Allen Aircraft Chip Division

Metal particles in the lubrication system of an aircraft engine or hydraulic system may be an indication of wear. Chip detectors are used to monitor these systems to provide early warning of impending failure so that maintenance can be performed on a timely basis. The detector houses magnets incorporated into an electric circuit. Magnetic lines of force attract ferrous particles. Collection of these particles continues until the insulated air gap between the magnets (two magnet configuration) or between the magnet and housing (one magnet configuration) is bridged, effectively closing the circuit. The result is an electronic signal for remote indication.

Chip detectors may be positioned in the application with a self-closing valve/adapter through either a bayonet or threaded interface. As the chip detector is disengaged from the valve, the valve closes minimizing any fluid loss from the system

Type 1
Description

Type 2
Description

Type 3
Description

Type 4
Description

Self closing valves offer a practical, economical solution to fluid loss problems in applications requiring more frequent inspection of magnetic plugs or chip detectors.

Available in threaded or bayonet designs, the valves close down automatically as the magnetic plug or chip detector is removed. This eliminates the loss of expensive lubricants and reduces the need for clean up after inspection. As a result, inspection is faster and more convenient for maintenance personnel.

Both types of self closing valves offer maximum exposure of the magnet to the flow of lubricant or hydraulic fluid. The wide open design is essential to proper functioning. If free flow is restricted, ferrous chips and particles are less likely to come is contact with the magnet.

Self closing valves are sealed with "O" rings, providing a positive seal under the low pressure condition generally associated with their application. The "O" rings seal the valve with the plug in position and when it is removed for inspection.

Threaded
Self-Closing Valve shown here with magnetic plug fully installed
and also with magnetic plug removed.

Bayonet
Self-Closing Valve shown here with Chip Detector fully installed
and also with Chip Detector removed.