Backpack sprayer - procedures for preparing equipment for use

A backpack sprayer is a chemical spraying device consisting of a tank and a pump, which is carried on your back, and a hand-held spray. The tank can be heavy duty plastic or metal such as brass.

Before you use the equipment you need to check that all parts are working correctly and there are no leaks. Follow these steps to try out the backpack sprayer: Fill the tank with water to approximately a quarter full. Close all the caps, taps and lids. Pump the handle to pressurise the tank.
Look for leaks, particularly in joints and seals, and repair or replace if necessary. If there is a leak in the joints, release the pressure by using the pressure release valve and check the joints are connected properly (ie no cross threading). Tighten if necessary. If there is a leak in the seals, you may need to replace the O rings and seals.
Check the spray stream and adjust the nozzle to get an even spray (ie correct size and amount), and clean or replace parts if necessary. Keep in mind: Spray stream must be within the manufacturer's specifications (ie no more than 10% variation) because small droplets may be blown off target and large ones may result in runoff and poor coverage of weeds. Spurts indicate a blocked line. Take the line apart and clean it out gently with compressed air.
Clean blocked nozzles using an old toothbrush. Never blow or suck to clear blocked lines and nozzles. Check with your supervisor for procedures to follow for calibrating backpack sprayers.
If you cannot fix a problem, advise your supervisor and tag out the sprayer.

You may have to calibrate the backpack sprayer before use.

These procedures are a guide to show you the steps involved with preparing chemical spraying equipment, such as backpack sprayers, for use. You also need to:

follow the manufacturer's guidelines to ensure equipment is not damaged and the herbicide is applied correctly
carry out safety measures to ensure your safety, for example, wear appropriate personal protective clothing such as overalls, boots, gloves and a face mask
carry out safety measures to ensure public safety, for example, set up barriers such as 'witches' hats to cordon off the work site
check with your supervisor for procedures relevant to your workplace.

Preparing a chemical backpack sprayer for use

	Fill the tank with water to approximately a quarter full.

	Close all the caps, taps and lids.

	Pump the handle to pressurise the tank.

Photo of someone looking for leaks in the joins and seals.

Look for leaks, particularly in joints and seals, and repair or replace if necessary.

For leaking joints: release the pressure by using the pressure release valve and repair using plastic thread tape.
For leaking seals, you may need to replace the O rings and seals.

Photo of the spray stream and the nozzle being adjusted.

Check the spray stream and adjust the nozzle to get an even spray (ie correct size and amount), and clean or replace if necessary.

Check workplace procedures and manufacturer's specifications for:

spray stream margins
cleaning blocked lines
cleaning blocked nozzles.

Remember, never blow or suck to clear blocked lines and nozzles.

	If you cannot fix a problem, advise your supervisor and tag out the sprayer.

Please note that the backpack sprayer is not calibrated in this demo.