The CDM/FP/00 (Continuous Debris Monitor with Flushing Plug) is an on‐line magnetic plug designed to measure the amount of ferrous debris in oil‐lubricated and hydraulic systems. It is superior to existing self‐sealing magnetic plugs in that a continuous reading is given when the unit is plumbed into an oil line. Further, it has the advantage of being self‐flushing, thereby obviating the need for removal and inspection. The sensor consists of a patented mechanism whereby the accumulation of ferrous debris causes a flux change in a magnetic circuit. A magnetic sensor converts this flux change into an electrical signal, which is proportional to the amount of debris captured. A sensor is incorporated into the mechanism to monitor the lubricant temperature and so provide compensation for changes in temperature. As debris accumulates, the magnetic circuit would eventually saturate. The CDM/FP/00 senses this and initiates a patented flush cycle, whereby the magnetic circuit is withdrawn from the oil line enabling the flow to wash off the accumulated debris, which can then be filtered out. Withdrawal is accomplished by a linear electric actuator. Fluid integrity is maintained by a thin non‐magnetic barrier between the oil line and the magnetic circuit. The magnetic circuit is then accurately repositioned and debris accumulation recommences. The CDM/FP/00 is fully approved by the Health and Safety Executive for use in Class 1 atmospheres as defined in BS 1259:1958. This unit incorporates both Gabriel Microwave Systems Ltd, and Central Electricity Generating Board devices, each the subject of separate Patents Pending. Manufacture and sale, therefore, is under licence with respect to the CEGB device.