Safety rules during work with alternative refrigerants
Alternative refrigerants are not inflammable and explosive. However, they should not be mixed with any combustible gases and liquids no matter what reasons can occur, because these blends can acquire unpredictable qualities, can become combustible and, as a consequence, dangerous.
Refrigerants should not be exposed to naked flame or electric heating elements. High temperatures and flame can cause decomposition of refrigerants with emission of toxic and decomposing fumes. Moreover, burner flame can abruptly increase or change color at presence of many ozone-dangerous refrigerants, including R500 or R22, as well as many other alternative refrigerants under the condition their high concentrations. Such increasing of flame can cause consternation of the personnel or even lead to injury. Many HCFC and HFC refrigerants can become combustible if mixed with the air and then warmed up with pressure increasing at the same time. In the past, during work with CFC there were usual tests of blending the air with the refrigerant with increasing of pressure. However, during operation with HCFC or HFC, such tests should be avoided because R134a, for example, can ignite at absolute pressure 139 ªP and temperature 177 oÑ, if it is mixed with the air in the concentrations usually exceeding 60 % (as to air volume). At lower temperatures, in order to add combustibility to the blend, higher pressures are required. R22 also can ignite at pressures exceeding atmospheric pressure, if it is mixed with the air at high concentrations. Since alternative refrigerants contain components of HCFC or HFC, it is assumed that their behavior will turn out to be analogous. Due to this reason, they should not be mixed with the air in any concentrations for performing test with the aim of leakage discovery. Also it should not be allowed for these refrigerants to be under pressure exceeding atmospheric, in the blend with the air.
 Influence of refrigerants on human body
Thermal decomposition. Refrigerants are decomposed under influence of high temperatures caused by flame or electric heaters. During decomposition, there can emit toxic and irritating contextures, in particular, hydrogen and fluorine chlorides. Strong smell emitted by the decomposed refrigerant causes irritation of nose and throat mucous tunic of the personnel. Emitted acid vapor are dangerous, and in order to avoid their effect on the personnel production areas should be immediately emptied of people and ventilated. A person, having been exposed to the effect of refrigerant decomposition products, should be immediately taken outside for fresh air and should be immediately given medical care. Work should not be continued at presence of these vapors because it can influence harmfully the health of the personnel.
Alternative refrigerants do not cause acute or chronic poisoning during work with them if their concentration does not exceed recommended levels of maximum permissible effect, for example, admissible effect level (AEL), established by "Du Pont" company, or admissible threshold level value (TLV), established by the American conference of governmental industrial hygiene specialists (ACGIH). There have been established also short-term effect level STEL and emergency effect level EEL.
AEL level determines weight-average in time refrigerant concentration in the air which can influence repeatedly almost all the workers with any negative effects within 8 or 12-hour working day or 40-hour working week. In practice short-term effect should not exceed more than three times more the effect level (AEL, PEL, TLV or other index), established by the company-manufacturer, or 1250 (parts per million) depending on what level is lower. Repeated influence of refrigerant vapors at the level of concentration exceeding limit values, recommended by the company-manufacturer, can be injurious to the health of the personnel, and thus, it should be avoided. In case of discovering leakage, there should be immediately performed repair and in future it is necessary to look after leakages out of the refrigeration equipment for maximum reduction of refrigerant concentrations on a working place.
Short-term effect level STEL defines weight-average in time concentration effecting within 15 minutes, which should not be exceeded any time during a working day.
Emergency effect levels EEL define concentrations in the air within a short period of time in emergency cases, which should not cause persistent health problems. EEL values are established by "Du Pont" company for the period of time up to 1 hour with the threshold level which should not be exceeded. These limit values should be considered as a landmark while planning actions in case of emergency, however they cannot substitute technical control means. As to R123 refrigerant, EEL has been established on the level 1000 mln-1 with the threshold level on the level 2500 mln-1.
Inhalation of SUVA® refrigerant vapors in large concentrations can cause time depression of activity of the central nervous system accompanied with drowsiness, lethargy and weakness. To other possible effects, there can be related dizziness, pleasant feeling of intoxication, as well as loss of coordination of movements. Long-term inhalation of the refrigerant vapors can cause disturbance of heartbeats, loss of consciousness, and inhalation of very big doses can cause even fatal outcome. A person who felt any of initial symptoms should be immediately taken outside for fresh air and provided with rest and immobility. At respiratory standstill it is necessary to make artificial ventilation. If respiration is difficult, it is necessary to provide oxygen and call for a doctor. Such symptoms can show up at the influence of different concentrations; therefore, at showing up of any of these symptoms it is necessary to leave production area, even if other workers who are nearby do not show these symptoms.
In the process of experimental research, experimental animals were exposed to the effect of refrigerant vapors of different concentrations, after that they were injected with adrenalin for modeling of stress reactions of a human. Disturbance of heartbeats under the influence of components of alternative refrigerants is observed under concentrations from 20 to 150 mln-1 or more, which considerably exceeds expected effect level on a working place. For comparison we'll remind that such reaction under the effect of R11 and R12 is observed correspondingly under concentrations of about 5 and 50 mln-1. Due to possible disturbance of heart rhythm, catecholamine drugs, in particular, adrenalin can be used as the last means in the situations when life is under real danger.
At big emission of the refrigerant, vapors can be concentrated at the floor surface or on the low areas and displace available oxygen which causes asphyxia. In case if a considerable amount of liquid refrigerant will pour out or there will happen considerable leakage, it is necessary to put on proper individual protectors. While working in closed areas, for example, in basements, where there can accumulate refrigerant vapors, it is necessary to use autonomous respiratory systems or respirators with external air delivery. Before coming in, it is necessary to check all the production areas for oxygen availability with the help of proper control equipment. When the first worker is coming in, the second one should stay outside, and there should be stretched rescue layer between them.
In order to ensure air circulation on the floor level and in any basement and low areas, one can use blowing engines and ventilation.
The majority of refrigerants have so weak smell, that it is difficult to discover it even in dangerous concentrations. One should not count on smell for estimation of safety of production areas designed for the personnel.
The only safe means are regular checks of leakages and monitoring of the air quality.
Deliberate inhalation of refrigerant vapors can cause death.
Ingress on skin and eyes. Under the room temperature, vapors of SUVA® refrigerants do not expose serious effect on skin and eyes. If there exists danger of ingress of liquid refrigerants on skin, it is necessary to wear protective clothing, including that with long sleeves and gloves. Among individual protectors, the personnel should have protective glasses and face shield for eye protection. In case of ingress into eyes of liquid refrigerant, they should be thoroughly washed with water and then call for medical care.
Frostbite. Ingress of liquid refrigerant SUVA® on skin or into the eyes causes their immediate cooling, resulting in frostbite. If liquid refrigerant has been splashed out on a worker, it is necessary to take off immediately all the clothes where the refrigerant hit in order to avoid more extensive frostbite. One has to wash an injured area with warm water (neither cold nor hot). One does not have to put bandage or use ointment. It is necessary to call for medical care immediately.
Ensurance of safety while working with refrigerants and vessels under pressure
Requirements to machinery hall. In machinery hall there should be installed air quality monitor being able to determine concentrations of used refrigerants up to EEL or STEL levels. It is also necessary to foresee proper signal systems starting to operate at reaching of AEL level of the refrigerant concentration or at the level lower than AEL and warning the personnel outside machinery hall about the leakage. Discharge collectors of safety valves and purgers should be moved outside machinery hall and disconnected from all the air inlets connected with the building. In case of worsening of the air quality it is necessary to use local air funnel to ventilate production area.
Safety rules while working with equipment in closed areas. Before starting of work they make sure that discharge collectors of safety valves and purgers are moved outside machinery hall and disconnected from all the air inlets connected with the building. They check if the building is being ventilated properly. In case of necessity, in order to disperse vapors of refrigerants one can use auxiliary ventilation systems ( for example, blowing engines or fans). Before coming into closed buildings, they check them on availability of oxygen. For oxygen presence testing one cannot use leakage availability monitor, because you cannot figure out with its help if there is enough oxygen in the building for vital functions. To control oxygen presence in production areas there should be provided special devices.
Safety rules while working with vessels under pressure. Some of the dangerous factors occurring while working with vessels under pressure are the following:
- In the overfilled container, reservoir or pipeline when temperature increasing there can happen dangerous elevation of hydrostatic pressure which, in its turn, can cause leakages under high pressure or even blowout of a reservoir;
- In case if a properly filled return or disposable ballon is heated up to the temperature exceeding the recommended one (52 oÑ), it can cause elevation of pressure up to the dangerous level exceeding the pressure supposed for the ballon;
- ‚return or disposable ballon for storage of refrigerants connected with the saturation line of the refrigeration system, can be exposed to the effect of pressures for which resistibility of safety valves of the ballon is not supposed, and it can cause destruction of the ballon.
General safety rules while working with refrigerants. It is forbidden to increase pressure in the systems or reservoirs containing SUVA® refrigerants , by the air for leakage testing or with any other aim. It is forbidden to heat ballons up to temperatures above 52 oÑ, as well as locate them close to sources of flame or heat, to throw them into the fire. One cannot store ballons under direct sunrays where temperature can exceed 52 oÑ. One does not have to use injection cups or naked flame to heat the ballon during charging of the refrigerant. It is forbidden to touch valves or pressure release devices. It is forbidden to fill again disposable ballons with discharge refrigerants or lubricating materials, as well as with anything else. Any residue of refrigerants are to be necessarily used or poured into collecting containers; empty ballon is subject to corresponding recycling. Transportation of initial ballons filled with discharged refrigerants is prohibited by the law.
It is prohibited to use disposable ballons for refrigerants as reservoirs for the compressed air. Ballons with refrigerants do not have corresponding internal covering, and due to this fact moisture contained in the damp air will cause corrosion. It can weaken resistibility of the ballon and cause explosion. Before the ballon destruction, trails of its resistibility weakness can be not discovered.
It is necessary to store the ballons with refrigerants in a dry place. Storage in damp places can cause corrosion which in due course will lead to weakening of resistibility of ballons.
While working with ballons, it is necessary to open valves necessarily. It is necessary to make sure that the refrigerant label corresponds to the color code or labels on the equipment. Obne should not try to regulate without proper preparation any safety devices on the ballons placed close to the refrigeration equipment. One should not let the ballon fall, let appear dents and other mechanic breaks. One should not fix connections with strength. It is categorically forbidden to use naked flame to heat the ballon.
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