The storage of chemical reagents should not only keep the reagents well to avoid deterioration or loss, but also pay attention to the toxic effect of dangerous reagents to prevent the occurrence of accidents such as fire, poisoning, damage and radioactive pollution. General measures for reagent storage are as follows:
• Airtight
The container containing the reagent is separated from the environment that can make it deteriorate as far as possible, that is, sealed containers are used, such as tightly closed iron barrels, closed metal containers and tightly closed glass bottles with a capacity of not more than 1 liter. Closed storage is suitable for reagents with volatilization, sublimation, delixing, weathering, crystallization, hydrolysis, oxidation, reduction, mildew and other properties, and is the most commonly used method for storing reagents.
Ground glass stopper (suitable for nitric acid, hydrochloric acid, sulfuric acid and liquid bromine, etc.) or screw cap with plastic liner. In order to make the sealing tight, the preparation method of the rubber sleeve can be used: pour the mixture of the rubber sleeve (nitrocellulose: glue: castor oil: ether: ethanol = 13:0.5:36:50) into the bottle stopper mold, and form a film after a few seconds. Take off the film while it is not dry, soak it in 75% ethanol and set aside. When sealing, put the appropriate rubber on the already good bottle stopper, and after it shrinks, the bottle can be sealed. For the reagent that is easy to decompose and produce gas, it must not be sealed, otherwise it is easy to explode, such as hydrogen peroxide, ammonium carbonate, etc.
Active metals or non-metals that can interact with air should be stored in liquids or inert gases that are relatively stable to reagents, such as sodium and potassium that can be immersed in kerosene, and white phosphorus that can be immersed in water.
• Light protection
To avoid the radiation of light, the reagent should be in brown glass bottles, wrapped in black paper, and stored in a dark room or a light-shielded reagent cabinet. Dark storage is suitable for photochemical reaction reagents, such as amines, phenols, aldehydes and so on.
• Low temperature
Keep the reagent at a low enough temperature. It is stored in water tank. Low temperature storage is suitable for biochemical reagents that are easily lost and substances that are easily decomposed. For example, standard serum should be stored in a water tank at ± 4 ℃, while carboxypeptidase B and carboxypeptidase Y should be stored in a low temperature water tank at -20 ℃. Common reagents should be stored in a cool place with low temperature.
• Ventilation
Even if the reagent container is sealed, it is inevitable that there will be accidental leakage phenomenon, in order to prevent the formation of explosive mixed gas or toxic vapor storage, large flammable liquid and toxic liquid reagent storage room should be installed exhaust device to keep the storage room air clean.
• Isolation
It refers to the classification and storage of reagents to avoid leakage and fire interaction resulting in greater accidents. All kinds of reagents should be identified according to their nature after the category, can enter the class warehouse.
• Fire prevention
In order to avoid the burning and explosion of reagents, inflammable and explosive reagents should be fireproof storage measures. In addition to the above ventilation and storage, fireproof storage needs to meet the following conditions:
Fire-proof building Flammable and explosive reagent storage building, should use light non-combustible building materials, steel frame structure. The walls of the building should use a hollow firewall, and must have a fire resistance of 3-4 hours. The floor and ceiling of the building must be resistant to fire. Room temperature should not exceed 30 ℃, doors and Windows should be opened outwards. There are multi-storey (building) storage buildings, flammable liquids are best stored in the lowest level of the storage room, and the floor must not leak, and need to have drainage devices. Because the basement is difficult to drain or ventilate, the basement is not suitable as a storage room for flammable liquids.
Flammable and explosive reagents should be stored at a certain safe distance from the surrounding buildings, traffic arteries, and power transmission line friction. The distance between the single-storey flammable liquid storage building and the main building should be at least 150 meters. When the storage capacity is large, the fire spacing shall be agreed by the fire department.
The most common causes of accidents are open flames, electrical equipment, overheating, hot surfaces, spontaneous combustion, sparks and embers, static electricity, friction and impact. Corresponding measures must be taken to eliminate the above hidden dangers.
Open flame refers to electric arc, oxyacetylene flame, various combustion flame and electric furnace, drying oven, oven is working in the electric wire. These must be isolated from the flammable and explosive reagent storage room. Oil lamps, candles and other open flame lighting are prohibited in the room where flammable and explosive reagents are stored. It is not allowed to bring tinder, inflammable materials and iron objects that easily cause sparks into the storage room. It shall not be carried out in the storage room of inflammable and explosive reagents in buckets, packaging, welding and sealing; Smoking is strictly prohibited in flammable and explosive reagent storage rooms.
The explosion-proof electrical equipment in the storage room shall be inspected by the power company before it can be installed and used and inspected regularly. The lightning rod in the warehouse should be checked frequently, and the grounding resistance of the lightning rod should be less than 10 euros.
Reagent storage room should be set up effective fire and alarm equipment, in case of fire, timely extinguish or alarm signals. The storage room of flammable and explosive reagents shall be equipped with automatic water sprayer and special fire extinguisher.
Automatic water spray is a basic fire equipment for flammable and explosive reagents (except for potassium, sodium, calcium, calcium carbonate, sodium peroxide and other reagents that are burned in water), and should be installed on the ceiling, and where water police are prone to occur. The automatic water sprinkler can extinguish the fire of flammable liquid with flash point above 66 ° C, and the cooling effect of the water spray can make the general fuel temperature as low as below the ignition point, so it can effectively prevent serious damage to buildings and equipment.
The foam emitted by the foam extinguisher can cover the surface of the flammable liquid for a short time, which can isolate the flammable material from the air and contact. However, foam extinguishers cannot be used for carbon disulfide, certain ethers, and other very volatile liquids because their vapors can diffuse through the foam covering and burn on it.
Carbon dioxide fire extinguishers can be used for water and other fire extinguishers, such as water can burn reagents fire. However, due to the limited amount of carbon dioxide, it can not last for a long time, so the use of strict requirements.
Dry chemical fire extinguishers can also be used for the fire of combustible reagents, such as the fire of reagents that are burned by water. However, due to the limited amount of carbon dioxide, it can not last for a long time, so the use of strict requirements.
Dry chemical fire extinguishers can also be used for fire alarms of combustible reagents. Ventilation equipment will cause flame spread or dry powder blowing, so the ventilation equipment should be turned off when in use.
Portable fire extinguishers (foam, carbon dioxide, dry chemicals) should be placed in a place that is easily accessible in case of fire. Small fire engines with spray nozzles are also recommended, especially for fires with flammable liquids that can be extinguished by water mist. Fire hydrants should be located in such a way that they are not more than 100 metres away from any part of the storage building.
• Anti-poisoning
In order to avoid the occurrence of poisoning accidents in reagent storage room, measures should be taken to store toxic and damaging reagents. In addition to the above-mentioned sealing, ventilation, storage and fire prevention measures, anti-toxic storage needs to meet the following requirements:
Use personal protective equipment in emergency situations and when performing hazardous work (such as dealing with spills, dumping, and fire alarms). Wear safety goggles and face mask when pouring acid and sputtering and working. Cup goggles protect the eyes from fine particles flying in from the side. Wearing a mask that securely protects your head, face and neck is even safer. Wear rubber gloves when handling corrosive reagents. Gas masks can be worn in emergency rescue work. Gas masks with canisters should not be used in areas where there is a lack of oxygen or where the concentration of toxic gases and vapors is very high, and should generally only be used for 15 or 30 minutes. The mask should fit securely to the face, and even then you should always be on the lookout for leaking symptoms. A gas mask with a regenerator (which removes carbon dioxide and adds oxygen) can be used for 2 hours. This kind of gas mask and master the use of gas masks require more training time than those with filter canisters. The cleaning and disinfection methods of the gas mask are described as follows: disassembly the respirator, clean the mask and breathing tube in 49 ℃ liquid detergent solution, rinse with warm water, and then soak in any of the following solutions for 2 minutes: (1) Hypochlorite solution containing 50ppm chlorine (diluted with 5% chlorine hypochlorite solution)