Hedland TB Series

Metal Body, Variable Area Flow Meters for Petroleum-Based Liquids. Replaces the EH55-TB

The Hedland TB Series flow transmitter/ flow switch combines the rugged, proven technology of a direct reading, piston-type, variable area flow meter with a linear potentiometer. This compact package provides the user instantaneous flow rate indication as well as the capability to interface with virtually all analog process control devices. The Hedland TB Series has a surrounding aluminum enclosure to seal against industrial contamination. This enclosure is rated NEMA 12 and 13 (IP65).

The pressure rating for aluminum and brass variable area flow meters is 3,500 psi/241 bar maximum with a 3:1 safety factor for liquids and 1,000 psi/69 bar maximum with a 10:1 safety factor for gases. The pressure rating for stainless steel meters in the Hedland TB Series is 6,000 psi/414 bar maximum (5,000 psi/345 bar maximum for 3/4" to 1-1/2" series) with a 3:1 safety factor for liquids and 1,500 psi/103 bar maximum with a 10:1 safety factor for gases.

Operating Principle

All Hedland TB Series variable area flow meters use a sharp-edged annular orifice, formed between the open-centered piston and a contoured metering cone. The piston is held in a "no flow" position at the base of the contoured cone by a calibrated retention spring. Flow through the meter creates a differential pressure across the piston orifice, moving the piston against the spring. The greater the volume, the further the piston moves. Externally, the flow indicator is magnetically-coupled to the moving piston. The indicator is visually "read" against a graduated flow scale.

The electronics convert fluid flow rate to proportional analog output signals of 4-20 mA, 0-5 VDC, and 0-10 VDC. Each sensor is "loop powered" and inherently isolated, operating on 4-20 mA current. A DC power source must be used to provide the necessary excitement to your flow meter.

Features of the Hedland TB Series variable area flow meter

• Automatically signals alarm if flow is too high or too low
• Automatically opens or closes electrical circuits
• Triggers warning lights, buzzers and other devices
• Shuts down pumps and/or other equipment to protect your operation against permanent damage
• Available in aluminum, brass, and stainless steel
• Installs in any position
• Easier-to-read linear scale
• No flow straighteners or special piping requirements
• Relatively insensitive to shock and vibration
• Special scales available