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|03-16-2014, 08:59 PM||#11 (permalink)|
Join Date: Sep 2008
Location: Nashville, TN
|03-16-2014, 09:09 PM||#12 (permalink)|
Join Date: Nov 2007
With stock springs the Phantom valve system seems to self compensate for changes in input pressure.
When the pressure is high, the pressure behind the valve causes it to shut faster, but as pressure drops, the valve closes slower, therefore allowing more air to escape and somewhat compensate for the lack of pressure. Basically the dwell varies with the input pressure.
I've played with a reg on my phantom, and the velocity stays fairly consistent from 500psi all they way up to ~900.
|03-17-2014, 02:13 AM||#13 (permalink)|
I'm Stock Classy!
Join Date: Dec 2010
However, I've never seen a Phantom (or any other CO2-based gun) whose valve has the ability to automatically compensates for changes in temperature/pressure.
Large temperature shifts are pretty common for late Spring/late Summer/Early Fall around here. Through first-hand experience, I and many of the guys I play SC with know that we need to re-chrono and readjust our guns accordingly to compensate for the 20° to 30° temperature shift in order to stay within the legal velocity limits of the field.
Read this LINK for more info on CO2 pressure.
Yes, a stabilizer should help to decrease large fluctuations, but that's not always the case. I use my stab to fine tune my velocity in the AM before the game. By late afternoon, I may or may not have to readjust the stab pressure depending on how hot it got.
Here is an example of temp and CO2 pressure...
In January I tested an un-regulated Phantom in 10° F weather (61% humidity, bore-matched barrel) using 12-grams that had been left in the 10° temps for over 5 minutes. The first 12-gram produced an amazing 9 usable shots over 250fps with a gauge reading of just over 400psi after the first 6 shots. The second 12-gram (which had been sitting in the cold a few minutes longer) produced 1 usable shot over 250fps. As we all know, this same test conducted in 80° weather will yield drastically different results because the pressure will be considerably higher.
Here's my thing with gauges... the majority of them are crap. Just cheaply made crap that have dubious accuracy. PPS sells Ashcroft gauges that boast a 2% accuracy rating. They don't list the accuracy rating of all their other gauges (which I believe they used to do), and I doubt they're anywhere near 2%. These cheap gauges are just there to "look cool" and give you a ballpark idea of what's going on.
Listen, if you're getting over 20 shots per 12-gram with an average of 280fps to 260fps then you're doing pretty good. You don't need a gauge for that.
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Last edited by Slim; 03-17-2014 at 02:16 AM.
|03-17-2014, 07:20 PM||#14 (permalink)|
Join Date: Apr 2013
Opinions on phantom w/ Gauge
^^^^^ Slim is dead on. I would add that your gauge may or may not be accurate but it is probably precise. Accuracy is how close your gauge is to the actual value. Precision is how close your gauge reads psi over and over again. So if your psi is 850 and your gauge reads 800-900psig average ing at 850psig it could be considered accurate but not precise. If the gauge reads 1000psig every time it is very precise but not accurate. I chrono my gun then check my psig and make a mental note. If I notice an increase between my chrono rechecks through the day, I stop and rechrono.
Last edited by 1shot; 03-17-2014 at 07:24 PM.
|03-17-2014, 08:58 PM||#15 (permalink)|
Join Date: Mar 2014
Location: Charleston, SC
thanks guys. ^^ exactly what my next question was going to be. So you DO notice a psi increase on your gauge as the day goes on and gets hotter? An increase in psi would mean an increase in velocity (simple physics?)? I live on the Southeast coast and we have major temp increases from morning to afternoon.
|03-17-2014, 09:19 PM||#16 (permalink)|
Join Date: Apr 2013
Yes, as the temperature increases so dose pressure. Velocity will increase with pressure although there is a limit to this. For the pressures we are talking about on a Phantom valve, increased temp = increased psi = increased velocity.
|03-17-2014, 11:56 PM||#17 (permalink)|
Join Date: Nov 2009
Mine came with a gauge. I looked at it once when i first popped in a 12g, then again when i first aired up with compressed air. Sooo, only out of curiosity and not necessity. As is usually the case, the chrono is the only reading i care about.
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