Parker Velcon FDPM

It continuously reads the fuel flow rate and the differential pressure across a filter or filter/separator vessel, then computes the flow-corrected differential pressure. Because raw differential pressure rises with flow, ATA 103 and JIG require it to be normalized to a reference flow before it can indicate element loading. The FDPM does this automatically and warns as the corrected value approaches the change-out limit.

Differential pressure across a filter changes with flow rate, so a raw reading cannot be compared against a single fixed limit. Corrected differential pressure scales the measured value to a standard flow (per ATA 103 / JIG), giving a flow-independent number that reflects true filter condition. On Aethair, both the raw and corrected values map to the Fluid Differential Pressure parameter, which is kept separate from room differential pressure measured in air.

Over an RS-232 ASCII stream at 9600 baud, 8-N-1. The logger sends START and the module streams comma-separated records carrying a timestamp, a unit id, and the measured flow, differential-pressure, and corrected-DP values; the driver averages each field over the reporting interval before posting flow (US gpm) and differential pressure (psi).

The MK II is the current unit and keeps the same flow and differential-pressure sensing and ATA 103 / JIG corrected-DP calculation. It adds a glove-friendly touch-screen display and condition-based alarms that can be set to halt fueling, and suits both mobile and stationary equipment. The original FDPM is its field-tested predecessor.

On aviation-fuel filter, filter/separator, and filter-monitor vessels (on refueler trucks, hydrant dispensers, and fixed installations), to monitor coalescer and filter-element condition during fueling and support ATA 103 record-keeping.