STIHL Backpack Sprayer Manual

The STIHL Backpack Sprayer is a professional-grade, portable spraying system designed for applying liquids such as herbicides, pesticides, fertilizers, and water over medium to large areas. It features a durable chemical-resistant tank, adjustable shoulder straps, a pressure pump with pressure relief valve, a telescopic lance with adjustable nozzle, a filter system, and a comfortable carrying frame. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Chemical-resistant polypropylene tank, Pressure pump with integrated pressure gauge and relief valve, Adjustable telescopic spray lance, Variable spray nozzle (fan, jet, cone), Shoulder straps with padded back support, Filter at tank outlet and lance inlet, Carrying handle.

Assembly & Preparation

Unpack all parts and inspect for damage. Assemble on a clean, flat surface.

1. Attach the shoulder straps: Clip straps to designated hooks on the tank frame.
2. Install the spray lance: Screw the lance handle onto the hose connector. Attach the desired nozzle tip.
3. Connect the hose: Attach one end to the tank outlet and the other to the lance inlet. Ensure connections are tight.
4. Install the filter: Ensure the pre-filter basket is placed inside the tank fill opening.

WARNING! Always wear appropriate Personal Protective Equipment (PPE) including gloves, goggles, and long sleeves when handling chemicals. Read chemical manufacturer's label before use.

First-Time Use

Prepare the sprayer and mixture before operation.

1. Prepare mixture: In a separate container, mix the chemical with water as per label instructions. Never mix inside the sprayer tank.
2. Fill the tank: Use a funnel. Fill with clean water first for testing, or with your prepared mixture. Do not overfill. Leave air space.
3. Prime the pump: Close the tank lid securely. Pump the handle 10-15 times to build initial pressure.
4. Test spray: Point lance in a safe direction. Squeeze the lever to test spray pattern and check for leaks.
5. Adjust pressure: Pump to desired operating pressure (refer to gauge if equipped). Engage the pressure lock if available.

CAUTION! Never pressurize with hot liquids or flammable substances. Ensure pressure is released before opening the tank.

Specifications

• Tank Capacity: 4 gal (15 L)
• Tank Material: Chemical-resistant polypropylene
• Max Pressure: Typically 60-80 PSI
• Hose Length: Standard 6.5 ft (2 m)
• Lance Length: Telescopic, 24-40 inches
• Spray Patterns: Fan, jet, cone (via interchangeable nozzles)
• Weight (Empty): Approx. 8.8 lbs (4 kg)
• Carrying System: Padded back frame and adjustable straps

Controls and Parts

Main parts: Tank, Pump Handle, Pressure Gauge, Pressure Relief Valve, Tank Lid with Seal, Hose, Lance with Control Lever, Nozzle, Shoulder Straps, Carrying Handle.

Operation: Pump handle builds pressure. Pressure lock maintains pressure. Lance lever controls flow. Pressure relief valve "hisses" to release over-pressure. Nozzle selector changes spray pattern.

Adjustments: Strap length for fit. Lance length for reach. Nozzle type for pattern. Pressure for droplet size and distance.

Operating Instructions

1. Donning: Loosen straps, put arms through, tighten straps so tank sits comfortably on back.
2. Pressurizing: Pump handle until desired pressure is reached. Engage lock if equipped.
3. Spraying: Hold lance with both hands. Point nozzle at target. Squeeze lever to start spray. Release to stop.
4. Maintaining Pressure: Periodically pump handle 3-5 times during use to maintain consistent pressure.
5. Shutting Down: Release pressure by triggering the relief valve or slowly unscrewing the tank cap. Point lance into an empty container or back into the tank while releasing pressure.

Tip: Maintain a steady walking pace and consistent lance height for even application.

Spraying Techniques

For effective and efficient application.

1. Fan Nozzle: For broad, uniform coverage of flat surfaces (e.g., lawns, walls). Hold 12-18 inches from target.
2. Jet Nozzle: For targeted, long-distance spraying (e.g., weeds in cracks, under eaves).
3. Cone Nozzle: For foliage penetration (e.g., shrubs, bushes).
4. Overlap: Overlap spray swaths by 30-50% to avoid streaks.
5. Wind: Spray with the wind at your back for distance, or in low-wind conditions to avoid drift.

WARNING! Avoid spraying on windy days to prevent chemical drift onto non-target areas, people, or pets.

Cleaning & Storage

Thorough cleaning is essential after each use, especially when changing chemicals.

1. Empty any leftover mixture properly according to local regulations.
2. Rinse: Fill tank 1/4 with clean water. Pressurize and spray through the system. Repeat 2-3 times.
3. Clean Filters: Remove and rinse pre-filter and inline filter under running water.
4. Disassemble & Dry: Disconnect hose. Remove nozzle and lance. Allow all parts to air dry completely.
5. Storage: Store in a cool, dry place out of direct sunlight. Store with tank cap off to prevent odor buildup. Do not store under pressure.

CAUTION! Never use bleach or strong solvents for cleaning as they may damage seals and plastic. Always clean immediately after use.

Regulatory Information

This sprayer is designed for use with approved agricultural and horticultural chemicals. User is responsible for complying with all local, state, and federal regulations regarding the application, storage, and disposal of chemicals. STIHL is a registered trademark. For genuine parts and accessories, see your authorized STIHL dealer. For support, visit www.stihlusa.com or contact customer service.

Troubleshooting

Service: For repairs, contact an authorized STIHL service dealer. Use only genuine STIHL parts.