North Texas Dentistry Volume 10 Issue 3 | Page 18

Gas Safety in the Dental Office

safety & compliance by Michael Jones and Jeff Palmer
Medical oxygen and nitrous oxide are safely used every day in dental offices and oral surgery centers , but these gases must be understood and handled correctly to avoid accidents .
Combustion . Both O2 and N2O are oxidizing gases which can support fires and possible explosions under the right conditions . Three factors must exist for a fire to occur : oxidizer , fuel , and ignition . In a compressed oxygen cylinder , pure oxygen gas is the oxidizer , not the fuel – it is not a flammable gas and will not ignite or burn by itself , but it makes materials more flammable and easier to ignite .
Since grease or oil will burn in combination with pure oxygen , all connectors , valves , and regulators must be clean and oil-free . Pipes , fittings , and threads which are exposed to oxygen and have been touched with oily hands must be cleaned .
Exposure . In high concentrations , N 2 O is an oxygen-displacing asphyxiant and misuse or overexposure can be dangerous . If you experience possible side effects of acute nitrous oxide exposure like a headache , cough , or shortness of breath , check your equipment and ventilation system . Reduce secondhand exposure by starting the nitrous oxide gas only after securing the mask to the patient . Turn off nitrous oxide gas flow before turning off the oxygen flow when concluding gas use to reduce post-procedure nitrous oxide exposure to patients . Without exception , dental offices should use equipment like nasal scavenging masks and local exhaust ventilation ( LEV ) to help prevent the concentration of nitrous oxide in the room .
Loss of pressure when the cylinder valve is closed or a hissing sound indicates a leak . OSHA recommends that low-pressure connections be tested for leaks prior to first use of the N2O machine each day and whenever a gas cylinder is changed . Highpressure line connections should be leak-tested quarterly . A soap solution may be used to test for leaks at connections . A portable infrared spectrophotometer can detect hard-to-locate leaks .
Faulty connections . Regulators and cylinder valves for a given gas application are specially designed to match to eliminate incorrect gas connections . Regulators should be fitted directly to the cylinder valve and no other fittings , connections , or lubricants should ever be used to connect a regulator to a gas cylinder valve .
When changing connections , the cylinder valve should be in the off position ( the valve wheel turned tightly in the full clockwise position ). The CGA nut on the regulator is then loosened with a crescent wrench then backed off , being careful not to let the nipple of the CGA connection hit the cylinder or floor which could cause galling and create a leak at the connection point .
Never open a cylinder valve without the regulator connected . Reconnect the regulator to the gas cylinder valve by threading the nut until finger-tight , then tighten a quarter-turn with a crescent wrench to ensure there are no leaks . Then , open the valve counter-clockwise very slowly until the regulator gauge reaches pressure before opening fully .
Pressure . Compressed oxygen filled to 2,400 psig and nitrous oxide filled to 800 psig are considered relatively high-pressure cylinders and must be handled carefully . All compressed gas cylinders should be used with caution due to their highpressure contents . If dropped , a cylinder can become a rocket if the isolation valve is damaged or sheared off .

aClear identification . Identify cylinders by the content shoulder label , not by the color of the cylinder paint . All gas cylinders are also fitted with a barcode by the supplier for tracking purposes that should not be tampered with or removed . The Material Data Safety Sheet for each gas should be readily available and employees should be familiar with the information .

Store safely . Full and empty cylinders should be segregated and empty cylinders should be marked “ EMPTY ”. Use a first-in , first-out inventory system to prevent full containers from being stored for long periods of time . Precautions should be taken to minimize the possibility of theft .
Cylinders should be kept in a dry , well-ventilated area , away from heat , direct sunlight , or electrical sources to prevent possible explosion or fire .
Full and empty cylinders should be secured with wall brackets or chained against a wall . Do not restrain cylinders around the
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