Electrical test is the purpose of the introduction to -- test fire risk assessment on fire risk
Fire hazard testing is the purpose of the evaluation of fire risk. First we distinguish the following two commonly used terms: fire hazard and fire risk. Fire danger refers to fire damage life river (or) potential ability of damaging property. The probability of fire risk refers to the fire.
In order to better understand fire dangerous experiments, we know about the basic knowledge about first.
Often understood as a fire in the different material and different situations or during the processing of the possibility of development, it depends largely on the use of material and material combustibility.
Combustibility is mainly refers to material and components, materials, mixture combustion independently. The fire hazard is a broad concept, it contains the combustibility, and considering the existence condition of the combustible mixture and the development of ignition process and other factors. Therefore correctly evaluating materials, processes or production units of the whole fire risk, to take preventive measures and formulation of fire fighting and rescue work plan has the very vital significance. However, to determine the fire danger index is an extremely complex problem, there is no a unified approach to determine the indicators. Electrical and electronic products fire test is an evaluation to the product material combustibility.
Due to fire risk includes not only the concept of material itself tend to burn ability, but also related to material of the state, namely the fire risk not only associated with the ability of material is on fire, and with the combustion process and combustion phenomenon associated (generated smoke, toxic) intensity, also related to the termination to the difficulty of the combustion process. To assess fire risk degree, therefore, must be based on quantitative parameters associated with these processes, however, these quantitative is not constant, and the fuel properties, their existence state, environment temperature, the concentration of the fuel and oxidant, storage conditions, as well as the system is closely related to the factors such as heat dissipation capacity, these parameters have considerable difficulty, therefore in the burning test for material status of the experimental conditions are clear rules is presented.
Fire hazard material or substance is the most common index of combustion performance.
Generally divided into can burn, and difficult to burn the burning of three types, material is qualitative classification based on after lead fire and evacuation under fire burning ability.
Combustible material is refers to under fire is burning, and removed after ignition source can still burning material on its own. This kind of material is divided into easy to fire and difficult to fire.
Difficult to burning material refers to the ignition source under the action of heat can catch fire, but after the ignition source, removed not burning material itself. It should be pointed out that flame retardant and burning material fire risk evaluation index has a lot to do with its state of aggregation.
Continued when heated to 900 ℃ still cannot be burning substance is considered is burning. But some of burning material under certain conditions there is a fire risk. Common has the following categories:
1, oxidant, such as potassium permanganate KMn04, nitrate HN03, oxygen, peroxide, etc.;
2, the water precipitation reaction of combustible gas substances, such as calcium carbide (commonly known as calcium carbide), metal phosphide, metal hydrides;
3, heat is easy to generate high-pressure compressed gases and liquefied gases, as well as the instability of thermal decomposition gas substance;
4, the water react to emit a large amount of hot material, such as lime CaO.
Electrical and electronic product fire hazard classification experiment
Test electrical and electronic products, the best way to fire danger is real to now existing in the actual conditions, but in most cases, this is not possible. Best according to the reality, therefore, to simulate actual effect as real as possible fire danger test for electrical and electronic products. Fire danger test is divided into four kinds, see the table below:
Fire danger test types
Fire simulation test
Fire test
Fire response test
Basic performance test
Test object
Electrical and electronic products
Products or parts
The standard sample
material
Test purpose
Evaluation and the use of the product have contact some aspects about the dangers of fire.
Evaluation of products or parts under the condition of the provisions of the fire exposure, within the prescribed period of time to keep the ability of all sorts of practical functions.
Check standard specimen under prescribed conditions, responding to the fire, in most cases, is used to give the combustion state related data and used to compare the performance of evaluation, such as flaming, still smoke, flame buy rate, and the close degree, the products of combustion, heat release rate.
To ensure that the measurement of physical or chemical properties of materials is given at least can approximately be restricted in technology and has nothing to do with the test method of the information, this performance entry calorific value (heat of combustion), thermal conductivity, melting point, heat of vaporization, and such as flash point, ignition point and natural temperature, etc.
Common light-off electrical and electronic products
Phenomenon cause secondary effects temperature anomalies
Note: some products during normal operation of fever
A) wire overload;
B) joint defective link (bad);
C) leakage current (insulation damage and fever);
D) components, internal parts or associated systems (such as ventilation) failure;
E) mechanical deformation cause electric contact failure or insulation structure.
F) thermal aging prematurely.
A) at the start of the protection device j, no action (except for special protection object). After unstable for a period of time, possible protection device
B) the temperature rising. Sometimes very slow; Near the product set of ripe and emissions, and thus, burning together form a fire;
C) easy to tender aggregation and diffusion of gas in the air can cause a fire or explosion. Especially in the air tightness equipment.
A short circuit
A) direct contact with the different potential of charged parts (terminal loose, loose guide electricity body, conducting foreign objects into the, etc.);
B) some components for its insulation impedance change gradually degradation
C) components or the sudden failure of the internal parts.
A) 3 "protection device:
B) the temperature of the local place after a very short time rise significantly
High;
C) may send out light, smoke, flammable gas;
D) released a variety of hot material.
Accidental electrical discharge and arc
Note: during normal operation of certain products in produce electric arc and spark.
A) equipment external causes (grid system overvoltage, accidental leakage or mechanical action make charged parts touch together, and so on);
(b) the internal reasons of the on-off switch some components gradually deteriorating HeJinRen moisture);
C) components or internal parts failure accidentally.
A) protection 3 "is not necessarily actions;
B) may shine, a flammable gas, and come up to the fire; Light-off considerable risk in explosive atmosphere;
C) the surrounding components or gas may be local light-off.
1) any of the three phenomenon is produced by a mechanical deformation and structure change can lead to two other accidents.
2) listed in the table are the most frequently encountered situation, the cause of the permutation order and has nothing to do with the frequency of such importance.
3) protection device can be temperature, mechanical, electrical or electronic.
