Power Sprayer - Tank Agitation

Key Takeaways:

• Jet agitators in sprayers work for most spray applications and cost less to install and maintain. Mechanical agitation adds $500-1,000 but handles heavy granular materials better.

• For spray tank agitators, most liquid materials need 8% of tank volume for agitation. Granular or non-soluble materials need 12%. A 3X booster cuts the required volume by a third.

• Never plumb agitation on the pump return – some manufacturers warn it creates back pressure. Use separate lines with a gate valve for easy adjustment.

• Fill the tank and check the agitation pattern before accepting a rig. Dead spots let material settle and can compromise your spray mix consistency.

Power sprayer tank agitation can be either jet or mechanical. It’s important to understand the two different types of spray tank agitators. Jet agitation utilizes a portion of the pump’s output to stir up the tank. Mechanical agitation utilizes paddles (usually of stainless steel) on a shaft that is turned by belts and pulleys connected with the engine.

Jet agitation is cheaper to install and service and is sufficient for most applications. Mechanical agitation, which can add $500 - $1000 to the cost of your rig, is best for mixing heavy granular, or non-soluble materials.

This entry will focus on jet agitation, or jet agitators in sprayers. The pros at QSpray.com will discuss mechanical agitation in a future blog.

Volume:

A spray tank jet agitator requires a spray pump that has output volume sufficient for your spray application PLUS the volume required to agitate the tank.

Rule of Thumb – Most liquid materials require 8% of tank volume for agitation. Most granular or non-soluble materials require 12%. For example, to agitate a 200-gallon tank that you will be mixing a liquid concentrate into, you need 8% times 200 gallons, or 16 gallons per minute (gpm), for agitation.

Agitation boosters reduce the volume required by creating jet action. Most commonly used boosters are 3X (5X are also available). What this means for your spray tank agitator is that instead of 16 gallons per minute, you’ll need 16 divided by 3 or 5.33 gpm.

You need to select a pump with output equal to the desired spray volume PLUS the required agitation volume. If you need to spray at 5 gpm, you need a pump that will provide at least 10.33 gpm (5 gallons for spray plus 5.33 for agitation in this example) when it comes to agitators in your sprayer. You actually want a pump that will do more than this because the rated output is for a new pump with no restrictions. Actual output from your spray tank jet agitator will almost always be lower.

Plumbing:

Some power spray equipment providers plumb the agitation on the pump return. QSpray.com strongly believes this is a bad idea. Some pump manufacturers (e.g., Hypro, Udor) specifically warn against this as it creates back pressure that can affect the pump's performance. 

Regardless, it is a bad idea because return lines cannot have shut off valves on them (Note – centrifugal pumps are the exception). Because you can’t shut off the line, if the pump requires service when the tank is full, you will have to dump the tank since you can’t shut off the line. 

For spray tank agitators, QSpray.com recommends separate lines with the return to the top of the tank and the jet agitator to the bottom. It is sometimes helpful to put a gate valve on the agitation line so that the agitation can be easily adjusted. This is also an easy way to adjust the pressure of your spray line. More agitation means less pressure on the spray line.

Agitation Jets:

Jet agitators in sprayers must be positioned to ensure that the entire tank is agitated and no dead spots exist for material to settle. Be sure to fill the tank of the spray tank agitator and observe the agitation pattern before accepting the rig from your supplier.