Czy można piec muflowy 1200 degrees directly open the furnace door?

According to the theory, it is not possible to open the furnace door directly for the muffle furnace at 1200℃, because opening the furnace door at high temperature will reduce the service life of the furnace and heating elements. It is recommended to open the furnace door at normal temperature or open the furnace at a customized professional high temperature. Door of the muffle furnace.