Averaging Pitot Tube (Annubar)

An averaging pitot tube, best known under the Annubar name, is an insertion element that spans the pipe diameter. Ports on the upstream face sense the impact pressure at several points across the flow profile, ports on the downstream face sense the reference pressure, and the internal chambers average them into a single differential that a standard DP transmitter reads. Because it needs only one tapping, it costs a fraction of a flanged element in large sizes and can be installed without cutting the line.

Sizes cover 2" to 60" pipes and ducts with threaded or flanged mounting; the pressure rating follows the chosen connection and flange class. Standard material is AISI 316, with other alloys on request for high-temperature and high-pressure service. Permanent pressure loss is negligible, so the element suits energy-conscious applications such as cooling water, boiler air, compressor discharge and steam mains.

Options include isolation valves, an opposite-wall support end for long spans, welding couplings and flanged branches, and a retractable assembly with shut-off device that lets the probe be inserted or withdrawn with the line in service, valuable for contaminated fluids where periodic cleaning is expected.

Users range across oil and gas, petrochemical, chemical, power generation, water, HVAC and energy systems, including boiler and compressor monitoring.