We purchased the Parker Balston unit also back in 2009 and use it to run the carrier gas to 14 columns and fuel for 4 FIDs, it is the 800ml/minute model. We have begun to have problems with it keeping up with demand, which we calculate to be about 500ml/min as we can now only run at about 24psi. After asking around 5 years is about the expected lifetime of the cells for many applications so ours is getting due for replacement, and it will cost about half the price of the total unit.
Even with those costs it has still paid for itself many times over considering the cost of about 4 cylinders per week of UHP Hydrogen we used before. We have the cylinders in a tank farm outside and have the building plumbed for gasses, so we put the Hydrogen generator at the other end of the gas run, keep it set slightly above the pressure of the cylinder end of the line so that if we have a power failure or generator failure we still have carrier gas as once the generator supply drops below the pressure set on the tank regulator the tank will begin to flow.
Most Hydrogen generators are of good quality just be sure to ask the sales person what the expected lifetime is for the cell and what the replacement cost will be when it is needed. If you size it correctly and have several instruments the payback will usually be two years or less, for us it was about 1 year since we use so much.
