Pipe Hammer

[islandengineer]

Another question for those in the know, During the past week or so while I have been examining our system for leaks, I noticed a incessant hammering in the Main liquid line, I originally thought it was our plate freezers creeping down on the hydraulics but it is not. I traced this hammering back to a LPR, it sounds like it is originating in a liquid pump but I cannot be sure as it telegraphs the entire system. I have asked around and searched the net and the best I can come up with is "non condensable" in the system, I thought our purger would have taken care of this if it were indeed non condensables. Any Ideas?

[US Iceman]

The hammering noise you may be experiencing could be due to liquid line solenoid valves quickly closing or check valves slamming shut.

How often does the noise occur and for what duration?

When this occurs is there anything else that happens in the plant at the same time?

Are you using liquid overfeed with pumps, or gas powered pumper drums?

[islandengineer]

The noise is continuous , not in a rythmic fashion.

Nothing else happens in the plant.

We are not using liquid overfeed with pumps, or gas powered pumper drums, this plant is a hodgepog of old tech and relatively new tech. I am suspecting some sort of check valve is giving up the ghost but we literally have hundreds of valves in this system for instance, on 1 of 7 plate freezers and just on the hot gas sytem there are 14 valves.

[Paulajayne]

Sounds like a job for a crawl around the pipe work with a long shaffed screwdriver.

When the system is "Knocking" place the sharp end on valve/pipework and the handle to your ear - trial and error will eventually find the leak.

Paula

[US Iceman]

Is the liquid line "a high pressure liquid line" or a low pressure liquid line"?

[nh3wizard]

Ive seen this happen on the liquid makeup valves when filling, it was high pressure liquid feeding an intermediate pressure vessel. The lines vibrated when filling, then stopped when satisfied.

[islandengineer]

The Liquid line comes off a LPR pumped with a Cornell pump at approx. 30 psi. Today I had the entire plant running and noticed that the Knocking had subsided, this leads me to believe even more that the problem is either a Check Valve or a Solenoid issue.

[US Iceman]

In an earlier post you mentioned this...


We are not using liquid overfeed with pumps,...



and now you are saying this...


The Liquid line comes off a LPR pumped with a Cornell pump at approx. 30 psi.


It's hard to help with answers when the information is conflicting.:(

[islandengineer]

I was not aware of the term "liquid overfeed with pumps" so I assumed that it did not pertain to this plant, never the less, thanks for your help.

[nestor_greg1220]

I have also experienced the same hummering in the liquid line of the blast freezer. it only hummers upon reaching the low temp near the cut off. We have been advise to checked the Expansion valve operating range and the orifice number.The hummering may be due to hunting in the oversized exp. valve orifice. We replaced it with new smaller one and got the problem solve. im not sure if this is the same in your case.

[John Hunter]

Hi
One cause of hammer in pumped liquid lines can be caused if the pumps cavitates. This is a condition when the for what ever reason the liquid feed to the pump suction orifice is interrupted. Can be caused by sudden change in vapour pressure and or liquid level above pump. The indication of this is normally a harsh sound at the pump as attempts to pass gas, rattle of NRV fluctuating line pressure, and fluctuating amperage.

[smpsmp45]

One of our customers too was complaining on similar issue. But I am not able to get his problem exactly. But it seems what Mr. John has explanied. It is on the similar lines. Next week I am going to the site to check out the exact situation on this point. But atleast I know , now what it can be