What Is an Oxygen Mask?

The oxygen mask provides a way to transfer the oxygen needed for breathing from the tank to the human lungs. There are mainly medical oxygen masks, aviation oxygen masks, and oxygen masks used by aviation passengers, which play an important role in treating diseases and protecting the safety of passengers and pilots. Mainly made of plastic, silicone, or rubber.

Oxygen mask

The oxygen mask provides a place to put

The oxygen mask is mainly made of plastic,

Oxygen mask medical oxygen mask

Main performance and structure

The oxygen storage system is composed of a mask, an oxygen storage bag, a T-shaped tee, an oxygen delivery catheter, and a fixed member.

use

For dyspnea and hypoxia patients.

Instructions

Oxygen is directly injected into the oxygen storage bag, and the mask is placed on the patient's face and her mouth and nose are closed. The mask is fixed to the patient's head using a fixing member, and oxygen is absorbed.

Oxygen mask military aviation oxygen mask

Introduction

Modern fighter aircrafts all have automatic booster seats, which makes the pressure inside and outside the aircraft cabin equal when flying at high altitude. At the same time, when the aircraft is flying above 6000 meters, the pilot needs to wear an oxygen mask and breathe oxygen because the outside air starts to thin.

These oxygen are stored in the oxygen cylinder. Before the aircraft takes off, the ground crew will not only refuel the aircraft but also inject mixed oxygen into the oxygen cylinder.

The cabin is sealed, otherwise, when flying at high speed at high altitude, slight pressure changes in the cabin will endanger the pilot. At the same time, when the fighter is flying at high speed (especially during combat), the pressure and G force on the pilot are huge. At this time, in addition to automatically pressurizing the pressure flight suit to protect the pilot, the oxygen pump will also automatically pressurize to increase the oxygen supply. At this time, the pilot's lungs are compressed and breathing will be more difficult. This automatic system can protect the pilot from Hypoxia coma ...

Because the cabin automatically adjusts the pressure according to the flight altitude, the pilot can choose to open the air exchange device to allow the air outside the cabin to enter the cabin when the fighter flies to a low altitude, or continue to use an oxygen mask.

Therefore, pilots of modern supersonic fighters, oxygen masks and pressure flight suits are indispensable.

When the fighter takes off, the pilot will first use an oxygen mask, and will not choose to breathe the air outside the aircraft, because when the fighter is waiting for takeoff on the runway, it will emit a large amount of toxic exhaust gas, in order to prevent the exhaust gas from entering the cabin and causing poisoning

Aviation oxygen mask

Therefore, the pilot would turn off the air exchange device and use an oxygen mask to breathe.

effect

The aviation oxygen mask is the pilot's main personal protective gear, and it is the key interface of the human-machine interface. It is used most frequently in actual flight and is closest to the human body. Its protective performance is extremely important for ensuring the pilot's high-altitude oxygen supply and rescue. Aviation oxygen masks play an inestimable role in avoiding the threat of high-altitude hypoxia and ensuring flight safety!

Equipment status

In the past 20 years, aviation technology has developed rapidly, and the tactical performance of modern military aircraft has continued to improve, which has further promoted the improvement and development of aviation oxygen masks. The oxygen masks of foreign air force pilots have been modified several times, and they have been updated several times to make them suitable for the use of high-tech aircraft. For example, the U.S. military has developed from MBU-5 / P and MBU-12 / P oxygen masks serving for more than 20 years to MBU-20 / P and MBU-22 / P oxygen masks; the former Soviet Union has developed from KM-18 to KM-36 oxygen Masks; the British and French Air Forces have also developed high-performance Q / P and MP90 oxygen masks. The common features of these new oxygen masks are: overall light weight, low breathing gas resistance, large instantaneous flow, reasonable hanging mechanism, high anti-overload ability, comfortable and convenient wearing. And has the characteristics of anti-nuclear, anti-chemical, anti-biological war invasion and high-speed airflow attack comprehensive protection performance, as well as positive pressure resistance overload and compatibility with communication devices and other characteristics.

The oxygen masks used by the Chinese Air Force's existing fighters, fighters, and bombers still use the imitation Soviet products in the early 1960s. The active oxygen mask does not conform to the characteristics of the pilots in China. It has backward technology, unstable performance, and poor wearing comfort. The existing problems of active masks, coupled with the continuous improvement of the performance of our military aircraft, such as the application of air tankers, extended battery life, and improvements in electronic fire control equipment have made the requirements for the comfort and safety of pilots' personal protective equipment more high. There is an urgent need for improvement.

development trend

From the perspective of the engineering design and physiological requirements of foreign aviation oxygen masks, improving the oxygen protection performance of pilot oxygen masks is mainly in the following aspects:

1. Improving the compliance rate of oxygen mask air tightness: The air tightness of an oxygen mask is a key technical indicator of its oxygen supply performance. The quality of air tightness directly affects flight safety. Raymam reports that 19 of the 89 cases of loss of air awareness in the United States Air Force were due to hypoxia, accounting for 21.3%. Talbot analyzed 620 first-class accidents and believed that 30.3% were due to poor air tightness of the mask. The British Air Force reported 400 hypoxia accidents during the 10-year flight, of which 22% were leaking from the oxygen mask, and 11% were not connected to the oxygen mask and the oxygen regulator. The Chinese Air Force flight unit has also experienced a number of flight accidents due to poor mask performance. It can be seen that the air tightness of the oxygen mask is the key to ensuring the safety of the pilot's oxygen supply. Increasing the compliance rate of airtightness is mainly realized in the design of the face of the mask body, the design of the peripheral seal, the design of the hanging system and the design of dynamic airtightness.

(1) Improving the face shape design of the mask body The rationality of the face shape design is the key to the air tightness of the oxygen mask. Because the individual characteristics of the pilot group's facial characteristics vary widely, a uniform mask model is difficult to meet the group's wearing requirements. The comfort of foreign equipment comes from scientific design, using human body measurement of high-tech (laser scanning technology), collected 131,000 data points of the pilot's head and face within 17 s, and advanced 3D digital technology and high-performance image processing The software processes it to form a three-dimensional image, and then places it into the helmet image or oxygen mask to be designed, and directly inputs the computer-aided design system (CAD) to modify the prototype design of the helmet and oxygen mask. In this way, the compliance rate of the helmet and the oxygen mask is greatly improved. Oxygen masks are most prone to leaks on both sides of the bridge of the nose, followed by the lower jaw and the corners of the mouth. Due to the large variation of human body shape, the British P-type mask uses a curled design to make it under the pull of the strap When the face is pressed tightly and there is a residual pressure (P) in the mask, the larger the residual pressure value, the tighter the fit with the facial skin. The leakage around the seal design has a great impact on the oxygen partial pressure of the inhaled gas. If it occurs during emergency pressurized oxygen supply, it will be difficult to maintain the oxygen supply pressure in the mask, which seriously endangers flight safety. Another reason for mask leakage is the use of problems, such as improper mask model selection, careless wearing, can also cause leakage. Mask aging, deer skin falling off, and sponge pad defect are also important factors affecting the safety of oxygen supply. This should attract the attention of individual aviation equipment managers and users.

(2) Reinforced mask hooking device The key connecting point is the matching part between the oxygen mask and the flight protection helmet. As for which connection form is good and easy to use, the methods adopted by the air forces of different countries are different. The U.S. Air Force MBU-20 / P and BA / LP oxygen masks use offset pin-type bolts and are fixed to the flight helmet. The bolt can flexibly adjust its tightness and meet the requirements of pressurized oxygen supply, which is welcomed by users. The British P-mask uses a quick manual tensioning toggle-chain system. This structure can usually be worn loose. When pressurized and oxygen is supplied, the handle is pressed down by hand to tighten the mask to make it close to the face. However, in the event of an emergency decompression of the cockpit, if the pilot is too late to pull the elbow handle to tighten the chain belt, there is a danger of severe hypoxia. Most of the original Soviet-style oxygen masks were strap-type, similar to the masks of our military. Usually wear it and hang it on the helmet hook. When pressurized oxygen is supplied, the role of the compensation bag located behind the head is used to tighten the oxygen mask accordingly. In recent years, they have borrowed from Western design methods and also used bolts, which were applied on Su-27 aircraft.

(3) Development of a dynamic pressurized breathing oxygen mask In order to meet the development of the next generation of advanced mobile aircraft life support systems and meet the needs of high overload pressurized breathing and high-altitude pressurized oxygen supply, the British Camlock company invented a G-sensitive oxygen regulator Provides a pressurized breath that automatically seals the oxygen mask. Normally, the material is soft and comfortable. When external force is applied, stress deformation occurs, which makes it close to human skin and achieve air tightness. The strength of the automatic seal is corresponding to the pressure of the mask cavity. Eliminates mechanical and pneumatic mask tensioning devices for pressurized breathing, reducing weight. However, the structure and principle of such an automatic dynamic sealing device are unclear and have not been reported in detail.

2. Improving the wearing comfort of oxygen masks: In recent years, the rapid development of aviation technology, the application of air tankers and on-board oxygen generation technology, the increase of aircraft endurance, and the time for pilots to wear oxygen masks have also increased. Higher requirements are placed on oxygen masks. According to reports, due to the poor comfort of the oxygen mask, five pilots were reluctant to wear the mask because of the nasal bridge. As a result, after the decompression of the cockpit in the high altitude, all of them showed different degrees of hypoxia and decompression sickness. These examples show that the comfort of an oxygen mask is extremely important. The current aviation oxygen masks of the British, American, French, Swedish, Canadian, and Russian Air Forces all focus on improving their wearing comfort. Its comfort is important to ensure that long-term (6-8 h) flight does not produce boredom. Therefore, to improve the wearing comfort of oxygen masks, the following aspects should be considered:

(1) By reducing the resistance of breathing gas and increasing the instantaneous flow, in addition to the effect of the oxygen mask's own cavity on the human body, the effect of its added resistance also has an impact on the human physiology and psychology. Zhang Lifan et al. Believe that resistance has an effect on the physical stimulation of the increased mechanical load of the respiratory muscles and the combined mechanism of elastic resistance. Therefore, reducing the resistance to breathing air is a need for physiological and psychological comfort. Based on the MBU-5 / P oxygen mask, the inhalation resistance of the P / Q oxygen mask has been reduced. According to the Air Force Institute of Aeronautics and Astronautics, six subjects had better subjective perception of P / Q oxygen masks than MBU-5 / P, and their inhalation resistance was low. Under the TLSS program, the United States has designed a high-altitude-low-profile positive-pressure breathing (HN / LP-PPB) oxygen mask. Its suction resistance is also significantly lower than that of MBU-5 / P and MBU-12 / P oxygen masks. The human body requires the oxygen breathing system of the aircraft to ensure the instantaneous flow of human breathing. Some people think that the oxygen system needs to achieve an instantaneous oxygen supply capacity of at least 300 L / min, otherwise, when flying is overloaded or speaking, the phenomenon of tritium is prone to affect the anti-loading effect. However, the oxygen system flow is provided through the mask, and by increasing the valve circulation area, the pilot's air supply during high overload flight can be guaranteed. In addition, the French EROS company has an anti-asphyxia valve on the combined breathing valve of the oxygen mask, and the US Navy has an asphyxiation valve on the mask shell. When the pilot falls into the water, the inhalation resistance increases to a certain threshold (2 kPa) The valve opens to breathe outside air to prevent drowning.

(2) Improve the design of sealing and curling, and use a new material. Oxygen mask curling should be in direct contact with the skin of the pilot's face. It should be comfortable, without allergic reactions and special odors. From the perspective of active oxygen masks in the United Kingdom, the United States, and France, which are under development, all are made of soft silicone rubber materials that are not easy to age, resist oxidation and ozone, and have no abnormal odor, and have sufficient elasticity and rigidity to maintain Cover shape.

(3) Reducing the weight of the mask body and improving its forward center of gravity The weight of the oxygen mask and its forward movement after being matched with the flight helmet will cause fatigue of the neck muscles. Especially under the effect of flight overload, its apparent weight doubles and the mask shifts, which affects the oxygen supply of the flight. Therefore, improving the design and reducing the weight is also one of the key requirements for measuring the design indicators of the mask. The United States Air Force advocates that a "low-profile" oxygen mask should be designed to reduce the height of the mask protruding from the face and move the center of gravity of the mask back into the helmet. This can not only improve its comfort, but also reduce the impact of the oxygen mask on the field of vision, and increase stability during overload flight.

(4) Increase ear protection and reduce tympanic membrane damage. The guiding principle of the French EROS company in the design of the oxygen mask is to consider lightness and flexibility, ease of use, and ensure the comfort performance when pressurized and airtight. The pressurized earcups and pressure compensating capsule (connecting the mask to the face and pressurizing the ear during pressurized breathing) in communication with the oxygen mask can alleviate the discomfort of the ear of the pilot during pressurized breathing. In addition, a round hole is left on the front and upper sides of the hard shell outside the mask, in order to prevent the nose from inflating the ear when the flight crew descends quickly.

3. Strengthen the hooking performance to meet its requirements for anti-overload use: The hook performance of the oxygen mask is directly related to the anti-overload effect. According to reports, during a large overload, the oxygen mask moved downwards and could not supply oxygen, and the pilot had to support the mask with his hands to distract attention and affect the control. The U.S. Air Force adopts an offset knife-type structure, which is characterized in that the tension of the bolt can be adjusted, and it can be worn looser in normal times, and tighter when flying at high altitudes and under overload. This device places high demands on the jaw material of the insert. Considering the protection of high overload, the French EROS company has taken the following measures: The mask has a jaw strap and a four-point attachment point mask with a total upward force, which adjusts the center of gravity of the mask and helmet. Reduce the weight of the helmet and mask, and reduce the weight load on the head and neck. The mask oxygen supply hose is fixed on the left shoulder, and then connected to the oxygen breathing regulator through the T-shaped joint of the vest. This not only facilitates head movement, but also improves the field of vision, and also prevents the mask from moving down when overloaded. In other countries, the mask oxygen supply hose hangs down from the front of the mask naturally, and it is easy to fall off under acceleration. Make the breathing combination valve perpendicular to the fuselage, that is, parallel to the longitudinal axis of the human body. This can prevent the valve's apparent weight from increasing during flight overload and affect the breathing. Both the former Soviet Union and our army used suspenders to connect to the helmet. From decades of use, this structure is inconvenient to use and has poor anti-overload effects, and should be improved.

4. Improving anti-blown ability: With the continuous improvement of aircraft performance, the probability of ejection at low altitude and high speed increases, so that when the aircraft ejects and leaves the aircraft, the face is subjected to the impact of a strong oncoming airflow, causing the helmet mask to fall off , So that facial damage. Therefore, the problem of high-speed airflow attack is getting more and more attention. At present, the protection against high-speed airflow has become one of the focuses and difficulties of current aviation lifesaving research. But today, equipment that can meet 1 200 km / h blow-up protection is rare, only the former Soviet Air Force has reported. Other countries have only met the test results of 1 000 km / h. For example, the U.S. military's TLSS tactical lifesaving system final test report, the oxygen mask has passed 16 air blow tests at an airspeed of 650 to 1 090 km / h. The shape design of the mask mainly has a good aerodynamic shape to reduce the air blow effect when the ejection machine leaves the machine. In addition, the valve position of the oxygen mask should also try to avoid the effect of upwind airflow. Otherwise, the valve will be damaged and life-saving will be affected. The method of hooking the helmet has been mentioned previously. To meet the needs of its anti-blowing effect, it must be easy to hook and easy to adjust, and it must be secure and strong. In addition, the matching of the mask and the goggles is also an issue that should be considered in the overall mask design. The shapes of the two should be compact. Our military's active oxygen mask has a poor anti-blown ability and is inconvenient to use. Its anti-blown ability is less than 900 km / h. Therefore, in the development of the modification, attention should be paid to the design of the appearance of the mask, the way of matching with the helmet, and the matching with the goggles.

Oxygen mask for civil aviation

Introduction

On passenger planes, oxygen masks are emergency lifesaving devices that provide passengers with oxygen. If the cabin suddenly loses airtightness or encounters other hypoxia conditions, passengers can always get an oxygen mask to replenish oxygen. After the plane flies to a certain altitude

How to use an oxygen mask

To supercharge the cabin. If the cabin of the aircraft loses pressure, it will cause hypoxia, and passengers will be dizzy, unconscious, and even life-threatening. In the case of cockpit pressure loss at different altitudes, people can withstand different periods of hypoxia. The higher the altitude, the less time it takes. On a civil aviation passenger plane, each person's seat is equipped with a personal oxygen mask for emergency use, so there is no need to scramble to prevent the oxygen mask from being damaged and delayed.

Construction principle

The oxygen mask is connected to the automatic coupling through an elongated rubber oxygen supply tube and a bayonet joint. The oxygen continuously flows into the airbag of the mask. The gas storage bag stores gas first, and then it can hold a certain amount of oxygen when it expands. When the passenger takes a deep breath to evacuate the air bag, the intake valve on the mask can allow oxygen to enter.

Instructions

In the event of a decompression in the cockpit of the aircraft, the oxygen hood will automatically fall off the top of the cabin. Above the passenger seat, there is an emergency manual release of the oxygen mask, which is marked with a "push". After being pushed away, the oxygen mask is automatically lowered in front of the passenger. There are graphic and text instructions on how to use it on the release board. Passengers should follow the instructions correctly.