I got the vernier calipers out and although it's a bit difficult to get to the service valve on the QL nitrogen reservoir tank to measure it, it does in fact appear to be the same service valve that is used on the low pressure side of an R134a A/C system. That must be why the knob on the Mopar short adapter that is used to fill the JGC QL nitrogen reservoir tank is the color blue. So that simplifies being able to put nitrogen into the QL system tremendously as those R134a quick release couplers are cheap. I called around in my search for a supplier for grade or class 5 nitrogen (99.999% pure) and every person that I spoke with said that you can just use industrial grade nitrogen(99.995% pure) which is cheap @ $15 for 60cft, the smallest cylinder that it comes in at the first distributor that I spoke with, that quoted a price. I had to explain to the salesman that the Factory Service Manual specs class or grade 5 nitrogen and emphasizes the point with bold text so he looked into the cost of Ultra High Purity(UHP) Grade 5 nitrogen and came back with a price of $75 for an 80 cft cylinder, the smallest size that it comes in there, which is almost four times as expensive as their industrial grade nitrogen. The whole QL system probably requires a couple cft to fill, at most, so you end up buying way more than you need, in any case. I called the local Airgas distributor and the girl I spoke with insisted that the only size that their UHP nitrogen comes in is a 300 cft cylinder, which I know isn't true but I didn't want to argue the point. It is cheaper per cft, at 50 cents a cft but you're buying 300 cft when you only need a couple and the high pressure steel cylinder is five foot tall and probably weighs more than I do. It was almost as if she was trying her best to not make a sale. I spoke with a salesman of a third local specialty gas distributor about two other types of grade 5 nitrogen that they sell other than UHP nitrogen, as the smallest cylinder that they produce of UHP is 200 cft. The two other types of grade 5 nitrogen are for specific applications and spec purity rates for other contents in the gas which I don't think is important as far as the QL system goes but they come in the smaller A3 size, which is a 31 cft aluminum cylinder, so I was hoping that it would be less expensive than buying the 80 cft cylinder of UHP from the first specialty gas distributor that I spoke with. The salesman from the third specialty gas distributor that I spoke with took my name and phone number and said that he'd look into it and would call me back with a price but he never did. I'm going to call again on Monday morning to get a price. There is some money to be made here if a specialty gas distributor would supply a small cylinder, such as a 20 cft bottle of UHP nitrogen as I expect that there would be a lot of interest from QL equipped JGC owners who would like to maintain the QL systems in their JGC without getting screwed over by the dealers.
