10 Crucial Facts You Must Know Before Buying A Positive Displacement Pump

A positive displacement pump (PDP) and a centrifugal pump are the two major pump types that are offered for commercial applications. PDPs are able to maintain a relatively consistent fluid flow rate, at a particular speed, irrespective of discharge pressure. This is the essential characteristic that sets them apart from their centrifugal counterparts, which are also called negative displacement or non-displacement pumps.

PDPs move liquids by getting them drawn into an expanding cavity or space. The cavity then goes on to decrease, functioning to get same liquids discharged.

Generally, PDPs are offered in three kinds – reciprocating, rotary, and linear. The categorization is based on the kind of mechanism on which the pump relies to move liquids. The first kind utilizes rotating mechanisms like screws and gears to get the job done. The second kind attains positive displacement via the utilization of a plunger or piston mechanism – hand pumps are excellent examples. The last kind depends on chains and ropes. This article lists a couple of crucial things you must understand before buying your next PDP.

  1. PDPs could be utilized when a constant flow rate is needed.
  2. The pumps must never be operated when the valve is closed. This is as, unlike their centrifugal counterparts, they do not feature shut off heads and thus keep pumping. This can end in the discharge line developing leaks or even bursting.
  3. An external or internal safety valve should be fixed on the discharge end when utilizing all positive displacement pump types to avoid damage.
  4. PDPs are most suited for applications that demand only moderate pressure as well as flow rates.
  5. The rotary type PDP is highly efficient, but is not suitable for applications that demand high flow rates. The RPM (revolutions per minute) could be increased to get flow rate stepped up, but this will ultimately wear the rotary mechanism down, thus increasing the clearance between the pump’s side walls and rotor, thereby getting efficiency decreased.
  6. Similar to their centrifugal counterparts, PDPs are not self-priming pumps. They will have to be primed every time they are started.
  7. Unlike the majority of centrifugal pumps, nevertheless, these pumps are capable of getting rid of air that is trapped within the system on their own.
  8. Nevertheless, the pumps are capable of operating only when the pressure at the inflow end offers the minimum pressure that is needed by the unit. This is also needed to get rid of any air that might be trapped within the system.
  9. The pumps are most suited to the handling of fluids that feature high viscosity.
  10. PDPs are reliable yet simple machines that are offered in a truly wide variety of different configurations, making them the most preferred pump type for handling a broad range of different fluids that include chemicals, wastewater, oils, and hazardous liquids among other varying things.

In conclusion, if you want more detailed information as regards the positive displacement pump, or want to obtain professional advice about choosing the most appropriate pump type that suits all of your needs, then reach out to the foremost suppliers. The experts specialize in a wide variety of different installation and advisory services.

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