What is a Hard Hat?

A hard hat is a hat that protects a person's head from injuries caused by falling objects and other specific factors. The safety helmet is composed of a hat shell, a hat lining, a chin strap and accessories. ^[1]

The safety helmet is composed of a hat shell, a hat lining and a chin strap.

(1) Hat shell: This is the main part of the helmet, and generally adopts an oval or hemispherical thin shell structure. This structure, in

(1) Shock absorption: There is a gap of 25 ~ 50mm between the cap shell and the lining. When an object hits the helmet, the cap shell does not directly affect the top of the head due to force deformation.

(2) Dispersion of stress: The cap shell is oval or hemispherical, and the surface is smooth. When the object falls on the cap shell, the object cannot stay and slide down immediately; and the force of the cap shell's impact point is transmitted to the surroundings. The reduced force through the cushioning of the cap lining can reach more than 2/3, and the remaining force is transmitted to the human cranium through the moving area of the cap lining, so that the force point becomes the force surface, thereby avoiding the impact force on the cap shell. Stress concentration at a point reduces the stress per unit area.

(3) Biomechanics: The standard stipulates that the helmet must be able to absorb 4 900N. First, this is because of the biological test, the maximum limit of the human cervical spine under stress. If this limit is exceeded, the cervical spine will be injured, and the milder will cause paralysis The severe ones are life-threatening. ^[2]

Hard hat products are divided into two categories: general work (Y) hard hats and special work (T) hard hats, of which T is divided into five categories:

T1 is suitable for working places with fire sources;

T2 is suitable for underground, tunnel, underground engineering, logging and other operating sites;

T3 category is suitable for flammable and explosive working places;

T4 (insulation) is suitable for live working places;

T5 (low temperature) is suitable for low temperature work places.

Each safety helmet has certain technical performance indicators and applicable scopes, so when choosing the appropriate products according to the industry and operating environment used, consumers can choose the appropriate variety according to the industry and operating environment used. For example, the construction industry generally chooses class Y helmets; in the power industry, because it contacts the power grid and electrical equipment, it should choose a T4 (insulation) helmet; when operating in a flammable and explosive environment, it should choose a T3 helmet.

The choice of the color of the helmet is relatively arbitrary. Generally, light or eye-catching colors are suitable, such as white and light yellow. It can also be selected according to the requirements of relevant regulations, selected in accordance with the principles of safety psychology, and selected by department. Select according to the workplace and environment.

(I) General requirements

(1) The cap hoop is straightened according to the applicable range.

(2) The forehead area of the headband should be sweat-absorbent or increase the width of the band, and its width should be greater than or equal to the width of the headband.

(3) The lacing shall be made of soft textiles, a belt with a width of not less than 10mm or a rope with a diameter of not less than 5mm.

(4) Do not use toxic and harmful materials, and materials that contact human parts must not cause allergic irritation to the skin.

(5) The aging resistance of the material should not be lower than the date indicated on the product identification. During normal use, the helmet must not cause performance below the standard due to material reasons. All materials used should have the same life expectancy.

(6) The helmet attachment must not destabilize the helmet during normal wearing.

(7) Weight (mass): ordinary hard hat does not exceed 430g; cold hard hat does not exceed 600g.

(Two) basic performance

(1) Impact absorption performance: According to the prescribed method, the impact test is performed after pretreatment at high temperature, low temperature, water, and irradiation, and the force transmitted to the head mold does not exceed 4900N; there should be no chipping of the cap shell.

(2) Puncture resistance: The puncture test is performed after high temperature, low temperature, water immersion, and irradiation pretreatment according to the prescribed method. The steel cone does not contact the surface of the head mold; the cap shell must not have debris falling off.

(3) The strength of the mandibular band: according to the prescribed method, the force value when the mandibular band is broken should be 150 ~ 250N.

(Three) special properties

(1) Electrical insulation performance: tested according to the prescribed method, the leakage current does not exceed 1.2mA.

(2) Flame retardant performance: tested in accordance with the prescribed method, the afterflame time shall not exceed 5s, and the cap shell shall not burn through.

(3) Lateral rigidity: tested according to the specified method, the maximum deformation does not exceed 40mm,

Hard hat products are products licensed by the state. There are more than 100 companies that have obtained licenses. There are many types of products. How to choose and use them properly?

1. Should choose qualified products

Hard hats must be produced in accordance with the national standard GB2811. Products shipped from the factory must pass the quality inspection department to meet the standard requirements before being issued a product certificate. When purchasing a hard hat, you should see whether you have a production license and a validity period.

2. Choose the right variety

(1) Selection according to the performance of the helmet: each safety helmet has certain technical performance indicators and its scope of application.

(2) Choice of style, big brim hat and big bonnet are suitable for open-air operation. This helmet has the function of preventing sun and rain. The small brim hat is commonly used in indoors, tunnels, culverts, wells, forests, scaffolding. The first-class range of activity is small, and the narrow place is prone to collision with the brim.

(3) Regarding the color of safety helmets, the principles of safety psychology should be followed. Internationally more commonly used yellow and black bars are warning signs, red is a sign indicating restrictions and prohibitions; blue is used for display. Therefore, it is advisable to use white, light yellow, and light green for the helmets used in ordinary trades. For mining helmets, coal mines are accustomed to using black colors. This may not be visible because coal dust is black and stained, while other colors are easily noticeable. However, the use of black miner hats is obviously not in line with safety ergonomics. Because the lighting in the mine is poor, black miner hats are prone to safety accidents due to blurred vision when the light-dark contrast is not obvious, so bright colors should be used for easy discovery Be alert. The color of the miner's hat is other than black, and it is glued on the helmet

A suitable and qualified helmet is selected, and it should also be used correctly to play the role of the helmet and ensure the safety of using Lei. Pay attention to the following principles when using a helmet:

(1) Before wearing, check whether the accessories of the helmet are damaged, whether the assembly is firm, whether the adjustment part of the cap lining is tight, whether the socket is secure, whether the strap is fastened, etc., if the distance between the cap lining and the shell is not Between 25 and 50mm, apply the top rope wither to the specified range. Make sure all parts are in good condition before using.

(2) Adjust the length of the cap hoop to a suitable position (moderate tightness) according to the size of the user's head. The helmet worn by aerial workers must have a chin strap and a rear neck hoop and be fastened to prevent the cap from falling off. Take off.

(3) After the helmet is subjected to a large impact during use, it should be discontinued and replaced with a damaged helmet regardless of whether there is any obvious crack or deformation in the shell. The life span of general helmets does not exceed 3 years.

(4) The helmet should not be stored in places with acid and alkali, high temperature (above 50 ° C), sunlight, humidity, etc., to avoid heavy objects from being squeezed or punctured by sharp objects.

(5) The cap shell and the cap liner can be washed with cold water and warm water (below 50 ° C), and should not be baked on a radiator to prevent the cap shell from deforming. ^[2]