Why it take long time for the safety device to cut off the gas when the flame is out ?

Poor quality safety device.--- If the safety device is not good quality, the spring of the solenoid valve does not return to its original position or the coil of the solenoid vale is burnt. It will take long time for the safety device to cut off the gas . CHEFF pay much attention on the safety of the gas hob, all the safety device we used are high quality types. The safety device can cut off the gas in 5-15 seconds . It much less than the universal standard .