×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

psi wont stay up
5

psi wont stay up

psi wont stay up

(OP)
hello,
im working on a test station to measure water flow of irrigation parts at 20 psi . problem is that when i start testing parts that put out 14 gph and higher (up to 60gph) i cant get to 20 psi. i have a pressure releif valve in front of the regulator and the small procon series 1 pump has a pressure releif vale too. am i putting out the same amount of water that im putting in on the larger volume parts? would a larger pump be the answer?
any help would be appreciated.

RE: psi wont stay up

It looks to me like a higher capacity pump would be the answer.  Check if you can get flow curves of gpm vs pressure or the equivalent beforehand.

RE: psi wont stay up

2
Two things you need to specify for your pump; Head and Flow.
You need a pump that can deliver a 50 ft discharge head (apx 20 psi with water) at the maximum flowrate you want to be able to run through your test station.

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

(OP)
thanks for the help!
happy new year!

RE: psi wont stay up

Another thing is you may have air trapped in the system and as you know, air is not nearly as compressible as water, so if you do have air entrapped you will have some difficulty getting up to pressure.  

Normally this is the case when pressure testing systems to higher pressure, I assume even at the lower pressure air is still an issue.  You will need some vents at the high points of the system to bleed the air out.

Greg Lamberson
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com

RE: psi wont stay up

"air is not nearly as compressible as water"???  Is that what you really meant to say?  

Air is pretty compressible and in this case it would delay the pressure traverse across the system through the liquid having to compress the gas.

David

RE: psi wont stay up

(OP)
how about changing the systems main filter?

RE: psi wont stay up

(OP)
pump releif valve set at 250...press releif valve for main reg set at 105...max press is 148.3 dead headed. when outlet is o-pened and part is applied rated @ 24gph, psi wont go past 4.4psi.

RE: psi wont stay up

(OP)
sorry... pressure relief for main reg is wide open (250psi) deadheaded and max press is 148.3 w/ main reg closed.

RE: psi wont stay up

David

When you test a pipeline system and there is air in the system you cannot get a good test or get up to test pressure.  That is the reason you must evacuate all of the air from the system and do air volume calculations to validate it.  

Air is compressible, but in a closed system not nearly as much so as water.  Air will cause you big headaches when hydrotesting.

Greg Lamberson
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com

RE: psi wont stay up

Air will indeed cause you big headaches while hydrotesting.  It is very compressible (a couple of orders of magnitude more compressible than water) and not as susseptible to changing pressure with temperature as water.  When you pressure up a system that contains significant air (either free or entrained), the system will not respond in the typical liquid-full manner.

David

RE: psi wont stay up

Air is compressible, but in a closed system not nearly as much so as water.  Air will cause you big headaches when hydrotesting.

You are saying water is compressible? More compressible than air?

Charlie
www.facsco.com

RE: psi wont stay up

There's no air in this system.
Don't go off on that tangent.  

We all know water is slightly compressible and air very much so.



BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

It's pretty clear that the pump is undersized.

RE: psi wont stay up

The pump is fine, check your motor to be sure it is the right horsepower.

http://proconpumps.com/Series%201.htm

The pump is not undersized.

tell us exactly how it is set up... from supply to outlet, what is in between?

Charlie
www.facsco.com

RE: psi wont stay up

"I can't get to 20 psi... at 14 to 60 gpH

The OP's statement implies that all he wants to do is to get to 20 psi, ie 50 ft head at ONE GPM maximum.  That flow and head is micro watt power and probably not the kind of pump where you have the option to buy a new motor.  Neither is it the kind of pump or motor worth spending any time on repairing.

Its not the motor.  I feel if the motor was turning, he wouldn't be writing us.  If its turning at all, its making 0.02 horsepower and that's all it needs to make to get 20 psi and 1 gpm with the right pump.

If this garden fountain pump doesn't work, he needs to scrap it and buy a new unit.... one with the right head and flow.  That will be the only cost effective solution.  

No air, probably no clogged filter, probably no motor problem.  End of story.

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

pump releif valve set at 250...press releif valve for main reg set at 105...max press is 148.3 dead headed. when outlet is o-pened and part is applied rated @ 24gph, psi wont go past 4.4psi.

what do you mean when you say that "outlet is opened and part is applied"?

Is the pump generating pressure at dead head?

Charlie
www.facsco.com

RE: psi wont stay up

LOL.... BigInch.... I wish we could delete our own posts....

Palecactus,

Sounds to me, from what I read... that the system does not NEED to go past 4.4 psi.

Perhaps if the oulet valve was postiioned at the outlet of the "part". Then, the outlet valve is slowly closed to increase the pressure......

maybe, yet I'm lost.

Charlie
www.facsco.com

RE: psi wont stay up

You can delete your own post, just hit the red flag and ask management to delete it.  They're very responsive to red flags.

David

RE: psi wont stay up

Big-

As David pointed out, use the Red Flag option. Management is indeed very responsive to red flags. There's even a little box to type in some comments as to why you think a post should be removed or you can request the entire thread to be removed.

jt

RE: psi wont stay up

We'll leave it as a lesson in not being explicit in requests for assistance, not giving the correct or confusing data... and trying to be too helpful.  I think most of the time we are all trying to be so helpful in cases like this that we actally make things more confusing in the process.

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

BigInch,
Several of us went on a mission a couple of years ago to try to be the first responder to unclear/incomplete posts and ask the OP to clear up their question prior to people making-up stuff to fill in details.  You won't believe the grief we got from other regular members.  A couple of us still do it sometimes, but it rarely does any good.  Too often the OP will ask an incomplete question and then go away and never respond in the thread again.

The only thing that I've found that works is to respond to the discussion instead of the OP (and often be accused of taking the conversation into the weeds when I ask a responder if they really believe that water is more compressible than air).

David

RE: psi wont stay up

I backed out after the thread became incoherent and petty.  

No, I realized I made a mistake in my wording but by the time I logged back in, the thread had deteriorated to sniping.  I simply mentioned that air in the system could be a potential problem as air is a problem in hydrostatic testing as it occasionally prohibits reaching nad maintaining the required test pressures and it can also cause an air-lock in the system.  I, obvioulsy mistakenly, thought that since the system could not reach the required pressure, one of the things that could be looked at was air in the system.  

I no longer responded because a member made the comment of going off on a tamgent.  I understand how water and air interact in a closed system and again made a mistake in the wording of my post, my apologies and I'll purpose to not make a mistake again.

Greg Lamberson
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com

RE: psi wont stay up

(OP)
sorry for not responding when it is appropriate for you..tho i appreciate the help from the others. sometimes people get agitated when they cant find the solution and scrap the whole thing. im not like that. the motor is fine,the filter is replaced, the pump is too small and the main regulator needs to be changed. period.everybody makes mistakes at one time. should we a be so critical?

RE: psi wont stay up

Greg, no offense ment.  I realized you just made a simple mistake and I was only trying to pre-empt the next 30 posts from ripping you apart.

Palecactus,  I didn't intend to be "critical", just critical...and nothing personal intended.  You gotta' admit you muddied the water with the posts after "happy new year" and confused most all of us.  That's all.  In any case, glad you got everthing worked out and we all hope its a start for a good coming year.  

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

Just out of curiosity, how did you determine that the pump is too small and the regulator needs to be changed?

Never change more than one thing at a time.

And please, I'm just curious so don't start ripping me apart. I look at the pump curves, and see a pump that has the output capabilities. Why would you scrap the pump before changing the regulator?

Charlie
www.facsco.com

RE: psi wont stay up

Charlie, the symptoms described by the OP are usually the result of an undersized pump. Not always but probably 9 times out of 10.

Without knowing the system curve it is impossible to say that the pump has the output capabilities.



RE: psi wont stay up

The datasheet for the pump series in the OP seems to imply more than adequate for the task at hand:
http://www.proconpumps.com/Series%201.htm

If the pump's not meeting its specifications, then you need to get a new pump.

TTFN



RE: psi wont stay up

What data sheet?  

FACS did not make the original post and that's the only data sheet I see referenced in this thread.  

I have no idea why FACS posted that.

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

RE: psi wont stay up

IRstuff,
That's what I was thinking, and that's why I posted the same page.

I'm trying to get the set-up so I can get an idea of what the system looks like.

I've designed and tested many pumps,If we know how the system is organized, we might get a picture at what's wrong.

But I suppose I'm giving up on this thread... seems like a lost cause now.

Charlie
www.facsco.com

RE: psi wont stay up

The OP states that he's using "small procon series 1 pump."

TTFN



RE: psi wont stay up

Well, my apologies to FACS for missing his posting.  

TTFN



RE: psi wont stay up

If there is only one part I agree that it is not a pump problem.  I read the OP as "parts" but reading again he later said "part".

Is there one part or multiple parts on a header?

Or is this thread dead?

RE: psi wont stay up

IRstuff,
Thank you, that was kind
 

Charlie
www.facsco.com

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!


Resources