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Chip Detectors  
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

Self Closing Valves
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.
   Self-Closing valve shown here with
   magnetic plug fully installed
   Self-Closing valve shown here with
   Chip Detector fully installed

Allen Aircraft supplies a full range of screens with or without chip detectors. The screens are provided in either aluminum or stainless steel material. The screens are sintered, resistance welded or brazed. The screens in a forced flow oil lubrication systems come in various screen openings. Wear debris particles that are larger than the screen openings are retained by the screen. When a screen assembly is equipped with a integral electronic chip detector, the debris is attracted to the chip detector and electronically shows an indication. Many screen assemblies with integral chip detectors are also provided with a self closing valve. The self closing valve permits quick removal of the chip detector for inspection without the need to drain the oil system.

Allen Aircraft Products, Inc.  ●  PO Box 1211  ●  6168 Woodbine Avenue, Ravenna, Ohio 44266  ●  (330) 296-9621  ●  Fax (330) 296-5532