A suction control valve is disclosed that vents to atmosphere the residual vacuum pressure presented to a suction catheter or similar device when the central bore of the valve is completely blocked by a valve member and the device that the suction control valve is controlling becomes occluded. A vent...http://www.google.es/patents/US5320328?utm_source=gb-gplus-sharePatente US5320328 - Suction control valve with vacuum breaker
