The base model Series 57 is a visual flag indicator with manual reset.
It is a popular member of Apache’s pigPRO Series, a patented line of intrusive pig passage indicators that reliably detect the previse location of a cleaning pig as it travels within the pipeline network. When a cleaning pig passes the system’s intruding plunger, it activates the plunger and triggers a visual flag indicator, signalling the pig’s location.

Aluminum extensions can be attached to enable detection of the pigs passage on buried pipelines. All pressure sealing components remain below the extension module. Available in lengths 2’ to 10’