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"Compression Ratios" for pumping liquids

"Compression Ratios" for pumping liquids

"Compression Ratios" for pumping liquids

(OP)
In compressible flow we use the very useful concept of "compression ratios" as a shorthand notation for the ratio (in absolute terms) of a compressor discharge pressure to the suction pressure.  This ratio has significant physical characteristics in addition to being very concise for communications.

When talking about the differential head in a pump, does anyone know of a similar widely used term?  When I talk about a centrifugul pump operating at 2-3 "ratios" per stage I get a blank stare because "ratios" implies "compression ratio" and most liquids are largely incompressible at low differential head.  Calling it a "lift ratio" gets me even more blank stares.

David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com

RE: "Compression Ratios" for pumping liquids

to simply state, when dealing with pumps, terms used are head or head/stage, expressed in feet or meters of water and flow expressed in gpm, lps, gph, etc.

i would definitely have a quizical or questionable facial appearance and would ask for clarification.

regarding gas compressor terms, your statements are understandable.

good luck.
-pmover

RE: "Compression Ratios" for pumping liquids

pmover has it correct.

PUMPDESIGNER

RE: "Compression Ratios" for pumping liquids

Thanyou Zdas04 for your question. It has helped me very much.

RE: "Compression Ratios" for pumping liquids

David

The reason why you talk of compression ration with gasses is that this is fairly constant with no regards to initial pressure but only for a limited inlet pressure range.

For a pump however the HEAD (as it is called) is constant when measured in height of liquid collumn - regardless of inlet pressure and medium. Providing that the casing dosnt burst i has the same head regardless of the inlet pressure beeing 1 or 10 barg.

The head is allways the same regardsless of liquid properties - but the outlet pressure (or even perssure rise) is no: Eg a pump with a head of 10 m (at a given flow rate) and a inlet pressure of 0 barg will have a outlet pressure of 1 barg when pumping water (density=1000 kg/m3) but out 0.8 barg if pumping a oil with a density of 800 kg/3m)

Best regards

Morten

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