Received two of these Allen Air 3×18 LF units from eBay Tuesday.
I got around to testing one of them last night and there is a lot of air leakage under 50 PSI. I wrote Allen Air’s engineers and they wrote back:
O-Rings have a Shelf Life of about 15 years. In a cylinder it could be less due to compression set. The O-Ring will flattens out on the O.D and the I.D. This happens when the cylinder is not in use. There is a date code on the cylinder #106. The cylinder is 6 years old. All you may need is a packing kit #A3LFP (field serviceable).
I am waiting on a quote from their distributor on this “packing kit” before I return them to the eBay seller at his cost. There is nothing else wrong with them except that they aren’t made to sit around apparently. I haven’t had this problem with Norgren or Parker products but those are for smaller bore applications anyway maybe there is a difference with the O-rings.