Progressive Cavity Pump

Read the first line of the paragraph in the link you posted...

it reads:

"seepex pumps belong to the group of rotary positive-displacement pumps"

Yes I saw that, just looking for confirmation. I'm not one to believe that because it's on the internet it must be true.

The aristocrat is right. This one's simple.

Cheers!

Seepex is a progressing cavity type of positive displacement pump. Robbins and Myers Moyno pumps are the same type and have been in production for over 50 years. Suggest you consider both sources for this type pump.

These pumps are quite expensive as positive displacement (PD) pumps go; so they are usually used only on applications where other PD pumps are not suitable. If you consider an alternative type it is important you fully understand the application and report as much as you can about the conditions of service to the pump manufacturer for proper application selection.

Ed Weldon

Another pump style which may fit your needs might be a peristaltic pump. These are often cheaper to purchase and easier to maintain than a progressive cavity pump, but similar in that a rotating device pushes a progressing cavity containing fluid.

It's similar to the peristaltic motion of muscles as food is pushed through the digestive tract or a snake swallowing its prey. Please forgive the unpleasant mind pictures.

With the progressive cavity pump described by other posters, the dimensions of the rotor and stationary part (stator) along with the rotation speed of a progressive cavity pump dictates the flow rate. The liquid is in contact with both the rotor and stator (and with the pump seal). The longer and larger the pump, the more pressure can be generated.

With a progressive cavity pump only an internal hose is in contact with the liquid, and dimensions of the hose and rotation speed together dictate flow rate. There is no need for a pump seal.

Advantages of the peristaltic pump: Often smaller footprint than a progressive cavity. Inexpensive, light, and simple, easier/faster to change hoses than to change rotors/stators/seals (can be done with one person where a progressive needs two), requires no seal that can leak, and most importantly PERISTALTIC PUMP CAN BE ALLOWED TO RUN DRY - In contrast a progressive cavity pump running dry can quickly tear the rubber stator apart (however a safety interlock can minimize this risk). Both styles can handle water and very thick difficult or abrasive liquids or slurries.

Disadvantages of the peristaltic pump: Each rotation produces a wide pressure swing while a progressive pump discharge pressure is very steady; peristaltic pressure is typically only 100 psi or a bit higher while progressive cavity pumps can go much higher. Hoses can wear with time as rotor moves along the outside of the hose. Designs with rollers moving along the outside of the hose rather than shoes which rub along the outside of the hose can double hose life, and save money because they require less lubricant. Sensors to detect hose breaks are available and cheap.

A quick search can bring you to suppliers for the progressive, peristaltic shoe-type and peristaltic roller-type. Be sure to chose materials of construction and seals, if any, wisely. Consider safety sensors for either type. Always do cost-benefit.

Happy pumping!

Your conclusion is right.

Located in Edmonton,you are right amidst the Petroleum Industry equipment manufacturers and Oil wells.

Progressive Cavity Pump normally implies that there is a metallic Rotor and an elastomer stator.In fact all screw pumps are progressing cavity pumps in a way!

Downhole pump implies that the pumping elements are located in the well -usually

near the pay zone or production zone.

You also have an all metal twin screw pump doing the same job -pumping sandy, gas laden crude.This one overcoming the limitations of high temperatures.

Single screw and twin screw nomenclature keeps them differntiated by design.The application areas are similar.

The Downhole PC pumps comes in two different versions : one with a top drive and the other with downhole electric motor.

Regards

Chuck Cowlagi

Just a note: The Seepex animation is actually incorrect as it has the 'impeller'/rotor 'flailing' after the first coupling joint from the motor/gearbox. It should show the rotor concentric with the final drive. As stated, it pumps by progressing the cavity down the resilient rubber, internal helix stator. Uniflow progressing cavity pump.

Just a thought for those who haven't had exposure to these types of pumps.

Here in Aussie, they are represented by The Mono brand, and are legendary in their service to those who have to pump dirty water. In our business we have a couple of dozen of them, from one-and-a-half inch through to three inch. The big ones have a reduction gear between the motor and the pump.

Cheers,

Stu.

Thank you all for your input and confirmations.

For those of you who don't know my posts yet a little explanation. I don't USE this stuff, I am charged with getting it through customs (into Canada) properly. More specifically I have to "classify" goods using the Harmonized Tariff System.

The tariff section on pumps for example diferentiates between

1. Reciprocating positive displacement.
2. Rotary Positive displacement.
3. Centrifugal
4. Other (incld liquid elevators)

There are dozens of subcategories within each of those listed above but thats a story for another day. As often happens I am dealing with people who don't know much about the product and don't know anything about the tariff. They are usually the carrier (truck driver) or an accounts payable clerk. The tariff is written by experts in the field along with the "help" of diplomats and bureaucrats and is incredibly detailed. Furthermore the consequences if I get it wrong can be quite expensive for the importer. So....... I come to you guys for expert help in many many fields, and have never been disappointed. With what I learn here I am able to discuss a myriad of products intelligently when I do get a knowledgable person on the phone. I'm also just a curious guy who likes to learn stuff and get great enjoyment from CR4's daily roundup of topics, the first e-mail I open every morning.

So once again thanks for the assistance.

You're very welcome, and yes, you're right , it's a rotary positive displacement pump.

Cheers

Stu.

Apothicus -- I got a good laugh at myself when I read your last post. The language of your original question had me scratching my head wondering just where you were coming from. The word "tariff" that you used ony served to make it all the more mysterious since I had never before seen your posts on CR-4 (I'm a bit of a newbie)...... Now it all connects.

Sure, I can understand what you are running into in your work. Some non-technical shipping or international sales clerk has to write something in one line on a customs form and all he knows is that it is a "Super A model 1340" because that is what the sales order says.

You must see a lot of strange stuff like this.

Ed Weldon