Classification and use of respiratory protectors

Dust masks, respirators, respirators, etc., according to the structure and principle of action, can be divided into two categories: filter type and isolation type respirators.

(1) Filter type respiratory protector

It is based on the wearer's own breathing as the power to filter and purify harmful substances in the air. It is suitable for the place where the concentration of harmful substances in the air is not very high and the oxygen content in the air is not less than 18%, there are two kinds of mechanical filtration and chemical filtration.

1. The mechanical filter type is mainly a dust mask for preventing various dust and smoke and other solid harmful substances with large particles. Its filtration and purification rely on the mechanical blocking effect of porous filter material. Can be divided into simple and compound two, simple filter material directly into a mouth and nose mask, simple structure, but the effect is poor, such as general gauze masks. The compound divides inhalation and exhalation into two paths, each controlled by two valves. Good performance filter material can filter out fine dust, good ventilation, small resistance.

2. Chemical filtration is simple with a simple gas mask immersed in the gauze filter mat, as well as the general gas mask, composed of a thin rubber mask, a short leather tube, medicine pot three parts, or directly connected to one or two medicine boxes on the mask, such as some harmful substances do not stimulate the skin or mucous membranes, do not use a mask, Only use a mask (also known as a half mask) with a medicine case attached.

Gas masks (masks) should meet the following hygiene requirements:

(1) The filter toxicity is good, and the type of filter material depends on the nature, concentration and protection time of the poison;

(2) The air tightness of the mask and the exhalation valve is good;

(3) Low respiratory resistance;

(4) Does not hinder the field of vision, light weight.

(2) Isolation (air supply) type respiratory protection device

The air inhaled by such respirators is not purified field air, but is supplied separately. According to its gas supply mode, it can be divided into two categories: built-in type and external input type.

1. The self-contained type is composed of a mask, a short airway, a gas supply regulating valve and a gas supply tank. The gas supply tank should be pressure-resistant and fixed on the worker's back or front chest, and its breathing path should be isolated from the outside world. There are two types of gas supply:

(1) The tank contains compressed oxygen (air) for inhalation, and the exhaled carbon dioxide is removed by the filter material (sodium lime, etc.) in the breathing path, and then recycled for inhalation, such as the commonly used two-hour oxygen respirator (AHG-2 type);

(2) The tank contains peroxides (such as sodium peroxide, potassium peroxide) and a small amount of copper salt as catalysts, and chemical reactions occur between exhaled water vapor and carbon dioxide to produce oxygen for inhalation. This type of protective device can be maintained for 30 minutes to 2 hours, and is mainly used in accidents or close-ventilated and extremely high concentration of harmful substances and anoxic working environment. However, when using peroxide as a gas supply source, attention should be paid to prevent its gas supply tank from leaking and causing accidents.

2. There are two common types of input:

(1) Snake tube mask: consists of a mask and a long snake tube connected to the mask, and the snake tube is fixed on the gas supply regulating valve on the leather belt. The end of the snake tube is connected with an oil-water dust separator, and then the compressed air machine or blower for gas transmission. In winter, an air preheater should be added before the separator. The length of the snake tube with the blower should not exceed 50 meters, and the snake tube with the air compressor can be up to 100-200 meters. Another is to place the end of the snake tube in the air cleaning place, and input air by the user's own inhalation, and the length should not exceed 8 meters;

(2) Air mask and helmet: Air mask is a mask with suction and exhalation channels separate, connected with a short snake tube, the tail of which is connected to the air supply valve on the belt. An air supply helmet is a special head cover that covers the head and extends to the shoulder. One end of a small rubber tube is extended into the helmet to supply air, and the other end is also fixed on the leather belt to supply air. The air required by the air mask and helmet can be supplied by the air pipe installed on the nearby wall through the small rubber tube.