8 replies to this topic

[J_Leo]

Hi There,

 

I didn't see any ARC (Automatic Recirculation) valves used for pump minimum flow protection until the recent project. People put a couple of ARC valves on pump discharge side for pump minimum flow protection. I used to see FE/FV combinations instead.

 

Is it a good practice to use this kind of valves? It appears to be cheaper. Rather than this, any advantages / disadvantages based on your experience?

 

Regards,

Leo

Edited by J_Leo, 15 April 2014 - 09:32 AM.

[ColinR33]

As with anything, there are situations where it works well, and situations where it will not work well.  I have looked at these in the past, they are expensive and sometimes cost more that the recycle control valve system (depending on how much jewellery  is required), but other times are an economic alternative. I have seen situations where they work well and others where they do not.  Basically what I am saying is that you cannot make a general statement but have to evaluate on a case by case basis.  One this that can have a huge effect on the suitability is the pump curve.  Generally a pump with a flat curve will not be a good application for an ARC valve as you will not get a significant change indifferential head over a wide range of flows, and even though they say the valves sense "flow" it is really the change in discharge pressure (resulting from TDH variation) that is sensed.  Also if your suction conditions fluctuate a lot that will cause problems.

 

HTH

 

Cheers,

Colin

[J_Leo]

Thank you, Colin. Do you how often people use ARC valves? It appears that not a lot of design firms use them in their design.

[ColinR33]

I cannot make any general comment on usage, as I said, case by case evaluation.  Personally, I don't use them much.

[oscarsender]

ARC valve initial cost is not always cheaper than the combination of flow element and control valve. If its size is above 8", it may likely cost higher than control valve. And this ARC is applied only in clean services. Its operation is flexible but not as fine adjustment as that of control valve and flow element combination.

[Art Montemayor]

I believe Colin's advice is valid and should be applied.  For added assistance to his explanation regarding the pump curve and the importance it plays in applying an ARC minimum flow protection valve, refer to the attached information from the Yarway ARC valve catalog.

 

I think you'll see how Colin's recommendations seem to be validated by the valve's operational characteristics.

 

 ARC Valve Operation.docx   108.13KB   162 downloads

 

[J_Leo]

Thank you very much for your valuble inputs. The curve provided by Art is very helpful to understand Colin's statement 

 

Regards,

Leo

[David Livingston]

The times that I have seen an ARC valve used have been in boiler feed water service.  The use of an ARC in this application is probably dictated by the expense of a BFW pump as well as the fact that its operation is independent of a control system (and failures of power and instrument air) as it is exclusively mechanical.

[uttaminternational]

Hi there,

 

I am thinking for ARC Valve and QCNRV Valve project.... I need some basic designs and calculations to start....

 

Anyone knows where I can get ARC valve and QCNRV Valve Calculations( with formulas ) and basic Designs.... ?

 

and any good book for ARC Valve and QCNRV valve which I can refer?

 

Regards...

KK