Previous in Forum: Glass Fiber Manufacturing   Next in Forum: Heat Exchanger - Shell and Tube Type
Close
Close
Close
12 comments
Rate Comments: Nested
Power-User

Join Date: Feb 2009
Location: India
Posts: 155

Pumps and Suction Strainers

04/01/2009 12:36 AM

In a CR4 discussion of another topic, a person said he does not allow strainer on pump suction. Strainers are provided on suction side of pumps to protect the impeller. The strainer mesh size should suit the impeller mimimum clearance with the casing of centrifugal pumps.

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Popular Science - Biology - New Member Hobbies - Musician - New Member APIX Pilot Plant Design Project - Member - New Member Hobbies - CNC - New Member Fans of Old Computers - ZX-81 - New Member

Join Date: Jan 2007
Location: Centurion, South Africa
Posts: 3921
Good Answers: 97
#1

Re: pump suction strainer

04/01/2009 1:54 AM

To clarify - The strainer referred to is mostly used with a foot valve when pumping from a stream or a dam with a centrifugal pump situated above water level.

The total hole area must be big enough not to impede the flow even with some holes blocked.

If the effect of a partially blocked strainer is included in the NPSH calculations there should be no reason not to allow it.

__________________
Never do today what you can put of until tomorrow - Student motto
Register to Reply
Power-User

Join Date: Feb 2009
Location: India
Posts: 155
#2
In reply to #1

Re: pump suction strainer

04/01/2009 2:06 AM

As far as possible, NPSH should be calculated with strainer 50% blocked.

Register to Reply
Guru

Join Date: Aug 2007
Posts: 1790
Good Answers: 87
#3

Re: pump suction strainer

04/01/2009 3:06 AM

Pumping water out of a river or a sump, ok use the strainer.

Pumping in a closed circuit, like a circulating water pump in a power plant or a hot oil pump in a refinery, or a process pump in a chemical plant, then the screen should only be used for commissioning and then removed for running.

The main reason is that it is unnecessary as there should be nothing to protect the impeller from, and there is a risk (over time) of the strainer coming apart and going into the impeller.

Register to Reply
Power-User

Join Date: Feb 2009
Location: India
Posts: 155
#7
In reply to #3

Re: pump suction strainer

04/02/2009 12:17 AM

Even in a closed circuit, workers tend to leave debris in the piping system during maintainance. Hence suction strainer is a good feature. Differential pressure transmitter/gauge should be provided to the strainer to learn the blockages.

Register to Reply
Guru

Join Date: Aug 2007
Posts: 1790
Good Answers: 87
#9
In reply to #7

Re: pump suction strainer

04/02/2009 6:36 AM

That is why you put the strainer in for commissioning, and then take it out when the system is cleaned up...

Register to Reply
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#4

Re: pump suction strainer

04/01/2009 4:04 AM

The reason (the other person being me ) said that (it was explained too)

you put a suction strainer to protect the pump.

There is a contamination and the strainer slowly starts getting blocked

At a certain stage, there is a possibility that the block is so much that you get a heart attack ie cavitation.

For pumps it is necessary that the suction should be unhindered. So if you put a suction strainer, ensure there is a vacuum gauge too to protect the pump.

It was further mentioned that it is better to put a return oil filter/ strainer or a tank partition strainer ( we do either/both based on the requirement)

Was is not better to clarify on the same thread ? (Heat exchanger if I remember) so that repetition of information was not necessary.

__________________
Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Register to Reply
Power-User
Engineering Fields - Mechanical Engineering - New Member Technical Fields - Technical Writing - New Member

Join Date: May 2007
Location: Parallel 45
Posts: 226
Good Answers: 21
#5

Re: Pumps and Suction Strainers

04/01/2009 9:49 AM

Hello

Have a look to http://cr4.globalspec.com/thread/26513/Pump-strainer.

Hope this helps

__________________
Look over to the next challenge
Register to Reply
Associate
APIX Pilot Plant Design Project - Member - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: Mar 2009
Location: India
Posts: 27
Good Answers: 1
#6

Re: Pumps and Suction Strainers

04/02/2009 12:04 AM

I partially agree with you and partially not. Because in all the process plants the strainers are placed based on the property of the mediyum being pumped initially. The type of strainer choosen could be temporary or permanent. The temporay strainers are generally Conical strainers and permanent strainers are T-Strainers.

The temporary strainers are provided only during commisioning of the plant and the piping arrangement is made in such a way that the strainer can be removed out of function by means of providing a "REMOVABLE SPOOL PIECE". Once the pump is put down in normal operation after some cycles the strainer is removed allowing the medium to flow withour any distractions.

Hope this helps

Register to Reply
Guru

Join Date: Aug 2007
Posts: 1790
Good Answers: 87
#8
In reply to #6

Re: Pumps and Suction Strainers

04/02/2009 6:33 AM

Yep that was what I was trying to say...

Register to Reply Off Topic (Score 5)
Active Contributor

Join Date: Mar 2008
Location: Mumbai
Posts: 23
Good Answers: 1
#10
In reply to #6

Re: Pumps and Suction Strainers

04/02/2009 11:15 AM

Strainers should be used as mentioned earlier by other experts at the suction of the Pump. What type of strainers should be used is dictated by the time and application. At the time of commissioning fine strainers are to be used, which is obvious as debris is maximum during the first use. Later on coarse strainers, the size of which should be consulted with the pump manufacturer, should be installed.

__________________
GVK
Register to Reply
Guru

Join Date: Aug 2007
Posts: 1790
Good Answers: 87
#11
In reply to #10

Re: Pumps and Suction Strainers

04/02/2009 7:20 PM

So you are saying that a strainer of some kind should "always" be used?

If so, I am sorry to inform you that this is simply incorrect. I agree that there are applications where a strainer should be used. There are also applications where a strainer should not be used.

I also agree that consulting the pump manufacture is the best approach.

Register to Reply
Associate
APIX Pilot Plant Design Project - Member - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: Mar 2009
Location: India
Posts: 27
Good Answers: 1
#12
In reply to #10

Re: Pumps and Suction Strainers

04/03/2009 12:11 AM

Dear Gautam,

As steve mentioned the strainer will not be in function always. As I mentioned earlier it is governed by the nature of medium and the frequency of cycles that will be put in operation. Thoufh it is kept in cycle for some time it the piping arrangemnt will make it inactive after the strainer performs its desired function of removing the coarse or fine debris whatever it may be so while commisioning.

Hope this helps.

Kumaran

Register to Reply
Register to Reply 12 comments
Copy to Clipboard

Users who posted comments:

b v rao (2); gautamkum (1); Hendrik (1); Kumaran (2); sb (1); Steve S. (4); user-deleted-1104 (1)

Previous in Forum: Glass Fiber Manufacturing   Next in Forum: Heat Exchanger - Shell and Tube Type

Advertisement