Progressive Cavity Pumps

[vecnaj1978]

hello every one
I am currently working on centrifugal pumps for fresh water pumps for a supplier. I have got an interview call from a progressive cavity pump manufacturer for an interview. can you please help me on the basic knowledge of these pumps

1. what are progressive cavity pumps?
2. where and under what conditions are they used?
3. what are the key information to be known on these pumps??

can I convince the manufacturer with my experience with centrifugal pumps


please help me if there is any study material available on it

regards

 

[LittleInch]

I'm sure you can look it up on the web, but basically they are PD pumps, long and thins with a weird inner "knobbly" core which rotates around a static equally knobbly stator. I'm sure Mr google could enlighten you more than me.

They are normally used for liquids with significant solids particles and can take some large stones / rocks etc with the liquid.

Kind of limited in head and power, but are good if you want to pump out drains, ditches, sumps etc where you have all manner of things in the water / liquid.

They tend to be really quite long (3-4m is not unusual).



My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[TenPenny]

PC pumps are sometimes called 'eccentric screw' pumps, they have a long rotor, with a convoluted shape, which rotates inside a housing (the stator). Generally speaking, the stator is rubber lined, sometimes Teflon, the rotor makes contact with the stator.

Used a lot for sludges and similar services, also smaller ones can be used for fairly precise dosing/metering applications. Typically, the speed will be kept to 300 rpm or less, usually driven by a gearmotor or a belt drive.

Can be good for pumping shear-sensitive liquids as well.

 

[DubMac]

Prog.Cavity pumps are positive displacement pumps; operate on different theory than centrifugals. As stated above, PC pumps good at preventing solids damage from blockage due to size as well as erosion due to small, hard particulate (i.e. sand). You will see a lot of these used in Waste Water services with sludges and stringy solids.

All types of materials are available for rotor and stator, so most any type of corrosive chemical can be pumped as well. Very high pressures can be achieved with metallic rotor AND stator; one of the original services for this pump was as a fuel pump in airplane engines.

NOV, the oilfield equipment co., uses the English version (Mono) as an artificial lift pump by putting a PC pump on bottom of sucker rods and spinning the rods, doing away with the up and down pumping action of sucker rods. A very clever application to replace reciprocation with rotation; saving on infrastructure and maintenance costs.

This is a niche pump. When a PC pump is very well suited to an application, it is usually because nothing else will work. Anytime a centrifugal can also perform the service well; my experience says use the centrifugal.

Go look at Robbins&Meyers site for info on Moyno Pumps which are the biggest selling by far.

 

[SNORGY]

PCs might be more often used where the fluid is shear sensitive. If you used a centrifugal as a skim pump or transfer pump from an emulsion tank, for example, you tend to re-emulsify the very fluid you would otherwise prefer to segregate. Among the more common PCs that I have used are Moyno, Roper, Seepex,all (and more) of whom have excellent technical data on the web.

 

[MartinLe]

Additional manufacturers are Pumpenfabrik Wangen and Netzsch, where you can look for info.

In the plants we build, we use centrifugal slurry pumps for everything we can, and pc pumps where the solids content is to high for centrifugal and when more control over volume flow is necessary.

From an employment/interview perspective, sides the technical knowledge and understanding of the pumps, the applications willdiffer vastly, with pc used in process, waste and food industries and practically never for freshwater. If you need understanding of the applications for your new position (as you will in sales), try to look into that too.

 

[vecnaj1978]

Dear All

Thanks you very very much for your support and guidance

The above provided information was very very helpful

regards