... operation,fireproof certification:ISO9001 The introduction of air damper,volume control damperThe functions of fireproof damperNameModelFunction ... 250rectanglePYK-5IISFDlong distanced leafy discharge smoke vent PYK-3 IBSDDC24V turned on,manual open,hand reset, ... torsional moment of movement5~60KG.cm movement way spring 9wind leakage quantityIn standard condition,the differential ...