Pumps in food and beverage applications are used to transfer container to another during the processing application.
There may be hundreds of pumps in any food or beverage processing plant, depending on the size of the facility. In the food and beverage industry there are three common types of pumps used, namely centrifugal pumps, rotary lobe positive displacement pumps and progressing cavity positive displacement pumps.
The pumps used for these processes are subject to a variety of manufacturing and hygiene standards and guidelines. In addition to FDA-approved materials like 300-grade stainless steel necessary for the pump housing, the elastomer materials used in pump seals also needs to be submitted and approved. FDA-approved food-grade lubricants are required for pump lubrication.
Pump types: advantages and disadvantages
centrifugal pumps are the most commonly used kinetic-energy pump, where the centrifugal force pushes the liquid outward from the eye of the impeller where it enters the casing.
A progressive cavity positive displacement pump transfers fluid by means of the progress through the pump, of a sequence of small, fixed shape, discrete cavities, as its rotor is turned.
A rotary lobe displacement pump like the Waukesha Universal 2 Series pump has two counter-rotating pumping elements (rotor), each with two or more lobes. With rotary lobe pumps, fluid flows around the interior of the casing.
The main advantage of a rotary lobe displacement pump is its small footprint, allowing it to take up less real estate on the processing line.
Choosing the right pump for a particular application
To select the right pump for an application, there are a few questions to consider.
What are your flow requirements?
centrifugal pumps run at higher speeds. A PC pump, running at a slower speed, will not wear as quickly.
What is your suction/discharge head requirements?
The net positive suction head (NPSH) requirements are typically much lower on rotary lobe pumps and progressing cavity pumps compared to those of a centrifugal pump. There is a minimum positive head required on any pump, and if there isn’t enough, the material to be pumped will not get through.centrifugal pumps may need nine metres of positive head compared to a progressing cavity pump which may need only one-and-a-half metres of positive head. This difference ban be critical, depending on pump placement in relationship to the head. Both progressing cavity and rotary lobe positive displacement pumps feature self-priming suction lift.
What is the viscosity of the product?
Progressing cavity pumps can handle higher viscosities than rotary lobe pump. centrifugal pumps, on the other hand, are designed for moving water or thin liquids. When working with more viscous products, positive displacement pumps like the Waukesha Universal 2 Series is preferred. Positive displacement pumps are also a better option for metering applications. They are more forgiving with changes of viscosity.
Is the product shear-sensitive?
Secondary to this question is the percentage of solids present in the product and the size of the solids. Positive displacement pumps do not produce shear, which could change the consistency of the product. Shear is a strain in the structure of a substance produced by pressure when its layers are laterally shifted in relation to each other. The progressing cavity pump operates gently and doesn’t impart shear or change product consistency. Rotary lobe pumps are also a good choice for similar applications. Both are gentle positive displacement pumps that impart little shear, can handle shear-sensitive products, and can pass solids through the pump.
Yoghurt is one product that benefits from this gentle transfer. If the the yoghurt includes fruit, the positive displacement pumps can move the fruit with the yoghurt through the pump without causing any damage to the fruit.
Does the pump need to be CIP-able?
Cleanability, serviceability and durability are incredibly important features to look for when purchasing a pump in the food industry. You need to determine if the pump can be cleaned in place (CIP) and/or steamed in place (SIP). All pumps are CIP-able, but rotary lobe pumps are also SIP-able, giving them an advantage.
Other considerations
- What is the specific gravity of the product to be pumped?
- What is its pH?
- Are there abrasives present in the product?
- What will be the pumps’ hours of operation?
- What types of pump accessories must be integrated into the system, like variable speed drives, load cells or monitoring systems?
The perfect pump for your needs
Pumps and Accessories is a leading distributor of Waukesha Universal 2 Series pumps. For more information about our food processing pumps, contact us today.