Important information regarding centrifugal pump designs

There are different types of pumps and one of the most prevalent is the centrifugal one.  This pump boasts varied applications in the agricultural field, power generation sector, petroleum industry and wastewater plants among others. There are multistage centrifugal pumps that serve major uses and boast a lot of horsepower and efficiency. Centrifugal pumps are categorized in a class of pumps known as kinetic pumps.

How do centrifugal pumps work?

They have a swiftly rotating impeller (at a speed of 1750RPM to 3500RPM) that is driven by a shaft and placed in a casing. So the liquid flows into the inlet of the casing and then tossed to the outside of the casing to flow out through a discharge port.  When the impeller is working at a high speed, the high velocity is transformed to pressure energy. As a result of their unique structures, centrifugal pumps can produce high or super high flow rates.

They could be better than positive displacement pumps with regards to this. When there are changes in the TDH (Total Dynamic Head) of the specific piping system, the flow rate changes as well. Due to this, the centrifugal pumps’ flow rate can be throttled with a simple valve secured into the discharge pipe and this can be done without triggering excessive pressure buildup. For that reason, these pumps can cover a variety of liquid pumping applications without failure.

Throttling flow rates are a major benefit of multistage centrifugal pumps. While you can get throttling centrifugal pumps with a discharge valve easily, you are much more likely to achieve energy efficiency with a VFD (Variable Frequency Drive). The VFD is costlier to install, but it can slow down the` motor speed. Although throttling is a good idea, it should be done in moderation to prevent excessive shaft deflection that could put the bearings and seals within the pump in danger of damage.

Additionally, excessive throttling can lead to too much recirculation within the pump casing and this can result to excessive heat buildup of the liquid. So, make sure that you only throttle the pumps up to the minimum safe flow rate allowed by the manufacturers of centrifugal pump in India. If you do this, make sure you don’t exceed a minute.

BEP is the perfect flow rate for a centrifugal pump. The pump’s BEP is where efficiency is the highest. If you wish to reduce damage on seals and bearings by about four times, ensure that you reduce the running speed of your centrifugal pump to 1750RPM. But, to increase the pumps’ efficiency levels, you must obtain bigger casings and impellers than the ones you need to run the pumps at 3500RPM. So, running the pumps at a lower speed to increase their longevity is costlier initially.

Head-Flow Curves and viscosity

As you explore various centrifugal pumps, you will come across the term Head-Flow Curves. It is included for each pump model along with the RMP and impeller diameter. All pumps run along their indicated Head-Flow Curve; the flow rate that results will always be at the intersection of this feature and the System Curve. It is therefore imperative to select a centrifugal pump in India that could go with your unique system and its flow rate requirements. Centrifugal pumps are made for liquids with a rather low viscosity, such as water or very light oil. However, they can be used with liquids with a slightly higher viscosity but with extra horsepower to increase the pumps’ efficiency.

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