1, vertical spacing: measured according to specified conditions, its value should be between 25 and 50 mm.

2. Horizontal spacing: measured according to specified conditions, its value should be between 5 and 20 mm. ..

3. Wear height: measured according to specified conditions, its value should be between 80 and 90 mm. ..

Second, the size of the hoop: divided into the following three numbers:

1, trumpet: 5 1-56cm

2, medium: 57-60cm

3. Large size: 6 1-64cm

4. Weight: a complete helmet, the weight should be reduced as much as possible, not more than 400G.

5. brim size: minimum 10mm, maximum 35mm. The inclination of the brim is 20-60.

6. Ventilation holes: Both sides of the helmet can be provided with ventilation holes.

7. Sun visor: minimum10mm and maximum 55mm. ..

8. Color: The color of safety helmet is generally light or eye-catching color, such as white and light yellow.

Under the three conditions of high temperature, low temperature and water immersion, the impact test was carried out with a 5Kg steel hammer falling from the height of 1m, and the maximum impact force on the head mould should not exceed 4900 N (1n = 1kg m/s, even if an object with a mass of1kg obtains/kloc-. The experiment was carried out with a steel cone weighing 3 kg falling from the height of1m. The steel cone shall not contact with the head mold, and the fragments of the cap shell shall not fall off.

According to the national standard, the safety helmet should meet the requirements of GB 281-2007 "Safety helmet", and the selection of safety helmet should meet the requirements of GB/T 3004 1-20 13 "Selection standard of safety helmet for head protection".

Extended data

Protective mechanism of safety helmet:

(1) Buffer and shock absorption: there is a gap of 25~50mm between the cap shell and the cap lining. When an object hits the helmet, the cap shell will not directly affect the top of the head due to stress deformation.

(2) dispersed stress: the cap shell is oval or hemispherical with smooth surface, so when the object falls on the cap shell, it can't stay, but immediately slides down; In addition, the force borne by the impact point of the cap shell is transmitted to the surroundings. More than 2/3 of the force can be reduced through the cushioning of the cap lining, and the rest of the force is transmitted to the human skull through the area of the cap lining, so that the focus becomes the focus plane, thus avoiding the stress concentration of the impact force at a certain point of the cap shell and reducing the force per unit area.

(3) Biomechanics: It is stipulated in the standard that the helmet must be able to absorb 4 900N N. This is because in biological tests, the human cervical vertebra will exceed the maximum limit when stressed, and the cervical vertebra will be injured, which may lead to paralysis or life-threatening.

Baidu Encyclopedia-Safety helmet standard

Light. Com- a "safety helmet" that gives a safety alarm when it is touched.

Baidu encyclopedia-safety helmet