Abstract
The ventilation system is important in underground mines, because the system flows clean air into the mine. If this system is not done or not as it should be, it will cause insecurity and discomfort in the hole. Lubang Pendidikan is a learning facility that has been provided by PT. Bukit Asam Tbk UPO, visitors can learn how to mine well underground, educational pits using a suction ventilation system and using a 2 x 50 Hp fan machine. So a calculation is needed to find out the number of visitors who can enter in safe and comfortable conditions in the hole. Air quantity and quality are parameters that must be known to determine the number of visitors who can enter the hole, air quantity consists of hole area data and wind speed, while air quality consists of gas content data, wet temperature, dry temperature and relative humidity. The evaluation results obtained the maximum number that can enter in safe and comfortable conditions, namely fan machine A is 25 people, fan machine B is 30 people, and fan machine 2 x 50 Hp is 100 people.