ASTM F1506 (Standard performance specification for textile materials used in protective clothing worn by electrical workers exposed to instantaneous arcs and related thermal hazards)

ASTM F1506 has developed performance specifications for flame-retardant textile materials used in clothing for electrical workers exposed to instantaneous arcs and other thermal hazards. The relevant requirements of ASTM F1506 protection include vertical combustion method ASTM D6413 (new material after washing) and arc rating.

In addition, the standard requires that the fabric is not easy to be ignited or can contain combustion and extinguish itself after being ignited. The flame retardant performance is tested by the FTM5903.1 vertical burning method (the maximum length of damage after being exposed to the flame for 2 seconds is about 15 cm). The arc rating is assessed by ATPV value or EBT value after passing ASTMF1959 test.

NFPA70E electrical safety requirements standard in working environment: The latest version of the NFPA70E standard published by the National Fire Protection Association in 2004 contains all aspects of safe electrical rules in the working environment of various industries. NFPA70E recommends that in the case of arc generation, arc protection and flame-retardant personal equipment must meet the performance standards of ASTMF1506, ASTMF1891 and ASTMF2178 when used, and the revised version requires companies to conduct arc hazard analysis in advance to determine arcs. Safety boundaries. The standard is set in order to protect employees within the arc safety limits, and protect employees by using protective clothing with the ATPV value of the corresponding hazard risk classification. The unit of ATPV value is cal/cm2, which represents the arc thermal protection value, which is used to reflect the maximum protection performance of arc protection materials, especially arc protection clothing.

NFPA70E sets safe electricity standards for workers working near live equipment, regulates and designs necessary steps to prevent serious injuries caused by arc accidents. According to NFPA70E regulations, every person working within the arc safety limit (the energy released within this range is greater than 1.2cal/cm2) must be competent and wear appropriate flame-retardant arc-proof clothing. NFPA70E divides the hazard risk classification into 0~4 levels to represent different hazard levels.

The minimum risk level is the burn caused by the energy of 4cal/cm2 from the arc explosion, which is the hazard classification of NFPA70E. In order to be adequately protected in the event of an arc explosion, workers must wear thermal protective clothing with an ATPV certified by NFPA not less than Grade 4. Another important rating of arc protective clothing is the HAF rating. HAF stands for thermal attenuation coefficient, which represents the size of the fabric to prevent heat.

ASTMF1891 standard specification for arc-proof and flame-retardant raincoats: This standard applies to flame-retardant and waterproof materials for raincoats. Flame-retardant coatings or laminated fabrics can be used to produce clothing. Its flame retardancy is measured by ASTMD-6413 vertical combustion method, ATPV value also needs to be recorded. Measure 5 times by ASTMF1959 arc thermal performance test method and select the smallest ATPV value to record.

What is an arc

Arc injury generally refers to the arc thermal burn caused by the huge arc heat generated by electricity when the air is ionized when the human body is not in contact with current. Other electrical injuries are often caused by Destructive damage to internal and external human tissues caused when the human body is directly exposed to power current.

Under normal circumstances, what people know more about is accidental electric shock. In fact, the more dangerous thing in the power industry is the hidden arc damage. The arc hazard is often different from other electrical injuries. It is often negligible and difficult to avoid without contact.

Incidental arc event is defined as a non-subjective and unexpected accident. Compared with deflagration, occasional arc accidents are more common. Arc accidents are very rapid. Because safety devices such as circuit breakers are automatically triggered when an accident occurs, the arc duration is often less than 1 second.

The total energy produced by the arc may be more than 3 to 4 times that of a serious deflagration accident. This high energy intensity acts on a small area of ​​the skin in a short period of time and may have a fatal impact on nearby workers. Another significant difference is that deflagration is visible to the naked eye, because smoke is produced during deflagration, half of its heat energy is transferred by convection (flame), and half is transferred by radiation. As for the heat formed by the arc, more than 90% is radiant heat, which means that even if the arc does not produce flames or produces a small amount of flames, it will cause serious damage.

The heat generated by the arc can ignite or melt the protective clothing of workers, which can cause the clothing to crack and cause serious damage to the skin. Burns can be divided into three categories: first-degree burns are painful and the skin is red, but no blisters are formed; second-degree burns are blisters formed on the skin, and the epidermis must be regenerated; third-degree burns will completely destroy the epidermis, and the skin itself cannot be regenerated, forming knots. Scar tissue.

Arc protective clothing must have permanent flame-retardant properties. When exposed to an electric arc, it must not melt or ignite, continue to burn, and must not crack. It can isolate the heat of the arc. Many daily work clothes can be ignited and burned, increasing the burn range of workers. Fabrics that are easily ignited include cotton, viscose, and wool, and fabrics that can be ignited and melted include polyester and nylon. In an arc accident, protective clothing cannot protect against a large amount of thermal energy, which can cause severe burns or even death. Therefore, protective clothing made of heat-resistant and flame-retardant fibers should be used to improve the level of protection against arc hazards.

Note: Level 0 has been deleted in th