Where is it stipulated that cell phones are not allowed in gas stations?

Gas stations belong to fire and explosion places with high oil and gas concentration. When mixed with air, it will form explosive gas. When the concentration of mixed gas reaches the explosion limit, it will deflagrate when it meets an open flame. As long as the mobile phone is turned on, it should contact the base station at regular intervals to find the signal source. At this time, pulse current and RF spark will be generated. Therefore, it is not safe to answer the phone at the gas station as long as the phone is turned on. According to the regulations, a safety warning sign prohibiting the use of mobile phones will be hung in the gas station to remind customers not to use mobile phones. It's a serious violation of the regulations for gas station operators to use mobile phones. Light is dealt with, heavy is fined, and heavy is dismissed. Both PetroChina and Sinopec have anti-violation regulations and safety instructions for entering the station, as well as regulations prohibiting cell phones.