Peristaltic pump tackles troublesome pH levels at food manufacturer

Leading convenience food manufacturer, Greencore Group Plc, has achieved significant savings in downtime and repair costs on the water treatment plant at its Greencore Grocery site in Selby, North Yorkshire, thanks to the installation of a Bredel SPX50 high pressure peristaltic hose pump from Watson-Marlow Pumps Group.

Greencore Grocery is one of the UK’s leading manufacturers of bottle/jar-packaged recipe products, producing a wide range of both branded and customer own-brand sauces, pickles, and soft drinks. The cleaning and change over process between different products, produces a small quantity of liquid waste (food effluent). This can lead to significant fluctuations in pH levels, from 4 up to 12 in some instances. Until recently, pH levels at Selby were corrected using 32% caustic soda (sodium hydroxide – NaOH) through the facility’s water treatment plant, which is owned and operated by United Utilities, the UK’s largest listed water company. With Greencore responsible for consumable costs, a cost-down exercise was commenced to seek an alternative to NaOH.

“The Greencore Grocery facility at Selby is a high volume plant where there can be between 10 and 26 ‘washouts’ a day depending on order schedules,” says Peter Wadsworth, Craft Technician at United Utilities. “In order to find a more cost effective method of correcting the pH in the processing machinery, we trialled a product called ‘Mag Mex 1060’, which is a magnesium hydroxide solution [Mg(OH)2], to Correct the pH levels.

Carrier water is used to dose the Mag Mex into the system at Greencore Grocery, but to do this effectively a suitable pump is required.

“To be honest we started off using fairly ‘cheap and cheerful’ dosing pumps, but this proved to be inefficient as we spent two days a week repairing them,” says Mr Wadsworth. “Because magnesium hydroxide has low solubility in water it makes for a pretty abrasive fluid. We found the grit would attack the mechanical seals and drain plugs on the dosing pumps, thus requiring repair.”

It so happened that one of United Utilities sister sites was using a peristaltic pump from Watson-Marlow, and this was subsequently recommended to the process engineering team at Selby. As a result, a Bredel SPX50 high pressure peristaltic hose pump (50mm diameter) was installed in September 2009, and ever since there have been no abrasion issues causing downtime or repair.

The reason for this successful outcome is simple: in peristaltic pump technology, nothing but the hose or tube touches the fluid, hence there is no chance of the abrasive fluid damaging pump components. The peristaltic design means there are no valves, seals or glands to repair or replace. Replacing a hose or tube takes only minutes and they are relatively low-cost items compared to spares for other pump types.

At Greencore’s Selby site, this all adds up to a low maintenance, low cost solution, which is just as well for an operation that produces around 250 million jars per annum across circa 500 different product lines.

“Any downtime in an operation of this magnitude can be very costly,” says Mr Wadsworth. “I’m sure the SPX50 paid for itself extremely quickly. In fact we are going to trial an identical pump on site for sludge transfer between tanks.

The success of the SPX50 at Greencore, Selby is indicative of a site that has received considerable investment over the past 10 years and now boasts some of the most modern, hygienic and efficient production facilities in the UK. The site has achieved the prestigious AIB accreditation, being placed in the ‘superior’ category, achieving BRC Grade A. The site supplies every major UK retailer and exports to over 21 countries. Over 600 people are employed at the 23-acre Selby plant.