STIHL SR 450 (02) PDF Document

The STIHL SR 450 mistblower is suitable for applying fungicides, herbicides, and pesticides at ground level. Typical areas of application include fruit, vegetable, wine, and crop growing, plantations, flower growing, grassland, and forestry. In its dusting and spreading mode, it can apply plant protection products over a wide area in powder form or as dry granulate.

Proper protective clothing and equipment must be worn when using, filling, and cleaning the STIHL SR 450. This includes:

Clothing that is snug-fitting but allows freedom of movement.

Impermeable coveralls for certain plant control chemicals.

Impermeable head covering if spraying overhead.

Close-fitting safety glasses in accordance with European Standard EN 166.

A suitable respirator to protect against health risks and allergic reactions.

Personal sound protection such as ear defenders.

Impermeable gloves resistant to plant control chemicals.

Impermeable safety boots with non-slip soles resistant to plant protection products.

When handling chemicals for the STIHL SR 450, read the chemical manufacturer’s manual prior to use. Follow all instructions regarding mixing, using, personal protective equipment, storage, and disposal. Chemicals should only be used by persons trained in their handling and first-aid measures. Keep the chemical manual or label available at all times to inform a doctor in an emergency.

Follow these rules when mixing solution for the STIHL SR 450:

1. Mix the product strictly in accordance with the manufacturer’s instructions.

2. Never spray liquid plant control chemicals undiluted.

3. Mix the solution outdoors only or in well-ventilated locations.

4. Only prepare enough solution for the job at hand so nothing is left over.

5. Do not mix different plant protection products unless the mixture is approved by the manufacturer.

To fill the container of the STIHL SR 450 safely:

1. Fill the container outdoors only in well-ventilated locations.

2. Stand the unit on a level surface and do not fill above the maximum mark.

3. Do not fill the container while wearing the unit on your back.

4. Close the valve lever and the metering lever before filling.

5. Before filling with spray solution, perform a test run with fresh water to check for leaks.

6. Fit the filler cap and tighten it down firmly after filling.

In order to reduce the risk of damage to the environment and plants, do not operate the STIHL SR 450 in windy conditions, at temperatures above 25 degrees Celsius in the shade, or in direct sunlight. Unfavorable weather can result in incorrect chemical concentrations, leading to plant damage or unsuccessful treatment.

To reduce the risk of accidents and damage, never operate the STIHL SR 450 with flammable liquids, viscous or sticky liquids, caustic or corrosive chemicals, or liquids hotter than 50 degrees Celsius.

Refueling the STIHL SR 450 requires strict safety measures:

1. Shut off the engine before refueling and allow it to cool; never fuel a hot engine.

2. Remove the unit from your back and place it on the ground.

3. Refuel only in well-ventilated areas and stay clear of naked flames.

4. Open the fuel cap carefully to release pressure slowly.

5. After refueling, tighten the screw-type fuel cap as securely as possible.

6. Check for fuel leakage; if fuel has spilled, do not start the engine.

Before starting the STIHL SR 450, perform the following checks:

Check the fuel system for leaks, especially the fuel cap, hose connections, and manual fuel pump.

Ensure the setting lever moves easily to the STOP or 0 position.

Verify the throttle trigger moves freely and springs back to the idle position.

Check that the spark plug boot is secure.

Check the condition and tightness of the container, hose, and metering unit.

Inspect the harness straps and replace them if they are worn or damaged.

To start the STIHL SR 450:

1. Place the machine on level ground and ensure you have a secure footing.

2. Move the setting lever to the RUN position (I).

3. Press the manual fuel pump bulb at least five times.

4. For a cold start, press the choke knob and turn it to the cold start symbol.

5. For a warm start, press the choke knob and turn it to the warm start symbol.

6. Hold the unit with your left hand and put one foot on the base plate.

7. Pull the starter grip slowly until it engages, then give it a brisk, strong pull.

8. Once the engine runs, pull the throttle trigger to return the choke knob to the run position.

Carry the STIHL SR 450 on your back using both harness straps. Hold and control the blower tube with your right hand on the control handle. Move only in a forward direction and observe the discharge area. Keep the unit and container upright and do not bend forward to avoid chemical leaks.

The STIHL SR 450 features an antistatic system to reduce the risk of sparking or explosion when working in dusting and spreading mode. It consists of a conductive wire in the spray tube connected to a metal chain. The metal chain must make contact with a conductive surface to dissipate electrostatic charges. Never operate the machine on non-conductive surfaces like plastic or asphalt in this mode.

To stop the engine of the STIHL SR 450, move the setting lever in the direction of the 0 position. The engine will stop, and the setting lever will spring back to the on position.

After finishing work with the STIHL SR 450:

1. Close the valve lever and the metering lever.

2. Shut off the engine before taking the unit off your back.

3. Place the machine on a level, non-flammable surface.

4. Drain and clean the solution container and hose system with clear water.

5. Wash your hands, face, and clothing if necessary.

To fit the pleated hose on the STIHL SR 450 blower tube:

1. Push the wide hose clamp onto the blower tube.

2. Push the ring seal onto the stub on the blower tube with the wide lip facing left.

3. Push the pleated hose over the ring seal.

4. Position the hose clamp over the pleated hose, line up the marks, and secure it with the screw.

To adjust the throttle cable on the STIHL SR 450:

1. Ensure the unit is completely assembled.

2. Set the throttle trigger to the full throttle position as far as the stop.

3. Rotate the screw in the throttle trigger in the direction of the arrow until you feel resistance.

4. Rotate it another full turn.

To adjust the harness on the STIHL SR 450, pull the ends of the straps downwards to tighten them. The backplate should fit snugly and securely against your back. To loosen the harness, lift the tabs of the sliding adjusters.

The STIHL SR 450 engine requires a mixture of gasoline and two-stroke engine oil. The mixing ratio is 1:50, which is 1 part oil to 50 parts gasoline. Use high-quality gasoline with an octane rating of at least 90 ROC.

The setting lever on the STIHL SR 450 has several positions:

Run position (I): The engine is ready to start or run; the throttle trigger can be moved freely.

Stop position (0): The ignition is interrupted and the engine stops; the lever then springs back to the run position.

Throttle trigger limiter: Can limit the travel of the throttle trigger in two stages (1/3 throttle or 2/3 throttle).

Throttle lock: Can lock the throttle trigger in any required position.

Calculating the solution for the STIHL SR 450 involves three steps:

1. Determine the surface area in square meters. For ground crops, multiply field length by width. For high-growing plants, calculate based on row length, foliage height, and number of rows.

2. Determine the quantity of active ingredient based on the manufacturer’s instructions for one hectare and the actual area in hectares.

3. Calculate the total quantity of solution required (TB) using the formula: (Quantity of active ingredient / Concentration in %) x 100.

The discharge rate (Vc) for the STIHL SR 450 is calculated by multiplying the quantity of solution (Va) by the walking speed (vb) and the working width (b), then dividing by the area (A). Formula: Vc = (Va x vb x b) / A.

The valve lever on the STIHL SR 450 starts and stops the solution feed. When the lever is in the vertical (up) position, the feed is open. When the lever is in the horizontal (down) position, the feed is closed.

Dosage pieces allow for different discharge rates on the STIHL SR 450. The standard dosage piece has positions 1 to 6, where position 1 is the minimum flow and position 6 is the maximum flow. There are also specific dosage pieces for pressure pumps and ultra-low volume (ULV) nozzles. To change one, pull the existing piece out of its seat and push the new one in as far as it will go.

Discharge rates (liters per minute) for the STIHL SR 450 without a pressure pump are as follows:

To check the flow rate of the STIHL SR 450:

1. Place the machine on the ground and fill the container with water to the 10-liter mark.

2. Set the standard dosage piece to 6.

3. Start the engine and run it at full throttle.

4. Hold the blower tube horizontally and spray until the water level reaches the 5-liter mark.

5. Note the time taken; it should be between 110 and 150 seconds. If not, check for contamination or incorrect settings.

To convert the STIHL SR 450 to dusting and spreading mode:

1. Empty and clean the solution container.

2. Close the valve lever and the metering lever.

3. Remove the strainer from the solution container.

4. Squeeze the tabs on the container levers to release it from the housing.

5. Turn the container to position B (dusting and spreading mode) as indicated by the symbols.

6. Reinstall the container on the housing and ensure the levers click into place.

7. Rotate the nozzle lugs on the blower tube to the correct position and pull the nozzle off.

In dusting and spreading mode on the STIHL SR 450, the discharge rate is variable via the metering lever. Position A (vertical) indicates the feed is closed. Position B (parallel to the blower tube) indicates the feed is open. The rate depends on the density and grain size of the product.

The STIHL SR 450 can be fitted with different screens to alter the spray shape:

Without screen: Long distances and maximum range.

Fan jet baffle screen: Broadens and softens the spray for close range plants.

45 degree deflector screen: Diverts the jet for under-leaf treatment or upwards spraying.

Dual deflector screen: Splits the jet in two directions for treated two rows simultaneously.

To drain the STIHL SR 450 container, close the valve lever and shut off the engine. Turn the dosage piece to position 6 or E and collect the remaining solution in a suitable container. Rinse the container and hose system with clear water afterward.

If the STIHL SR 450 will not be used for 30 days or longer:

1. Drain and clean the fuel tank in a well-ventilated area.

2. Dispose of fuel properly according to local requirements.

3. Run the engine at idling speed until it stops to empty the carburetor.

4. Thoroughly clean the machine, cylinder fins, and air filter.

5. Store in a dry, frost-free, and secure location away from children.

6. Do not expose the solution container to direct sunlight for long periods to avoid the material becoming brittle.

If there is a loss of engine power in the STIHL SR 450:

1. Turn the choke knob to the cold start position.

2. Loosen the screws and remove the filter cover.

3. Remove the filter element and replace it if it is dirty or damaged.

4. Fit the new filter into the housing and reinstall the cover securely.

The standard settings for the STIHL SR 450 carburetor are:

High speed screw (H): Turn counterclockwise as far as the stop (no more than 3/4 turn).

Low speed screw (L): Turn clockwise as far as the stop, then turn it back 3/4 turn.

Check the spark plug of the STIHL SR 450 if the engine is down on power or difficult to start:

1. Pull off the spark plug boot and unscrew the spark plug.

2. Clean a dirty spark plug and check the electrode gap (0.5 mm).

3. Replace the spark plug after about 100 operating hours.

4. Use only suppressed spark plugs approved by STIHL (NGK BPMR 7 A or Bosch WSR 6 F).

The STIHL SR 450 has an air speed of 90 m/s. The maximum air flow rate without the blower tube is 1300 cubic meters per hour, and the air throughput with the nozzle is 920 cubic meters per hour.

For the STIHL SR 450, the sound pressure level is 102 dB(A) and the sound power level is 109 dB(A). The vibration level at the right handle is 1.9 m/s².

If the STIHL SR 450 engine does not start in the warm start position, move the choke knob to the cold start position and continue cranking until the engine runs. Also, check that there is fuel in the tank and that the spark plug boot is properly connected.

To determine walking speed for the STIHL SR 450, carry out a trial run with water. Determine the distance walked in one minute while swinging the spray tube. Dividing the distance in meters by the time in minutes gives the walking speed in meters per minute (m/min).

The solution container of the STIHL SR 450 has a capacity of 14 liters. When filled with product and fuel, the maximum operating weight is 28.1 kg.

The unfilled weight of the STIHL SR 450 is 12.8 kg. The maximum operating weight when the fuel and solution container are fully filled is 28.1 kg.

Do not dispose of the STIHL SR 450 with domestic waste. Take the machine and its packaging to a suitable collection point for recycling in accordance with local regulations. Improper disposal can be harmful to health and the environment.

Common causes for spark plug fouling in the STIHL SR 450 include using too much oil in the fuel mix, a dirty air filter, or unfavorable running conditions. These issues should be rectified before installing a new or cleaned spark plug.

To adjust the idle speed on the STIHL SR 450:

1. Perform the standard carburetor setting first.

2. Start and warm up the engine.

3. If the engine stops while idling, turn the idle speed screw (LA) clockwise until the engine runs smoothly.

If the idle setting is too lean, turn the low speed screw (L) counterclockwise until the engine runs and accelerates smoothly. If the idle is too rich, turn the low speed screw (L) clockwise. Usually, the idle speed screw (LA) must be readjusted after changing the low speed screw (L).

For high altitude operation of the STIHL SR 450, perform the standard setting and warm up the engine. Turn the high speed screw (H) slightly clockwise (leaner), but no further than the stop. Reset the carburetor to the standard setting when returning to low altitude to avoid engine damage from overheating.

If the air filter is clean and the carburetor is properly adjusted but the STIHL SR 450 still runs poorly, the muffler may be contaminated with carbonization. This should be checked by a servicing dealer.

To clean the STIHL SR 450 strainer, insert a tool like a screwdriver into the two recesses to loosen it. Pull the strainer upward and out of the container. Clean it with clear water and a brush before reinstalling.

The antistatic chain on the STIHL SR 450 must be attached to the blower housing with a screw and must make contact with a conductive surface during operation to dissipate charges. Check the chain regularly and replace it if it is damaged.

The STIHL SR 450 fuel tank has a capacity of 1700 cubic centimeters, which is equivalent to 1.7 liters.

The electrode gap for the spark plug on the STIHL SR 450 should be set to 0.5 mm.