Compare the possible options and make a choice on basis of the process requirements you value most.
The four basic criteria that are to be considered at the column “mitigations” are:
- The viscosity of the medium
- The presence or absence of changing back pressures
- The regulation of the flow
- The desired flow rate of the pump
Viscosity: A centrifugal pump is ideal for thin liquids (<approx. 150 mPasc). Thicker liquids can also be pumped (limited), but the flow will drop very quickly, also as a result of higher energy consumption. (viscosity conversion table)
Changing back pressures: In the event of changing back pressures, a centrifugal pump will quickly deviate from its characteristic curve and start to function below standard or even stop completely. A positive displacement pump is virtually insensitive to changing back pressures (as long as there is no slippage internally).
Flow regulation: In applications where the flow rate must be controlled, a positive displacement pump is usually the best choice. The positive displacement principle makes this pump ideal for dosing applications. Optionally, centrifugal pumps can also be adjusted to be a dosing pump, but the increase in speed makes this solution almost always difficult.
Desired flow rate: With a desired flow rate of less than 300 l / h, usually a positive displacement pump is chosen because centrifugal pumps are virtually unavailable in this low capacity range. The principle of a centrifugal pump is not suitable for a low flow rate (partly from an economic point of view).
Above are the basic criteria for choosing a pump. Off course there are a number of other factors that are important, such as the nature of the medium (abrasive, solid parts, shear sensitive liquids), the process environment where the pump is used, such as hygiene, ATEX, cleaning (CIP or SIP) and last but not least: must the pump be leak free or pulsation free, must the pump be equipped with dosing function?
If all these points have been taken into consideration, then you can say: we have the right pump at the right place!