spaces there is an annular intermediate space c which is defined by the exterior wall of hood 28 the interior wall of cover 26 partition wall 42 and an annular portion of seating surface 24 of the scrap bucket as shown in fig3 the intermediate space is provided with a first seat 50 which comprises the seating ring 30 and seating surface 24 adjacent inlet space a as well as a second seat 44 between partition wall 42 and seating surface 24 as shown in fig1 the intermediate space c also is provided with an inlet pipe 52 for purging gas which is to be described hereinafter in a first embodiment the inlet pipe comprises an inlet connection piece 52 having a flow control damper 56 in a second embodiment according to fig2 the purging inlet comprises a pipe 54 with a flow control damper 56 pipe 54 is connected to the outlet of a fan 60 the inlet 62 of which is connected to tubular space b surrounding the bucket the fan is driven by a motor 64 pipe 54 fan 60 and inlet 62 suitably are provided with heat insulation or a heat insulated case not shown in inlet space a a first pressure sensing means 66 is provided as is shown in fig1 this pressure sensing means may also be placed in inlet pipe 5 and consequently it is protected against scrap which is pushed upwardly since when a bulky scrap is charged it may extend upwardly above the upper edge of open top of the scrap bucket in intermediate space c a second pressure sensing means 68 is provided wires 70 and 72 respectively connect the pressure sensing means to a regulating device.