Pumping highly shear-sensitive fluids: Graco to the rescue

Shearing of a pumped product can lead to serious problems. Thankfully Graco has a solution.

A France-based manufacturer of cookware and kitchenware products was becoming extremely frustrated at a specific problem caused by its peristaltic pumps. The company was applying a non-stick coating to their pans (saucepans, stewpots, frying pans, pancake pans, woks etc.) in a new and specially formulated way. The non-stick coating used is a highly shear-sensitive material that was being applied in a carefully controlled spraying process.

The non-stick material circulates between a 3-liter reservoir and the pans. Unused material returns to the reservoir. As the non-stick material is highly shear-sensitive, peristaltic pumps were used to move and apply the coating material. A peristaltic pump is normally the go-to pump for shear-sensitive fluids as only the hose of the pump comes in contact with the fluid, which reduces shearing. Moreover, a peristaltic pump delivers a gentle pumping action, which again makes it suitable for shear-sensitive products.

Unfortunately, after only three weeks of applying this new formulation the company discovered that the reservoir of non-stick coating had to be totally discarded. Moreover, their peristaltic pumps had to be stopped and thoroughly cleaned. Upon investigation, it was found that the peristaltic pumps were causing molecules in the non-stick material to shear. This was indicated by a color change of the non-stick material recirculating to the reservoir. If this sub-optimal product was to be applied, the coating would peel, rendering the pan useless as a non-stick implement. Due to the high cost of the non-stick formulation, significant financial losses were being incurred.
 

Putting peristaltic pumps to the test

The company decided to run a six-month test of peristaltic pumps from a number of manufacturers in an attempt to find a pump that would reduce shearing to a minimum. One of the companies invited to participate in the test was Graco, who entered the Graco SoloTech Peristaltic Hose Pump into the competition.

“We were highly confident that the SoloTech would perform well,” recalls Gaetan David, a European Key Account Manager at Graco. “The SoloTech utilizes just one single roller that compresses the hose at a single point. The company’s troublesome peristaltic pumps had up to three compression points. The more fixed compression points, the greater the chance that shearing will take place.”
 

One clear winner

The results from the test were conclusive. During the six-month trial period, the Graco SoloTech pump reduced shearing to such a small amount that the reservoir of non-stick coating had to be replaced only once – after four months – instead of the current three weeks. None of the other peristaltic pumps could reach this high level of performance.

Seeing these results, the company immediately ordered 12 SoloTech i10 pumps (10 mm hose), followed shortly afterwards by a further 20. This enabled them to replace this whole production line with the new Graco pumps. The pumps were purchased naked – without an electric motor – as the company wanted to equip the pumps with their own motors.  

They also purchased six SoloTech pumps as spares. Now, should one of the pumps break down or need servicing, they can easily remove it from the production, replace it with one of the spares, and keep production running.

Moreover, the company purchased a number of Graco Leak Detectors. These monitor the pumps and indicate a problem such as a ruptured hose. The faulty pump can then immediately be removed from the line and serviced. Again, production downtime is avoided.

Thanks to the Graco SoloTech pumps, the production line has returned to running non-stop 20 hours a day, including weekends, for a period of four months before the reservoir of non-stick material needs to be replaced and the pumps cleaned.
 

Reducing costs even further with the SoloTech

A SoloTech pump offers other advantages. As it uses only one roller, and the hose is compressed only once per 360-degree revolution, there is less contact between roller and hose. This reduces wear and tear on the hose, which significantly increases hose lifetime.

“The company would normally replace the hoses on their peristaltic pumps every six months,” adds Gaetan. “Now that they have moved to SoloTech pumps they are finding that the hoses are showing minimal wear and tear. They estimate that the hoses will need replacing only every two years. This will immediately slash their hose costs by 75%.”

The fact that the SoloTech pumps perform a complete 360-degree rotation is a further competitive advantage. To move the same quantity of product, other peristaltic pumps need to rotate at least one and a half times. The higher efficiency of the SoloTech pumps contributes to longer pump lifetime. Finally, SoloTech pumps are virtually lubrication-free, and are inexpensive to maintain (no valves, seal or gland), enabling further cost savings.

As the company was extremely satisfied by the performance of the SoloTech pump, they have now started to use these pumps for another application of a highly shear-sensitive coating material. For this they are using ten of the larger SoloTech i32 pumps (32 mm hose).
 

Want to try out a SoloTech?

If you require more information about the Graco SoloTech peristaltic pump, would like a demonstration, or want to give it a trial yourself, fill in the contact form below. SoloTech pumps are also available for sanitary and food applications.