- 20
- Mar
fire door panic bar exit device,fire door controller,fire door knocker
The fire resistance rating of steel fire doors is divided into three types. The fire resistance time of Class A steel fire doors shall not be less than 1.5 hours; the fire resistance time of Class B steel fire doors shall not be less than 1.0 hours; the fire resistance time of Class C steel fire doors shall not be less than 0.5 hours.
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