Spectacle Plates, Blinds and Spacers
Spectacle plates are a flow control and safety device used in piping. Spectacle plates are usually found between a pair of pipe flanges. When placed in one position, with the blank portion sticking out, flow through the pipe is possible. If the position is changed so the portion that has the center cut-out is exposed, the pipe is blocked off and no flow is possible. The plate thickness is chosen to withstand the full pressure that the system can exert.