Organizationally-technical arrangements in guaranteeing the fire safety.
Organizationally-technical arrangements must include:
- organization of fire guard (in fixed kilter) of suitable appearance (professional, voluntary and etc.), quantity and technical being equipped;
- passport system of matters, materials, wares, technological processes and objects in part of guaranteeing of fire safety;
- wide sociality entangling to guaranteeing questions of fire safety;
- workers teaching organization, white collars, collective farmers and populations to regulations of fire safety;
- development and norms realization and regulations of fire safety, directions about work order by fire dangerous matters and materials, about movement of fire-fighting mode and about peoples actions at beginnings of conflagration;
- arrangements development as for administration actions, work, white collars and populations on conflagration beginnings case and peoples evacuation organization;
- making and application of methods of obvious agitation on guaranteeing of fire safety.
At design of medical equipment it need turn out access possibility of that, that treat, to apparatus, its defense and replacement.
In all projects it is necessary to give an attention on guaranteeing of normal thermal office hours of schemed elements and device by total - mounting, placing of elements, that heat. It must be a turned out surplus device heating, equipment, combustible neighboring materials (transformer substation, diesel engine-generator stations and etc.). It need provide for general or local schemes of cooling and ventilation At necessity to bring over ventilation computation.
It is needed also to pay attention to such arrangements of fire safety, as coverage of mounting details, pays by special varnish for removal of hit on moisture scheme elements, that causes shorting, corrosion and occupying.
Lighting (initiation of explosion) source appearance probability Computation it need see out on methods, driven into state standard ГОСТ12.1.004-91.
3.4.5. Probability’s computation of lighting source appearance and initiation of explosion (all-Union State Standard 12.1.004-91)
1. Lighting (explosion initiation sources) source Appearance in element object (ИЗ event), that analyses, conditioned by appearance in it thermal source (ТД event) with energy (by temperature), and at times its contact with combustible environment, sufficient for its inflammation (ЕД events and ВД accordingly).
Probability Qi (DZ) of source appearance of firing at an i-elementi object is calculated on a formula
Qi(DZ)= Qi(TD) Qi (ED) Qi (VD)
where Qi (TD) - probability of appearance for a year at the i-elementi object of thermal source;
Qi (ED) - conditional probability of that energy (temperature) of object of thermal source is conditional, that appeared in i-elementi is sufficient for firing of combustible environment, that is found in this element;
Qi (VD) - conditional probability of that time of existence (contact with a combustible environment) of object of thermal source is conditional, that appeared in i-element, sufficient for inflammation of combustible environments.
Appearance in object the element under analyses of thermal source (ТД event ) is appearance result in it though one of thermal sources. That's why a Qi (ТД) probability calculate by formula
Qi (ТД)=1-
where Qi (ТД)- appearance probability into to and-ohm element of for year k-го thermal source;
k is an ordinal number of thermal source;
m is amount of thermal sources, which can appear.
2.1. Strike of atmospheric electricity in object element, that analyses is possible either under object defeat by lightning (С1 event ), or at second its impact (С2 event ), or at skidding high potential (С3 event ). Qi Probability (ТИ1)( to digit of atmospheric electricity in and-м object element calculate on formula)
Qi (ТД1)=1- ,
where Qi (Cn) is a realization probability of any from causes, directed beneath:
Qi (C1) is a hitting probability object element and-го by lightning for year;
Qi (C2) is a probability of second lightning impact on object element for year;
Qi (C3) is a recording probability into object element of high potential for year;
n is an ordinal cause number.
2.2. Hitting object element i-th by lightning it is possible at joint realization of two events - straight thunderbolt (event t_{2}) and lack, of disrepair, irregular constructive execution or lightning transfer refusal (event t_{1}).
Qi (С1) probability is calculated by formula
Qi(C1) = Qi (t_{1})· Qi (t_{2}),
where Qi(t1) is a lack probability, of disrepair, irregular constructive execution or lightning transfer refusal, that sticks up for object element;
Qi (t_{1}) is a probability of straight thunderbolt in i-th element per year.
2.3. A Qi (t_{2}) Probability of straight thunderbolt into object calculate on formula
Q_{i}(t_{2})=1- (1)
where Nym is amount of straight thunderbolts into object for year;
t_{р} is a supervision period duration, year.
For objects of rectangular form
N_{ym}=(S+6H)(L+6H)n_{y}·10^{-6 }^{}(2)
For round objects
N_{ym}=(2R+6H)^{2}n_{y}·10^{-6}, (3)
where S is length of object, м;
L is an width of object, м;
Н is a max. height of object, м;
R is radius of object, м;
n_{y} is a middle number of thunderbolts on 1 км2 of earthly surface from table
Duration of thundery activity per year | 20-40 | 40-60 | 60-80 | 80-100 < |
Average lightning stroke number per year for 1 km^{2} |
2.4. Probability Qi(t1) is adopted even by units in the case of absence of earth protection on an object or at presence of errors at its planning and making. Conclusion about accordance of basic parameters of lightning-rod to the requirements, that are produced to the earth protection objects 1, 2 that to the 3th category, do on the basis of results of checking calculation and detailed inspection of lightning-rod. The basic requirements to the lightning-rods for objects 1, 2 and to the 3th category are laid out in SN-305-77-305-77. At presence of earth protection probability Qi(t1) is calculated by a formula
Qi(t1)=
where C_{0} - factor of safety;
t_{r }- period of time, that is analyzed, min;
t_{j }- time of existence of disrepair of lightning-rod during its j-y realization for a year, min;
b - probability of faultless work of earth protection b=0,995 at presence of earth protection type But also b=0,95 at presence of earth protection type;
m - amount of the defective states of earth protection.
For objects, that are designed, probability of error at planning of earth protection is not expected.
At computation of Qi(t1) existent earth protection violation of periodicity of verification of resistance of grounding (one time in two years) consider how finding of earth protection is in the defective state. Time of existence of these disrepair verifications is determined as duration between the planned and actual terms.
2.5. Probability of the Qi(C2) repeated influencing of lightning on an object is calculated on a formula
Qi(C2)= Qi(t2) Qi(t3) (4)
where Qi(t3) probability of refusal of the protective grounding is for a year.
2.6. Probability Qi(t_{3}) in default of the protective grounding or bridges in the places of rapprochement of metallic communications is adopted to even unit. Probability of the Qi(t3) disrepair of the existent system of protection from the repeated influencing of lightning is determined on the basis of results of its inspection like probability Qi(an) on a formula
Qi(а_{n})= (5)
where C_{d} - factor of safety;
t_{r }- period of time, that is analyzed, min;
m - amount of realization of an-y reason in the i-m element of object for the period of time, that is analysed;
t_{j }- time of existence of an-y reason of appearance of k-go type of combustible matter or other reason of occupation.
For objects, that are designed do not expect probability of disrepair of the protective grounding, and accept even to unit or zero depending on its presence in a project.
2.7. Probability of the Q_{i}(С_{3}) skidding of high potential in an object, that is on the defensive calculate like probability Q_{i}(C_{2}) by a formula (4).
2.8. Probability Q_{i}(t_{2})) at computation Qi(C_{2}) and Qi(C_{3}) is calculated on a formula (1), thus value of parameters S and L in (2) and (3) it is necessary to increase on 100 m.
2.9. An electric spark (arc) can appear in the element of object (event TD_{2}), that is analysed at the short circuit of the electric wiring (event e_{1}) during conducting of electric welding works (event e_{2}) at sparkling of electrical equipment, short of on implementation of category to the T group of combustible environment, that is found in this element (event e3) at the digits of static electricity (event e4). Probability Qi(TD_{2}) is calculated by a formula
Q_{i}(ТД_{2}) = 1 - Q_{i} (e_{n})],
where Qi (e_{n}) - probability of realization of any of the en reasons stated below, and;
Qi(e_{1}) - probability of appearance of sparks of short circuit of the electric wiring in an i-m element for a year;
Qi(e_{2}) - probability of conducting of electrical welding works in the i-m element of object for a year;
Qi(e_{3}) - probability of disparity of electrical equipment of i-go element of object of category and group of combustible environment for a year;
Qi(e_{4}) - probability of origin in the i-m element of object of digits of static electricity for a year;
z - amount of e_{n} reasons;
n - sequence number of reasons.
2.10. Calculate probability of Qi(e_{1}) appearance in the i-m element of object of spark of short circuit only for the operating elements of object and those, that are built, on a formula
Qi (e1) = Qi (v_{1})· Qi (v_{2})
where Qi(v_{1}) - probability of origin of short circuit of the electric wiring in the i-m element of object for a year;
Qi(v_{2})· - probability of absence or refusal of vehicles of protection from the short circuit for a year.
2.11.Probability Qi(v_{1})· short circuit of the electric wiring on operating objects and those, that are built, calculate on the basis of statistically given on (5).
2.12.Probability Qi(v_{2}) is calculated for the operating elements of object and those, that are built, like probability Qi(a_{n}) by (_{5}). For elements, that are designed, in default of vehicle of protection Q_{i}(v_{2}) adopt units to even, and at their presence calculate like probability _{Qi}(_{an}) on a formula, how probability of their refusal is
Qi(a_{n}) = 1 – R1(a_{n})= 1 – e-^{l}^{t},
where R1(a_{n}) - probability of faultless work of production education, that eliminates marketability an-y reason;
l - intensity of refusals of production education;
t - common time of work of the given education for the period of time, that is analyzed, year.
2.13. Calculate probability of the Qi(e_{2}) conducting in the i-th element of object of electric welding works only for the operating elements of object and those, that are built on the basis of statistic data on (5).
2.14. Probability Qi(e_{3}) during continuous work of electrical equipment is adopted on all objects even by units, if the electrical equipment does not answer a category and group of air-gas, or 10-8 - if answers. During periodic work of electrical equipment and his disparity of category to the group of combustible environment calculate probability Qi(e_{3}) like probability Qi(a_{n}) on (5) - If an electric spark appears only at the inclusion and shutdown of electrical equipment incongruous to the category and group of combustible environment (at the n inclusions and exceptions), probability Qi(e_{3}) is calculated like probability: Qi(t_{2}) on (1). In the case of accordance of electrical equipment of combustible environment, the calculated for (1) the value of probability Qi(e_{3}) is multiplied on 10-8.
2.15. Probability of Qi(e_{4}) appearance in the i-m element of object of sparks of static, electricity calculates on a formula
Qi(e_{4})= Qi(h_{1})· Qi(h_{2})
where Qi(h_{1}) - probability of appearance in the i-m element of object of terms for static electrization for a year;
Qi(h_{2}) - probability, presence of disrepair, absence or uneffective of facilities of defence from static electricity for a year.
2.16. Probability Qi(h_{1}) is adopted even by units, if in the i-th element of object apply and produce the matters with specific by a volume electric resistance, that exceeds 10^{5} Om·m. In other case Qi(h_{1}) accept even to the zero.
2.17. Probability Qi(h_{2}) is adopted even by units in default of or ineffective of facilities of defence from static electricity. Calculate probability of the Q_{i}(h_{2}) disrepair of facilities of defence in operating elements on the basis of statistical data like probability Q_{i}(a_{n}) on (5)
Probability Q_{i}(h_{2}) in the elements of object, that are designed calculate like probability Q_{i}(a_{n}) on (6) on the basis of data about reliability of facilities of protection from static electricity (for example, facilities of ionization or moistening of air and etc.).
2.18. Friction sparks (sparks of blow and friction) appear in the element of object (event TD_{3}), that is analysed, at application of spark-dangerous instrument (event f_{1}), at destruction of mobile knots and details (event f_{2}), at application by working of the shoe lined by the metallic printed fabrics and nails (event f3), at the hit in the mobile machineries of strange objects (event f4) and etc Probability Q_{i}(TD_{3}) is calculated on a formula
Qi(TD3)= 1 - Qi(fn)]
where in Qi(fn) - probability of realization of any of f_{n} reasonsstated below, and;
Q_{i}(f_{1}) - probability of application in the i-m element of object of intrinsically unsafe instrument for a year;
Q_{i}(f_{2}) - probability of destruction of mobile knots and details of i-go element of object for a year;
Q_{i}(f_{4}) - probability of hit in the mobile machineries of i-s element of object of strange objects flow of year;
n - sequence number of reason;
z - amount of fn reasons.
2.19. Calculate probability Q_{i}(f_{1}) only for the operating elements of object and those, that are built, on the basis of statistical data like probabilities Q_{i}(a_{n}) and Qi(t_{2}) by (5) or (1).
2.20. Probability Q_{i}(f_{2}) for operating and elements of object, that are built calculate on the basis of statistically given like probability Q_{i}(a_{n}) on (5).
For are designed elements of object of probability Q_{i}(f_{2}) calculate like probability Q_{i}(a_{n}) on (6) on the basis of parameters of reliability of his component parts.
2.21. Probability Q_{i}(f_{3}) is calculated only for operating and elements of object, that are built like probability Qi(an) on (5).
2.22. Probability Q_{i}(f_{4}) is calculated for operating and elements of object, that are built on the basis of statistical data like probability Q_{i}(a_{n}) on (5), and for elements, that are designed on (6), how probability of refusal of protective facilities is.
2.23. It is opened flame and spark appear in the i-th element of object (event TD_{4}) during realization to any of reasons of hn. Probability Q_{i}(TI_{4}) is calculated on a formula
Qi(TD4)= 1 - Qi(hn)]
where Q_{i}(h_{n}) - probability of realization of any of the reasons stated below, and;
Q_{i}(h_{1}) - probability of incineration of fuel in the stoves of i-th element of object during a year;
Q_{i}(h_{2}) - probability of conducting of fire works in the i-th element of object during a year;
Q_{i}(h_{3}) - probability of failure of the mode of smoking to observe in the i-th element of object during a year;
Q_{i}(h_{4}) - probability of absence or disrepair of spark-arresters on internal-combustion engines, located in the i-th element of object during a year;
n - sequence number of reason;
z - amount of f_{n} reasons.
2.24. Probability Q_{i}(h_{1}) is calculated for all elements of object by a formula
Q_{i}(h_{1}) = (7)
where t_{j}. - time of work of stove of i- go element of object at i-m its inclusion during the period of time, that is analysed, minutes;
m - amount of inclusions of stove during the period of time, that is analysed;
C_{0} - factor of safety, determination of which is laid out in chapter 4 of the work [6];
t_{r }- period of time, that is analysed, minutes.
2.25. Probabilities Q_{i}(h_{2}), Qi(h_{3}) and Q_{i}(h_{4}) calculate only for operating objects and those, that are built, on the basis of statistical data like probability Q_{i}(h_{1}) on (7).
2.26. Warmed the matters, separate knots and surfaces of technological equipment of i-th element of object, that contacts with a combustible environment, higher than possible temperature (event TD_{3}) is possible: as a result of overload of electric communications of machines and vehicles (event C_{1}); at the refusal of the system of cooling of vehicles (event _{C2}); at the promoted transitional resistances of electric connections (event C_{3}); as a result of origin of friction between two surfaces for lack of greasing (event C_{4}); after the terms of technological process (event C_{5}). Probability (TI_{3}) is calculated on a formula
Q_{1}(TD_{3})=
where Q_{1}(К_{n}) - probability of realization of any of the К_{n}reasons stated below, and:
Q_{1}(K_{1}) - probability of heating of combustible matter or surfaces of equipment of i-th element of object in case of beginning of overload of the electric system, machines and vehicles during an year;
Q_{1}(K_{2}) - probability of refusal of the system of cooling of vehicle of i-go element of object during an year;
Q_{1}(K_{3}) -probability of heating of surfaces and combustible matters in case of beginning of the promoted transitional resistances of electric connections of i-th element of object during an year;
Q_{1}(K_{4}) - probability of heating of surfaces at friction for lack of greasing in the i-m element of object during an year;
Q_{1}(K_{5}) - probability of heating of combustible matters in the i-th element of object to the dangerous temperatures after the terms of technological process during an year.
2.27. Probability Q_{1} (K_{1}) is calculated using the formula Q_{1}(K_{1})= ,
where Q_{i}(y_{m}) - probability of realization of any of the у_{m} reasons resulted below;
Qi(y_{1}) - probability of disparity of crossing of electro-explorers to loading of electro-receivers in the i-th element of object during an year;
Q_{i}(y_{2}) - probability of connecting of additional electro-receivers in the i-th element of object to the electric wiring, that is not counted on this loading;
Q_{i}(y_{3}_{) }- probability of increase of moment on the billow of electric motor in the i-th element of object during an year;
Q_{i}(y_{4}) - probability of lowering of tension in the network of i-go element of object during an year;
Q_{i}(y_{5}) - probability of absence, disrepair or disparities of vehicles of protection of electric networks of i-th element of object from the overload during an year.
2.28. Probability Q_{i}(y_{1}), Q_{i}(y_{2}) and Q_{i}(y_{4}) is calculated for operating objects only
Q_{i}(r_{2}) - probability of heating of matter, inclined to spontaneous combustion higher of safe temperature.
2.29. Calculate probability Q_{i}(y_{1}) for operating objects and those, that are built, like probability Q_{i}(h_{1}) on (7), and for objects, that are designed, like probability Q_{i}(a_{n}) on (6), how probability of wedging of machineries, that are set by an electric motor in motion.
2.30. Calculate probability Q_{i}(z) for the operating elements of object like probability Q_{i}(h_{1}) on (7), for elements, that are designed in default of vehicles the protection accept to even unit, and at their presence calculate like probability Q_{i (}a_{n) }on (6).
2.31. Probability Q_{i}(C_{2}) is calculated for the elements of objects, that are designed, like probability Qi(a_{n}) on (6), how probability of refusal of devices, that provide cooling of vehicle is, and for operating elements and those, that are built, like probability Q_{i}(h_{1}) on (7).
2.32. Probability Q_{i}(K_{3}) is calculated only for operating objects and objects being built, like probability Q_{i}_{(}h_{1}) on (7).
2.33. Probability Q_{i}(K_{4}) is calculated for the elements of objects, that are designed, like probability Q_{i}(a_{n}) on (6), how probability of the system of greasing of machineries of i-th element is, and for operating elements and those, that are built, like probability Q_{i}(h_{1}) on (7).
2.34. Probability Qi(K_{5}) is adopted even to unit, if according to a technological necessity there is heating of combustible matters to the dangerous temperatures, or zero, if such process does not take place.
2.35. Probability of Q_{i}(TД_{4}) appearance in the combustible matter or material of fire of exothermic oxidization or decomposition, that is led to spontaneous combustion, is calculated by a formula
Q_{i}(ТД_{4}) = 1 - ,
where Q_{i}(m_{n}) - probability of realization of any of the m_{n} reasons stated below:
Q_{i}(m_{1}) - probability of appearance in the i-th element of object of fire of thermal spontaneous combustion during an year;
Q_{i}(m_{2}) - probability of appearance in the i-th element of object of fire of chemical spontaneous combustion during an year;
Q_{i}(m_{3}) - probability of appearance in the i-th element of object of fire of microbiological spontaneous combustion during an year;
2.36. Probability Q_{i}(m_{1}) is calculated for all elements of object on a formula
Q_{i} (m_{1}) = Q_{i} (r_{1})· Qi (r_{2})
where Q_{i}(r_{1}) - probability of appearance of the matters in the i-th element of object during an year, which is inclined to hot spontaneous combustion;
Q_{i}(r_{2}) - probability of heating of the matters inclined to spontaneous combustion, higher than safe temperature.
2.37. Calculate probability Q_{i}(p_{1}) for all elements of the object using (7) or (6).
2.38. Probability Q_{i}(p_{2}) is adopted even to 1, if temperature of environment, in which this matter exists, higher or equal to the safe temperature, or to the zero, if temperature of environment is less than safe value. The safe temperature of environment for the matters inclined to thermal spontaneous combustion is calculated on a formula
t_{0} = 0,7 t_{c}
where t_{c} - temperature of spontaneous combustion of matter.
2.39. Probability Q_{i}(m_{2}) is calculated for all elements of object by a formula
Q_{i} (m_{2}) = Q_{i} (g_{1}) · Qi (g_{2})
where Q_{i} (g_{1}) - probability of appearance in the i-th element of object chemically active matters reactive between itself with the selection of a plenty of heat, during an year;
Q_{i}(g_{2}) - probability of contact chemically of active matters during an year.
Probabilities Q_{i}(g_{1}) and Q_{i}(g_{2}) are calculated like probability Qi(h_{1}) on (7), if realization of events _{of }g_{1 }and g_{2} is conditioned by technological terms or measures of organizational character and calculate like probability Q_{i}(a_{n}) on (6), if these events rely on reliability of equipment.
Probability Q_{i}(m_{3}) is expected only for operating and objects, that are built, like probability Q_{i}(h_{1}) by (7).
3. Probability Q_{i}(ЕД) of that energy (temperature) of thermal source is sufficient for inflammation of combustible environment, accept even to one or zero, depending on the results of comparison of parameters of thermal source with the proper indexes of fire danger of combustible environment.
If a temperature of thermal source higher than 80 % sizes of minimum temperature of spontaneous combustion of matter, adopt Q_{i}(ЕД) to even unit, in other case Q_{i}(ЕД) equals a zero. If temperature of thermal source (environments) higher after 80 % sizes of temperature of spontaneous combustion of matter, that feeds a weakness to thermal spontaneous combustion, adopt Q_{i}(ЕД) even to unit, in other case Q_{i}(ЕД) equals to zero.
If the case of occupation, called as ignition, will be realized, energy is the characteristic size of process of occupation that is passed by the source of ignition to the combustible matter. If the energy passed by a thermal source to the combustible matter (vapour, gas-, powdered mixture), higher after 40 % the value of minimum energy of ignition, adopt Q_{i}(ЕД) even to unit, in other case Q_{i}(ЕД) equals a zero.
For the hard and liquid combustible matters Qi(ЕД) accept even to unit, if in time of thermal source cooling it is able to warm the combustible matter higher than temperature of its inflammation, in other case Q_{i}(ЕД) equals a zero.
4. Probability Qi(ВИ) of that time of contact (existence) of thermal source with a combustible environment sufficient for his inflammation, accept even to unit, if a thermal source for this time will have time to warm a combustible environment to the temperature of occupation (spontaneous combustion, spontaneous combustion), or zero in other case.
4.1. At heating of combustible matter to the temperature, that exceeds 80 % from the size of temperature of spontaneous combustion, probability Qi(ВИ) is adopted even to unit, in other case Qi(ВИ) equals a zero.
4.2. At estimation of danger of thermal spontaneous combustion probability Qi(ВИ) is adopted even to unit, if a thermal source exists during time necessary for heating of combustible matter to the temperature of spontaneous combustion of matter. If time of existence of thermal source less from time necessary for heating of combustible matter to the temperature of spontaneous combustion, adopt Q_{i}(ВИ) to even to the zero.
4.3. At estimation of danger of forced ignition probability Qi(YOU) is adopted even to unit, if time of cooling of thermal source from an initial temperature to the temperature of inflammation of combustible environment, exceeds the sum of period of its induction and time of heating of local volume of this environment from an initial temperature to the temperature of inflammation. In other case Q_{i}(ВИ) accept even to zero.
4.4. The data about the fire danger parameters of thermal sources is given in Chapter 5 of the work [6].
5. At the ground of impossibility of computation of probability of Qi(ДЗ) appearance of source of ignition in the i-th element of object, that is examined, taking into account concrete his external environments, is assumed to calculate this parameter on a formula
Qi(ДЗ) = 1 - ,
where t_{nz=3,03·104} - mean time of work of i-go element of object to appearance of one source of ignition, hr;
E_{0} - minimum energy of ignition of combustible environment of i-th element of object, J;
t - time of work of i-th element of object for the period of time, that is analyzed, hours.
Other events, that lead ignition to appearance of source, are taken into account if necessary.
3.4.6. Choice of power equipment for the highly explosive & fire risk areas & apartments of POL (petroleum, oil, lubricants) storages
Safety of exploitation of electrical equipment, that is used in highly explosive & fire risk areas & apartments, is provided subject to the condition correct his choice, timeliness of review, repair and test. The explosion-proof equipment provides safety in explosive and highly explosive apartments and external options of depositories POL. It is classified and all-Union State Standard 12.2.020-76. is marked after the requirements
The explosion-proof electrical equipment depending on the level of implosion protection is distributed on the following:
- electrical equipment of the promoted reliability against the explosion, in which implosion protection is provided only in the set normal mode of his operations;
- explosion-proof electrical equipment, in which implosion protection is provided both at the normal mode of operations, and at the acknowledged reliable damages, that are determined by external environments, except for the damages of facilities of implosion protection;
- especially explosion-proof electrical equipment, which the additional facilities of implosion protection, foreseen by standards, are accepted in.
- explosion-safe electrical equipment for setting inwardly and outdoor the apartments has the following appearances of implosion protection:
- a shell, that wards off the explosion, maintains pressure of explosion into her and prevents distribution of explosion in an explosive environment;
- intrinsically safe electric chain, in which an electric digit or his heating can not inflame an explosive environment under given experiment conditions;
- implosion protection of «e» type consists in that in the electrical equipment which has not parts, that sparkle normally, accepted row of additional measures, which bother appearance of the dangerous heating, electric sparks and arcs;
- filling or blowing of shell under surplus pressure, which is carried out by clean air or rare gas, out;
- filling of shell by a butter or liquid incombustible dielectric;
- quartz filling of shell;
- special type of implosion protection, based on principles excellent from above than enumerated, but sufficient for providing of implosion protection.
The explosion-proof electrical equipment for the internal and external setting behaves to the group II, and equipment which has a explosion penetrative shell or intrinsically safe electric chain, in addition, to the sub-group IIA, IIB, IIC. For the equipment of group II temperature classes are set: T1 - maximum temperature 4500С, T2 - 3000С; T3 - 2000С, T4 - 1350С; T5 - 1000С, T6 - 800С.
Marking of implosion protection of explosion-proof electrical equipment of group II is disposed in a rectangle, in which is contained the following data:
- the sign of implosion protection level (for special explosion-proof electrical equipment - «0»; for explosion-proof electrical equipment - «1»; for the electrical equipment of the promoted reliability against the explosion - «2»);
- the sign E_{h}, which specifies that the electrical equipment answers ГОСТ 12.2.020-76;
- the sign of type of implosion protection (explosion-protected shell - «d»; intrinsically safe electric chain - «I»; protection of kind «e» - «e»; oily filling of shell - «O»; filling or blowing of shell under surplus pressure out - «r»; quartz filling of shell -«q»; special type of implosion protection - «s»;
- the sign of group or sub-group, one of the following - II, IIA, IIB or IIC;
- the sign of temperature class.
For example, the explosion-protected electrical equipment with the explosion-proof shell of the IIA sub-group temperature class ТЗ has marking
IExdIIAT3 |
The choice of electrical equipment for highly explosive areas of apartments of POL storages is made in accordance with Rules of the mode of electrical equipment ПУЭ-86.
Explosion-proof electrical equipment, which is used in chemically active, moist or dusty environments which can prang the isolation of electrical equipment, that are used in external options, choose from insomuch defense, that it was suitable for work outdoors, that is must be protected from the atmospheric influencing of rain, snow, sunbeams and etc.
Electric machines, that have defense of «e» type, are set on machineries that aren’t often overloaded, switched on and reversed. The explosion-proof electrical equipment saves the properties, if is found in an environment with the explosive mixture of those categories and groups, which implosion protection is foreseen for. It is assumed to use the electrical equipment in an environment with the explosive mixture attributed to the less dangerous categories and groups, at their proper equipment.
Setting of explosion-proof electrical equipment with the type of implosion protection of «filling or blowing of shell out under surplus pressure» is executed at the proper implementation of the vent system (with the devices of control of temperature, surplus pressure and other parameters), and also at the observance of requirements ГОСТ 22782-78 that the instructions on editing and exploitation of concrete electric machine or vehicle.
In explosive areas explosiveness of which is determined by combustible liquids (ГЖ), with the temperature of flash vapour higher after 61^{0}С the electrical equipment with any kind of protection for any categories and group with the temperature of heating of his surface can be used, that does not exceed the temperature of spontaneous combustion of combustible liquid.
Methodical Guidings
At designing the new equipment it is necessary to devise the measures providing its operating safety. The special attention should be turned on revealing of potentially dangerous and harmful factors. It’s necessary to study how the premises are divided on shock hazard of men. It’s necessary to stop on calculation of earthing, illumination while studying the technical actions of excluding or limiting influences on technical staff of dangerous and harmful factors. It is necessary to execute the rates of resistance of earthing devices. It is necessary to know the fire safety measures. Pay attention to calculation of fire probability to this end.
The important question under designing is the choice of electric equipment for dangerously-and-fire explosive zones. Study safety requirements of ГОСТ 12.2.020-76.
Technical maintenance of the new equipment should be conducted with safety requirements compliance, therefore it is necessary to make instructions to this equipment. It is necessary to know subdivisions of instructions, their contents.
References:
[1], [3], [4], [6], [7].