manifold

Date 03-03-2016 18:59

I have a guy telling me to use our oxygen and acetylene with cylinders missing from the manifold. There is no shut off valve for each cylinder, only a master shut off valve for the group. He said that because there is a reverse flow check valve at each cylinder connection it is safe to use with the missing cylinders. I know that it is wrong to depend upon a check valve to do the work of a shut off valve. Does anyone have any specific information on this?

By WeldinFool (**)

Date 03-03-2016 19:15

I don't have any specific information for you, but common sense tells me "NO!" I would not trust any in-line check valves I have ever seen to prevent gas from escaping the manifold.
I guess maybe if nobody smokes near it, and you turn the pressure way down... :eek:

By newinsp (**)

Date 03-03-2016 19:21

Thanks. I agree, it's common sense. I'm quitting this job anyway, this will be an excuse to leave now.

By aevald

Date 03-03-2016 19:22

We run a manifolded Acetylene system at our shop and it does have shut-offs for each bottle as well as reverse-flow check valves and flash arresters. Best choice: operate the system as it was designed to be run, with all bottles connected.

If we run less than the number of bottles that were designed into the system we shut off that particular feed and we also leave the empty bottle attached and turned off (if you did have a hiccup in the backflow preventer you wouldn't want acetylene coming from other bottles and feeding into an empty one should the valve inadvertently be left open) and also WELL IDENTIFIED as "empty". The main reason not to disconnect and leave the "pigtail" open is to prevent contamination to the system. Yes the theory would be that the reverse flow would prevent loss of product, but that doesn't address possible contamination that would likely occur. How you address this is certainly your call, however, I would error on the side of caution and safety. Best regards, Allan

By newinsp (**)

Date 03-03-2016 19:34

Thanks Allan!
I hadn't thought about that.

By newinsp (**)

Date 03-03-2016 20:22

I just called the company that installed the manifold system. He said that it was a bad idea to use it without all the cylinders connected, that the check valves were intended to stop the flow from one cylinder to the next. He also said that, in an emergency, it may be OK to use for a day, but that the pig tails should be removed and replaced with a plug if this was a permanent arrangement.
I will suggest that this be done.
Thanks for the help.