Positive Pressure Oxygen Mask Structure Introduction

With the rapid development of China's economy and the drastic changes in the international and domestic situation, the natural environment and social environment have also undergone great changes, and various types of natural disasters and human factors have been increasing. When chemical gas disasters such as gas leaks occur or when terrorist attacks occur, it is difficult to control the spread of toxic gases. In addition to on-site rescue fire officers and soldiers must be equipped with protective equipment, on-site command personnel and the people in the gas leakage area must also wear universal respirator masks to protect them. Personal security. At the scene of the disaster, the evacuees should be given timely measures such as anti-virus isolation and oxygen supply to maintain positive oxygen supply to prevent people from suffocating oxygen. Most of the existing gas masks use negative pressure inhalation methods, which have large suction resistance and easily cause the wearer to breathe hard and even suffocate.

1 positive pressure oxygen supply gas mask structure

Positive pressure oxygen masks use a modular technology form, which consists of full face gas masks, oxygen supply devices, micro oxygen cylinders, and drug atomization devices. The airtightness of the gas mask is good, and can completely isolate the wearer's respiratory organs, eyes, mouth and nose, and the entire face from the outside. The positive pressure oxygen supply device and the drug atomization and inhalation device installed on the gas mask provide the personnel with the gas mask. Positive pressure oxygen and emergency medications. Therefore, the gas mask can be used by individuals in sudden public events to provide oxygen alone and on-site emergency use, which is suitable for the use of the disaster-affected personnel, and is also suitable for the medical personnel to rescue the wounded under the condition of toxic gas leakage, or lack of oxygen and even anaerobic conditions. .

1 . 1 gas mask

The gas mask is mainly composed of a cover, a water blocking cover (a shroud, an oronasal mask ) , an eye window, an exhalation valve, an inhalation valve, a headband, and a close frame. The mask and headband of the gas mask are made of silicone rubber and butyl rubber blended materials. The eye window uses a monocular large-eye window to cover the high-temperature reflective film material. The monocular large-eye window structure can greatly improve the visual field and reduce wear. The eye fatigue and claustrophobic discomfort, and other uncomfortable feelings, high temperature reflective film can isolate the outside temperature. Both the sealing frame and the oronasal mask are designed as a flexible folding back structure to ensure that the mask forms a close contact with the human face interface and has a good airtightness. The folded back edge of the oronasal mask and the folded back edge of the cover body together form a complete closure. The oronasal mask has good airtightness and waterproofness, and completely isolates the wearer's face, eyes, mouth and nose from the surrounding environment, and is comfortable to wear. Redesign the gas mask breather valve to ensure proper ventilation and proper respiratory resistance. Positive pressure oxygen mask, as shown in Figure 1 .

Figure 1 Physical map of a new type of ambulance mask

1 . 2 positive pressure oxygen supply device

The positive pressure oxygen supply device is mainly composed of micro oxygen cylinders, oxygen pressure reducing valves, oxygen delivery tubes, and oxygen delivery interfaces. Micro oxygen cylinders are used as high-pressure oxygen reservoirs for oxygen and positive pressure gas supplies for emergency gas masks. Oxygen pressure reducing valve is used as a micro high-pressure oxygen gas control component. It is connected with a high-pressure oxygen reserve to form an independent micro-supply device. Oxygen flow rate can be adjusted according to the wounded person's injury to form an isolated new positive pressure oxygen supply emergency gas mask.

1 . 2 . 1 structure of oxygen relief valve

Oxygen supply device is a personal self-rescue and mutual rescue respiratory protection equipment that must be worn while emergency rescue personnel, firefighters rescue disasters, deal with accidents, and when disaster victims escape. Oxygen pressure reducing valve decompresses high-pressure oxygen gas to relative pressure. The device for stabilizing air pressure is the core component of the oxygen supply device. One end is connected to the oxygen bottle and the other end is connected to the gas mask. The function is decompression and pressure regulation. The performance of the device directly affects the oxygen supply effect and the rescue efficiency. The structure of the piston pressure reducing valve is shown in Fig. 2 .

1 . 2 . 2 oxygen relief valve works

Reduced oxygen valve works are: oxygen input switch 6 is turned on, high-pressure oxygen oxygen bottle 10 via the oxygen inlet pressure reducing valve and the diaphragm into the oxygen channel 8, is divided into two parts, one on the oxygen pressure gauge 7 The pressure in the oxygen cylinder is displayed. The other oxygen flows through the valve core and diaphragm 3 of the pressure reducing valve and enters the cavity through the narrow oxygen channel in the diaphragm. The gas is throttled to cause the pressure to drop; the oxygen after the throttling enters the crucible. When the chamber is pressed, it acts on the top surface of the diaphragm, compresses the main spring 5 through the diaphragm , adjusts the pressure adjustment nut l1 to change the volume of the crucible chamber, clockwise rotates the pressure adjustment nut, the volume of the crucible chamber decreases, and the pressure in the crucible chamber changes. Large, the spring is compressed; on the contrary, the volume of the cavity increases, the pressure in the cavity decreases, and the spring rebounds. Adjusting the oxygen flow screw 2 can regulate the oxygen output flow. The pressure relief valve is always in a state of equilibrium and has a relatively stable outlet pressure.

Figure 2 Schematic diagram of the pressure reducing valve

1 . 3 drug atomization device

The drug atomizer is designed as a three-stage butt-connected thin rod-like tube, and a cavity is provided with a dielectric core strip for impregnating the drug. In use, the drug is atomized by the supply of oxygen gas to achieve direct administration during first aid. The impregnated drug can be 30 % alcohol, and can also be sodium bicarbonate, aminophylline, dexamethasone, and procaine. For those who have breathing difficulties or even respiratory failure, drug nebulizers can improve their efficiency.

2 Gas mask test results

Gas masks are tested by authorities in accordance with GB 2890-2009 "Respiratory protection self-priming filter gas mask". The testing includes classification, mask, mask assembly airtightness, face mask breathing valve hermeticity, and mask resistance to air flow. The aging of the breathing valve, the appearance of the canister and the canister ( box ) , the strong combination of the components and the connection requirements of the components, etc. All technical indicators are in compliance with the requirements, and they have passed the military logistics science and technology achievement appraisal. This achievement has been promoted and applied in many units and has achieved good military and social benefits.

3 Analysis of the situation at home and abroad

Ordinary gas masks are designed for the use of traditional chemical poisons and those with normal respiratory functions. The principles of negative pressure filtration and inhalation are used, and the suction resistance is large. Due to the design's failure to take into account special environmental factors such as toxicants and smoke, it cannot be used in high concentrations of harmful gases, oxygen deficiency ( oxygen volume fraction below 17 % ) or in an oxygen-free environment, nor does it prevent the penetration of new chemical agents. Its filtration performance can not meet the requirements of the type and quantity of pollutants. In addition, its infiltration resistance is formed by its poisonous layer, which can easily lead to breathing difficulties due to weakened respiratory function and insufficient air supply. In foreign countries, positive-pressure air-supply first-aid devices generally use portable ventilators, oxygen cylinders for oxygen supply or electric air-blowing for pressurized air supply. They are bulky and of heavy weight. It is inconvenient to wear and carry emergency supplies. In mass moments, there may be a large number of When the wounded needs to be rescued at the same time, they cannot be brought into the rescue scene in large numbers and the routine medical treatment cannot complete the mission.

4 Comparison with existing gas masks

The new rescue gas mask is an isolated gas mask with positive pressure and oxygen supply. The active gas supply greatly relieves the pressure on the wearer's lungs, enabling them to maintain their physical strength and spirit. Active airflow can also block the window of the eye. Fog, to ensure that the wearer's vision is clear; monocular large eye window structure greatly improves the visual field and reduce the wearer's discomfort such as eye fatigue and claustrophobia; positive pressure oxygen supply and emergency drug aerosolization is conducive to breathing difficulties Defective wounded cardiopulmonary resuscitation. In addition, the new type of gas mask cover for ambulance use silicone rubber material, there is no rubber smell, the wearer does not have bad feelings; the oropal mask and return edge are formed by one-time compression molding, not easily deformed, and make the mouth and nose cover folded back The reentrant sides of the shell together constitute a fully-closed nose mask, which has good airtightness and waterproofness. The new type of gas mask with special ambulance features a conversion interface and can switch different gas masks. The comparison of new gas masks and domestic and foreign gas mask parameters is shown in Table 1 .

Table 1 Comparison of gas mask parameters

5 Summary

Filter-type gas masks are now widely used in firefighting forces and chemical defense units to handle large-scale disasters such as earthquakes, explosions, fires, and leakage of dangerous chemicals. They play a very positive role in protecting the personal safety of rescue workers and on-site escapees. By installing positive pressure oxygen supply and drug atomization devices on self-inhalation gas masks, people can effectively solve the problem of escape and rescue in toxic pollution and oxygen- and oxygen-free environment, and reduce the number of people in public emergencies. The casualty rate is of great significance.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.