Laboratory safety measures

Chemical laboratories are the key units of firefighting and are places where accidents can easily occur. Safety is always the top priority. The reasons for accidents in chemical experiments are subjectively two-fold: First, there is not a strong sense of safety, and one is that they do not understand or know little about the situation of chemical laboratories.

The so-called safety mainly refers to the "three defenses", that is, preventing poisoning, preventing explosions and burning, and preventing corrosion, chemical burning, burns and cuts.

1. Antivirus

Most chemicals have varying degrees of toxicity. Toxic chemicals can cause poisoning through the respiratory tract, digestive tract and skin into the body. If HF invades the human body, it will damage the teeth, bones, hematopoietic and nervous system; hydrocarbons, alcohols, ethers and other organic substances have different levels of anesthetic effects on the human body; arsenic trioxide, cyanide, chlorinated high mercury, etc. are highly toxic, inhaling small amounts Will die.

Anti-virus precautions

Before the experiment, the toxicity, performance and protective measures of the used drugs should be known; the use of toxic gases (such as H2S, Cl2, Br2, NO2, HCl, HF) should be performed in a fume hood; benzene, carbon tetrachloride, ethyl ether, nitro Benzene and other steam often prolonged absorption will reduce the sense of smell and must be highly vigilant; Organic solvents can penetrate the skin into the body, should avoid direct contact with the skin; highly toxic drugs such as mercury salts, cadmium salts, lead salts, etc. should be properly kept; experiment The operation should be standardized and leave the laboratory to wash hands.

2. Fire prevention

Prevent gas pipes and gas lamps from leaking. After using the gas, you must close the valve.

Organic solvents such as ether, alcohol, acetone, carbon disulfide, benzene, etc. are flammable. The laboratory must not store too much and must not be poured into the sewers to avoid agglomeration and fire.

Metal sodium, potassium, aluminum powder, calcium carbide, yellow phosphorus and metal hydride should be used and stored carefully, especially not in direct contact with water;

In case of fire, you should calmly judge the situation and take appropriate measures to extinguish the fire; According to different situations, use water, sand, foam, CO2 or CCl4 fire extinguisher to extinguish the fire.

3 explosion-proof

The explosion of chemical products can be divided into branch explosions and thermal explosions. Hydrogen, ethylene, acetylene, benzene, ethanol, ethyl ether, acetone, ethyl acetate, carbon monoxide, water gas, ammonia, etc. Combustible gases mixed with air to the explosive limit, once there is a heat source Induced, prone to branch explosions;

Peroxides, perchlorates, lead azide, copper acetylide, trinitrotoluene, and other explosive substances may be thermally exploded by shock or heat.

Explosion-proof measures

For the prevention of branch-chain explosions, it is mainly to prevent flammable gases or vapors from being dissipated in indoor air and maintain good indoor ventilation. When using flammable gas in large quantities, use of open flames and appliances that may generate sparks should be strictly prohibited;

For the prevention of thermal explosion, strong oxidants and strong reducing agents must be stored separately, and be handled gently and away from heat sources.

4. Prevent burns

In addition to high temperatures, liquid nitrogen, strong acids, strong bases, strong oxidants, bromine, phosphorus, sodium, potassium, phenol, acetic acid and other substances can cause skin burns; care should be taken not to contact the skin, especially to prevent splashing in the eyes.

• Mercury is a commonly used substance in chemical laboratories. It is highly toxic and does not easily enter the body and forms cumulative poisoning.

• High mercury salts (such as HgCl2) 0.1-0.3 g can cause death;

• The vapor pressure of mercury at room temperature is 0.0012 mmHg, which is 100 times greater than the safe concentration standard.

• Operating regulations for the safe use of mercury:

(1) Mercury cannot be directly exposed to air and should be covered with water or other liquids

(2) Any remaining amount of mercury cannot be poured into the sink;

(3) The mercury storage vessel must be a solid, thick-walled vessel, and the vessel should be placed on a porcelain plate;

(4) Containers containing mercury should be kept away from heat sources;

(5) In the event that mercury is dropped on the ground, in a countertop or in a sink, mercury beads should be collected by suction pipes as much as possible, and then a metal strip (Zn, Cu, Sn, etc.) capable of forming an amalgam should be used to sweep the mercury several times. Over, finally covered with sulfur powder;

(6) The laboratory should be well-ventilated; there should be wounds on the hand and do not contact with mercury.

5. Safe use of electricity

• Personal safety protection

• Frequently used in laboratories is 50 Hz, 200 V AC. When the human body passes a current of 1 mA, it has the sensation of tingling or acupuncture. The muscles of humans above 10 mA will strongly contract. If the breathing is difficult above 25 mA, there is a danger of life; DC also has similar danger to the human body.

• To prevent electric shock, do:

(1) When repairing or installing electrical appliances, the power should be cut off first;

(2) When using electrical appliances, keep hands dry;

(3) The exposed part of the power supply should be insulated, and the electrical enclosure should be grounded;

(4) The test pencil cannot be used to test high voltage;

(5) Do not use both hands to touch the appliance at the same time to prevent the current from passing through the heart when an electric shock is applied.

(6) Once someone has electric shock, cut off the power first and then rescue.

Safety of equipment and equipment

• All instruments should be fitted with appropriate power supplies in accordance with the instructions; grounding must be grounded;

• If it is a DC electrical device, pay attention to the positive and negative polarity of the power supply, and do not connect the wrong one.

• If the power supply is three-phase, then the neutral point of the three-phase power supply should be grounded, so that the contact voltage can be reduced in case of electric shock; when connecting the three-phase motor, it is necessary to pay attention to whether the forward rotation direction is in compliance; otherwise, it is necessary to cut off the power supply and the phase adjustment line. ;

• When connecting, pay attention to the connection, and select the appropriate connection wire according to the rated current of the appliance.

• After the circuit is connected, it should be carefully checked before it can be powered on.

• Switch off the power in a timely manner if the instrument fails.

Use of radiation source instrument safety protection

• Radiation from chemical laboratories, mainly X-rays, undergoes repeated exposure to X-rays over a long period of time. This can lead to fatigue, memory loss, headaches, and a decrease in white blood cells.

The method of protection is to avoid direct X-ray irradiation on all parts of the body (especially the head). When shielding and shrinking are required during operation, the shield is often made of lead, lead glass, etc.

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