Pig Signal Detector - TD Williamson PIG-SIG®A pig signal detector is a mechanical switch to verify that a pig has left the launcher or has entered the receiver. Can also be used to provide a discrete input (DI) into the PLC for automated pigging. A pig signal may be known colloquially as a pig-sig which should not be confused with a PIG-SIG® which is a registerd trademark of TD Williamson.
