Parker A4AS Valve Issue

[brian_chapin]

Parker A4AS valve warning:

I recently became aware of an incident that had occured with the A4AS pressure regulator. The valves larger than 1 1/4" are bolted, so this problem only exists on the smaller valves.

It seems that in very rare circumstances, the seal cap covering the manually opening stem can corrode fast to the valve bottom cap. If this valve has been insulated, the technician may think they are loosening the cap when they are in fact taking the entire bottom of the valve off.

This leads to a very unpleasant suprise and a significant refrigerant release. This has actually happened to two technicians I know. Simply removing the insulation to the point where you can see what parts are turning is all that is needed to avoid this issue.

Of course, the occasional exercise of the valve and application of anti-seize is always a good idea too.

[Grizzly]

Thanks for the info Brian.
Sadly there are other Manufacturers Valves out there with similar faults.
So as you point out it has become prudent.
Nowadays to expose more than the Valve Cap Head prior to removal.
cheers Steve.

[pweng]

I need operating instructions for an A4AS regulating valve please

[keepitcool]

Try this.

http://www.parker.com/portal/site/PA...6f849420d1ca/?

vgnextoid=d195f87357e28110VgnVCM10000048021dacRCRD&vgnextfmt=default&division=9b17981ef31a0110VgnVCM 10000048021dacRCRD&literaturetype=Bulletins&searchAttr=searchResult&languages=EN&parentCh=Division#r esults

[keepitcool]

Sorry, link did not come out right.

[Mark Selby]

this problem can be fixed. Anytime we install valves we dress all threads with anti sieze

[CHIEF DELPAC]

I have the same problem with 1 inch and smaller valves in NH3 service . Isolating valves and hand expansion valves have a screw in bonnet. I have had these valves start to unscrew the bonnet rather than the valve spindle.

These valves cannot be used on new installations. But there are lots of these valves in older refrigeration engine rooms.

[Iceehot]

Ran into a left-hand threaded bonnet last week, pulled new valve from stock and it was right-hand threaded bonnet! Two different brandnames. Be very careful of any threaded bonnet.

[Loafa]

Hi Pweng if you email me plougher@slingshot.co.nz I will send you a manual