Select the right pump for your process

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With multiple different pumping technologies, a device’s method of operation can determine its suitability to a particular application. So, many considerations are involved in selecting the right pump for your application, as Castle Pumps explains.

When producing chemicals, food, drink or cosmetics, product consistency is vital. Inaccuracy in transferring a liquid can result in an inconsistent product, which other parts of a process, or indeed customers, won’t accept without good reason. The right pump can help control the consistency and accuracy of ingredient dosing.

Using a smooth, non-pulsing flow pump, with the addition of a batch meter, you can guarantee that the same quantities are added to each mixture. This is a lot more effective than relying on the human eye. Some pump types, such as flexible impeller pumps and progressive cavity pumps, offer a constant output without any pressure spikes, making them ideal for dosing applications.

Changes in consistency
Where product consistency is critical, the focus should be on fluid shear sensitivity – which refers to a fluid that changes the structure of viscosity when under force. Some pump designs apply more shear to a fluid than others when they operate, such as centrifugal pumps, resulting in a fluid being altered beyond what is acceptable.
Double cream is a good example. If you used a centrifugal pump to transfer this, the cream would thicken and even end up as whipped cream. In this instance, it is critical that a low shear, positive displacement pump is selected for the application.

Clogging and crushing solids
When a fluid contains solids, it is always important that the pump can handle the particles’ size without clogging or damaging the device’s internal components. For example, a fluid containing solids such as sand, oily sludge or tissue paper could result in impellers or valves becoming blocked if the wrong pump is selected.
When it comes to some applications, particularly those common in the food industry, it isn’t just a case of moving the solids but also doing so without damaging them. For example, if you have a soup that contains meat and vegetables, you need the pieces to remain whole and not become mushed into the liquid. In this instance, not only do you need a pump design capable of handling the solids, but also a low shear, positive displacement pump.

Excessive wear
Any pump will have wearing parts that eventually need replacing, but if you’re finding some components are wearing quickly, this is a clue that the pump may not suit the application. Common issues, including premature seal failure and damaged impellers, could be caused by problems such as fluid incompatibility, abrasives in the fluids that the pump can’t handle, or excessive pressure and temperature requirements.
Pump models will have specified maximum duties and temperatures. If these are exceeded once the pump installed, then damage to the internal components can be expected. Make sure that when selecting a pump, your supplier is fully aware of the application requirements.

Manual intervention
Are your team members spending more time than necessary operating the pump? The time involved in walking to and from a pump to start or stop it can result in significant productivity losses. Selecting the right pump should include the consideration of automation control features such as pump timers, dry run protection, batch meters or level switches that allow the pump to be left to do its job with as little manual intervention as possible.

Product Wastage
When dealing with expensive ingredients or hazardous liquids, any product waste can be costly and should be avoided. Many pumps struggle to completely empty containers, which means that a percentage of product from every container can end up being wasted. To prevent this, some immersed barrel pumps with long down tubes can empty up to 99.98% of a drum or IBC. Waste can also be incurred if the absence of batch meters on a pump results in too much of a product being transferred and having to be disposed of without being used.

www.castlepumps.com

 

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