Based on two precision swivelling limb Micromanometers, the Airflow Type 4 Precision Manometer Test Set covers 0 to 5000 Pascals (0 to 20 in. H2O) with a total of seven limb positions, and has a resolution considerably better than 0.25 Pascals (0.001 in. H2O) on the most sensitive setting. A plate mounted inside the case gives details of the range covered by the various limb positions.
Each manometer has a reservoir tank with a built-in metal bellows system which allows fine settings of the fluid level without changing the calibration. Once set up, the instrument panel is accurately leveled with a three-point rapid leveling system using a precision compound built-in spirit level. The close fitting of the scale to the glass tube minimizes parallax and the choice of manometer fluid ensures a crisp meniscus for accurate reading. Each instrument is individually calibrated and comes complete with a Pitot static tube, connecting flexible tube, spare fluid and a manometer balancing valve which isolates the pressure signal to allow zero checking without disconnecting the pressure lines.