Food & drink: monitoring the cost of faulty pumps

“These can pump a drum of boiled eggs without damaging them,” says Rozee.

“But if you put too much air pressure into diaphragm pumps on one side without balancing the system, then the diaphragms can stretch and blow prematurely.”

Even beyond this a pump may just reach the end of its natural lifespan.

“A diaphragm pump might have 20 million strokes to failure,” says Rozee. “We sell pneumatic-to-electric feeds companies can plug into and work out that, on average, 20 million strokes takes them six months – then they will replace the diaphragm after five months.”

Rozee believes such preventative action is critical for food and drink manufacturers looking to avoid expensive downtime and stressed phone calls.

“Condition monitoring and education towards it is essential,” he says. “Any site not using that might be getting away with it but they have a potential can of worms. With vibration analysis you will see there is something wrong with the pump.”

Jean-Luc Goutagny, reliability solutions Europe director at Emerson, agrees with the need for a close eye on the condition of pumps in the sector.

“Cavitation, bearing defects, imbalance, looseness or poorly lubricated parts all effect pump performance and are potential causes of pump failure,” he says.

You don’t want to be halting production and throwing batches away – lost production can cost thousands of pounds an hour

Andy Cruse, general manager of ERIKS UK

Goutagny also backs vibration analysis as the tool for the job. “An increase in vibration is an early indicator of a problem that can lead to pump failure,” he says.

“If problems are not detected and maintenance carried out, then not only is pump performance reduced, but adjoining equipment and the overall balance of the process is affected.”

Andy Cruse, general manager of ERIKS UK’s pumps product business unit, says about 70% used in the food and drink sector are centrifugal, imparting kinetic energy, while the remainder are positive displacement, moving a fixed volume of thicker product.

“In many industries a partner pump will be already piped in and, isolated by valve, ready to join a process if one breaks down,” says Cruse.

“They don’t generally have that luxury in this sector because each system tends to be kept as simple as possible for process cleaning. Some of these factories have very tightly packed systems so additional pumps are not practical.”

This makes condition monitoring vital to ensure pumps can be repaired and replaced at the optimal time.

Good vibrations

“You don’t want to be halting production and throwing batches away – lost production can cost thousands of pounds an hour,” says Cruse. “Reliability is critical.

“Vibration analysis is used to interpret the mechanical integrity of rotating equipment. You are looking for ???vibrations that suggest bearing wear, out of balance loads and possibly misalignment on long coupled units.”

This is often carried out on a planned route using a portable transducer and data collector. But one problem with this method in the food and drink industry can be the use of shrouds over motors to prevent water penetration during washing down of equipment.

“This cylindrical stainless steel shroud over the motor – which is where the pump bearings are housed – prevents an accurate reading from vibration analysis,” says Cruse.

“Fitting permanent sensors on the kit under the shrouds would be the best thing, but may be cost prohibitive for the hundreds of pumps in a typical food or drink manufacturer – you would need four on each close-coupled pump.”

There can also be difficulties with the set-up in some food plants. “A lot of pumps in food and beverage can be semi-portable so sit on legs rather than a base plate,” says Cruse. “You may not have an ideal platform. It can lead to more vibration. There may also be pipework strain and you can get resonance from the pipework.”

Other variables can be monitored instead of, or as well as, vibrations.

“As flow increases on a centrifugal pump the current absorbed rises, so if operators can note the current drawn that gives an indication of where the pump is operating,” says Cruse.

“Differential pressure readings can help build a picture. Flow monitoring helps you build up a picture.

“There are some new systems being used in the heating and ventilation industry where a sensor watches the seal and picks up leaks. I haven’t personally seen that technology in food and drink but it might be the next step.”

Review performance

Whatever methods you employ, perhaps the most important thing is to use condition monitoring tactically.

“We will decide which plant is a production stopper and put in a production monitoring regime to suit,” says Cruse. “For historically problematic pumps, you might want to consider remote condition monitoring so you can keep a constant look. More reliable pumps might be under a monthly or quarterly review. As you go along you can establish a mean-time-to-failure of plant.”

This way you can work out where your pump selection may be sub- optimal, and where you could design your production system better to get fewer alerts and ultimately require less costly intervention.

“From the frequency of the vibration you will see if it’s a bearing; a loosening of the rotating equipment; if there is vibration induced by resonance of the pipework; a misalignment issue,” says Cruse.

“You can hone in – 80% of your problems will be in 20% of plant and you can tackle those areas.

“You can fine tune the plant to increase reliability and get control of your equipment.”

Condition monitoring should be used alongside failure mode analysis to build up the fullest possible picture of how a production line is functioning, Cruse advises.

“There is a massive move in use of technology to monitor pumps in the heating and ventilation market but I haven’t seen it as much in food and drink yet.

“There is room for some pump owners to benefit from these techniques. ERIKS has its own training, there are courses through the BPMA.” [Triark Pumps and Alfa Laval, who Process Engineering spoke to, are also members of the BPMA.]

For historically problematic pumps, you might want to consider remote condition monitoring so you can keep a constant look. More reliable pumps might be under a monthly or quarterly review

Not only centrifugal pumps can be monitored. Seepex supplies progressive cavity positive displacement pumps to the food industry and says these can also be watched for signs of imminent problems.

“We have smart dosing pumps that can monitor flow, pressure and temperature,” says food and beverage business development manager Lesley Eaton.

The information can be displayed through a company’s supervisory control and data acquisition system to give an indication when changes need to be made.

“Once the required flow rate has been set, the pump automatically monitors and corrects pump speed to ensure the right volume is delivered. If this is not possible it sends an alarm to the supervisory system.”

Ripe for revolution