Before commencing any experimental work with either flame(emission) photometer or an atomic absorption spectrophotometer, the following guidelines on safety practices should be studied. These following steps are recommendations
1. Ensure that the laboratory in which the apparatus is housed is well ventilated and is provided with an adequate exhaust system having air-tight joints on the discharge side; some organic solvents, especially those containing chlorine give toxic products in a flame.
2. Gas cylinder must be fastened securely in an adequately ventilated room well away from any heat or ignition sources. The cylinders must be clearly marked so that the contents can be immediately identified.
3. When the equipment is turned off, close the fuel gas cylinder valve tightly and bleed the gas line to the atmosphere via the exhaust system.
4. The piping which carries the gases from cylinders must be securely fixed in such a position that it is unlikely to suffer damage.
5. Make periodic checks for leaks by applying soap soluion to joints and seals.
6. The following special precautions should be observed with acetylene.
(a) Never run acetylene gas at a pressure higher than 15 psi; at higher pressures acetylene can be explode spontaneously.
(b) Avoid the use of copper tubing. Use tubing made from brass containing less than 65% Copper, from galvanised iron or from any other material that does not react with acetylene.
(c) Avoid contact between gaseous acetylene and silver, mercury or chlorine.
(d) Never run an acetylene cylinder after the pressure has dropped to 50 psi; at lower pressures the gas will be contaminated with acetone.
7. A nitrrous oxide cylinder should not be used after the regulator gauge has dropped to a reading of 100 psi.
8. A burner which utilises a mixture of fuel and oxidant gases and which is attached to a aste vessel (liquid trap) should be provided with a U- shaped connection between the trap and the burner chamber. The head of liquid in the connecing tube should be greater than the operating pressure of the burner; if this is not achieved, mixtures of fuel and oxidant gas may be vented to the atmosphere and form an explosive mixture. The trap should be made of a material that will not shatter in the event of an explosive flash-back in the burner chamber.
9. Care must be exercised hen using volatile flammable organic solvents for aspiration into the flame. A container fitter with a cover which is provided with a small hole for the sample capillary is recommended.
10. Never view the flame or hollow cathode lamps directly; protective eye wear should always be worn. Safety specacles will usually provide adequate protection from ultraviolet light, and will also provide protection for the eyes in the event of the apparatus being shattered by an explosion.
11. Never leave a flame unattended.
