I live in New England. It is cold here this time of year, sometimes I'll be out shooting and it is below freezing. I've put a few tins through my FX Crown, and the reg has broken in nicely sitting at 130BAR and filling quickly after each shot now. Nothing out of the ordinary. However, on some occasions, I'll notice my gun having sat for a while will creep up to 135 sometimes almost 140BAR. (on the reg side this is) This doesn't make any sense. If the reg were leaking, it would continue to climb, but it doesn't. If the reg were inconsistent, why not jump by a larger margin or at least be consistently inconsistent?
I did a bit of digging, and there isn't a good technical diagram on the Crown reg I could find that really lets me visualize how it works, but seeing the new FX Master Class video (link below) I realized something: The FX Crown doesn't run a balanced reg design. I may be wrong, or messing up my terminology here, but stick with me. Part of the reason you can't turn the reg down on the Crown is that there is nowhere for the vented air to go, so you're just stacking more and more force on the piston. This means that, if there were a pressure rise in the plenum, it would be trapped there and would be reflected in the post-reg gauge pressure.
Okay, brilliant and all, but what relevance does that have? Well a little napkin math and the ideal gas law (PV=nRT) and I estimate you should expect to see a 5BAR jump in your plenum pressure (remember IDEAL gas law, meaning not perfect/exact) if it went from 50F to 70F. And you could/should see more if you went from 30F to 70F. The Crown action is a big chunk of aluminum, and acts as a heatsink, so you're not going to see this pressure increase quickly, only slowly, if you were shooting outside for say an hour in the freezing cold and then came in to your nice warm house. On most guns you don't have a gauge after the reg, so you can't be anal-retentive like me and watch your pressures so closely, but on the Crown you can. So yay? This also holds true for the tank, which I've noticed loses some pressure after recharging (because the air is quite warm going into it), and that loss is directly proportionate to the decrease in temperature. Similarly if I fill the gun when everything is cold cold cold, I can watch the tank pressure rise by several BAR as it warms up.
Food for thought. I hope someday this post helps a newbie terrified that he has reg creep or a leak, when actually he is just changing temperatures.
And the video I was referring to:
https://youtu.be/SRuQHlHDW1g
I did a bit of digging, and there isn't a good technical diagram on the Crown reg I could find that really lets me visualize how it works, but seeing the new FX Master Class video (link below) I realized something: The FX Crown doesn't run a balanced reg design. I may be wrong, or messing up my terminology here, but stick with me. Part of the reason you can't turn the reg down on the Crown is that there is nowhere for the vented air to go, so you're just stacking more and more force on the piston. This means that, if there were a pressure rise in the plenum, it would be trapped there and would be reflected in the post-reg gauge pressure.
Okay, brilliant and all, but what relevance does that have? Well a little napkin math and the ideal gas law (PV=nRT) and I estimate you should expect to see a 5BAR jump in your plenum pressure (remember IDEAL gas law, meaning not perfect/exact) if it went from 50F to 70F. And you could/should see more if you went from 30F to 70F. The Crown action is a big chunk of aluminum, and acts as a heatsink, so you're not going to see this pressure increase quickly, only slowly, if you were shooting outside for say an hour in the freezing cold and then came in to your nice warm house. On most guns you don't have a gauge after the reg, so you can't be anal-retentive like me and watch your pressures so closely, but on the Crown you can. So yay? This also holds true for the tank, which I've noticed loses some pressure after recharging (because the air is quite warm going into it), and that loss is directly proportionate to the decrease in temperature. Similarly if I fill the gun when everything is cold cold cold, I can watch the tank pressure rise by several BAR as it warms up.
Food for thought. I hope someday this post helps a newbie terrified that he has reg creep or a leak, when actually he is just changing temperatures.
And the video I was referring to:
https://youtu.be/SRuQHlHDW1g