Emergencyvent Manhole Cover is a kind of rapid relief-pressure device. Its technical performance, main material and main parts'materialare the same as HXF-HR type breather manholes.
紧急放空人孔是快速泄压装置，其技术性能、主要零部件材料与HXF-HR呼吸人孔相同。
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All UL142 tanks supplied by FMC tanks are supplied with the properly sized normal and emergencyvent openings to affect the safe venting of tanks in the event of a fire or rapid temperature increase.