Chromatography Forum

My lab is considering switching over to hydrogen to save on gas. We use two GC's and two GC/MS's. My concern is the split vent and septum purge for these 4 instruments vent into the room. Should I be worried about the hydrogen igniting? Most of the methods used use a 50:1 split with a total flow between 50-60 mL/min.

We have 10-20 GCs in one room that have been switched over to H2. We plumbed the vents into a house "vent" that has a slight amount of suction on it. There should be a technical article on the Agilent website about plumbing their GCs with H2 (that's what we use, here).

The MSs will work with H2, but there are other considerations that should be made. There are 2-3 threads in the MS sub-forum on the topic of using H2 in an MS.

Another option is to plumb all of the GCs into a fume hood if you have one of those available. I think the danger from hydrogen venting into a room from only 4 GCs is pretty low due to the speed in which hydrogen diffuses.

We also have ~40 GCs in a large 1 room Lab and are currently moving as many as possible to hydrogen carrier. We do not have vents, however, since we are ina new building with excellent air exchange/ventilation. We currently use multi-packs of hydrogen on an automatic switchover manifold but are thinking of moving to hydrogen generators. Does anybody have any thoughts or experience with the use of generators for this many GCs?

Some practical considerations:

Be certain if you use generators that you have a few extra, as split ratios and flow rates will change the hydrogen supply requirements if you make any changes in the future. Also if one has a problem you will want to have backup capacity according to "Justin Case".

Another comment:

If you vent hydrogen into the lab in goes in one direction: straight UP.

If you have a ceiling vent with a heat exchanger you will have a GREEN solution to the elimination of hydrogen in the lab.

I worked in a run out situation with dozens of hydrogen GCs venting and we never had a problem with this design. It had run 10 years before I got there and it has been another 15 years since I left. No problems.

best wishes,

Rod

My personal experience with hydrogen generators has been poor. They produce high quality hydrogen and are relatively maintenance free, but I found that their ultimate reliability is a problem, often having to be sent back for repair of major components.

I believe that the choice between cylinders and generators is approximately even, but would definitely take the previously given advice on having a few extra units if unexpected GC downtime is a concern of yours.

Not only if your split ratio's change or additional GCs are added, but also the generators don't have to work as hard if you have extra capacity being produced which will help reduce failures.

Most hydrogen generators produce a small volume of hydrogen at a relatively low pressure, maybe 100 mL/min at 60 psi. That's fine for an FID, may not be enough pressure or flow if you are using long or microbore columns, or if you are running concentrated samples at a high split ratio. To get a generator that will handle several GC systems will be very expensive. For most people a generator doesn't make much sense economically.

Has anyone found an inexpensive wall mounted or bench mounted hydrogen sensor? I have a customer who is interested in switching over but they keep asking about the safety issue and want a room sensor.

Best regards.