The Hedland Flow Meter for Water-based Fluids are low cost, yet rugged variable area flow meters. These in-line flow rate indicators are industrial class and can be used in high temperature water-based fluids and emulsions. These Hedland flow meters features quality metal construction in aluminum, brass, or stainless steel .

These variable area flow meters can be used in applications in which the temperature ranges from -20 to 400°F (continuous) and 400 to 500°F (intermittent). Stainless steel flow meters are pressure rated for 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. Aluminum and brass flow meters are pressure rated for 3,500 psi/241 bar maximum with a 3:1 safety factor. Brass models are highly recommended for water systems or for systems where galvanic corrosion may be a problem .

The operating principle uses a sharp-edged annular orifice formed between the open-centered piston and a contoured metering cone. Flow through the meter creates a differential pressure across the piston orifice, moving the piston against a calibrated retention spring. Externally, the flow indicator is magnetically-coupled to the moving piston and read against a graduated flow scale. Features include direct reading, installation in any position, 360° rotatable guard/scale, linear scale, no flow straighteners required, and insensitivity to shock and vibration .