Safety valve is for tank used for storage and transport of oil and chemicals and permits evacuation of excess gas in tank for adjustment of internal pressure to normal level, where less than atmospheric pressure occurs in tank

摘要

The safety valve is for a tank used for storage and transport of oil and chemicals and permits evacuation of excess gas in a tank for the adjustment of internal pressure to a normal level, where a less than atmospheric pressure occurs in the tank. The valve comprises a lower body (50) and an upper body (40) and a shaft (30) extending from the upper to the lower body, together with a plate (34,36) fitted on the shaft between the upper and lower bodies, blocking a connection between them. - The plate has a channel (34A) on its underside and a projecting part (34B,34C) along one edge. A polytetrafluoroethylene bush is fitted between the plate and the valve shaft. The plate has a greater diameter than the internal diameter of the lower body.