The Hedland Flow Meter for Caustic Air and Gases is a rugged variable area flow meter designed for caustic and corrosive gases. Featuring a stainless steel body, piston and cone; this flow meter is rated for temperatures to 240°F and pressures to 1500 PSI. A hostile environment version of this meter is available with enhanced materials and a temperature range up to 400°F (500°F intermittently) which is suitable for the toughest conditions.

The Hedland Flow Meter for Caustic Air and Gases is available with port sizes ranging from ¼" to 1½" with resulting flow ranges from 2-20 SCFM to 80-800 SCFM. Standard accuracy for this meter is ±2% full scale with ±1% repeatability. This flow meter can be installed in any position and does not have a straight piping requirement making installation easy. The scale is 360° rotatable and easy to read. The meter is relatively insensitive to shock and vibration.

The operating principle uses 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.