Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

PSV Sizing for a PD Pump

Status
Not open for further replies.
Ian19

Ian19

Mechanical
Joined
Feb 28, 2012
Messages
1
We have a Positive Displacement Pump on a very old system which requires a new PSV. We have no information on the previous PSV and it has been machined during maintenance over the years. The valve must be set to crack at 17 MPA, the manufacturer has sent us a new valve which is physically about 1/4 of the size of the previous valve although it is set to relieve at 17 MPA. Question is what other parameters need considered given that the orifice through the valve is smaller and inlet and outlet are also smaller.
 
Sort by date Sort by votes
Please don't take this the wrong way, but why are you not asking the manufacturer these questions? 1/4 the size is huge! For example, 1" vs. 4". Flow is porportional to diameter squared. 1/16th the flow? Wow!!! Are they working off a make, model. and serial number? They should be almost identical, or about the same size. Something is wrong somewhere!

Good luck,
Latexman
 
Upvote 0 Downvote
Any such pump that I have ever had to specify required the PSV to be sized for full pump flow at its set pressure. If you have pump nameplate data then that ought to be all you need.

Regards,

SNORGY.
 
Upvote 0 Downvote
The difference in apperat size could e.g. be if the original was a spring loaded and the new was a pilot. But you should do as Latexman says: Ask the vendor!

Best regards

Morten
 
Upvote 0 Downvote
Is the reliving rate similar to [or larger than] the PD pump's pumping rate? If so, its fine. Otherwise, ask ASAP! Somebody at the mfr may have transposed a number. It happens.
 
Upvote 0 Downvote

This is speculation but I have run across systems where a relief valve between a pump and a vessel was sized for scenarios that protected both.

It may well be that that the pump alone only requires a small PSV, but another relief scenario is depending on the rate the large PSV provides. A indication this might be the case on older systems is the lack of block valves between pump and vessel, close physical proximity with minimal piping runs, etc...


Take a system approach when evaluating relief valves and sudden size changes such as what you are experiencing here.


 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

D
  • Question Question
PSV sizing acc. to IGC
Replies
4
Views
7K
Snickster
Snickster
C26M13
  • Locked
  • Question Question
PSV Sizing Calculation (Swagelok Relief Valve)
Replies
17
Views
11K
C26M13
C26M13
D
  • Question Question
Medium for calculation of PSV relief rate
Replies
8
Views
13K
The Obturator
The Obturator
D
  • Question Question
Relieving temperature PSV
Replies
13
Views
16K
mlazard
mlazard
Sharik
  • Locked
  • Question Question
PSV Serial Number
Replies
3
Views
6K
Sharik
Sharik

Part and Inventory Search

Sponsor

Back
Top