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High Pressure Safety Code
(Preview)
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Due to the higher gassing pressures that can be obtained by Co2, the following usage and safety information is provided as a general guideline. Each rocketeer should be familiar with the flight safety code and all applicable safety codes related to the type of pressurization system they deploy.
Pressurization System:
Use, storage, and transportation of compressed air tanks and other gas cylinders should be according to all applicable safety codes.
Pressurization System – Function:
The system in use should allow the rocket to be pressurized, depressurized (if necessary) and launched from a safe distance as described in the IWRA Safety Code. If the rocket does not launch when triggered, DO NOT allow anyone to approach it until the rocket has been depressurized.
Pressurization System – Hoses and Hardware:
All hoses and fittings must be rated at or above the intended launch pressure. Hardware should be rated for the type of gas being used. See Pressurization System - Solutions for Common Co2 Problems for additional pressurization system add-on accessories.
Pressurization System - Tank Safety:
If the tank is larger then 9 ounces, it will need to be hydro tested periodically. Hydro testing ensures the integrity of the tank and that the tank can still be filled. However, this service is reasonably expensive and it may be more economical to simply replace the tank. Do not try to fill or use any tank that may be damaged, including deep scratches and gauges. Pay special attention when disconnecting the tank that the valve (Brass Part) does not unscrew from the tank body (Black Part). If this happens "STOP IMMEDIATELY". Unscrewing a pressurized tank from the valve can create, essentially, a small missile.
Pressurization System - Tank Maintenance:
Inspect tank and pressurization system for worn parts. Replace tank o-ring as soon as any damage is noticed. Frayed rubber, cracks, or warping. Lightly oil (Gun Oil) the o-ring as basic maintenance. Protect the tank threads with a thread-saver cap. Never place tank next to a heat source due to Co2 can expand in the tank when exposed to heat.
Pressurization System - Tank Filling:
Co2 tank size is referred to by the amount of Co2 (the combination of liquid and air) that the tank is designed to hold. When filling the tank the entire contents of the tank needs to be dumped so that the tank is chilled and then filled. Co2 is a liquid. Liquid Co2 needs enough space and heat to expand into a gas, so it is important to not "overfill" a Co2 tank. Caution: Never fill any Co2 tank by time or guess - a accurate scale must be used to insure a safe fill.
Use an "fill station" designed for Co2 only. The station is a combination of hoses and valves. Make sure it consists of a bleed valve, a fill valve, and a pin depressor. The bulk tank needs to be located at a permanent location and secured to the wall. A "siphon tube or dip tube" should be installed.
Pressurization Co2 Tank-Filling Procedure:
• The fill station should already be attached to the bulk Co2 tank.
• Screw the pressurization Co2 tank into the fill adapter.
• Bleed the pressurization Co2 tank until it is empty. This procedure chills the tank and make it easier to fill. Unchilled tanks that are all ready empty will only be filled between 25% and 35% full.
• If the tank is completely empty, fill tank with 1 to 3 ounces of Co2 depending on the size of the tank. Then bleed the entire contents before filling.
• Attach the pressurization Co2 tank to the fill adapter. Make sure it is tight.
• Weigh the pressurization Co2 tank before opening the valve on the bulk tank.
• Make sure the "Bleed" valve is closed.
• While watching the scale with the pressurization Co2 tank attached, open the valve to the bulk tank.
• Fill the pressurization Co2 tank under it's rating by about 10% to 20%. As the tank warms, the gas will expand to the proper levels.
• Turn off the main valve on the bulk tank. Do not take off the pressurization Co2 tank.
• Unscrew the fill adapter until you feel the resistance decrease then stop twisting.
• Open the bleed valve to relieve the pressure that is still in the air line between the bulk tank and the pressurization Co2 tank.
• Finish unscrewing the pressurization Co2 tank.
Pressurization System – Co2 Notes:
Rapid pressurization of the water rocket pressure chamber can cause the temperature in the Co2 tank to drastically drop which produces less pressure. Lower tank temperatures can cause damage to pressurization system parts by sucking in liquid Co2. When liquid Co2 enters system parts the sub-zero temperature can "freeze up" and break O-rings, seals and other internal mechanics.
Pressurization System - Solutions for Common Co2 Problems:
Several add-on accessories can be added to the pressurization system to minimize the occurrence of liquid Co2 'freezing up' as well as hardware to stabilize the pressure.
Anti-siphon valve is a tube that is placed inside a Co2 tank to prevent liquid Co2 from entering pressurization system.
An expansion chamber "X chamber" attaches to the Co2 tank and the pressurization system to prevent liquid from entering the pressurization system and stabilize the air pressure.
A regulator controls the gas pressure that is released from the tank to ensure that a more consistent air pressure is fed to the pressurization system.
International Water Rocket Association © Copyright 2007
All Rights Reserved.
Updated: December 03, 2007
