PEEP SIGHT FOR FURNACE

PURPOSE: A peep sight for a furnace is provided to prevent the configuration member from being damaged and the hot-air in the furnace from being flowed out to the outside. CONSTITUTION: The peep sight(100) for the furnace includes a check valve(150), vent valve(160) and first cap(110). The body is mounted in the furnace. The check valve is installed in one side of the body. The vent valve is installed in the other side of the body. The first cap is mounted in the tip-end part of the body and enables the operator to observe the inside of the furnace. The purge gas flowed through the check valve is ejected through the vent valve. The pressure of the purge gas is bigger than the pressure within the furnace. The second cab is mounted on the tip-end part of the body in the state that the first cap is accommodated. In the tip-end part of the body, a first tip-end part(101) and second tip-end part(102) are successively formed. The first tip-end parts have the first diameters and second tip-end parts have the second diameters longer than the first diameters. The first cap is mounted in the first tip-end parts and the second cab is mounted in the second tip-end parts.