I do not recall any others at SSC who used these tanks.
Unfortunately, there are two volumes reported for these tanks: the overall volume (water and air) and the maximum water volume. It can be hard to know which is being used in the product literature. From what I've seen manufacturers and sellers assume that one half of the overall volume is available for water. The Groco tank is very similar to the tank I have, actually, as they report the water volume and I reported the total volume. This can be verified by looking at the dimensions of the tanks, which are similar. (Will add link later.)
I have a smaller British tank bookmarked at work, si good to know about the compatibility of the threads. I will add a link later when I am there. I also found an accumulator for fire protection that has a better volume and can post it later. I am not certain the price of the latter is acceptable, however.
The Johnson Pump accumulator looks promising. I might not have the time in the coming weeks to contact the manufacturer, so if you do, let me know what you can find out about the attachment.
Tim wrote:Charging with Nitrogen would be best because temperature fluctuations will have a lesser effect on pressure compared to charging with air.
Why would this be true? For an adiabatic process the difference between air and N2 should be fairly negligible, as their ratio of specific heats is about the same. (If the process is reversible adiabatic