Static vs rotating tank cleaning nozzles

No matter what is being produced at scale, from foodstuffs to beverages, manufacturers must thoroughly clean their tanks to avoid contamination and meet health and safety standards.

A clean-in-place method that uses different types of spray nozzle technology is most commonly employed to avoid dismantling and rebuilding equipment that needs cleaning. It also prevents operators having to enter tanks or other confined spaces to clean manually.

Tank cleaning nozzles are industrial quality equipment, specifically designed for washing and sanitising tanks, cans, scrubbers and containers of all sizes. They can, for the most part, be divided into two types: static or rotating. The rotating type can then be divided into free-spinning, controlled rotation or gear controlled.

This article will outline the differences between static and rotating tank cleaning nozzles to help determine which solution is better fitted for financial and environmental targets.

Static spray nozzles (spray balls)

Used across many industries for its reliability, this is the most basic of tank washing devices. Liquid from the static spray nozzle hits the tank interior in a pre-defined cleaning pattern which is fixed as a result of holes being drilled into the nozzle. This freefalling film then cleans the tank walls; however, it takes a relatively long time and can result in excess water/chemical usage. Its low-impact and high-volume fluid requirement limits its use to small tanks and processes where easily cleaned liquids and non-sticking products have to be rinsed.

Free spinning (rotating) spray nozzles

The free-spinning rotating spray nozzle offers a rotating spray pattern. The liquid itself drives the movement, which cascades and wets the internal surfaces of the tank walls. The fan pattern creates a vibration off the tank’s internal surfaces, agitating the residue and making it easier to remove. This rotating spray nozzle can reduce water and chemical usage by up to 30% compared to static spray nozzles, while also cleaning the tank faster and consequently reducing downtime.

It is worth noting, though, that the operating pressure has a direct influence on the rotation speed. It must be limited to prevent the liquid jets from breaking into minute droplets, losing part of their impact value on the wall. While these rotating spray nozzles are suitable for larger tanks with a wetting radius of up to 6 m, they may not be effective for harder-to-clean residues, but they do offer a 360° guaranteed repeatable cleaning coverage.

Controlled rotation nozzles

Controlled and gear-controlled rotation nozzles are kept in motion by a friction motor and generate high-impact water jets that clean the inside of the tank in a repeatable predefined pattern to remove even the most stubborn of residues and effectively clean the entire tank surface with high mechanical impact. This nozzle technology can provide additional efficiencies such as reducing water and chemical usage, while reducing cleaning cycle times.

So, which is best?

Each application may require a different approach. When choosing the right cleaning head for your application there are a few questions to consider:

• Is the product water soluble and easy to clean?
• What size is the tank?
• Are there any obstacles in your tank that might shadow areas from direct cleaning fluid impact?
• Is reducing water and chemical usage a company focus?

As a rule of thumb, when carrying out simple cleaning tasks in smaller tanks or vessels that require a simple rinse, the fixed or static spray nozzles continue to provide excellent cleaning. So, if the product is water soluble and has only light residue to remove, this may be a good option.

If you have high flow rates, fixed spray balls may also be a good solution; however, for larger or more complex tanks, rotational spray nozzles use less water, have faster cleaning cycles and use fewer chemicals. Their flat fan or jet spray patterns can penetrate a larger surface area inside the tank with greater impact. Moreover, droplets created by controlled rotation spray nozzles are larger and strike at higher speeds, enabling them to remove tough, heavy soiling.