Tired of that white snow shooting from your barrel and that recocking problem as well? What about the continual broken paint because the snow seems to be freezing your balls!!!! Not to worry, help is on its way once you install one of these anti-siphons to your tank valve. Now rather than liquid C02 running through your marker, there's just good clean pressure instead. You can't find a less expensive upgrade that will help your marker deal with C02 better than adding an anti-siphon to your tank. We're going to show you how simple it is to install your own in this article.

NOTE: This modification can be potentially dangerous if not performed properly. If you do not think that you can perform it sufficiently, don't attempt doing it and have a qualified technician perform it for you.

Tools You'll need

The tools you will need for this modification are a vice, strap wrench, 2 open end wrenches that fit the hex size of the compression fitting, heat gun or similar, thick paper clip, needle nose pliers, piece of bicycle tubing or corrugated cardboard, scribe, small wire brush and some red Loctite.

Proceedures

• First you 'must' purge the tank to make sure all of the pressure is released from the tank. A simple way to do this is to drive a flat head nail into a piece of wood and depress the pin of the valve by pressing it on the flat  nail head.
• Screw the purged tank on your marker all the way and make a line on the 12:00 upper center part of the valve. You can use a scribe and  scratch it into the metal. It is a permanent mark then and won't rub off like a marker or similar. This will show you later where the up position of the anti-siphon tube is if you need to know.
• You will now need a vice to grip the valve body with. You will also need a heat gun or hair dryer to heat the Loctite that bonds the valve to the bottle. It is suggested to use a piece of rubber like an inner tube or a couple pieces of corrugated cardboard to wrap around the valve body so not to scratch or mar it.
• Heat the top portion of the bottle where the valve meets the bottle until it's warm enough to break the valve from the bottle. You can normally smell the Loctite softening once it's ready to be done.
• Quickly wrap the piece of rubber around the valve and put the valve in the vice upside down making sure not to clamp the top portion of the bottle. Once this is done put a strap wrench around the bottle and twist it CCW(to the left) to detach the valve from the bottle.
• Once you have separated the two you need to remove all of the old Loctite from the valve and bottle threads. A small wire brush usually does the trick and make sure none of the Loctite gets into the bottle. There should be 2 holes in the sides of the valve body threads. Those need to be cleared as well if there is any Loctite in them. These holes are drilled as a safety precaution to purge the tank in case the bottle is inadvertently unscrewed from the valve while pressurized. Better purged than to fly off like a rocket.
• Remove the allen head disk that holds the spring and pin in from the end of the valve.
• With the spring and pin in place, put a drop of red Loctite(optional) on the correct end of the compression fitting from the anti-siphon kit making sure that it seeps into the threads all around the compression fitting. Screw it into the end of the valve body and tighten it with a wrench. Test the pin to be sure that it depresses easily before going any further. If not loosen it a bit until it feels fairly easy to depress.
• Now it's time to attach the tube to the compression fitting. I prefer a short 3 - 5" tube depending on the size of the tank as shown in the cutaway illustration above. Put the small brass ring that came with the compression fitting on the end of the tube. Insert the ring and tube into the end of the compression fitting. Slide the hex nut retainer on the opposite end of the tube and thread it a little to the compression fitting. Making sure the tube is pushed all the way in, use 2 wrenches and tighten the retainer to the compression fitting body.
• Take the valve and anti-siphon tube assembly and screw it into the ASA of your marker again making sure that the mark you made earlier is in the correct position. Bend the copper tube upward on an arced 90* angle as shown in the illustration. Try screwing it into the bottle. It should be as close to the bottle wall as possible. If you hear it sporadically scraping on the bottle wall as you're turning it, that's where you want to be.
• OPTIONAL: I crimp the end of the tube, as it will let less liquid into the tube. Take a thick paper clip and insert it in the end of the copper tube. Use a pair of needle nose pliers and crimp the end of the tube horizontally to about 1/16" from the end until it stops on the paper clip. Remove the paper clip and there should be about a .75 - 1mm opening in the end of the tube. If there's less, pry it open a little with a small screwdriver or similar. That is enough open area to sufficiently let the high pressure out of the bottle.
• Now that everything is set up properly it's time to attach the valve back to the bottle. If the o-ring on the threaded neck of the valve is deformed, cut or damaged, replace it with one of the exact same size. Put about 2 - 3 drops of red loctite(don't use blue or a lesser strength) and let it seep into the threads. I put it towards the compression fitting end as it will distribute its way up the threads as you screw it on.
• Once you get it hand tightened put it back in the vise and tighten it further with the strap wrench.
• Wait at least 24 hours before you fill the tank so the Loctite has time to cure properly. If you don't the valve may possibly unscrew from the bottle after being pressurized and hurt or even kill you or someone else.
• Now you're ready to enjoy the benifits of using C02 without the liquid getting into your marker or a snowstorm spewing from the barrel. 
• As stated earlier, if you feel you cannot perform this modification in the proper manner, have a professional do it for you. If not properly installed, the results can be potentially dangerous.

Purchase an anti-siphon kit now 

Technical Information