Fill Whip Information Page

When you receive your fill whip kit, all connections will be made, parts oxygen cleaned, threads Teflon taped, and tightened for you, occasionally these connections may develop small leaks. If this occurs, simply use the proper size wrench and tighten the pieces on either side of the leak. You may also unthread and re-tape and tighten the connection. The needle valve on the oxygen fill has a small nut just below the knob. This will occasionally leak also and will just require tightening, do not attempt to do this while the whip is under pressure. Possession of this device does not automatically qualify a person to blend or transfer gas. I highly recommend a gas blending class from a scuba training agency taught by a qualified experienced instructor. This whip should also be occasionally cleaned internally by a non toxic degreaser, such as Simple Green or other similar cleaner and then rinsed with hot water and blown dry with a dry inert gas (nitrogen, argon, Helium or grade E scuba air. One should NEVER use a shop air compressor to dry off anything that is purported to be oxygen clean. This cleaning should be done annually at least.

If you have received a kit with the PSI Tronix digital pressure gauge, the PSI button on the front of the gauge is the power button. The unit turns itself off after a few minutes to conserve the battery. When turned on the display flashes for a few seconds, if one holds the PSI button while the unit is flashing it will temporarily rezero, do not use this feature to zero your gauge, instead, if the gauge is off of zero by more than 15psi, uncap the small screw to the left of the PSI button (labeled Z) and using a small flat tip screwdriver, turn the adjustment until the display reads 000. The screw cap to the right of the PSI button is used for full scale calibration of the unit and should not be touched except by a qualified calibration lab. For our gas blending purposes this gauge is plenty accurate if used for the entire blending process. Don’t switch gauges during blending or trust the SPG on your scuba unit to give you accurate pressures. The maximum inlet pressure of the digital PG is 5000 psi. All internally wetted parts are stainless steel. Blending is a skill acquired though instruction and practice, with proper amounts of each you can nail your gas percentages within .2% every time.

The key word to remember when transfilling high pressure gasses and especially oxygen is SLOWLY. Oxygen should never be filled to a point where the cylinder being filled becomes warm, the fill should be kept to less than 60 psi per minute and the origination of the fill should be started with extreme care. The gas molecules coming from the supply cylinder are moving at close to the speed of sound and every thing they impact they transfer heat to. This is called adiabatic heating and it is providing one side of the combustion triangle. Another side is fuel and we clean internally all parts that are exposed to high pressure oxygen to lessen the amount of fuel present. Fuel can be just about anything with oxygen under pressure, a small burr in the valve or line, leftover hydrocarbons from poor cleaning or other things that are normally not considered flammable become fuel in the presence of high pressure oxygen. So, by filling slowly, we can limit a part of the triangle, heat. The other third of the triangle is oxygen, hard to eliminate that when it’s the product we are transfilling. Remember this, you can light up just about anything, no matter how clean, with poor technique, and you can almost always stay safe, even if there is dirt in your whip, valve or tank, with good technique. So the verdict is…good technique!!

When you are blending gas, its very important to keep a logbook of what you are doing and have done. Pick your mix, do the math, write it down and after each step in the process, write down where you are in the process, this will make it easy to pick up where you left off if you leave and come back. Its important to let the tank cool between gas fills and top offs, keeping a record of what you are doing can prevent mistakes that could cost you a missed dive or worse, your life. Keep your blending area clean, clear, and free of distractions. Animals, kids or buddies who want to chat and are not part of the blending process can cause distractions that lead to mistakes. Likewise alcohol has no place when handling high pressure gasses. Miller time is after all blending is done.

I do not recommend blending at home and then duping some shop into topping off for you. The guy running the compressor may think he is only topping off an air fill. It is common practice for some shops to do hot fills of scuba air bringing the temp of the mix up to unsafe levels for HP oxygen. Be up front with your shop, let them know what you are doing and that you need a slower fill to be more accurate with your mix and to be safer. If you have your blending training and credentials this should be no problem, don’t have em?...GET THEM! You don’t want to be the guy who has to explain to the fire dept why your tank exploded and started a fire in the compressor room. An oxygen backed fire is something that no one ever wants to see.

Analyze your mix!!! This is important. Analyze your mix!!! When you are done blending, let the mix set for a bit, and put an oxygen analyzer on it to confirm that you did everything right. I have seen mixtures change as much as 10% by sitting for an hour. You can purchase an oxygen analyzer from just about any scuba shop, or online at www.oxycheq.com. I recommend Oxycheq, it is a great supply for oxygen and helium analyzers and technical diving equipment. Mark your mix with the contents, date and final pressure, duct tape and a magic marker work just fine. Write this information in your blending log too. Reconfirm your mixes just before diving with them, mistakes happen, they don’t have to be final.

After reading this, you may feel a bit overwhelmed when you are about to open that oxygen tank valve for your first blend. GOOD, this is the attitude you should have every time you get this fill whip out of its case. Please be safe.