SOLO 315-A Backpack Sprayer: 4-Gallon Viton(R) G7915559

Description

If your days are long and your routes are full, the SOLO 315-A Backpack Sprayer, 4 gal, Viton (G7915559) is the kind of reliable, no-nonsense tool that lets you focus on the job rather than the equipment. Built around a tough HDPE tank with FKM/Viton seals that stand up to acidic cleaners and oil-bearing solutions, it is purpose-designed for demanding, professional use in pest management and sanitation.

Key Customer Benefits

• Confident chemical compatibility for tough jobs. FKM, also called Viton, seals and O-rings hold up to acidic solutions and liquids that contain oils or harsh solvents, so you can spray with confidence for cleaning, sanitation, or professional pest control without the premature seal failures that plague standard EPDM sprayers.
• Built to last, yet easy to live with. The heavy-duty HDPE tank resists impact and UV, the large filler opening makes rinsing and refilling painless, and the steel-reinforced base plus wand retainer and lock-on or lock-off shut-off give you a durable, tidier rig that survives truck beds and busy routes.
• Real reach and output when you need it. A 20 inch polypropylene wand and a 48 inch hose help you reach under eaves, around shrubs, and into corners, while the system delivers up to 60 psi so you can get fine coverage with a flat fan pattern or step up flow for rinsing tasks.
• More consistent applications, fewer callbacks. A four-position pressure regulator helps you target a repeatable output, which supports uniform droplet size and steadier coverage for herbicides, disinfectants, and insecticides. That kind of control cuts drift, waste, and surprises.
• Less clogging, less downtime. An in-tank filter screens debris before it ever reaches the valve and nozzle, which means fewer mid-job cleanouts and steadier flow on gritty or outdoor mixes.
• Versatile by design. Rated for cleaning and degreasing, janitorial and sanitation, and lawn and garden use, the SOLO 315-A doubles as your go-to 4 gallon backpack sprayer for everything from alkaline cleaners to common landscape treatments, making it a smart one-tool solution for small businesses and serious homeowners.

Product Description

What it is and who it is for

The SOLO 315-A Backpack Sprayer, 4 gal, Viton seals is a professional-grade, acid-solution backpack built for facilities teams, vehicle detailers, and pest management pros who need a sprayer that stands up to harsh mixes. It belongs to SOLO’s CLEANLine range that uses FKM, also called Viton, seals for acidic solutions within a pH range of one to seven. The 315-A pairs that chemical resistance with a translucent HDPE tank, a steel-reinforced base, and a commercial shut-off that you can lock on or lock off, so you get durability and precise control in one rig. It is assembled with a 20 inch polypropylene wand and a comfortable harness, and it is made in Germany for consistent build quality.

How it works in real use

Under the hood is a smooth piston pump that you pressurize by hand. The system includes a four-stage pressure regulator, so you can dial output to a repeatable setting rather than guessing by feel each time. That matters when you are applying descalers in a restroom, rinsing equipment bays, or laying down a consistent fan pattern for perimeter insect work. The kit ships with a set of chemical-resistant plastic tips, including adjustable, flat fan, hollow cone, and jet stream, which lets you trade off coverage, droplet size, and reach without buying add-ons on day one.

What makes it effective and different

A few details separate the 315-A from generic four-gallon backpacks. First, the FKM sealing package is designed for acidic cleaners and oil-bearing solutions, which is exactly where standard EPDM sprayers struggle. SOLO’s own category guidance calls out FKM for acidic applications and EPDM for alkaline, so you choose the 315-A when your cleaning or pest program leans acidic.

Second, the hardware is tuned for uptime. You get a large four and one half inch fill opening that speeds rinsing and refills, an in-tank filter that catches grit before it reaches the valve, a 48 inch hose for maneuvering around obstacles, and a maximum working pressure around sixty psi for reach when you need it. Those are practical touches that reduce clogs, shorten setup time, and help you cover more area per hour.

Product Specifications

Category	Spec
Model	SOLO 315-A, CLEANLine series
Capacity	4 gallons, about 15 liters
Pump type	Manual piston pump, 4-stage pressure regulator
Max working pressure	Up to 60 psi
Seals and O-rings	FKM, also called Viton
pH suitability	About pH 1 to 7 for the 315-A
Tank material	HDPE, translucent with large opening
Fill opening	About 4 and one half inches
Hose	48 inches, nylon-reinforced
Wand	20 inches, polypropylene
Included nozzles	Adjustable, flat fan, hollow cone, jet stream
In-tank filter	Yes
Dimensions, empty	Approx 14.2 to 15 inches long, 9.25 to 15 inches wide, 20.25 to 20.6 inches high
Empty weight	About 9.5 to 11.3 pounds
Applications	Cleaning and degreasing, janitorial and sanitation, lawn and garden spot work
Country of manufacture	Made in Germany
Safety basics	Not for flammable liquids; do not spray diesel or solvents that are flammable; do not use liquids over about 110 degrees Fahrenheit; wear appropriate PPE
Coverage guidance	Calibrate to your walking speed and tip. Many turf and perimeter programs use about 1 to 1.5 gallons per 1,000 square feet as a starting point. Always follow the label
California Prop 65	No warning noted on common listing for this SKU

Detailed How to Use and Installation Guide

Before you start, safety and chemical check

Put safety first. Read the pesticide or cleaner label and wear the PPE it requires. At minimum for hand-held spraying, the U.S. EPA calls out chemical-resistant gloves, eye protection, and clothing that covers skin, and it reminds supervisors to inspect PPE each day and ensure respirators actually fit when labels require them.

Confirm the liquid you plan to spray matches the SOLO 315-A’s sealing package. This model belongs to Solo’s CLEANLine, built with FKM, also called Viton, seals for acidic solutions in roughly the pH one to seven range and for mixes that may contain oils or aggressive solvents. If your program is predominantly alkaline, Solo recommends EPDM-sealed variants instead. Never use flammable liquids and do not spray hot liquids, the company warns against both in its operator guidance.

Assembly out of the box

Straps and harness. The upper strap ends arrive attached. Clip each lower hook to the steel frame where the frame leaves the tank and bends. This anchor point keeps the straps from popping free when you shoulder the pack.

Pump lever. Slide the lever onto the pump shaft, align the bolt holes, then install the two bolts with their washers and tighten. If you prefer the lever on the opposite side, move the stop plate as Solo specifies and remount.

Wand and nozzle. Insert the wand into the shut-off and tighten the screw cap. The kit accepts Solo’s plastic tips. For a flat fan, assemble filter and gasket into the nozzle body, then the cap and retaining nut in the order shown in the manual.

Set the pressure regulator before filling. Lift off the cap and filter basket to access the regulator head. Solo’s four detents roughly target 15, 30, 45, and 60 psi from settings one through four. Higher pressure increases output but produces smaller droplets that drift more easily, so choose the lowest setting that still gives you good coverage.

First fill and priming

Mix chemicals in a separate jug, then pour through the tank’s filter basket so debris does not reach the valve. Pump the handle to pressurize, then in a safe area point the wand up and open the valve for about ten seconds to purge air from the hose and wand. Practice with clean water first to check for leaks and to learn the trigger and lock-on.

Calibrate your application rate, quick and accurate

Consistent results come from calibrating to your walking speed, your nozzle, and your regulator setting.

Method A, 1,000-square-foot plot. Stake out 20 by 50 feet on pavement or turf similar to the job. Fill halfway with water, spray the plot at the pressure and pace you plan to use, time yourself, then spray into a container for that same time and record the volume. That is your gallons per 1,000 square feet. Repeat and average.

Method B, 1/128-acre method. Mark 340 square feet. Spray the area at your chosen pressure and pace, then refill the tank to the starting line and measure how many fluid ounces it took. Since 128 ounces make one gallon and 340 square feet is one-hundred-twenty-eighth of an acre, the number of ounces you used equals your gallons per acre.

University extension programs teach both methods and stress steady pace, steady pressure, and a fixed nozzle height. Write down the setup that produces your target rate, for example 30 psi with a flat fan and shoulder-level wand yields one gallon per 1,000 square feet.

Choose the right tip and pressure for the job

For broadcast herbicide or disinfectant coverage on flat surfaces, a flat-fan tip is the standard choice because it lays down a uniform swath when used correctly. For perimeter insects or cracks and crevices, a hollow-cone tip can help target edges and joints.

Pressure matters as much as tip style. Higher pressure creates smaller droplets that drift more, while lower pressure makes larger droplets that are more drift-resistant. The ASABE droplet classification, used on many labels and nozzle charts, is built around that tradeoff. With the 315-A’s regulator, select the lowest detent that still gives even coverage.

On concrete, a flat-fan should paint a band with no heavy edges and no visible skips when you overlap passes. If you see striping, adjust overlap and walking speed before you bump pressure.

Technique that saves time and prevents callbacks

Work edges and around fixtures first, then fill the interior with overlapping passes that match your calibrated swath width. Keep nozzle height consistent and your pace steady. When labels say “spray to wet,” think like you are painting metal, even sheen, no runs. Extension guides recommend repeating your calibration if you change tips, hose, or strap length, because those changes alter wand height and flow.

After-spray cleanup that protects seals and avoids cross-contamination

Clean immediately. Drain the tank at the job site if the label allows, then run triple rinses using about ten percent of tank volume per rinse, purging the hose and nozzle each time. Remove and wash strainers and tips with soapy water. For stubborn residues from certain herbicide families, a detergent, ammonia, or a label-listed commercial cleaner may be required. Follow label and local rules for handling rinsate.

Solo’s operator guidance adds practical steps: pump until only air comes out so the air chamber resets, and never store chemicals in the tank. When cleaning after hormone-type herbicides, Solo describes an activated charcoal neutralization step before final rinsing.

Maintenance and storage, keep it smooth and leak-free

Lubrication. Solo repeatedly recommends lubricating seals with Solo Superior Grease or petroleum jelly. On piston models like the 315-A, clean and lube the Viton collar after use, and keep the cap gasket and other O-rings lightly greased with a non-water-soluble grease. Regional Solo service notes caution against silicone grease on some trigger valve O-rings, so use Solo’s own grease or petroleum jelly unless your manual specifically calls out silicone for a part.

What not to do. Do not run wettable powders through piston models, Solo flags extra wear for the 315-A and similar pumps. Choose diaphragm models if you often spray abrasive powders. Do not use flammable liquids and do not spray liquids hotter than about 110 degrees Fahrenheit. Store empty, clean, and dry, away from heat and sunlight.

Troubleshooting. If pumping feels gritty or stiff, Solo’s support points to a dirty cylinder or a dry or swollen piston O-ring. Remove the piston, clean, and re-lube. If pressure is low, check the pressure-relief valve O-ring, piston O-ring, and that the tank cap is tight.

Pro tips from real users

Pros on lawn-care and grounds forums repeatedly emphasize two habits that pay off. First, calibrate to your pace and write your setup on tape under the tank cap, which makes repeat jobs faster. Second, set the regulator and avoid feathering the trigger, since squeezing and releasing changes pressure and coverage. Users also share simple strap fixes and routing tricks that keep straps from slipping and make shouldering the pack quicker on busy days.

Frequently Asked Questions

What chemicals can I safely run in the SOLO 315-A?

The 315-A is part of SOLO’s CLEANLine series with FKM, also called Viton, seals. It is built for acidic solutions in the pH one to seven range, and for mixes that contain oil or harsh solvents. If most of your work is alkaline, pick an EPDM model instead.

Can I spray bleach with this acid-rated sprayer?

Bleach is alkaline. SOLO’s own guidance says you can use up to twenty percent bleach in a garden sprayer, yet it will shorten seal life over time. Their support literature advises using EPDM models for alkaline chemistries and even points users toward diaphragm models like the 475-B for bleach use. In short, the 315-A will tolerate occasional bleach, but if bleach is routine, choose an EPDM or 475-series diaphragm unit.

Does the 315-A have a pressure regulator and what are the settings?

Yes. The built-in four-position regulator is set inside the tank. The detents are 15, 30, 45, and 60 psi, which lets you repeat an application rate rather than guessing by feel. Adjust it before you fill the tank.

Can I run wettable powders through this sprayer?

SOLO warns against wettable powders in piston pump backpacks, which includes the 315-A. Those abrasives wear the piston quickly. If powders are unavoidable, SOLO recommends diaphragm models such as 475-B, 475-Prof, 473-D, or 485.

What is the maximum pressure, hose length, and wand length?

The 315-A has 60 psi max pressure, a 48 inch hose, and a 20 inch polypropylene wand, which matches typical field setups for a professional 4 gallon sprayer.

How heavy is a full 4-gallon tank to carry?

Water weighs about eight pounds per gallon. Four gallons adds roughly thirty-two pounds to the pack, plus the sprayer weight. SOLO’s manual reminds users to treat a liquid-filled backpack as significant weight and to avoid climbing while wearing it.

What thread type does SOLO use on wands and accessories?

Owners on The Lawn Forum have documented that SOLO commonly uses 3/8 BSPP straight thread on wand and accessory interfaces, which explains why some third-party parts need adapters. Always verify the specific part before ordering.

Is the 315-A appropriate for indoor work like restrooms or equipment bays?

Yes, with the right chemistry and label permissions. SOLO’s support page lists indoor uses such as detergents, vinegar, and cleaning solutions and notes warm water up to one hundred twenty degrees Fahrenheit. Never bring a sprayer indoors if it has been used with herbicides or other toxic chemicals.

What maintenance extends seal and valve life on this Viton seal sprayer?

SOLO recommends regular lubrication of cap gaskets and O-rings with Solo Superior Grease or petroleum jelly. Keep the pressure relief valve and shut-off internals clean and lightly greased, and store the sprayer clean and dry.

My trigger drips or will not hold pressure. What should I check first?

Start with SOLO’s repair checklist, then service the shut-off. The Shut-Off Valve Repair Kit replaces wear parts used across SOLO backpack models, including the 315-A. Inspect the cap gasket, pressure relief valve O-ring, and shut-off valve body, then re-lube and reassemble.

What about warranty and parts availability?

SOLO backpack sprayers carry a one-year limited warranty against defects. Replacement parts, from full shut-off assemblies to harnesses and check valves, are widely stocked by SOLO and independent parts houses.

Can I use hot solutions to improve cleaning power?

Warm is fine, hot is not. SOLO support cites warm water up to one hundred twenty degrees Fahrenheit as acceptable for cleaning tasks. Extremely hot liquids shorten seal life and are not advised.

Any field tips for drift control and consistent coverage?

Use the lowest regulator setting that still gives even coverage, and pick the right nozzle pattern for the job. Flat-fan tips give uniform bands on floors and walls, while cone tips help along edges. Keep pace and nozzle height steady so your droplets stay consistent across the whole pass. Then write your settings on a tag under the cap so you can repeat them next time.

Conclusion

If your day involves tough cleaners or oil-bearing mixes, the SOLO 315-A backpack sprayer gives you a proven platform with the right sealing package for acidic solutions, clear guidance on pressure control, and the accessory set you need to get moving without extra purchases. The CLEANLine design pairs FKM seals for a pH window geared to acids with a smooth piston pump and a four-position regulator, so you can match output to the label and repeat it job after job.

You do not have to take my word for it. The manufacturer page lists the included nozzle set, padded harness, and regulated pump, while Solo’s support note explains the regulator steps of 15, 30, 45, and 60 psi. Retailer specs for the G7915559 listing confirm practical details like the 20 inch wand, 48 inch hose, and 60 psi ceiling that pros care about for reach and coverage.

Whether you are outfitting a facilities crew or upgrading your solo rig, this acid resistant backpack sprayer is a dependable, parts-supported workhorse that travels well between cleaning, sanitation, and perimeter pest jobs. If your program is mostly alkaline, Solo’s EPDM options in the same family will suit that chemistry better, so you can choose confidently either way.