Research methods: This paper combined academic analysis，the operation practice and the research of the overseas instance in the subway. Also a special technical meeting with the fire fighting department was held to discuss the issue with many experts.
Research conclusions: In the cold area，the temperature of the tunnel could be under zero degree ; Dry hydraulic system needs no heat preservation measures; Dry hydraulic system can meet the time requirements of hydrant operation ; Drain tap ， deluge valve and other apparatus are needed for the dry system.
2007, Vol. 24 
