direct acting pressure reducing valve mislabeled?

[CrazyHorse81]

We just installed at PRV Station #2 a 1-1/2" Cla-Val Model 990 with a label of 80-140 psi on it - that caught my attention because I needed the other one with an adjustment range of 30-90 psi as my outlet pressure required is 40 psi.

This put me in a bit of a panic, so I ran down to the site and took the up and downstream pressures of the PRV. The gauge recorded 81 and 40 psi, respectively.

Unfortunately, I cannot get a flow measurement through the valve, but I could not hear the flow going thru (unlike the other PRV Stations that sometimes roar). I have a tech rep coming in June to look, but there is no way to tell what's in the valve because it is one piece. He said that you have the correct valve but mislabeled if the downstream pressure remains 40 psi in static conditions. He said that this valve should not work anyway because it is outside the adjustment range. ???

Has anyone experienced this before and what did you find out?

 

[gerhardl]

You have in my opinion actually three possible answers:

1. You are correct. The spring is changed without altering the (standard?) outer marking for the valve. This is not unlikely as changing of the spring for this type of valve is fairly common out from a stockist. Control: what does the underlying documents describe, your order and suppliers confirmation?

2. You are incorrect, presuming your pressure measurements are correct, and the valve is supplied with the stronger spring. In this case the downstream force on the diaphragm (40 psi) must be high enough to close the valve sufficiently against springforce and action of 80 psi, to give the reducing effect from 80 psi to 40 psi. Seems a bit farfetched, but not impossible. Control: only producer can confirm if this is within possible limits.

3. You are incorrect, eg. stronger spring, and your measurements are possibly not correct or deviating. The pressure reducing effect is caused by a fully (or mostly) open valve with low cv (large throtteling effect) and a high flow demand, or possibly additional restrictions in your pipeline. Not impossible but again a bit farfetched.

I will 80 to 20 go for number 1.

 

[SEP87]

We supply pressure regulators and regularly change the springs to provide alternative outlet pressures. When we change the springs not only do we change the the label, but every spec change is recorded and signed off by the person who did it.

A reputable supplier should be able to provide you with proof of the alteration.

Furthermore I would request a declaration of conformity from the supplier which states that the equipment can do what they say it can do, even with the wrong label in place.

Worst case scenario, the spring is wrong and something goes wrong, although the supplier is at fault, you have installed equipment which states an outlet range of 80-140 psi, which means its your head on the block.

Not only do you need proof of the correct spring to satisfy your own doubts but also to ensure the onus is on the supplier (and that they know it) if something goes wrong.

 

[gerhardl]

SEP87 - I fully agree with you on all points, and any reputable company will have the procedure you describe, but things tend to happen, and here something is wrong. In my opinion it still is most likely that the item itself is OK, and markings wrong.

But yes: the essence is in your two last sentences.