Eccentric Disc Pumps
In the second of the ITS ‘Pump It’ Series of guidance articles, we explore what an Eccentric Disc Pump can be used for within the food, dairy, beverage, brewery and personal care industries, how the technology works, and we will discuss some of the design options and advantages that the technology offers.
Eccentric Disc Pumps are often chosen for use in applications of low sheer product handling, low pulsation consistent flow requirements and product recovery for minimising waste in production.
What is Eccentric Disc technology?
Eccentric Disc pumps are a type of positive displacement technology which transfers product from point A suction side, to point B discharge side, using rotating components to push fluid through a cavity.
How do Eccentric Disc Pumps work?
The key component of an eccentric disc pump is its piston (disc) which sits inside a cylinder in the pump housing. The piston (disc) is mounted on a shaft which rotates eccentrically (off-centre) to the pump housing. This eccentric movement of the piston (disc) creates chambers which are continually expanding and closing. This in turn displaces fluid from the suction side to the discharge side.
Unlike typical positive displacement technologies which have clearances between the static and rotating parts, eccentric disc technology has the piston (disc) in constant contact with the stainless-steel cylinder. This is possible due to the piston (disc) being constructed of non-galling alloy materials. The absence of clearances between the rotating and static parts provides maximum efficiency of product transfer with zero product slip within the pump housing. Additionally, the contacting parts allow for the compression of air which generate suction and discharge pressures, leading to the ability to self-prime and recover product from suction and discharge pipework.
What applications Eccentric Disc Pumps suitable for and why?
Eccentric disc pumps are suitable for low to medium viscosity products from 1 – 10,000 cP. E.g., yoghurts, condiments, soups, soft drinks, shampoos, conditioners, beer, wine etc. Generally, viscosities above 10,000 cP are not suited to eccentric disc technology due to the inability to compress and push product through the small internal chambers of the pump.
They can handle small, soft particulates up to around 20mm without damaging the integrity of the product. The product must be self-lubricating in order to prevent friction between the piston (disc) and cylinder faces. Water in-particular is not self-lubricating enough for eccentric disc technologies so the transfer of water and CIP fluids are not recommended for this technology.
The main processes where eccentric disc pumps can be found are low to mid flow applications (0 – 60m3/hr) with differential pressures of up to 10 bar. Their most common applications are in processes which require gentle handling of fluids or product recovery to maximise yield and minimise waste.
It is important to consider with eccentric disc technology, the product that will be passing through the pump, including the viscosity, its particulates, and its lubricative nature. For applications which have higher viscosities, larger particles or do not provide suitable lubrication, ITS would suggest the use of alternative technologies such as, Twin Screw, Centrifugal or Rotary Lobe.
Design Features
Bellows
Mouvex Eccentric disc pumps are specifically designed without the use of mechanical seals. Instead they have a hermetically sealed double walled Stainless Steel bellow or rubber Bellows that encloses the bearings fitted to the shaft. When the shaft rotates, the bellows flex allowing for the movement of the piston through the cylinder. The method of using a double wall bellows allows for the elimination of traditional mech seals and removes a typical weak point of failure allowing for much longer process running times between failures.
With Mouvex Pumps it is possible to observe the bellows over time to ensure optimal performance by using a Bellows Monitoring System:
During transmission mounting the space between the bellows walls is pressurised with an inert argon gas and localised pressure switch is used to monitor for any changes in pressure.
Any hole or crack in one of the bellows walls leads to gas pressure drop which is detected by the switch. This system can detect very small leakages that are invisible to the naked eye which can be indicated using:
- A light alarm
- A sound alarm
- A motor stop by relay
Easy Clean Systems
Unlike other Eccentric Disc pumps that require an external CIP bypass, the Mouvex H-FLO series pumps with the new Easy Clean System (ECS), feature a design that incorporates the bypass directly inside the pump. The ECS System utilises compressed air to lift the piston off its seat allowing for CIP fluid flow to pass directly through the pump head without experiencing a pressure drop in the fluid.
With the ECS, the CIP process also does not negatively impact the pump’s efficiency as no extra clearance is needed to cope with CIP temperatures. Furthermore, the ECS balances the pressures inside and outside of the pump bellows creating a stronger resistance to water hammer. The ECS system is simple and easy to install, eliminates the need for additional piping, and can be operated without letting the pump cool down.
Sustainability and Eccentric Disc Technology
Eccentric disc technology can be used to optimise processes and support sustainability activities.
One of the main benefits of eccentric disc technology is its product recovery capabilities. As explained above, the piston (disc) and cylinder are in contact as they rotate which allows for the creation of internal chambers. As these expand and compress, the chambers push and pull air and fluid to generate suction and discharge pressures, which in turn recover remaining product out of any pipework towards the end of a production run.
Calculate your potential product recovery savings using Mouvex Eccentric Disc Pumps here.
Product recovery from pipework provides the following benefits:
- Maximises product yield for each batch to increase profits.
- Reduces product waste sent to drain, minimising effluent waste treatment costs.
- Reduces cost, energy and timings for CIP cleaning, due to less waste needing to be removed from pipework.
Servicing and Maintenance
The key to ensuring your eccentric disc pump continues to run effectively is to have a regular maintenance schedule. A physical inspection and testing of the equipment is crucial to identify any servicing requirements. Pipelines and surrounding areas should be examined for visible wear and leaks. Bearings should be greased and lubricated at all times and a preventative maintenance regime implemented.
There are numerous reasons why a pump may fail, but most of which can be avoided with regular maintenance, plus working knowledge of the system and process which is specific to the use of the pump.
Mouvex Eccentric Disc Model Options:
As Leaders of eccentric disc technology, Mouvex offer a wide range of model types and sizes all with Seal-less design and options for BMS & ECS. These can cover a range of applications and flow requirements to suit almost any needs.
https://www.industrialtradingsolutions.com/brand/mouvex/
How can ITS support you?
Industrial Trading Solutions Ltd are hygienic equipment specialists with over 100 years of combined technical knowledge and applied skills in the food & beverage, brewery, distillery, dairy, pharmaceutical and personal care industries.
Our technical team can support you with large system projects, one-off product purchases and maintenance & repair services & packages.
Formed in 2002 and based in the Midlands UK, ITS now distribute a multitude of top industry brands with a fast service, at competitive prices and all with an unmatched customer ethos. And as an ISO9001, ISO14001 & ISO45001 accredited business, you can expect the very best service and the highest standards from us.
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