Seals for 'Retract-A-Ball', the tank cleaning ball

A sealing configuration from Trelleborg Sealing Solutions for Retract-A-Ball, a unique tank cleaning spray ball, has given proven performance in stringent tests

The Trelleborg seals play vital parts in the operation of Retract-A-Ball, a retractable spray ball system for tank cleaning in CIP processes.

The innovative Retract-A-Ball operates pneumatically, giving it the major unique advantage of being fully self-draining, preventing trapping of fluid, a potential source of contamination.

Tank Cleaning Developments involved Trelleborg Sealing Solutions from the concept stage in specification of seals for Retract-A-Ball, a retractable spray ball system for tank cleaning in CIP processes.

The design of the seals presented a number of challenges, as on one side there was liquid and on the other air.

Operating under pressure from both sides and at high temperatures, the seals also had to withstand aggressive cleaning fluids.

In addition, as Retract-A-Ball is used in food and pharmaceutical processing, compliance to relevant standards, including FDA and USP Class VI, was essential.

Extensive tests were required to meet the stringent requirements of the processing equipment manufacturers and their customers.

In these, after cycles of 1,000 operations, there was no leakage and pressure was held.

The seals also continued to perform after a temperature test where the units were heated up to 140C (284F) for 24 hours.

"Trelleborg Sealing Solutions worked with us right from the start of the product design," says Andy Packman, Managing Director of Tank Cleaning Developments: "In the early days, they gave us help and attention, despite us being just a start-up company with a big idea".

The final sealing configuration in the Retract-A-Ball consists of a number of seals of various types and materials dependent on their position and function.

* Specially designed spring energized Turcon PTFE based lip seals.

* O-Rings in EPDM and Isolast perfluoroelastomer to ensure chemical compatibility.

* An O-Ring fitted on the neck of the ball treated with an FDA compliant PTFE coating to improve friction, enhancing movement in and out of the housing.

All the proprietary materials and the coating specified are specifically engineered to meet the needs of the processing industry, including compliance to FDA and USP Class VI standards.

Background to Retract-A-Ball.

In food and pharmaceutical production, Cleaning In Place (CIP) using a spray ball is almost universally employed when cleaning tanks.

In some cases the spray ball can be left in the processing equipment but in most it must be removed after cleaning.

In the past these were inserted and removed manually, but now this is generally an automatic procedure using a retractable system.

Standard retractable spray balls are pushed into the area to be cleaned by the force of cleaning fluid put through them.

This, though, has a major disadvantage.

Once the liquid stops flowing through the system, the spray stem is closed by a return spring, potentially trapping fluid within it.

This can be a possible source of contamination.

The Retract-A-Ball system from Tank Cleaning Developments is different from other retractable spray balls.

Uniquely, it operates pneumatically and is fully self-draining.

With pneumatics, the spray stem can be held in the open position while the cleaning media drains both backwards and forwards.

If necessary, a further air purge can take place to ensure no media remains.

In detail, a retractable spray ball is housed in a cylinder, enclosed with a cover, all of food grade 316L stainless steel.

If required this can also incorporate Hastelloy on the faces that are exposed to cleaning media or the product.

The cylinder is fitted into a ferrule on ducting or tanks within processing plants, primarily for food and pharmaceutical production.

When the system requires cleaning, the spray ball is operated pneumatically.

A telescopic mechanism extends the spray ball into the area to be cleaned.

It has between a 60mm (2.4inch) and 120mm (4.7inch) stroke.

This can be adjusted in 10mm (0.4inch) increments to exactly position the head in the target area for optimum cleaning.

Cleaning media then passes through the relatively small central telescopic system into the spray ball.

This design ensures most of the internal mechanism of the Retract-A-Ball remains dry, making complete draining easier.

After operation, the spray ball returns to its covered housing, ready for the processing system to run again.

The system has achieved ATEX category 1 and is the first retractable spray ball compliant to this standard.

This EU directive requires products to prove that they represent no risk of explosion, significant when handling dry powders.

Back to top