GB/T 26950.1-2025Explosion-proof industrial trucks - Part 1: Battery industrial trucks (English PDF)

4.2.1 Surface temperature

4.2.1.1 General requirements The maximum surface temperature shall be lower than the minimum ignition temperature of the explosive gas atmosphere present in the vehicle's operating environment. Heat insulation measures shall not be used to reduce the surface temperature of components. non-metallic materials (e.g., rubber). The stainless steel shall contain no less than 16.5% chromium and no more than 0.07% carbon by mass. -- Class IIC vehicles. The working equipment shall be made of copper-zinc (brass), copper, or stainless steel, or coated with copper-zinc (brass), copper, stainless steel, or non-metallic materials (e.g., rubber). The stainless steel shall contain no less than 16.5% chromium and no more than 0.07% carbon by mass. The aluminum by mass in the above materials shall be less than 10%. -- For vehicles used in environments containing acetylene. If the coating material is made of copper or a copper alloy, it shall comply with the provisions of

8.5 of GB/T 3836.1-2021. The coating of the working equipment shall allow for easy inspection of wear and cracks in critical locations of the forks. Appendix A provides typical examples of the coating of the working equipment.

Note. The classification of IIA, IIB, and IIC is given in

4.3 of GB/T 3836.1-2021.

4.2.2.2 Moving parts The seals shall comply with the provisions of

5.3 in GB/T 3836.29-2021. The bearings shall comply with the provisions of

5.7 in GB/T 3836.29-2021. The gap between unlubricated moving parts and stationary parts shall be designed to prevent ignition of hot surfaces or mechanical sparks caused by friction. Moving parts requiring lubrication shall comply with the provisions of 5.3.3, 5.4, or

5.6.3 in GB/T 3836.29-2021.

4.2.3 Static electricity

4.2.3.1 Potential equalization 4.2.3.1.1 General requirements All conductive and dissipative parts shall be connected to the chassis to maintain electrical potential equalization. Note

1.Conductive parts, for example metal parts or conductive plastic materials, with a surface resistance not greater than 104 Omega. Note

2.Dissipative parts, for example plastic materials with a surface resistance in the range of 104 Omega ~ 109 Omega when measured at 50% relative humidity, or with a surface resistance not greater than 1011 Omega when measured at 30% relative humidity, with a test voltage of at least DC (500 ± 25) V. If metal parts are securely fixed and have good electrical contact with the chassis, a separate conductor connection to the chassis is not required. This requirement also applies to components installed on the vehicle (for example. lamps, weighing equipment, attachments, side shifters, or bucket clamps, etc.). 4.2.3.1.2 Insulated metal parts For insulated metal parts with a maximum permissible capacitance not exceeding the following values, they may not be connected to the chassis if a high-efficiency electrostatic generation mechanism does not occur.

a) Class IIA. 10 pF;

b) Class IIB. 10 pF;

c) Class IIC. 6 pF. If insulated metal parts are likely to be subject to a high-efficiency electrostatic generation mechanism or if their capacitance exceeds the above specified value, such parts shall be connected to the chassis. Insulating bolts and nuts with a size not exceeding M6 may be left unattached to the chassis.

4.2.3.2 Earthing To prevent the accumulation of electrostatic charge, the vehicle earthing resistance shall not exceed 106 Omega, and shall be achieved through any of the following methods. -- Install at least two conductive wheels; -- Install at least two earthing straps (the distance between the earthing straps shall be as large as possible, and they shall extend as far as possible into the ground and make contact with it); -- Install at least one conductive wheel and one earthing strap. The chassis shall be permanently and reliably earthed, and the number and location of conductive wheels or earthing straps shall be clearly and permanently marked on the chassis.

Note. During normal operation, conductive wheels and earthing straps may become contaminated. Loss of conductivity can be prevented by installing two or more conductive wheels or earthing straps, or by using a combination of conductive wheels and earthing straps.

4.2.3.3 Wheels

a) The surface resistance shall not be greater than 109 Omega at 50% relative humidity, or not greater than 1011 Omega at 30% relative humidity, and shall be connected to the chassis.

b) Dangerous electrostatic charges shall not be generated by means of dimensions, shape and layout, or other protective methods.

c) The surface area of a single non-conductive part shall be limited to no more than 100 cm2 (for Class IIA and Class IIB) or 20 cm2 (for Class IIC). If the part is surrounded by and in contact with a conductive frame, the surface area may be four times the above values; if the long opposite sides of the part are surrounded by and in contact with conductive strips, the surface area may be twice the above values. The conductive frame and conductive strips shall be connected to the chassis.

d) If non-conductive parts are close to each other or the contoured surface has similar exposed parts, the surface area shall comply with the dimensions given in c), and the depth of the grooves between exposed surfaces shall not be less than 3 mm, and the width of the grooves shall not be less than 1 mm.

e) The width of exposed non-conductive parts shall not exceed 30 mm (for Class IIA and Class IIB) or 20 mm (for Class IIC), and the depth of the grooves between contoured surfaces shall not be less than 3 mm, and the width shall not be less than 1 mm.

f) If non-conductive materials are coatings on grounded metal or conductive surfaces, the coating thickness shall not exceed 2 mm (for Class IIA and Class IIB) or

0.2 mm (for Class IIC). Appendix B provides typical examples of the non-conductive surface areas specified in

d) and e). If the risk of electrostatic discharge ignition cannot be avoided by design, the marking shall conform to the symbol "X" specified in

11.2 l) of GB/T 3836.28-2021 and the warning sign specified in

11.3 of GB/T 3836.28-2021.