(1) Safety nets are essential personal protective equipment that directly affects both public safety and national property. Before production, the product quality must be inspected by a state-designated supervision and inspection department, and a production license is required. Every batch of safety nets must undergo inspection by the relevant authority before being shipped. Each net should have a certificate from the national supervisory department as well as an enterprise self-certification, clearly marked in different locations. Additionally, each safety net must bear a permanent label containing key information such as the manufacturer’s name, date of manufacture, batch number, material type, specifications, weight, and the production license number.

(2) Safety nets are categorized into flat nets (P), vertical nets (L), and dense-mesh safety nets (ML). The primary components of a safety net include side ropes, tethers, ribs, and netting ropes. A dense-mesh safety net consists of a net body, buckles, side ropes, and additional tethers. Key physical and mechanical properties determine the quality of safety nets, including the tensile strength of edge ropes, tethers, net ropes, and rib ropes. For dense-mesh nets, important characteristics include breaking strength, elongation at break, joint tensile strength, tear resistance, penetration resistance, retention of strength after aging, and flame-retardant properties of the eye-opening buckles. Both flat and vertical nets must have impact resistance. It is important to note that vertical nets cannot replace flat nets. The choice between them depends on construction requirements and the height of the load. Flat nets require higher load strength, use more materials, and are heavier than vertical nets. Typically, a flat net weighs over 5.5 kg, while a vertical net weighs over 2.5 kg.

(3) Given that safety nets are primarily used in open-air environments, they must be resistant to weather conditions. Common weather-resistant materials include nylon, vinylon, and polyester. All parts of the same net made from the same material should maintain consistent performance, with a wet-to-dry strength ratio of over 75%. The total weight of each net should not exceed 15 kg. Flame-retardant safety nets must not continue burning or smoldering for more than 4 seconds.

(4) The width of a flat net must be no less than 3 meters, while the width of vertical and dense-mesh safety nets must be at least 1.2 meters. The length of each tether should be no shorter than 0.8 meters. The spacing between tethers should not exceed 0.75 meters, and for dense-mesh nets, the distance between tethers should not be more than 0.45 meters. Additionally, the distance between the safety net and the supporting structure should be at least 0.3 meters. Safety nets can be hand-knotted or machine-knotted. Machine-knotted nets can be either knotted or knotless, with knotless knots generally offering higher strength. All knots must be securely fastened to prevent movement, which could lead to mesh expansion and uneven rope lengths. Such issues may cause stress concentration and eventually result in rope failure.

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