Pig Signal Detector Series III

Maloney Series III Detector is a ‘Pig Signaler’ for Pipeline Service & Meter Provers,
and is designed for both conventional pipeline and meter prover services.

The Series III functions as a bidirectional detector, by using rounded probe which
allows detection from either direction with equal response.

The Detector has a wide pressure range by providing pressure balancing holes drilled
through the shaft to equalize pressure across the seals. This allows the detector to be
used in all operating pressures up t1800 psi.


  • Two U-type, Teflon seals with stainless-steel spring inserts, maximizes shaft sealing to minimize the resistance of shaft-to-seal friction.
  • For meter prover service, sealed to ensure an accurate setting. The microswitch trips within .001 inch of a predetermined point and the sealed switch eliminates the need for recalibration after replacement.
  • Stainless steel is used for all metal parts to retard resistance to wear and aging. The welding base is carbon steel
  • When specified, an optional nace type detector can be provided in sulfide stress-cracking resistant stainless steel to meet NACE MR-01-75 requirements.
  • Multiple Accessory Flexibility: Twaccessories can be mounted on the standard, two-port, square accessory plate, with special four-accessory models available on request.


T0 prevent welding heat from damaging the seals. During installation, the top of the detector assembly must be disconnected from the base. To install the welding base, a 1-1/8″ -inch hole is cut in the top of the pipe. Then the base is centred and welded in place. Note: Where more than one detector is being installed for pipeline service, care should be taken to remount each detector assembly on the same base with which it was shipped. Caution: The Series III cannot be removed while under pressure

Examples of Typical Applications: