Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Lift Pumps

Lift Pumps

Lift Pumps

Can anybody please advise me on using a srew type pump as a lift pump. The question i need an answer to is probably a very basic one.
Would a Srew type pump pick up is own suction if it was to be sitting above a level of liquid, or would it need to be primed first? Is thisthe same with all kinds of pumps?
Also when priming a NEW screw type pump which has a positve suction head, should i expect to see the liquid bleed out of the discharge bleed, or would it not pass through the screw.

RE: Lift Pumps

Assuming you are talking about a positive displacement screw pump (as opposed to an Archimedes type inclined screw pump), the answer depends on the specific type you are using.

There are two, three and five screw type pumps that are all metal construction.  These either use timing gears or, in the case of three-screw designs a film of liquid, to locate the rotating screws and keep them from grinding against one another.  They can develop suction lift, but require priming by filling with liquid first.  Some types may be able to pump some gas out of the suction.  With all-metal screw pumps there are clearances between the screws, so liquid will pass through the pump easily.

Another type of screw pump is the single screw, or progressing cavity, pump.  This uses a metal screw, or rotor, turning inside of a rubber stator that is molded  to form cavities between the two.  These have excellent suction lift capabilities due to the compression fit between the rotor and stator.  To prevent damage to the rubber stator caused by heat build-up due to friction, this pump needs some lubrication when starting.  It will, however, evacuate the gas in the suction line and prime itself if given adequate NPSH.  The compression fit of the rotor and stator will hold liquid back when new at low pressures, but may allow liquid through if there is a significant positive head.

Generally, pumps are not intended to be used as valves and should not be relied on to prevent liquid from seeking its own level.

Air-operated diaphragm pumps can be used for suction lift without initial priming, provided the suction lift is within the capabilities of the particular pump.  

RE: Lift Pumps

A friend of mine used a helical rotor pump (a MONO pump with 316 stainless rotor and rubber stator)to draw bore water out of a dam on his property.  The pump sat about 3m meters above the water level and it pumped a good flow to a tank about 200 meters up the property with about 6 meters to the top of the tank from the pump.  He used a valve before the pump to keep the water in the line and then openned the valve before starting the pump to give it a prime.  It worked fine for years.

The things I give away for free!!!!!!!


Mike S

RE: Lift Pumps

I'm wanting to know why ferrous alloys were use in sewage lift screw pumps.  They rust, they're so bulky that they make maintenance difficult and expensive, and they're so huge as to make transport also expensive.

Why couldn't these things be made of aluminum or even plastic of some sort - and in linked segments so as not to always require a crew of riggers and a crane?

I visited a treatment plant in Indianapolis and about all they could tell us was that they were made in Germany at about a million bucks a pop and that the bottom bearings were always wearing out.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper – Data Security and Know-How Protection
Our data is constantly exposed to the danger of being intercepted or stolen as it wends its way over global data networks. Data security measures and measures for protecting intellectual property should not, however, first be implemented when data is exchanged – companies must lay the foundation for these measures within their own organization. Download Now
White Paper – Collaboration in the PLM Context
The influence exerted by the Internet of Things (IoT) means that there is a steadily growing need for collaboration in industry. Partners from new industries and areas of application need to be integrated in cross-company business processes to ensure that the lifecycle of smart, connected products can be managed from end to end. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close