Lab Scale Nitrogen Gas Generators vs. Cylinder Banks

Hi everyone,

I’ve been asked to look into centralizing a nitrogen gas utility that is used by a number of laboratories within a manufacturing building. Currently, the individual users that need nitrogen gas use something like this within the lab spaces:

The concerns from my client are: they are too loud, the heat buildup within rooms is excessive, and the PMs on the devices are getting to be a bit much (in terms of cost and downtime).

I am looking into replacing all these smaller generators with a central source of gas cylinders (dual bank with switching regulator) or maybe one larger generator unit. I’m not familiar with these nitrogen generators and am wondering if people have some ideas why this is preferable to a cylinder bank? My experience from college and other lab clients has been that cylinder banks are used in favor of these types of generators. Unfortunately my client contact is new and doesn’t know why the generators were used vs. cylinders from the get go.

My hunch is that capacity might be the (perceived) problem and that’s why the generators were chosen, but I’ll be digging more into the problem soon.

I think the optimal answer depends on throughput. If one cylinder a year, cylinders. If a gazillion cylinders a year, a generator (or liquid nitrogen tank with vaporizer).

What is the total throughput of all users?

I’ll be heading to the site on Tuesday and my survey plan includes getting the info needed to determine the utility flows, coincident load, peak load, etc.

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I’d bet cylinders would be cheaper if ordered in bulk (trailers), or LN2…gas plants are a lot more efficient than local generation, both due to economies of scale, and because gas plants make money selling “residual” oxygen.

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Unfortunately I couldn’t get much usage info during my site visit so I’m stuck waiting on answers from the client’s people. My client contact did mention he got a quote for a 300 lpm membrane GN2 generator, which was a back of the envelope recommendation from their current generator service people. I’ll have to see if it’s worth pursuing once I have usage information.

Meanwhile, if anyone’s ever worked with this type of GN2 supply technologies, I’d be happy to listen to your experiences with them.

Worked with it? Not really. Praxair put a unit in one of our plants. I think we rented or paid by the pound. It worked fine the first few years. As it got older it required more maintenance and more down time. It seemed Praxair did not respond to our needs and the plant grew to dislike it. The plant decided to do away with it and add capacity to a liquid nitrogen tank with vaporizer. Our other plants use liquid nitrogen tank with vaporizer.

But that’s only one experience.