National standards and the selection rules and the use of specification of the safety net 
 The safety net is a labor protective equipment, injury prevention and fall very wide scope, mostly used for a variety of work at heights. Fall height operating risks, and often occurs on the shelf, roof, windows, hanging, pit, deep grooves, etc.. Fall the degree of injury vary with the size of the fall distance, ranging from disability, while in the death. The safety net protection principle is: the flat screen role is to block the fall of persons and objects, to avoid or mitigate the fall transitive strike damage; established network is to prevent the fall of persons or things. The net force strength must withstand the weight and the distance from the longitudinal tension in the human body and carry tools or objects have fallen, the impact strength. 
 (A) the quality check of the safety net 
 (1) The safety net is a special labor protection articles involving state property and personal safety, supervision and inspection department of the quality of their products must be designated by the state inspection and to obtain the production license before production. Each batch of safety net factory, must have the supervision and inspection department of the inspection report. Each safety net should be national supervision departments in different locations, accompanied by inspection certificates and corporate self-test certificate. At the same time there should be signs, signs should be permanent signs, sign content should include: name of manufacturer, date of manufacture, batch number, material, specifications, weight and production license number. 
 (2) The safety net is divided into the flat screen (P), Legislative Network (L), dense mesh safety net (ML). Safety net from the edge of rope, tether, tendons, rope, net rope. Dense mesh safety net of mesh buckle, side rope and attached tether. Safety net for physical and mechanical properties, is to distinguish the merits of the main indicators of the quality of a safety net. Its contents include: side rope, tether, net, rope, tendons, rope breaking strength. Dense mesh safety net: breaking strength, breaking elongation, and seam tensile strength, tear strength, resistance to cross-cutting, breaking strength retention after aging, opening the eyes to buckle strong tail flame retardant properties. The flat screen and the network should have impact resistance. Established network can not replace a flat screen, according to the construction and load height to distinguish between flat screen or stand net. Load strength of the flat screen is greater than the vertical network, with more materials, weight is greater than the Legislative Network. Under normal circumstances, the flat screen greater than 5.5kg, the established network is greater than 2.5kg. 
 (3) safety net for the use of open workplace. So, you must have a resistance to weathering. Weatherproof material nylon, polyvinyl alcohol, and polyester. The materials used should be the same with a net, its wet and dry strength ratio should be greater than 75%, the total weight of each net is no more than 15kg. Continued burning, smoldering time of the fire-retardant safety nets shall not exceed 4s. 
 (4) flat screen width is not less than 3m, the width of the established network and a dense mesh safety net of not less than 12m. The tether length is not less than 0.8m. Tether and tether pitch of the safety net should not exceed 0.75m. Dense mesh safety net tether and tether pitch should not be greater than 0.45m, the distance between the tendon rope safety net may not too small, the general provisions in more than 0.3m. The safety net can be divided into hand-plaited and mechanical plaiting. Mechanical plaiting can be divided into a knot plaited and knotless plaiting. In general, no webs knot strength than webs knot strength. Network node and the section head must be firmly fixed, shall not be moved, to avoid the increased mesh and side length uneven. The above scenario, will lead to stress does not concentrate until the fracture of the net rope. 
 Use 
 1, below the site of work at heights must be linked to a safety net;, you must set a safety net increased gradually with the wall when the building height is more than 4m, after intervals of 4m to set a fixed safety net; outer frame bridge frame , on, under the hole must be a safety net. Safety net should be erected where low outside the high level of spending part of the poor in general about 5Ocm; rod pieces without breaking, bending; within the network edge and the wall gap to less than 15cm; net the lowest point below the surface distance In the 3m. Security grid set