227C dp indicator
The Range can also be adjusted without dividing the scaleplate or pointer. Linearity changes are accessible after removal of the scale stack. The 227A runs a Model 224 Differential Pressure Unit (DPU). The 227C is driven by a model 224C DPU. See the DPU’s separate manuals. The detector is linked directly to the actuating unit (DPU). The sensor consists of a control rod assembly, a link, and a movement module linked to the identification pointer.
The DPU bellows notices modifications in air pressure and transmits them to the moving plate device of the indicator as a revolving motion through the petrol tube.