Power plant boiler or industrial boiler is definitely installed with vacuum exhaust steam valve, which is used to exhaust steam and adjust boiler steam temperature within specified range in time of boiler startup. During normal operation, when the pressure and temperature of boiler increase and boiler safety door is not required to be actuated, vacuum exhaust steam valve can be used to reduce pressure and temperature Thus it can be seen that the operating condition of vacuum exhaust steam valve is quite bad. Mixture of gas and water is usually exhausted in time of startup while what is exhausted is high temperature and pressure over heat steam under full pressure state in the operating state. lf all-purpose stop valve is adopted and used frequently under bad condition of large temperature and pressure difference, valve seat and valve core will produce crack or cavitation leakage, greatly shortening the service lifetime of valve. According to the above instances, Shanghai Power Plant Valve Co.,LTD Factory has specially designed and developed DJ961HY type vacuum exhaust steam valve, which is a new king of valve and can endure the high temperature no more than 540℃ and pressure difference no more than 32MPa.lt is applied to the occasions like over heat steam.