PRB Articles

Spray-Equipment Filtration

Spray-Equipment Filtration

By Andrew Greess

When it comes to parks and recreation spray equipment, the single most effective means of boosting productivity, improving service, and reducing repair expenses is proper filtration. While filtration is defined as the removal of suspended foreign material, such as dirt, sand, rocks, or trash, it can also include unusual debris, such as chemical bottle labels, soda cans, rubber gloves, men’s underwear, and fish.

Filters are measured by plumbing size and mesh. Plumbing size (either ¾ of an inch or 1 inch) relates to water flow in gallons per minute, while filter mesh determines the size of the materials that pass through: too fine, and the machine will clog quickly; too coarse, and small debris will get through. A missing filter or a filter with too coarse a mesh will allow debris into the sprayer, where it can damage the pump, clog spray guns and tips, or accumulate in lines where it will eventually cause further damage or downtime. Too fine a filter or a clogged filter will prevent water from reaching the pump. The pump then runs too hot and destroys itself.

Filtration can be divided into three topics:

  • Design
  • Operation
  • Maintenance.

While this article focuses on power sprayers, much of the information also applies to compressed-air hand- and backpack sprayers.

Design includes filtration selection, placement, access, and standardization. Selection should be based on:

  • Quality of water
  • The type of material being applied
  • The type of pump and vehicle.

    Most applications can get by with one well-placed filter between the tank and pump.

Water Source
If the water source is poor (e.g., if filling a golf-course spray tank from a pond), use additional filtration. Add a line strainer on the hydrant fill line, a filter basket in the tank fillwell, and two line strainers between the tank and pump. Four filters on a sprayer are not necessary, but it is important that the right filters are on a sprayer.

Pump Type
Some pumps require more filtration than others. For example, roller pumps are more sensitive to debris, and require better filtration than diaphragm pumps. If the filter on a roller-pump sprayer is too coarse and allows sand into the pump, the sand will tear up the pump quickly. On the other hand, diaphragm pumps can usually pump sand and dirt with no problem.

Technician Access
Technicians don’t always like to check filters for various reasons--either it slows them down or they forget. It's critical the filtration device be located for easy technician access, which means filters should be placed toward the outside of equipment where access is not blocked or encumbered by other components.

Good access also requires that the system is plumbed so the filter can be checked without causing a spill. For example, if the suction line is at the bottom of the tank, there should be a shut-off valve in front of the filter. This allows the technician to check the filter even when the tank is full. If the suction line is at the top of the tank, this is not an issue.

Whichever filtration system is used, try to standardize it for all of the vehicles. This makes training, parts inventory, and maintenance simpler and cheaper.

For sprayers that have been already purchased and are having filtration-related problems, modify existing filters or increase the filtration.

Since most hand sprayers and backpacks already have filters, design is usually not a consideration. Do not buy a manual sprayer if it lacks an easy-to-clean filter.

Checking and cleaning the filter is the single most valuable preventative-maintenance task. It's also the easiest.

For new equipment, check the filter daily. If there's consistently no debris, consider reducing the frequency. When the appropriate frequency is determined, make it a departmental policy. Checking a filter too often is better than too seldom.

Make sure techs do not lose the filter’s rubber gasket when checking the equipment.

Reinforce with spray techs the importance of checking and cleaning the filter. Supervisors should spot-check equipment to make sure technicians are inspecting and cleaning filters regularly. Provide positive reinforcement to technicians who have clean filters and training to techs with dirty or clogged filters. If consistent violators are advised they will be responsible for any damage resulting from their negligence, performance should improve.

Eventually the filter will become too dirty to clean and should be replaced. Chemicals will eventually swell the gasket in the line strainer, making it impossible to create an airtight seal, causing the pump to suck air. When this occurs, replace the gasket.

Consider stocking each vehicle with a spare filter and gasket. This allows the technician to perform the repair in the field, saving downtime driving back to the shop. If the filtration has been standardized, stocking these parts is easy.

Eventually an aged filter body may crack, causing an air leak. This prevents the pump from sucking water from the tank, a situation that requires replacement of the entire unit. Supervisors and maintenance personnel should be trained to look for these problems.

These steps, if followed, will boost productivity, allow you to provide better service to all stakeholders. and reduce repair expenses.

Andrew Greess is the President of Quality Equipment & Spray, which designs and builds custom landscape spray equipment. He can be reached at, or follow him on Facebook. For more information or to share your thoughts, check out his blog at .

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