HPL feed to Accumulator hammer

[Ein]

Good afternoon all! I use an ammonia refrigeration system to cool wine at our small family winery. Recently, the HPL feed line to our suction accumulator/recirc tank has begun to hammer. Historically it hasn't, but shortly after replacing a leaky solenoid valve the hammer began. It will stop if I throttle the globe valve on either side of the solenoid valve almost shut, but then I'm unable to maintain sufficient liquid in the accumulator to keep the circ pump operating. This cycling of the circ pump and subsequent intermittent distribution of liquid to the wine tanks is keeping me from maintaining wine temps effectively. Local service guys want to tell me how my whole system was plumbed wrong all over the place but get real quiet when I ask why it hasn't been an issue for the previous 15 years. I've attached a drawing of the accumulator. The line in question is labeled 1" HPL. I'm hoping some of you might have some insight...

14155

[RANGER1]

Ein,
From first glance it looks ok.
Valve 4 in HPL should be restricted as it's a hand expansion valve, check how far open.
Maybe altered when solenoid changed!
Also check liquid receiver has a good working level & confirm sight glass is reading correctly, not dirty or stained, or oil in sight glass giving false or misleading level.


What brand & size in solenoid, I see it's a !" line, maybe a 1" valve installed, when previous was a 3/4" if say a
Hansen HS7.

Hand expansion valve should be set so liquid makeup solenoid on 60-70% of time when plant under full load

[RANGER1]

Ein,
From first glance it looks ok.
Valve 4 in HPL should be restricted as it's a hand expansion valve, check how far open.
Maybe altered when solenoid changed!
Also check liquid receiver has a good working level & confirm sight glass is reading correctly, not dirty or stained, or oil in sight glass giving false or misleading level.


What brand & size in solenoid, I see it's a !" line, maybe a 1" valve installed, when previous was a 3/4" if say a
Hansen HS7.

Hand expansion valve should be set so liquid makeup solenoid on 60-70% of time when plant under full load

Just to add valve no3 is the correct valve to restrict flow as that's what it is designed for.

Ammonia high pressure liquid receiver levels checked when everything satisfied for correct working levels in recirculator vessel

Also are pressures what they normally should be example suction & discharge pressures, what pressures are you running normally & now?

[Tycho]

I agree with Ranger1, valves marked as 3 should be full open, valve 4 is a regulating valve,
if you want to restrict flow, it should be done at this valve.

When you say the "replaced a leaky valve" was the whole valve and body replaced, or was the existing one serviced?


if they replaced the whole valve with a different make and model, play around with the 4 valve, start with it with one turn open, and keep opening until you can maintain equilibrium without getting hydraulic shocks in the pipes.

[Segei]

Had similar issue in the past. When solenoid open, liquid ammonia will "fly" into the empty pipe and suddenly stop at hand expansion valve and we have hammering. I think it depends of the speed of liquid ammonia before it stop at HEV. At higher speed we have hammering, at lower we don't. Solution. Hammering happen when we have solid flow of liquid. I would partly close valve before solenoid. When solenoid open, liquid ammonia will rush into the empty pipe, but partly closed valve will "rupture" liquid flow and you won't have hammering. Start with opening valve before solenoid 1 turn. HEV #4 should be open more, may be even fully open. Probably, someone have done the same in the past and you didn't have hammering. After replacing solenoid upstream valve was open fully and you have hammering.

[Ein]

Sorry for the delay in replying. Suction pressure operates 25-40 psi and discharge is 125-160 psi. Something I noticed upon further inspection of the drawing, there has never been a hand expansion valve installed after the solenoid valve.

[NH3LVR]

Is it possible that the HE Valve was removed when the new Solenoid valve was installed?
Shut off valves are not good at regulating flow.
The other issue is that the seat in a shut off valve will erode if you use it as a regulating valve. The HE valve will erode as well but that is not an problem as you do not use it as a positive shut off.
Not having a leak tight valve makes it very difficult to service the solenoid.

[Ein]

Yeah, I'm aware of the issues with throttling shut offs. There HAS NEVER been a HEV installed in the system. It's run fine for 16 years without one. There isn't even room the way it's pipe fit to install one without major changes.

[RANGER1]

Ein,
The only thing I can think of that might be possible in old solenoid valve there might have been an orifice plate installed between flanges.
Also old valve might have been a 3/4" & new 1" allowing more flow, should have some sort of identifying marks or something.
Unusual, but possible, check old solenoid, check on the floor, it might have been dropped, it could be a round disc with a hole in it.
Can you identify solenoid brand etc

If you can take a picture, also is high pressure liquid receiver level correct when everything satisfied.
If plant a bit short of ammonia it might change something in regards to hammer.
Level should be 4 to 6" minimum

Valve might look like this one

http://www.hantech.com/documents/PDF/s121.pdf

[Ein]

It's a Parker S4A. 25mm orifice. I looked everywhere but I can't find the old valve. The guys that replaced it probably took it with them...

[RANGER1]

It's a Parker S4A. 25mm orifice. I looked everywhere but I can't find the old valve. The guys that replaced it probably took it with them...

Is a picture possible?
Two bolt flange or four bolt flange on valve?
Can you tell us size, brand compressor/s & motor horsepower?
Maybe a smaller valve can be used that still fit in same flanges

I also ask for liquid receiver level just so we can interpret how system is working.

[Segei]

Is it possible that the HE Valve was removed when the new Solenoid valve was installed?
Shut off valves are not good at regulating flow.
The other issue is that the seat in a shut off valve will erode if you use it as a regulating valve. The HE valve will erode as well but that is not an problem as you do not use it as a positive shut off.
Not having a leak tight valve makes it very difficult to service the solenoid.
Eroding of HEV or shut off valve depends of pressure drop across the valve and operating time. HEV have pressure drop 100 psig and after several years of operation it can erode. Slightly open shut off valve has pressure drop 10-20 psig and no eroding at this pressure drop. Yes, it has significant pressure drop when solenoid open but this only for fraction of second. Know 2 plants which throttle shut off valves for more than 20 years and no problem to replace solenoid. Imagine, that seat of shut off valve was eroded. Valve can be replaced by closing outlet valve of HPR.

[hookster]

As some of the others asked what is the level in the receiver? What temperatures are you trying to achieve in the vats? Pressures seem low for the application. Is there sufficient refrigerant?

[RANGER1]

http://www.parker.com/literature/Refrigerating%20Specialties%20Division/Solenoid%20Valves/30-95.pdf

http://www.parker.com/portal/site/PARKER/menuitem.bb22d5a82bbb5b147cf26710237ad1ca/?vgnextoid=a2d9b5bbec622110VgnVCM10000032a71dacRCRD&vgnextchannel=a2d9b5bbec622110VgnVCM10000032a71dacRCRD&vgnextfmt=EN&vgnextcatid=114475&vgnextcat=SOLENOID%20VALVE%20TYPE%20S4A&vgnextdiv=687475&vgnextpartno=100952&Wtky=

http://www.parker.com/literature/Refrigerating%20Specialties%20Division/Solenoid%20Valves/30-94E.pdf

A few options, first link soft close solenoid to prevent liquid hammer, second S4A 3/4" valve has smaller capacity, roughly 2/3 & a 50% capacity version of same valve with kit to make valve smaller.
Without knowing anything else, they may be an option.