The DAP-RD-SL is a portable instrument for measuring temperature and gas velocity/differential pressure in pneumatic transport pipes of pulverized fuel, or other dry bi-phase powder transportations. This information may be used as an input for an isokinetic extraction by the PFS and PFS-A-SL.

The probe utilising RD has great advantage above other designs that it is relatively immune to undesired plugging of pressure tap holes.

The basic idea of the DAP-RD-SL is to measure the pressure difference between the upstream and downstream face of a measurement object inserted with its axis parallel to the main axis of the duct. The pressure near the upstream face of the object corresponds to the stagnation (total) pressure and the pressure near the downstream face corresponds to the static pressure. The DAP-RD-SL is designed for insertion into a fuel pipe via a Dustless Connection with Snap Lock (DC-SL). This design enables insertion of the probe into a fuel pipe with internal over pressure without leakage of air.