15 minutes. According to the inquiry of official website of Southwest University of Science and Technology, the library of Southwest University of Science and Technology swiped the card repeatedly within 15 minutes. If you can't swipe your card into the library on time within 15 minutes after the appointment is successful, the appointment will be cancelled and you need to make a new appointment. After the reservation is successful, you need to swipe your card into the library within 15 minutes. If you swipe your card out of the library, you need to make a new appointment. If you don't swipe your card when you leave the library, you can't make an appointment again. You need to swipe your card at the exit before you can cancel the reservation authority. If you can't swipe your card into the library on time within 15 minutes after the appointment is successful, the appointment will be cancelled and you need to make a new appointment.