Chemical laboratory-fire extinguishing equipment and fire-fighting facilities (1)

When working in a chemical laboratory, the first thing to know should be where, what types of fire extinguishing equipment are there, and how to use them.

1.

Fires can be divided into five categories: A, B, C, D, and E based on the burning characteristics of the material.

Class B fire: refers to liquid fires and meltable solid material fires, such as the fires of organic solvents, organic reagents and reaction liquids in the laboratory

Class C fire: refers to the fire of hydrogen and other gases

Class D fire: refers to metal fires, such as potassium, sodium, magnesium, and aluminum-magnesium alloy fires

Class E fire: refers to fires involving live objects and precision instruments

2.

Ancient fire extinguishers were relatively simple, and hand-pressing water guns were the most commonly used building fire extinguishing equipment

There are many types of modern fire extinguishing supplies, in addition to high-pressure water guns, they also include fire blankets and various fire extinguishers

Commonly used fire extinguishers in chemical laboratories include yellow sand, fire blankets, carbon dioxide fire extinguishers and dry powder fire extinguishers

(1) Yellow sand

For many small fires, dry yellow sand is a good fire fighting product

(2) Fire blanket

Fire blanket is also known as fire, extinguishing the fire escape blanket, fire blankets, fire blankets, blanket to escape

The fire blanket is very easy to cover or wrap the uneven surface of the object, forming an effective outer protective layer, blocking the air supply by covering the fire source to block the flow of air, so that the combustion cannot continue, and achieve the purpose of extinguishing fire

(1) It can be reused without damage

(2) There is no expiration date
.

(3) There will be no secondary pollution after use
.

(4) Insulation and high temperature resistance (depending on the material, generally 550～1100℃)
.

(5) It is easy to carry, can be large or small, can be folded on the countertop or drawer, can also be hung on the wall of a fire-prone part such as in a fume hood [Figure 10-1(b)], does not occupy a large area or Space can be used conveniently and quickly
.

(6) It can be used as a protective article for timely escape, as long as the blanket is wrapped around the whole body, because the blanket itself has the characteristics of fire prevention and heat insulation, the human body can be well protected during the escape process
.

(3) Fire extinguisher

There are many types of fire extinguishers, and chemical laboratories generally reserve carbon dioxide fire extinguishers and dry powder fire extinguishers
.

1.
Carbon dioxide fire extinguisher

Carbon dioxide fire extinguishers have more than one hundred years of application history, mainly relying on suffocation and partial cooling to extinguish fires
.
Carbon dioxide has a higher density, about 1.
5 times that of air
.
Under normal pressure, liquid carbon dioxide will immediately vaporize, generally 1kg of liquid carbon dioxide can produce about 0.
51m of gas
.
When extinguishing a fire, carbon dioxide gas can dilute and remove air, surround the surface of the burning object or distribute it in a relatively closed space, reduce the oxygen concentration around the combustible or in the protective space, and produce suffocation to extinguish the fire
.
In addition, when carbon dioxide is sprayed out of the storage container, it will quickly vaporize from the liquid into a gas, absorbing some heat from the surroundings, and cooling it down
.

Carbon dioxide fire extinguishers are suitable for extinguishing class B fires (such as fires caused by organic solvents, organic reagents, and reaction liquids), class C flammable gas fires, and fires caused by electric burning of class E objects (such as initial fires of equipment)
.

1) Portable

Quickly disassemble and remove the parts according to the operating sequence: pull out the lead seal (or key) → pull out the metal wire (or nylon wire) → pull out the safety plug (metal plug)
.
Then grab the handle with your right hand and lift the fire extinguisher.
Use your left hand to aim the nozzle of the nozzle at the bottom of the flame and then hold the bottom of the bottle.
Press the handle with your right hand to spray the fire extinguishing agent
.
It can be far and near, but the best extinguishing distance is 1.
2~1.
5m.
Too far does not have the effect of extinguishing fire.
Too close is dangerous to people.
The fire must be extinguished at one time without stopping in the middle
.
Follow the decomposition sequence of 1→2→3→4→5 in Figure 10-2(a)
.

Figure 10-2 Operation of portable carbon dioxide fire extinguisher

Generally, the effective spraying and extinguishing time of a 3kg small portable fire extinguisher is less than 10s, so it cannot be counted on to extinguish large-area or large-scale fires
.

2) Cart type

Cart-type carbon dioxide fire extinguishers are more suitable for larger fires in organic synthesis laboratories, as shown in Figure 10-3
.

When in use, the nozzle of the nozzle is aimed at the flame 2m away, and the main valve is turned on.
The nozzle of the nozzle will emit carbon dioxide gas.
The user should gradually approach the combustion zone.
As the effective spray distance is shortened, the fire will be extinguished in one breath.

.
The carbon dioxide in the cart-type fire extinguisher is generally 24kg, and the fire in the fume hood is usually shown in Figure 10-3.
The cart-type carbon dioxide fire extinguisher can be solved at one time
.

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