Regarding the issue of pressure measurement at the bottom of the carbonization chamber

.2.5 Measurement of pressure at the bottom of the carbonization chamber 2.2.5.1 Check in advance whether there is a pressure measurement port beneath the furnace door of the carbonization chamber, right below the air intake pipe, and determine when coke will be discharged and calibrate the pressure gauge accordingly. 2.2.5.2 Before the middle stage of coking, seal the end of the iron pipe with asbestos rope and extend it horizontally into the gap between the furnace inner wall and the coke (in the carbonization chamber directly below the air intake pipe). 2.2.5.3 Measurements shall begin one hour before coke discharge; do not open the cover of the rising pipe or the furnace cover during measurement, and check that the high-pressure ammonia solution for that unit is properly sealed. 2.2.5.4 Pierce the pressure gauge tube until yellow smoke is seen; at that point, measurement can be taken. Take three measurements and use their average value. 2.2.5.5 During the measurement process, the pressure in the gas collection pipe shall be measured at least three times, with one of those readings having to be negative. When the pressure at the bottom of the carbonization chamber falls below 5 Pa, the pressure in the gas collection pipe is increased to 5 Pa; this value represents the minimum pressure that must be maintained.