray distribution is the result of a clogged nozzle, which is easily removed and cleaned.
• Soap and water may also be used to clean tank.
• Do not use aggressive cleaning agents or abrasives.
• Follow the recommendations of the chemical manufacturer for disposal of waste water and chemicals.
• Activated charcoal in liquid or other form may be used to absorb chemicals in tanks or spills.

NOTE: When cleaning the sprayer after working with hormone weed killers, follow the instructions of the herbicide producers. Neutralize with activated charcoal. (Example: add 0.35 oz. /1 g. of activated charcoal to 1.7 pint/1 liter of water and leave this detergent in the tank and the lines approximately for 24 hours.) This is very important if other chemicals will be sprayed as the residues of the herbicide may damage susceptible plants. Cleaning after application of products containing carbolineum, a coal tar wood preservative, is imperative. If the chemicals are not water soluble, cleaning should be done with a 5% soda lye having a temperature of 104°F (40°C). Rinse with plenty of clean water.

MAINTENANCE AND STORAGE TIPS:

• After operation, the sprayer should be stored away from direct sunlight to prevent UV damage.
• After removing the pump or when mounting a new Viton® collar, treat both the collar and the piston with water- resistant grease.*
• Before winter, drain all liquid in tank, lines and air chamber. (See “Cleaning.”) Leave shut-off valve locked in the “open” position to prevent freezing.
• For service, visit our website to locate your nearest Solo dealer. Always insist on original Solo spare parts.
• Regularly inspect hose, wand, pump, tank and shut-off valve for wear, damage or leaks. Repair promptly.
• Occasionally lubricate cap gasket.*

Avoid excessive wear and prolong sprayer life by:

1. Regular lubrication of Viton® collar, cylinder and piston with water-resistant grease.*
2. Prompt and thorough cleaning and flushing of sprayer. Soap and water work well.
   *Use Solo Superior Grease (#9850-P). Petroleum jelly may also be used

SOLO LIMITED WARRANTY

Solo Incorporated guarantees the original purchaser of Solo equipment that any failure of Solo manufactured parts due to defects in material and workmanship, which occurs during the applicable warranty period, will be repaired or replaced without charge for parts or labor, except for those items not covered by warranty.
CONSUMER LIMITED WARRANTY: Solo equipment purchased for consumer use is covered by this Limited Warranty for a period of ONE (1) YEAR. Solo’s polyethylene tank is covered by this limited warranty for the life of the unit.
COMMERCIAL LIMITED WARRANTY: Solo equipment purchased for commercial use is covered by this Limited Warranty for a period of ONE (1) YEAR.
OWNER’S OBLIGATION AND RESPONSIBILITY: Proof of purchase must be provided by the owner in order to obtain warranty service. Should any failure covered by this Limited Warranty occur, deliver or ship the Solo products or parts to an authorized Solo service center. Freight, packing and insurance costs, if any, will be borne by the owner. Follow normal maintenance service to include applicable lubrication, operation and storage of the product as explained in the operator’s manual.
ITEMS NOT COVERED BY WARRANTY: Provisions of the Limited Warranty will not apply to the following:

• Any indirect or consequential damages that may result from the failure or malfunction of the Solo product.
• Normal service requirements arising during the warranty period, such as cleaning, normal wear, lubrication, filter, spray tips, etc.
• Normal service work over and above the repair or replacement of defective parts. Any failure that results from an accident, customer abuse, normal wear, neglect or failure to operate the product in accordance with the instructions provided in the operator’s manual or provided with the product.
• When an alteration or modification has been performed on a Solo product, Solo is responsible only for products as originally furnished by Solo, provided the alterations or modifications do not adversely affect the product’s operation, performance or durability. Parts or accessories that are incompatible with the product are not approved by Solo.

Full disclosure of Solo’s Limited Warranty is available from your local Solo dealer or SOLO INCORPORATED, 201 Enterprise Drive, Newport News, Virginia 23603 (800-765-6462).
This Limited Warranty gives you specific legal rights and you may also have other rights, which vary from state to state.
Solo’s new Professional sprayers, Models 425-Prof and 475-Prof, are equipped with Solo’s Deluxe Shoulder Saver Harness (part# 4300343) (see below). With its wide, padded straps, chest belt, padded waist belt and lumbar support, this sprayer will remain comfortable to wear even after hours of spraying.

SPARE PARTS LIST

Packaged Kits Not Shown in the Parts List

66, 106
0610407-K| Piston pump repair kit includes: 8, 11-13, 20 (2 ea.), 24, 25, 44
4900200-V| Piston pump repair kit (Viton®/FKM) includes: 8, 11-13, 20 (2 ea.), 24, 25, 44
0610411-K| Wand/Shut-Off Valve repair kit includes: 7, 8, 10, 22, 26, 34, 49,101,103
0610409-K| Piston, Rod & Collar kit includes: 2 (2ea.), 41-44, 54
4400203-P| Pump assembly (Piston) includes: 8, 11, 12, 13, 20 (2 ea.), 39, 40, 41, 42, 43, 44, 54, 107
4400221-P| Pump assembly (Diaphragm) includes: 8, 11, 12, 20 (2 ea.), 39, 60, 61, 63, 64 (12 ea.), 64A, 65, 66, 67, 106, 107
POS. #| Order #| For Model| Description
---|---|---|---
2
3
4
6
7
–| 00 10 138
00 12 185
00 30 131
00 12 185
06 10 402- K
06 10 413- K| 315- A, 475’s, 473D, 485| Bolt
Bolt
Washer
Bolt
Shut-off Valve repair kit
Shut- off Valve repair kit (Viton® )
8
10
11
12
13
14| 00 62 258
00 62 115
00 62 291
00 62 139
00 62 140
00 64 234| | O-ring
O-ring
O-ring
O-ring
O-ring
Hose 48 ” (inc l. 26, 34, 49, 103)
15
16
17
18
19
–| 00 66 388
00 66 394
40 43 123
40 35 111
40 73 725
40 73 727| 475’s, 473D, 485
10 1′ s , Deluxe’s , Prof’s HD’s| Hose clamp
Pump clamp
Stop plate
Pump shaft
Carrying handle (red)
Carrying handle (black)
–
20
21
–
–
22| 40 737 2539
40 61 257
42 00 242
40 73 181
32 00 503
40 74 148| 315- A
HD’s
315- A| Carrying handle (blue)
Valve plate
Tank cap (red)(incl. 48, 98, 99)
Tank cap (black}line 1. 48, 98,99)
Tank cap (bluelinc |. 48,98, 99}
Retaining nut
23
24
25
26
27
28| 40 74 323
40 74 350
00 70 260
40 74 337
40 74 344
40 74 410| | Valve body
Sealing plug
Compression soring
Retaining nut
Control knob
Bushing
29
30
31
32
33
–| 40 74 263
40 74 756
40 74 283
40 74 755
49 00 527
49 00 207| 10 1′ s , Deluxe’s , Prof’s , HDs| Fiatspray jet
wid plate
Jet fitter
jetcap
Plastic adjustable nozzle
Brass adjustable nozzle
34
35
36
–
–
37| 40 74 500
40 74 527
42 00 162
42 00 428
42 00 421
42 00 106| 425’s, 475’s
435, 485
473P, 473D| Clamp
Elbow
Tank and frame, 4 gal.
Tank and frame, 5 gal.
Tank and frame, 3 gal.
Fiker basket
38
–
–
39
–
40| 43 00 315
43 00 340
43 00 343
44 00 240
44 00 240N
40 73 190| 425, 475- B
10 1′ s , Deluxes , HDs
Prof’s
HD’s, P rof’s, 435, 485 425, 475- B, 473P, 473D| Shoulder strap (inc!. 73)
Deluxe shoulder strap (inc 1. 73)
Shouldersaverhamess
Pressure cvlinder{incl. 107)
Pressure cylinder
Piston cylinder (inc! 12, 13, 20×2)
41
42
43
44
45
–| 40 74 409
40 74 270
40 73 558
44 00 189
48 00 170
48 00 249| 425’s, 473P, 435
475’s, 473D, 485| Connecting tod without stud
Piston lever
Piston
Viton® collar
Shut- off valve
Shut- off valve (Bleach resistant)
–
46
47
–
48
–| 38 00 502
48 00 173 25
49 00 230
49 00 645
40 61 345
40 61 346| 315- A, HD’s
425, 475- B, 3 & 5 gal.
315- A
315- A, HD’s| Shut- off valve (Viton® /AKM)
Pump Lever
S pray tube 20”, plastic (incl. 8, 26)
Stainiess steel wand
Gasket
Gasket, Viton*
49
50
50A
51
52
53| 00 31 356
40 74 412
40 74 425
40 74 680
00 10 110
00 20 101| 473P, 473D, 435, 485
425’s, 475’s, 315- A| Washer
Strap buckle
Strap pin
Protective cover
Bolt
Hex. Nut
54
55
56
57
58
60| 40 74 408
49 00 454
00 20 119
00 12 192
40 74 996
40 73 411| 10 1′ s , Deluxe’s , Prof ‘s| Connecting rod with stud
Fold- away pump lever(incl. 4,56,57, 58)
Nut
Bolt
Wand retaining clip
Housing, diaphragm
61
63
64
64A
65
66| 40 73 412
44 00 222
00 18 275
00 18 275
40 74 256
40 74 246| | Flange, diaphragm
Valve assy. (incl. 12, 20×2)
Screw, flange
Screw, plunger
Plunger
Diaphragm (Bleach resistant)
67
68
69
70
72
73| 40 74 255
40 31 130
40 74 243
40 74 234
00 10 141
40 74 837| | Diaphragm lever
Wrist pin
“L”Leftconnecting bracket
“R” Rightconnecting braket
Bolt
Strap hook
90
97
98
99
100| 27 00 316
40 74 295
40 61 464
40 74 123
40 74 329| HD’s| No drip check valve
Pin
Vent plate
Ventcap
Lockclip
101
102
103
106
107| 40 74 336
40 74 335
00 62 271
00 62 324
48 00 182| Dlx,HD’s, P rof’s, 435, 48| Retaining nut
Shut- off valve lever
O-ring
O-ring
Pressure controlvalve (incl &8.23-25.27).
Accessories
1
76
80
93
94
95
96| 42 00 215
49 00 430
49 00 477
49 00 622
40 74 338
00 62 249
40 74 666| | Plug (incl. 8)
Drif guard
Double nozzle
Pressure gauge (incl. 94, 95)
Retaining nut
O-ring
Speed tip nozzle
–
–
–
–
–
–| 49 00 421
49 00 528
00 65 210
06 10 410- P
49 00 513
49 00 258N| | Brass wand 20″
60 ” Brass wand 2 pc
Brass flat spray jet
Brass adjustable nozzle kit (incl. 22, 31)
20 ” plastic extens ion tube
E bow nozzleassy.(incl.10, 22, 31, 33, 35)

References

• P65Warnings.ca.gov

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