The national standard GB/T17876-1999 specifically specifies the detection problems of this plastic anti-theft cap, such as the cap open torque, thermal stability, drop resistance, leakage and sealing performance. Among them, the sealing performance and the evaluation of the plastic cap opening and tightening torque are effective ways to solve the sealing performance of plastic anti-theft caps. Depending on the use of the plastic cap, there are different rules for the measurement method without the gas cap and the gas cap.

   The sealing plastic cap (without gas cap) needs to cut the plastic cap and closure to remove the anti-theft ring (bar), which is used for sealing with a rated torque of not less than 1.2 NM, tested with a sealing tester and pressurized to 200 kPa, hold the pressure under water for 1 minute to observe whether there is leakage or tripping, breathable plastic cap (gas cover) is pressurized to 690kPa, keep the pressure under water for 1 minute, observe the leak, and then increase the pressure to 1207kPa, finally hold pressure for 1 minute and observe if the plastic cap is tripped.