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(Occupational Safety and Health) HAIL CANNON HANDBOOK Acetylene This gas forms an explosive mixture over a wide range of mixtures. It is slightly heavier than air, but it normally disperses rapidly. While it produces a little less heat than a similar weight of petrol, it can The threshold of pain is produce very much higher usually reckoned as temperatures when it . - - -- - ---iLo-dBaT-- -- -- ~- -- - -- - -- ourns-w:Ltrl'oxygen,-louc- not with air). The extra power of this cannon compared with some others can be appreciated by noting that the level measured at the same distance from another make of cannon is 134dBa. WARNING - do not allow anyone to spend any extended period of time close to this machine in operation without using full hearing protection. Stay outside the 200 metre safety zone if you must remain in the vicinity for long penods. Code of practice While there is clear evidence that the effect on hearing is negligible outside the safety zone the operation of the unit can still cause annoyance to others who don't share the same incentive to accept the noise. A code of practice has been written. Essentially this requires you to operate the unit only when a hailstorm is approaching, and to give generous advance notice to your neighbours of your intention to test the unit. You should ensure you have a copy posted near the cannon. Acetylene should not be used with piping or fittings made of more than 70% copper, as an explosive compound will form. Use standard acetylene hoses and fittings, and if in doubt seek advice from a qualified expert. Pager Operation The pager units fitted have a three position switch; Off-Silent-Audible. When turned on to Audible from the Off position, the pager sounds a 4 second burst of loud tone indicating it is working. If the battery is flat, it sounds a ~~ries of quieter tones after the initial loud tones. Use this test to prove It the battery needs replacement. Test the operation of the unit by turning the gas off and then dialling the firing number. Confirm MIKE EGGERS LTD. Nelson, New Zealand """>'J::;~;"~.::::;,:;~,;""m': that the valves and ignition systems are all working, then dial the stop number to ensure that it also works. Cannon Test While the whole unit can be tested using the pager system, it is preferable to check the operation of the cannon using the -m-afiUa~ rTrl:ngouttons.- - - - - - The reason we say this is that as a result you get the most effective check, and create the minimum disturbance at the same time. You can see and hear that the valves and ignition are working with the gas off, and you need fire only one or two shots with the gas on to prove the full function. AS for the pager battery, either check the battery regularly, or replace it monthly. Make sure the replacement is a good battery! GAS PRESSURE The multiple cylinder manifold is used to provide enough gas fast enough, because there i"s a limit to how fast acetylene can be released from a bottle without carrying a significant amount of liquid acetone out of the bottle. Acetone adversely affects the operation of the Page 5