Laboratories can face a challenging situation when a lab employs multiple gas chromatograph analyzers and has made the decision to convert to hydrogen generators as the primary gas source to deliver the required hydrogen gas flow. Due to the larger flow demand that is required to operate a group of GCs within a lab, one of the key questions that often arises is, “Do we use one large capacity hydrogen generator to satisfy the total flow demand of our GC analyzers, or, do we utilize several hydrogen generators to provide the total hydrogen flow?”

While there are advantages and disadvantages for each approach, clearly such factors as capital costs, installation space, accessibility and most important, continuous operation without interruption, represent critical concerns when converting the hydrogen gas source from cylinders to onsite generators. Overall, the primary objective in implementing onsite hydrogen generators is to significantly minimize, or even eliminate, the dependency on using hydrogen from cylinders to operate the gas chromatograph analyzers.

When faced with the situation of having to supply hydrogen gas to multiple GCs and trying to determine whether implementing a single unit with a large capacity output is a better alternative than employing multiple hydrogen generators with smaller capacity outputs at key “points of use”; the overwhelming consideration centers around the importance of providing continuous gas delivery to the gas chromatographs.

Initially, the solution appears to be a relatively easy one – obtain the total gas demand required by all GC analyzers and size a single hydrogen generator to supply this demand. However, in labs where continuous operation of the GC analyzers is an absolute necessity, this approach may not be the optimum solution. Why? If a situation develops such that the single hydrogen generator experiences an operating malfunction – then it must be taken out of service and repaired; thus resulting in the gas delivery having to revert back to a cylinder source for a period of time until the single hydrogen generator can be returned into service. This represents a “traditional” solution that many laboratories elect to implement.

Matheson Tri-Gas has developed and integrated an advanced control system technology into their HPNM (High Performance NO Maintenance) Hydrogen Generator models, called “Cascading Flow Control (CFC)” that allows several smaller capacity hydrogen generators to be connected in a “parallel” operating arrangement to produce a combined output equivalent to a single larger capacity unit. Up to fifteen hydrogen generators can be linked together in a single CFC system.

The design of the CFC feature allows the units to be set-up in a “master-slave” operating mode. One unit is designated as the “master” of the CFC system and automatically controls the operation of the remaining “slave” units. At any time, only the controls on the “master” unit need to be adjusted and the same adjustments will be automatically made on the “slave” units.

The largest advantage a laboratory has in using the CFC system is that if a single unit in the system malfunctions, the remaining units will continue to operate and deliver hydrogen gas up to its maximum output trying to make up the flow lost by the unit that is removed for servicing. In this way, many of the GC analyzers can still be operated without having to switch back to using cylinders.

To obtain more information about the benefits of using “Cascading Flow Control” with Matheson's HPNM Hydrogen Generators, call 800–828–4313 to speak with a technical representative.