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1. Safety protection when using chemicals
1) Before the experiment, you should understand the toxicity and protective measures of the drugs used.
2) The handling of toxic gases (such as H2S, CI2, Br2, NO2, concentrated HCI and HF, etc.) should be carried out in a fume hood.
3) Vapors of benzene, carbon tetrachloride, ether, nitrobenzene, etc. can cause poisoning. Although they have a special smell, long-term smell will weaken the sense of smell, so they should be used under well-ventilated conditions.
4) Some drugs (such as benzene, organic solvents, mercury, etc.) can enter the human body through the skin, so avoid contact with the skin.
5) Cyanide, knocking salt (HgCI2, Hg(NO3)2, etc.), soluble barium salt (BaCl2), heavy metal salt (such as cadmium, lead salt) and other highly toxic drugs should be stored properly and be especially careful when using.
6) Drinking water and eating in the laboratory are prohibited. Do not bring eating utensils into the laboratory to prevent toxic contamination, and clean your hands before leaving the laboratory and eating.
7) Wear a gas mask when necessary.
When combustible gas mixes with air, when the ratio of the two reaches the explosion limit, it will be induced by a heat source (such as electric spark), which will cause an explosion.
1) When using combustible gas, prevent the gas from escaping, and the indoor ventilation should be good.
2) When handling a large amount of flammable gas, it is strictly forbidden to use an open flame at the same time, and also to prevent the occurrence of electric sparks and other impact sparks.
3) Some drugs, such as aluminum azide, silver acetylene, copper acetylene, perchlorate, peroxide, etc., can easily explode when exposed to shock and heat, so be careful when using them.
4) It is strictly forbidden to put strong oxidants and strong reducing agents together.
5) The peroxide that may be generated in the long-stored ether should be removed before use.
6) For experiments that are easy to bow and explode, explosion-proof measures should be taken.
(3) Fire prevention
1) Many organic solvents such as ether, acetone, ethanol, benzene, etc. are very easy to burn, and there should be no open flames, electric sparks or electrostatic discharge in the room when they are used in large quantities. Do not store too much of these drugs in the laboratory, and they must be recycled and disposed of in time. They must not be poured into the sewer to avoid gathering and causing fire.
2) Some substances, such as phosphorus, sodium, potassium, and electrolytic metal hydrides, are easily oxidized and ignited in the air. There are also some metals such as iron, zinc, aluminum and other powders, which have a larger surface area and are easy to oxidize and ignite in the air. These substances should be kept in isolation from the air, and special care should be taken when using them. If the laboratory is panicking, it should extinguish the fire according to the situation. Commonly used fire extinguishing agents are: water, sand, carbon dioxide fire extinguishers, carbon tetrachloride fire extinguishers, foam fire extinguishers and dry powder fire extinguishers. It can be used according to the cause of the fire. The following situations cannot be used to extinguish the fire with water:
(a) Metal sodium, potassium, magnesium, aluminum powder, calcium carbide, and sodium peroxide are on fire. Use dry sand to extinguish the fire.
(b) Inflammable liquids that are lighter than water, such as gasoline, stupid, acetone, etc., can catch fire. Foam fire extinguishers can be used.
(c) When there is a fire in a place with burning metal or molten material, use dry sand or dry powder fire extinguisher.
(d) If the electrical equipment or live system is on fire, carbon dioxide fire extinguisher or carbon tetrachloride fire extinguisher can be used.
Strong acids, strong bases, strong oxidizers, bromine, phosphorus, sodium, potassium, phenol, glacial acetic acid, etc. will corrode the skin, especially prevent splashing into the eyes. Low temperature such as liquid oxygen and liquid nitrogen can also severely burn the skin, so be careful when using it. In case of burns, they should be treated promptly.
2. The use and precautions of high pressure cylinders
(1) Use of gas cylinders
1) Install a matching pressure reducing valve on the cylinder. Check whether the pressure reducing valve is closed tightly by turning the pressure regulating handle counterclockwise until the screw is loose.
2) Open the main valve of the cylinder, and the high pressure gauge shows the total pressure of the gas stored in the cylinder.
3) Slowly turn the pressure regulating handle clockwise until the low pressure gauge shows the pressure required for the experiment.
4) When stopping use, first close the main valve, and then close the pressure reducing valve after the remaining air in the pressure reducing valve has escaped.
(2) Matters needing attention
1) Cylinders should be stored in a cool, dry place away from heat sources. Flammable gas cylinders should be stored separately from oxygen cylinders.
2) Carrying steel cylinders should be handled with care, and the cylinder caps should be screwed on.
3) Pressure reducing valve and pressure gauge should be installed when using. Flammable gas cylinders (such as H2, C2H2) gas i] screws are reverse wire; non-flammable or combustible gas cylinders (such as N2, 02) are positive wire. Generally, various pressure gauges cannot be mixed.
4) Do not let oil or flammable organic matter contaminate the cylinder (especially = cylinder outlet and pressure gauge).
5) When opening the main valve, do not direct your head or body to the main valve to prevent the valve or pressure gauge from rushing out and hurting people.
6) Do not use up the gas in the cylinder to prevent danger when refilling.
7) Cylinders in use should be checked every three years, and steel cylinders containing corrosive gas should be checked every two years. Unqualified gas cylinders cannot be used.
8) The hydrogen cylinder should be placed in a special room far away from the laboratory, introduced into the laboratory with a copper tube, and equipped with a device to prevent backfire.