The center distance of two holes is equal to the center distance of the corresponding ventinghole and the water hole of the boiler.
两孔的中心距与相应锅炉通气孔、通水孔的中心距相等；
2
The measures to control the vapor purging time and flow rate of vapour, enlarge the oil-gas space and increase the number of air hole as well as venting area are given, which can effective...