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Old 05-13-2008, 07:15 PM   #1 (permalink)
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Question about regulated CO2 and expansion...

Let's say I have a CO2 tank screwed into a female Stabilizer, regulated down to 650psi. The regulated gas runs to the valve via 12" of stainless braided hose. Will I lose/gain pressure through the hose, or will it remain at 650psi? I'm not sure if the internal volume of the line would affect my pressure once it has been regulated.

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Old 05-13-2008, 07:31 PM   #2 (permalink)
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It will remain at 650psi subject to variations due to flow rate. For example if you pull a high volume out the line, the pressure may drop in the line because the regulator cannot supply enough volume at the set pressure. The only way it could increase past 650 psi would be if the gas were to remain in the line and increase in temperature, but that would be a pretty minor increase.
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Old 05-13-2008, 07:41 PM   #3 (permalink)
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unless it runs through the reg as liquid?

because from what i understand you can regulate the liquid CO2 to 650, then it'll expand somwhere else and result in a higher pressure?

i could be wrong..
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Old 05-13-2008, 09:34 PM   #4 (permalink)
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Long lines act as expansion chambers you will see a drop how much depends on a lot of variables.
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Old 05-13-2008, 09:46 PM   #5 (permalink)
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also,if you set up your tanks with anti-siphons (w/ the ends closed up as much as possible...as small as a paperclip wire) it will help keep the liquid out of the reg,thus keeping the output pressure more regulated.

liquid=bad

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Old 05-13-2008, 10:02 PM   #6 (permalink)
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yeah if you get liquid through the reg, that pretty much eliminates any use for the reg in the first place. You will have spikes all over the place. Expansion chamger prior to the reg, vertical bottle, or anti siphon bottle.
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Old 05-13-2008, 10:31 PM   #7 (permalink)
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Quote:
Originally Posted by Eli View Post
Let's say I have a CO2 tank screwed into a female Stabilizer, regulated down to 650psi. The regulated gas runs to the valve via 12" of stainless braided hose. Will I lose/gain pressure through the hose, or will it remain at 650psi? I'm not sure if the internal volume of the line would affect my pressure once it has been regulated.

Thanks guys.
You'll be fine - Stabilizers will block pretty much all liquid from entering the marker (though you don't want to dump liquid CO2 into it if you can help it), and your air line will be at the same pressure no matter how long it is. The only thing it can hurt is recharge rate, and you won't see that with a hose that short.

I don't know what some of these people are talking about; there's just no way an air line can maintain different pressures at both ends. The only way pressure would change is if the system was sealed off and the volume, temperature or number of gas particles changed (Google "ideal gas law" if you want to know more). This won't happen in your system, at least not to a relevant degree. Your regulator doesn't care if your line is 3 inches long or 3 feet long, it'll keep dumping gas into it until it hits 650psi regardless of the line length. It would just take slightly longer to fill the 3 foot line because it's a higher volume.
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Old 05-13-2008, 10:45 PM   #8 (permalink)
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For the most part, it will remain at 650psi, unless the hose heats up, or sits after rapid firing. Then you have the age-old PV=nRT. If temperature goes up on the right side of the equation, and Volume stays the same, Pressure has to rise to balance the equation.

You might get a first shot hot situation if the marker sits for a while, but the length of hose does not affect the pressure, just the volume.
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Old 05-13-2008, 11:13 PM   #9 (permalink)
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You certainly can maintain different pressures at both ends of a line. Otherwise there would be no flow. The Ideal Gas Law is just that, Ideal. It really only applies to gas "at rest", or in steady state, after a system has stabilized after a change in P,V,n,R or T, not while the system is still in change. Mach flow applies to a gas in motion, and relates to the resistance caused by line diameter, changes in line diameter, changes in direction, flow restrictions etc. And it will cause a differential in pressure along the path of flow. Hence the reason your furnace ducts need to be taped, or they leak.

This may apply in this situation, but would be negligible when compared to recharge rate from the regulator in a high volume usage situation.

However I did not mention a pressure differential in the line, I mentioned a drop in regulated pressure in the line due to high volume usage - in other words recharge rate from the regulator exceeded by usage.
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Old 05-13-2008, 11:14 PM   #10 (permalink)
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some info taken from PPS






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Stabilizer Archive

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I have heard of Female Stabilizers being used as a bottom line. Does this mean they attach the Stabilizer to the grip with brackets or do they attach it TO the bottom line? Do you advise this, doesn't sound very sturdy?
The Female version of the Stabilizer was specifically designed to be used as a bottom-line style bottle receiver and when mounted with the available bracket, it is every bit as "sturdy" as any standard bottom-line adapter. The Female version can also be used directly on top of a bottle that is used as a remote tank, carried on the back.
NOTE : Any tank used in the horizontal position (bottom-line, etc.) should have anti-siphon tube installed to minimize the chance of allowing liquid out of the tank. A regulator can reduce the effects of liquid to the gun but cannot eliminate the velocity variations that would result.
I have a Tippmann model 98 with the CO2 bottle attached in the back as
usual. What type of stabilizer would I need and other accessories.
The most common setup for the M98 is a Female Stabilizer and ring mount to replace the existing bottom line ASA. No other parts of changes would be needed. Just unbolt the current ASA from the bottom of the grip, remove the ASA from the end of the hose, reconnect the output of the Stabilizer to the end of the hose. Then bolt the ring mount to bottom of grip frame and secure the Stabilizer into place. Screw in the tank and go. Anti-siphon tube in the CA tank recommended for best results."

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Stabilizer Instructions

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Stabilizer Instructions

Some experimentation may be needed to achieve the best setup for your particular gun. The following setup, adjustment and maintenance apply equally when the Stabilizer is used with either CO2 or N2/HPA propellant sources. Follow these same procedures when a Stabilizer is used as the second stage of regulation in high pressure systems. 2-stage regulation will generally yield several times better output pressure consistency than any single stage system.
The best way to establish an initial setup for velocity control is as follows... The goal here is to let the STABILIZER do most of the work and to use the gun's velocity adjuster only for fine tuning of the velocity. To accomplish this, you must first bypass the gun's regulator or velocity adjuster by setting it's velocity adjuster to a point well above normal shooting velocities. (approx.325 ft. per sec. or so) for a starting point.
Use a 3/16" Allen wrench to turn the adjusting screw, on the STABILIZER counter-clockwise to lower the pressure, slowly, (1/4 turn at a time) just until the velocity begins to come down from where you started. At this point the STABILIZER is providing most of the control and you then can "back off" on the gun's velocity control until the velocity is down to where you want it. (NOTE: You must fire a few shots between adjustments to allow pressures to stabilize.)
This method of initial setup will insure that the STABILIZER and the gun's adjuster are both doing their job properly. There isn't much need to know exactly what the pressures are because it will be different for each gun. What is important is to maintain consistent velocities; a chronograph is your best gauge. Setting up your system as described can virtually eliminate "Hot-Gun" and velocity spiking problems and allows quicker and easier velocity adjustments at the chronograph.
The STABILIZER will not be harmed by liquid and it will control pressure even if liquid is present. Although, best results in velocity consistency will always be achieved with anti-siphon tubes installed into your CO2 tanks. except vert. mount tanks)
There will be a short break-in period, (approx. 2000-3000 shots), in order for the springs and seals in the STABILIZER to "take their set". Once the regulator has settled in, you should find little or no need to make further adjustments to it. The gun's adjuster will need fine tuning from time to time. Play safe, play fair and maintain better accuracy; keep the velocity under 300 feet per second.
Lubricate the pneumatic system regularly. Apply a small amount of light weight, NON DETERGENT (no solvents) machine oil or air tool oil at the air supply inlet. Air moving through the system will lubricate the components internally. IMPORTANT CAUTION: Do not use spray type lubricants. Most spray lubricants contain solvents that will damage seals.
Any questions or comments; Please call.



What's the best way to index an anti-siphon tube?
Make sure that the tip of the anti-siphon tube is as close to the wall of the tank as possible. Also, it is usually best to crimp the tip of the tube in order to reduce the passage of liquid. Here, we use 1/8" OD copper tubing and crimp down, or flatten, the end of the tubing around a .025 piece of wire (a small paper clip will do). Then pull out the wire to leave a .025 air passage into the tube. You may think .025 is too small to get enough air but I can assure you that it is more than enough and it really helps with consistency. My own gun is fed entirely through a .014 air passage. My first and still my favorite semi (now over six years old) gets it's entire air supply through the air passage in a stock Nelspot piercing pin, .010.


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I have read that a remote acts as an expansion chamber, also I have read that you should not place an expansion chamber downstream from a regulator as chilled co2 will warm up and expand an increase PSI. Wouldn't this make the stabilizer less effective if I use it attached right off of the remote?
Personally, I do not advocate the use of an expansion chamber at all. I prefer to use a tank that is filled to about 10-15% less than stated capacity. A slightly larger gaseous area will be had by the use of a remote setup, but the actual effectiveness of it is ambiguous, at best. This is another concept that is very difficult to explain but it boils down to the fact that CO2 requires a certain amount of pressurized gas as a "cap" to keep the liquid in a stable state. All an expansion chamber can really do is provide enough room to compensate for what is needed. The best way that I know to explain the relationship of pressure and volume/capacity is show the static pressures of a tank that contains different amounts of liquid CO2. This example is for a 20 oz. tank at 72 degrees F. ( the numbers shown are approximates but close enough to demonstrate the diminishing pressure curve as it relates to the fill state of the tank)

amount of liquid CO2 in a 20oz tank pressure 21 oz 1150 psi+ 20 oz 950 psi 19 oz 875 psi 17 oz 825 psi 15 oz 815 psi 12 oz 810 psi 6 oz 805 psi 2 oz 800 psi
Note the diminishing pressure variance as the actual volume in the tank is reduced. There is one thing about CO2 that is very consistent and that is change. However, the changes are very consistent and very predictable. The trick to the effective use of CO2 is to be aware of what is going on and to operate within the nature of things.
An Expansion chamber can over expand the CO2 and reduce the saturation of liquid within the gas. So when you fire the ball, the gas has less potential energy when released. Therefore you must use more volume of gas with an expansion chamber. Another problem with expansion chamber is that once they fill up with liquid it's no longer an expansion chamber. Once Co2 is regulated under 600 psi it can no longer remain a liquid. Most remotes have a small hole, so they don't expand the gas too much.
A Stabilizer out performs an expansion chamber simply because it regulates the pressure within the marker. If you can keep the pressure consistent your velocity will be more consistent. Consistency equals accuracy. The Stabilizers also have a 70-1 ratio. So if your input pressure changes 70 psi your regulated output will only change 1 psi. Most other regs only have 30-1 ratio. So in short an expansion chamber is nothing more than a waist of gas.

Last edited by Brassballs; 05-13-2008 at 11:26 PM.
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