The pump industry relies on expertise from a large and varied range of specialists, from experts in particular pump types to those with an intimate understanding of pump reliability; and from researchers who delve into the particulars of pump curves to experts in pump efficiency. To draw upon the wealth of expert knowledge the Australian pump industry has to offer, Pump Industry has established a panel of experts to answer all your pumping questions.
Progressive cavity pumps
Our progressive cavity pump expert is Peter Vila, Managing Director of SEEPEX Australia. Peter has been involved with pumps for 35 years. He spent the first five years repairing them and the subsequent 30 years directly in technical sales, and for the past 15 years he has been predominately involved with SEEPEX progressive cavity pumps.
What are the most important considerations when selecting and installing a progressive cavity pump?
Consider the pumped media!
As with all pump selections, when choosing a progressive cavity pump, the properties of any pumped media must be carefully considered. What is the chemical composition? Viscosity? Pumping temperature? Solids content? Nature and size of solids? Is it shear-sensitive? Abrasive? Potentially hazardous?
What are the process requirements?
Again, not really different to the basic criteria for selecting all pump designs. Flow rate and discharge pressure as a minimum, together with an overview of suction conditions (i.e. lift or flooded, inlet pressure, temperature etc) must be considered.
Also – is it industrial or hygienic product handling? Is the mode of control DOL/VVVF/other?
Are there any installation and/or environmental considerations?
This is an area where many variables are possible. Fixed or portable? Horizontal or vertical? Dry or semi-submersible? Reversible flow? Indoor/outdoor? Harsh or hazardous environment? Specific customised drive? Special sealing requirements for product containment? Overpressure and/or dry-run protection?
It may surprise you to hear that over-pressure and dry-run, along with incorrect pump selection, are the most common causes of premature failure on progressive cavity pumps.
With due consideration to the above information, it is possible to confidently configure a progressive cavity pump which is fit for purpose.
Special care should be taken when selecting pump speed, giving due consideration to pumped media – viscosity, solids content and abrasiveness.
It’s quite common for the uninitiated to select a smaller pump running faster, with a view to saving a few dollars on the initial purchase, only to find their maintenance costs have soared out of control due to an inappropriate pump selection.
Typically consider 300-350 RPM as a guideline when initially selecting the suitable speed for a progressive cavity pump, then adjust down or up from this point, depending upon pumped media characteristics.
It’s not uncommon to see progressive cavity pumps running as low as 75-100RPM on media with high viscosity or solids content, or at the other end of the scale, up to 1000-1500RPM on easily handled media with high lubrication properties.
The important thing is to ensure you have the necessary information and experience to make a confident selection, or failing this, you have the contact details from a reliable source and seek their assistance.
For more information on progressive cavity pumps, please contact SEEPEX Australia on (02) 4355 4500 or info.au@seepex.com.
