1. Basic components

　　

Face mask: The face mask is a positive pressure type face mask with a tight fitting single eye window, large field of view, and double-layer annular sealing. The mouth and nose mask inside the mask reduces the actual harmful space of the mask. The mouth and nose mask is equipped with an inhalation valve, and fresh air from the supply valve is inhaled by the wearer through the inhalation valve of the mouth and nose mask. The exhalation valve is installed on the base of the mask, and the gas exhaled by the wearer is discharged into the atmosphere through a positive pressure exhalation valve. The supply valve is equipped with an automatic opening switch. When the gas cylinder switch is turned on, compressed air enters the supply valve through the pressure reducer and medium pressure conduit. At this time, the automatic opening switch should be placed in the closed position, and the supply valve has no air output. When the wearer takes 2 to 3 deep breaths, the automatic switch opens and the supply valve outputs air. During use, regardless of inhalation or exhalation, the supply valve ensures that the pressure inside the mask is always higher than the external atmospheric pressure.

　　

Conduits and valves:

　　

A、 Pressure reducing valve: reduces the high-pressure air from the inflation bottle to 0.4-0.9 megapascals. The pressure reducing valve is also equipped with a safety valve and a high-pressure conduit. The input end of the pressure reducing valve is connected to the cylinder valve of the gas storage cylinder;

　　

B、 Medium pressure conduit: composed of pressure resistant rubber hoses with joints at both ends, one end connected to a pressure regulator and the other end connected to a supply valve;

　　

C、 Pressure gauge: used to indicate the pressure of compressed air inside the gas storage cylinder. The pressure gauge is connected to the pressure chamber of the high-pressure conduit and pressure reducer, and the range of the pressure gauge is 0-40 megapascals;

　　

D、 Low pressure alarm: installed on the wearer's chest, connected to the high-pressure chamber of the pressure reducer through a high-pressure conduit. When the pressure of the compressed air in the gas cylinder drops to 4-6 megapascals, the low pressure alarm will sound and can only be used for 5-8 minutes after the alarm.

　　

E、 Quick connector: It can quickly connect and disassemble medium pressure conduits.

　　

High pressure gas cylinder: Currently, all gas cylinders are made of carbon fiber composite materials, with a maximum working pressure of 30 megapascals. The cylinder valve rotates counterclockwise to open and counterclockwise to close. When in use, the cylinder valve should be opened to the maximum position to ensure sufficient gas supply.

　　

Backpack and Strap: The gas cylinder is fixed on the backpack, and the shoulder strap and belt form the strap. The shoulder strap and belt can be adjusted according to the wearer's requirements.

　　

　　2. Working process of positive pressure air respirator

　　

The high-pressure air stored in the high-pressure gas cylinder is depressurized by the pressure reducer and enters the medium pressure chamber. The medium pressure air enters the gas supply valve through the medium pressure conduit, and the gas supply valve provides breathing gas in response to the user's breathing requirements. When inhaling, under negative pressure, the air supply valve injects fresh air into the human lungs at a certain flow rate; When exhaling, the gas supply valve stops supplying gas, and the exhaled gas is discharged through the exhalation valve on the mask, thus forming a complete breathing process. Throughout the entire breathing process, due to the fact that the operation of the air supply valve relies on both chamber pressure balance control and spring pressure regulation, the output air flow rate of the air supply valve is always greater than the intake air flow rate. So regardless of the inhalation speed of the user, the air output through the air supply valve always maintains positive pressure inside the mask, which can prevent external air from entering the mask and ensure the safety of the user.

　　

　　Correct use of positive pressure air respirator

　　

　　1. Pre use inspection

　　

Before wearing, the respirator should be checked to ensure that it can be used normally.

　　

Gas cylinder pressure: First, turn on the gas cylinder switch to check the storage pressure of the air. The normal value should generally be between 28-30 megapascals;

　　

Low pressure alarm: Turn off the gas cylinder switch and observe the reading on the pressure gauge. If the pressure drops by no more than 2 megapascals within 1 minute, it indicates that the gas supply pipeline system has good air tightness. At this point, gently press the supply valve again. When the pressure drops and the pressure gauge pointer rotates through 6-4 megapascals, a low pressure alarm will sound, indicating that the low pressure alarm is working properly;

　　

Airtightness of mask: Turn off the gas cylinder switch and take several deep breaths. If the mask is tightly pressed against the face and the wearer feels difficulty breathing, it indicates that the mask and breathing valve have good airtightness. However, it should be noted that the test time should not be too long.

　　

　　2. Instructions for use

　　

The respirator can only be used after it has been checked and everything is normal.

　　

Back, fasten, and retract: That is, carry the respirator behind your back, making sure the gas cylinder switch is facing downwards, then fasten the belt and tighten the shoulder strap.

　　

Hanging and connecting: After hanging the neck strap of the face mask onto the neck, grab the gas cylinder and the connecting end of the face mask with both hands, quickly connect the quick connector, and lock the safety ring.

　　

Open: Open the cylinder valve, rotate counterclockwise to open the cylinder switch, and turn it to the maximum position.

　　

Wear: Wear a breathing mask. When wearing, spread the straps with both hands and wear them from the top of the head downwards. After wearing, first tighten the straps on the top of the head, and then tighten the straps on the forehead and ears. After wearing the breathing mask, take 2-3 deep breaths to feel comfortable. Stop supplying gas to the supply valve when holding the breath.

　　

Usage: When using, pay attention to the pressure gauge and low pressure alarm. The wearer should observe the value of the pressure gauge at all times during use. When the pressure drops to 6-4 megapascals, the low pressure alarm will sound to warn the wearer to evacuate the scene.

　　

The configuration, storage, inspection, and maintenance of positive pressure air respirators on ships: Ship respirators are included in the equipment for ship firefighters, and their products must have a qualified inspection report from the National Fire Equipment Quality Supervision and Testing Center and a Chinese CCS certificate. According to the requirements of the SOLAS Convention and the Fire Safety System Regulations, each cargo ship is equipped with at least two sets of firefighter equipment, stored in an easily accessible location on board and in a readily available state. The location should have permanent and clear markings, and the two sets of respirators should be kept away from each other. At the same time, special attention should be paid to the ambient temperature of the storage location. If the ambient temperature of the storage location is high, it is easy to damage the mask and other components of the respirator.

　　

　　Inspection and maintenance:

　　

(1) Regular inspection: Check the air respirator once a month according to regulations, and refer to the product manual for inspection methods;

　　

(2) Cleaning after use: Remove the gas cylinder from the back support, wipe off oil stains and dust, remove the supply valve on the face mask, wash the face mask with neutral disinfectant, and then wipe it clean with water to let it dry naturally.

　　

(3) Maintenance of gas cylinders: Gas cylinders must be refilled after use, and the pressure inside the cylinder must be maintained at 28-30 megapascals. Avoid exposure to sunlight and avoid collisions or scratches. The gas inside the cylinder should not be completely depleted, and there should be a residual pressure of no less than 0.05 megapascals.

　　

(4) Carefully protect the face mask: The face mask glass should be protected from heat deformation and scratching. When not in use, it should be placed in a storage box and should not be in a compressed state. It should be stored in a clean and dry warehouse.