WHAT IS A TORBAR

The TORBAR is a multiport self-averaging flow meter with a design based on the classical pitot tube concept of fluid flow measurement.

Since its design and launch in 1985, thousands of TORBAR flowmeters have been installed into a wide variety of industries world wide.

A comprehensive list of major projects and letters of reference from international companies are available on request.

HOW TORBAR WORKS

TORBAR produces an averaged differential pressure (DP) signal proportional to the square of the flow rate.

The DP output is normally piped to a Differential Pressure Transmitter in order to generate an electrical signal proportional to the flow rate. A D.P. gauge or switch can be used to provide local mechanical indication or flow rate switching.

Each TORBAR is designed to span the process pipe diameter and comprises four basic components:

Outer impact tube
Internal averaging tube
Low pressure chamber
Head

The outer impact tube has a number of pressure sensing holes facing upstream which are positioned at equal annular points in accordance with a log-linear distribution.

The "total pressures" developed at each upstream hole by the impact of the flowing medium are firstly averaged within the outer impact tube and then to a second order (and more accurately) averaged within the internal averaging tube. This averaged pressure is represented at the head as the high pressure component of the DP output.

The low pressure component is generated from a single sensing hole located on the downstream side of the outer impact tube.

Unique profiled flats are positioned around the downstream hole in order to define the separation point at which the flow lines "break-off" as the fluid passes around the outer impact tube. This feature creates a stable pressure area at the downstream pressure sensing hole thereby maintaining a more constant flow coefficient K at high velocities enabling a very wide range of flow measurement (turndown).

The TORBAR is NOT suitable for the measurement of 2 phase fluids or where there is a heavy contamination of solids in the flowing medium.

However, satisfactory flow measurement can be achieved for certain contaminated gas flows (such as flue gas) by using an air purging system. Details are available on request. For water flows which may contain a relatively small amount of air, an air-venting package is recommended. Details are available on request.

• Unique profile shape enables high flow rate turndown
• Dual averaging for better accuracy
• One-piece outer tube for optimum strength
• Suitable for pipe sizes from 10mm to 5000mm and larger with a special 2 piece construction
• Suitable for square or rectangular section ducts
• Available as hot-tap for insertion into pressurised pipes
• Optional direct mounting transmitter arrangement (see TRIBAR)
• No coefficient drift - long term stability
• Low blockage characteristic means low energy consumption - hence cost savings

• TORBAR is suitable for liquid, gas, and steam flow measurement
• Accuracy ? 1% of actual flow rate - verified by independent flow laboratories. Copies of test reports are available on request.
• Repeatability of measurement ? 0.1%
• Reynolds number. Minimum Re:1.2x104
• Flow rate turndown typically 10:1 (100:1 of DP).
• Maximum working pressure up to 500 bar
• Maximum working temperature up to 600 deg. C with selected materials and fittings
• Maximum viscosity 500 centipoise
• Short upstream and downstream straight pipe lengths
• Long term accuracy unaffected by wear

• TORBARs are engineered and manufactured to stringent routines including BS, ANSI, ASME, ISO and DIN standards
• Welding is carried out by Lloyds qualified welders to ASME IX and European standards.
• Quality control system is approved to BS EN ISO 9001-2000
• CE Marking is in accordance with 97/23/EC
• TORBARs are leak tested before dispatch.
• Hydrostatic pressure testing to a maximum of 600 BAR is available by request for all flanged models.
• Standard material of construction is 316L stainless steel but other materials are available on request.
• All TORBARs have full material traceability.
• Material test certificates to EN 10204 (DIN 50049) and certificates of conformity are available for each component part of every TORBAR
• Stainless steel data plate

The TORBAR accuracy and repeatability of measurement has been verified by a number of independent testing organisations in the United Kingdom. Copies of these reports are available on request.