Gardner Denver is a global manufacturer of industrial compressors and vacuum products. Its vacuum sales manager, Gareth Topping, says that these pumps are used extensively throughout the food processing and packing sectors. With the focus on both hygiene and air quality, it's no surprise that more and more customers are looking to remove the possibility of any oil contamination from their equipment.
Gardner Denver has been talking about the issue of vacuum pump air quality for much of 2016 and raising it both with its customers and the industry as a whole.
The food processing industry has a strong commitment to hygiene and air quality, so it's no surprise that many companies have been keen to consider the implications of oil contamination across their entire vacuum and pressure equipment estate.

Vacuum pumps in action

Generally, there are a huge amount of applications for vacuum pumps in the food and drink industry, right from the initial harvesting of ingredients to the shipping and packaging equipment. 

The Elmo Rietschle V-VC303 rotary vane vacuum pump.

For example, vacuum pumps are used extensively in milking systems, both to transport the milk itself and to perform tasks ranging from attaching equipment to a cow's udder and holding the weight of the milking claw assembly to its teat.
At the other end of the production line, yoghurt-filling machines use pumps to simultaneously position the lids on a number of pre-filled containers. Suction cups on the machine grip the lids, separate them and move them into the correct position.
Food production processes
Vacuum pumps also play major roles in many of the food production processes themselves. When a butcher is producing sausages, for example, the meat mixture is chopped into small pieces and mixed with spices and other additives. Extracting air during this process can help to prevent the product from oxidizing, which can have a major effect on both its flavour and appearance.
Typically, the air will be evacuated using a vacuum pump working at approximately 100 mbar. The pump used must be insensitive to the meat particles and liquids that are also extracted.
Tea without unwanted visitors
A particularly innovative use of vacuum pumps can be seen when tea is imported from tropical regions. It is often shipped in large bales that potentially contain various pests, insects, fungi and bacteria that have to be destroyed before further processing can occur, but in a way that doesn’t damage the tea itself. This is achieved by placing the bales in vacuum containers and extracting all the air, killing any unwanted stowaways. The bales are then injected with steam or a sterilised gas.
Vacuum pumps are also used in many manufacturing environments to help dry the food during the production process, as well as to remove air during food packaging to extend the shelf life, which is directly related to the quality of the vacuum prior to sealing, and minimize any unwanted odours.
Regulating air quality
While all manufacturing plants should be aiming for the highest possible air quality, this is particularly important for sites operating in the food and drink sector. As with any industry whose products are ingested by the general public, the processing and packing environment requires a sterile environment. This means that air purity around these manufacturing processes is absolutely essential.
As mentioned above, there are already extremely stringent standards in place that regulate the quality and specification of compressed air applications. ISO8573 sets out everything from the amount of contamination allowed in each cubic metre of compressed air to how companies should be testing oil aerosol content and humidity.
Surprisingly, however, there is no matching regulation in place for the exhaust air quality from vacuum pumps. This is something that the industry must consider over the coming years, but given the slow progress of standards systems it is important that companies take the initiative and make sure they’re operating at the highest standards as soon as possible.
Most sites will already follow the recognised principles of the Hazard Analysis Critical Control Point (HACCP) to ensure they are complying with hygiene legislation, eliminating any potential hazards or reducing these to an acceptable level. Yet while manufacturing processes are scrutinized in great detail, ancillary processes and utilities – such as vacuum pumps – can often be omitted.
Potential risks
With vacuum systems generally located in and around the general production environment, a contaminated pump exhaust can be hazardous.
It's worth noting that the vast majority of vacuum pumps currently in use are oil-lubricated and many applications will operate without any problems arising. Nevertheless, there is the potential risk of oil discharging from the exhaust of this type of pump, which presents a particularly significant issue for sites where air quality cannot be compromised.
The Elmo Rietschle L-Series liquid ring monoblock vacuum pump.
In addition to oil discharge from the exhaust, operating at high temperatures and an open-ended inlet port could result in oil carrying over from the pump, while a separator element may fail due to misuse or through the use of non-genuine spare parts.
The potential risk of leaks from an oil-lubricated vacuum pump can be avoided through a range of measures, which include using a food grade lubricant that won’t cause any danger even if it does somehow contaminate a product. Other options include fitting a downstream exhaust filter or even piping the exhaust air away from the production environment.
For those concerned about the risks of oil-lubricated vacuum pumps, an experienced and knowledgeable pump manufacturer should be able to help identify and reduce any risks through a free site survey. This may extend to working with the production team to ensure the equipment is included in the HACCP assessment.
An oil-free solution
While the rotary vane technology traditionally used in this sector is entirely satisfactory if well maintained with genuine spare parts and can be made even more reliable with the options above, many food processers with concerns over even the slightest risks of contamination are choosing to opt for oil-free pumps instead.
Specially designed so that they can operate for extended periods without any need for oil lubrication, oil-free vacuum pumps have been developed specifically to meet the needs of manufacturers that require only the highest air purity environments. They can sometimes represent a higher initial investment, but in return they offer both a guarantee of air quality and lower maintenance costs, as there is no need to replace the oil or filters.
Elmo Rietschle's VSI range, for example, is comprised of totally oil-free, dry running screw vacuum pumps for packaging under protective gas, and need no coolant or sealing medium in the suction chamber. The pump is water-cooled and offers low heat emission into the environment.
The oil-free technology means that there is no chance of any oil-contaminated air being emitted into the environment. The design also means that there is no wear inside the compression chamber and the only service required is to change the oil in the gearbox and bearings, which helps to reduce maintenance time and the associated costs.
Another clear advantage to an oil-free vacuum pump is that it does not have to be removed to carry out essential maintenance servicing, resulting in no equipment downtime or associated costs from oil, waste oil disposal or labour.
Gardner Denver offers a free, six-year warranty called Assure on all new and existing rotary vane vacuum pumps for complete peace of mind, as well as an extensive network of qualified engineers that can deal with any on-site repair and maintenance should an issue arise. A professional service centre is also available, should a pump require a more comprehensive overhaul.
The Elmo Rietschle S-VSI oil-free screw vacuum pump.
Higher quality commitment
The food processing industry has a strong commitment to hygiene and air quality so response to Gardner Denver's initiative has been positve. Many companies are keen to consider the implications of oil contamination and vacuum pump air quality in general.
With on-going support from the British Compressed Air Society (BCAS), Gardner Denver has had a strong response from across the sector. Some customers are looking to ensure their conventional pumps are working as intended, supported by rigorous maintenance regimes, and others asking about the benefits of installing oil-free vacuum pumps that can help to mitigate the risk of contamination further.
Gardner Denver is glad to see that food and beverage industry is becoming increasingly aware of the issues around vacuum pump air exhaust quality and the opportunities available to reduce risk, improve uptime and therefore productivity.