All About Isolating Gas Masks

Gas masks are widely used to protect the eyes, respiratory system, mucous membranes, as well as the skin of the face from the penetration of pesticides and toxic substances accumulated in the inhaled air. There are a huge number of different models of breathing apparatus, each of which has its own operating characteristics. You should know about the purpose and mechanism of functioning of isolating models of breathing apparatus.

The isolation apparatus completely protects the respiratory system from harmful substances that have found themselves in the surrounding atmosphere during an emergency. The protective characteristics of the devices do not depend in any way on the source of the release of toxic substances and their concentration in the airspace. While wearing a self-contained breathing apparatus, the wearer inhales a ready-made gas mixture containing oxygen and carbon dioxide. The volume of oxygen is about 70–90%, the share of carbon dioxide is about 1%. The use of a gas mask is justified in situations where inhalation of ambient air is potentially hazardous to health.

• In conditions of oxygen deficiency. The limit beyond which complete loss of consciousness occurs is considered to be 9–10% oxygen, which means that when this level is reached, the use of a filtering RPE is ineffective.
• Excessive concentration of carbon dioxide. The content of CO2 in the air at the level of 1% does not cause deterioration of the human condition, the content at the level of 1.5–2% causes an increase in respiration and heartbeat. With an increase in the concentration of carbon dioxide up to 3%, inhalation of air causes inhibition of the vital functions of the human body.
• High content of ammonia, chlorine and other toxic substances in the air mass, when the working life of filtering RPEs quickly ends.
• If necessary, carry out work in an atmosphere of toxic substances that cannot be retained by the filters of the breathing apparatus.
• When carrying out underwater work.

The basic principle of operation of any isolating protective device is based on the absolute isolation of the respiratory system, purification of the inhaled air from water vapor and CO2, as well as on enriching it with oxygen without performing air exchange with the external environment. Any insulating RPE includes several modules:

• front part;
• frame;
• breathing bag;
• regenerative cartridge;
• a bag.

The front part provides effective protection of the mucous membranes of the eyes and skin from the toxic effects of hazardous substances in the air. It ensures the redirection of the exhaled gas mixture into the regenerative cartridge. In addition, it is this element that is responsible for supplying a gas mixture saturated with oxygen and free from carbon dioxide and water to the respiratory organs. The regenerative cartridge is responsible for absorbing moisture and carbon dioxide present in the inhaled composition, as well as for obtaining an oxygenated mass by the user. As a rule, it is performed in a cylindrical shape.

The trigger mechanism of the cartridge includes ampoules with concentrated acid, a device for breaking them, as well as a starting briquette. The latter is needed to maintain normal breathing at the initial stage of using the RPE, it is he who ensures the activation of the regenerative cartridge. An insulating cover is required to reduce heat transfer from the regenerative cartridge if it is supposed to use the RPE in an aquatic environment.

The breathing bag acts as a container for inhaled oxygen released from the regenerative cartridge. It is made of rubberized elastic material and has a pair of flanges. Nipples are attached to them to fix the breathing bag to the cartridge and the front part. There is an additional pressure valve on the bag. The latter, in turn, includes direct as well as non-return valves mounted in the body. A direct valve is necessary to remove excess gas from the breathing bag, while a reverse valve protects the user from air ingress from the outside.

The breathing bag is placed in the box, it prevents excessive squeezing of the bag during the use of the RPE. A bag is used to store and transport the RPE, as well as to ensure maximum protection of the device from mechanical shock. It has an inner pocket where the block with anti-fog films is stored.

At the moment of crushing the ampoule with acid in the starting device, the acid goes to the starting briquette, thereby causing the decomposition of its upper layers. Further, this process goes on independently, moving from one layer to another. During this time, oxygen is released, as well as heat and water vapor. Under the action of steam and temperature, the main active component of the regenerative cartridge is activated, and oxygen is released - this is how the reaction starts. Then the formation of oxygen continues already due to the absorption of water vapor and carbon dioxide, which a person exhales. The period of validity of insulating RPE is:

• when performing heavy physical work - about 50 minutes;
• with loads of medium intensity - about 60-70 minutes;
• with light loads - about 2-3 hours;
• in a calm state, the period of protective action lasts up to 5 hours.

Many inexperienced users do not fully understand the difference between filtering and isolating devices, believing that these are interchangeable designs. Such a delusion is dangerous and fraught with a threat to the life and health of the user. Filter constructions are used to protect the respiratory system through the action of mechanical filters or certain chemical reactions. The bottom line is that people who wear such a gas mask continue to inhale the air mixture from the surrounding space, but previously cleaned.

An isolating RPE receives a respiratory mixture by means of a chemical reaction or from a balloon. Such systems are necessary to protect the respiratory system in an environment of particular toxic air or in case of oxygen deficiency.

The classification of insulating RPE is based on the characteristics of the air supply. On this basis, there are 2 categories of devices.

These are self-contained models that provide the user with a breathing mixture during the regeneration of exhaled air. In these devices, the oxygen necessary for full breathing is released during the reaction between sulfuric acid and superperoxide compounds of alkali metals. This group of models includes the IP-46, IP-46M systems, as well as IP-4, IP-5, IP-6 and PDA-3.

Hose model, in which purified air is directed into the respiratory system using blowers or compressors through a hose from cylinders filled with oxygen or compressed air. Among the typical representatives of such RPE, the most demanded are KIP-5, IPSA and the ShDA hose apparatus.

Please note that insulating models of gas masks are not intended for domestic use. Such devices are used by the armed forces and units of the Ministry of Emergency Situations. The preparation of the breathing apparatus for operation must be carried out under the guidance of the detachment commander or a dosimetric chemist who has an official permit to check the breathing apparatus. Preparing a gas mask for work includes several steps:

• check of completeness;
• checking the health of working units;
• external inspection of equipment using a pressure gauge;
• selection of a helmet suitable for the size;
• direct assembly of the gas mask;
• checking the tightness of the assembled breathing apparatus.

During the completeness check, make sure that all units are present in accordance with the technical documentation. During an external examination of the device, you need to check:

• serviceability of carbines, locks and buckles;
• strength of fixation of belts;
• the integrity of the bag, helmet and glasses.

During the check, it is important to make sure that there is no rust, cracks and chips on the gas mask, seals and a safety check must be present. The overpressure valve must be in working order. To perform a preliminary check, put on the front part, then press the connecting pipes to your hand as tightly as possible and inhale. If air does not pass from the outside during inhalation, therefore, the front part is sealed and the device is ready for use. The final check is carried out in a space with chloropicrin. In the process of assembling a gas mask, you need:

• connect the regenerative cartridge to the breathing bag and fix it;
• take basic measures to protect the glasses from freezing and fogging;
• place the front part on the top panel of the regenerative cartridge, fill out the work form and place the device on the bottom of the bag, close the bag and tighten the cover.

The RPE prepared in this way can be used to carry out work, as well as for storage within the unit. When using any gas masks, it is very important to adhere to the rules.

• Individual work in a breathing apparatus in a separate room is not allowed. The number of persons working at a time must be at least 2, while continuous eye contact must be maintained between them.
• During rescue operations in areas with a high level of smoke, as well as in wells, tunnels, cisterns and tanks, each rescuer must be tied with a safety rope, the other end of which is held by an understudy located outside the dangerous area.
• Re-use of gas masks exposed to toxic liquids is possible only after a thorough check of their condition and the neutralization of harmful substances.
• When carrying out work inside a tank with residues of toxic substances, it is necessary to degas the tank and ventilate the room in which it was located.
• You can start work in the RPE only after you make sure that the cartridge has worked at the time of launch.
• If you interrupt work and remove the face piece for a while, the regenerative cartridge must be replaced while continuing to work.
• There is a high risk of burns when replacing a used cartridge, so keep the device out of sight and wear protective gloves.
• When operating indoor electrical installations, it is important to avoid contact of the RPE with electric current.

When organizing the use of insulating gas masks, it is strictly prohibited:

• remove the face of the breathing apparatus even for a short time during work performed in the hazardous area;
• exceed the working time in the RPE set for specific conditions;
• wear insulating masks at temperatures below –40 °;
• use partially spent cartridges;
• allow moisture, organic solutions, and solid particles to enter the regenerative cartridge during preparation of the device for operation;
• lubricate metal elements and joints with any oils;
• use unsealed regenerative cartridges;
• store the RPE assembled near radiators, heaters and other heating devices, as well as in the sun or near flammable substances;
• store used regenerative cartridges together with new ones;
• to close the failed regenerative cartridges with plugs - this leads to their rupture;
• to open the block with anti-fog plates without special need;
• to throw out regenerative cartridges in the zone accessible to the civilian population;
• it is not allowed to use gas masks that do not meet the requirements of GOST.

In the next video, you will find an overview of the IP-4 and IP-4M insulating gas masks.