Middle Class Pressure and Differential Pressure Transmitters

Middle class transmitters extend the basic range with differential pressure measurement and digital fieldbus communication, making them the standard instrument for DP flow across orifice plates, venturis and nozzles, for DP level in pressurised vessels and for interface measurement, alongside gauge and absolute pressure.

The differential range covers −137 to +137 bar with static pressure up to 1,034 bar; gauge and absolute ranges reach 689 bar. Accuracy is ±0.075 % of span, with an optional ±0.05 % DP version for flow measurement where every tenth of a percent counts, and 50:1 turndown keeps spares simple. Outputs are 4–20 mA HART, FOUNDATION Fieldbus or PROFIBUS.

Process connections are threaded, flanged, manifold-ready or via remote diaphragm seals; with seals the process temperature limit extends to +454 °C. Wetted parts are 316L stainless steel, Alloy C-276 or gold-plated for hydrogen service. Options include an LCD display, integral manifolds, remote seals, mounting brackets, special coatings and hazardous-area approvals.

Used across oil and gas, petrochemical, chemical, refining, power, water and marine plants. If you need 100:1 turndown, ±0.04 % accuracy, WirelessHART or advanced diagnostics, see the advanced class.