I have the FX Crown for a couple of weeks now and I noticed something in the past two weeks. The regulator seemed to creep a little less then 10-15 bar after each time I took it out for a shooting session. The Crown I have has been modded by Gijs (weatherby) which stabilized the reg creep that might happen with some guns at above 150 bar.
After observing the "creep" (it is inbetween quotes because it's not regulator creep) closely I noticed that this is caused by something else. Each time I went to the range the outside temperature was about 5 to 10 degrees Celsius, the storage temperature afterwards at home is about 20 degrees Celsius. Some of you might have already guessed it by now but for others this isn't that obvious: The increase in temperature causes the trapped air in the regulated chamber to expand which gives a higher pressure in the regulated chamber. On "normal" airguns you don't have a pressure gauge at the regulated chamber so probably nobody ever noticed this since it isn't visible on the outside.
By applying the ideal gas law: Pressure x Volume = n x R x Temperature). The regulator chamber has a fixed volume and also n and R are fixed (gas constant and the composition of the gas) which leaves the pressure and the temperature as variables. By looking at the formula it can be seen that pressure and temperature are linearly related on a scale 1:1. So an increase of temperature from 5 or 10 to 20 degrees celsius gives a pressure increase of 10 to 15 bar (of course this is the ideal gas law but this is quite close to what's happening at a very small temperature range). This was exactly what I was observing after checking my Crown the next day.
So for all of you that suspect regulator creep it might be a good thing to check the following first:
* If you went to the range/backyard/forest/wherever you shoot try to check temperature roughly (doesn't need to be that exact) and write it down.
* Afterwards write down the temperature at your house where the gun is left to rest after the shooting session. Celsius is the easiest in this case since this is directly related to the unit bar in this formula.
* Check the regulator pressure increase after your gun has heated up and note this down (this might take a while). If this value is equal to the amount of temperature increase you might have the same thing as I have.
* Fire the gun for one or two shots but make sure the temperature of the airgun remains stable (so a couple of shots out of the window, in the garage or something like that).
* Check the gun the next day to see what the regulator pressure has done. If the pressure is at the value it should be there is nothing wrong with your regulator, it's just the increase in pressure due to the temperature increase. If it has increased (by more than 1 or 2 bar) than it looks like the regulator is creeping.
This phenomena only happens when the outside temperature is lower than your storage temperature. During summer the gun will cool down when stored and the decrease in pressure will be solved by the regulator itself. Maybe if the gun is left in the sun the creep might also happen but that will be solved during shooting
Hopefully this helps for those who need it
After observing the "creep" (it is inbetween quotes because it's not regulator creep) closely I noticed that this is caused by something else. Each time I went to the range the outside temperature was about 5 to 10 degrees Celsius, the storage temperature afterwards at home is about 20 degrees Celsius. Some of you might have already guessed it by now but for others this isn't that obvious: The increase in temperature causes the trapped air in the regulated chamber to expand which gives a higher pressure in the regulated chamber. On "normal" airguns you don't have a pressure gauge at the regulated chamber so probably nobody ever noticed this since it isn't visible on the outside.
By applying the ideal gas law: Pressure x Volume = n x R x Temperature). The regulator chamber has a fixed volume and also n and R are fixed (gas constant and the composition of the gas) which leaves the pressure and the temperature as variables. By looking at the formula it can be seen that pressure and temperature are linearly related on a scale 1:1. So an increase of temperature from 5 or 10 to 20 degrees celsius gives a pressure increase of 10 to 15 bar (of course this is the ideal gas law but this is quite close to what's happening at a very small temperature range). This was exactly what I was observing after checking my Crown the next day.
So for all of you that suspect regulator creep it might be a good thing to check the following first:
* If you went to the range/backyard/forest/wherever you shoot try to check temperature roughly (doesn't need to be that exact) and write it down.
* Afterwards write down the temperature at your house where the gun is left to rest after the shooting session. Celsius is the easiest in this case since this is directly related to the unit bar in this formula.
* Check the regulator pressure increase after your gun has heated up and note this down (this might take a while). If this value is equal to the amount of temperature increase you might have the same thing as I have.
* Fire the gun for one or two shots but make sure the temperature of the airgun remains stable (so a couple of shots out of the window, in the garage or something like that).
* Check the gun the next day to see what the regulator pressure has done. If the pressure is at the value it should be there is nothing wrong with your regulator, it's just the increase in pressure due to the temperature increase. If it has increased (by more than 1 or 2 bar) than it looks like the regulator is creeping.
This phenomena only happens when the outside temperature is lower than your storage temperature. During summer the gun will cool down when stored and the decrease in pressure will be solved by the regulator itself. Maybe if the gun is left in the sun the creep might also happen but that will be solved during shooting
Hopefully this helps for those who need it
