Sundyne pump Maximum casing pressure VS its rated head

[Pejman Hatami]

Hi,
We have an application in which required head is 150 barg and we are about to check if we can size a Sundyne pump for it.
Though in Sundyne documents maximum casing pressure is limited to 155 barg, the same pump is supposed to deliver head up to 1900 meters, let say 190 barg, which is an inconsistency.
Can somebody help and to comment if such an application with Sundyne pump is healthy in principle?
(The model we have considered is LMV-331).
Thanks in advanced.

 

[SandCounter]

Your 190 barg is based on water, specific gravity of ~1. The 1900 meters of head is probably a rating for light oils of specific gravity 0.83 and less.

This page gives the hydrotest pressure of the pump I think you are talking about:

http://www.sundyne.com/Products/Model-Locator/LMV-BMP-331

If you use a test pressure of 1.5-times max working pressure, you're looking at about 149 barg rating.


I used to count sand. Now I don't count at all.

 

[LittleInch]

Pejman,

Don't mix units. Your head is not expressed in barg, it is expressed in metres (or ft)
Pressure is expressed in bar. They are not the same thing.

They state 155 kg/cm2 ( Hate that unit) - that is NOT barg, but something less than that (152), almost certainly ASME class 900 (these are offered as an optional flange).

As sand cuinter very correctly states, the head might be able to go to 1900m or something higher than 1500, but as soon as you submit a data sheet to them with an SG of 1, then they will tell you they can't supply that pump model as it will exceed the pressure rating.

With a SG of 0.8 however...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

SandCounter: not sure what you are saying here:
Developed head of a centrifugal is independent of SG - head is head, if you are discussing discharge pressure at the same head, then SG has an effect.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[SandCounter]

Artisi,

I may not have made myself clear. To clarify Pejman Hatami's second sentence equates 1900 meters head with 190 barg. This is only true for a specific SG, nominally 1. If Sundyne quotes 1900 meters and 155 barg, they must be using a lower SG. So, like you said, consistent head, but pressure driven by SG.

Regardless, I think we are on the same page.

I used to count sand. Now I don't count at all.

 

[JJPellin]

Sundyne is the only API pump manufacturer I know that does this. They sometimes rate the suction portion of their casing to a lower pressure than the discharge portion. They do this by performing a hydrotest on each section seperately. I am not sure if they leave a partition in the casting, and machine it away after the hydro. We have several Sundyne pumps that have this dual pressure rating.

Johnny Pellin

 

[JJPellin]

There is one other problem with this design. Since they can only test new pumps using water, they may be unable to perform a full test. They regularly insist on testing the pump at half speed and extrapolating the results. I consider this totally unacceptable and would reject the pump for this reason, alone.

Johnny Pellin

 

[Pejman Hatami]

Many thanks to you all.
As far as head is concerned, looks we are on the same wavelength.
Littleinch: you are wright, bar and that bloody unit(kg/cm^2) are slightly different, kn/cm^2 let say one Atmosphere is 101325 pa, and this additional 325 Pa difference makes the slight drift, however it is not a big deal. Wonderful comment about Sundyne that they will not quote for those discharge pressures which exceed the casing pressure, looks quite true.

Artisi: Concerning, head and the effect of SG on it,I think littleinch is correct, since in a certain power and flow, the achievable differential head is linked to SG: the lighter the fluid, the higher head.

Johnny Pellin: Is it really their test procedure?
If so, as you mentioned it would be totally unacceptable, who knows what is the logic of such extrapolating?
Could you do me a favor and let me know more about the fluid and machine performance of mentioned pumps?

Thanks again, have a pleasant weekend ahead!
Pejman.

 

[JJPellin]

Sundyne proposed a half speed test for our model LMV-346 pumps in water service at 150 gpm and 4800 feet TDH. We have pumps with dual pressure ratings on casings that are model LMV-313 in butane, propane and naphtha service.

Johnny Pellin

 

[Artisi]

OP:Incorrect,head is not linked to SG, discharge pressure is linked to SG.
As already pointed out twice, head and pressure are not the same.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Artisi]

Head in relation to SG, trust this puts the discussion regarding head and SG to rest.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)