Hedland — Variable-Area Flow Meters

A Hedland variable-area meter reads flow with a spring-loaded piston: flow pushes a piston against a calibrated spring along a contoured metering cone, and a magnetically-coupled indicator outside the body tracks the piston position against a 360° rotatable scale. Because the coupling is magnetic there is no glass tube to break and nothing leaks through the wall — and because the spring (not gravity) sets the balance, the meter installs in any orientation and needs no straight pipe run or flow conditioning. That makes it the practical choice for local flow indication and flow switching on hydraulic, lubrication, water, coolant, and compressed-air lines, where you want to see the rate at the machine and trip a switch — not feed a control system. When you need ±0.2% accuracy, fieldbus, or remote totalization, a different meter fits — a turbine, electromagnetic, or ultrasonic meter from the Badger Meter flow family; when you need a rugged, see-it-at-a-glance indicator that survives the shop floor, this is it.

Selection is by fluid first, then pressure, port, and size. The H-series splits into seven fluid families, each with its own materials and scale: petroleum and hydraulic oil (series H200–H901, calibrated for oil — specific gravity 0.876); phosphate ester (H294–H898, EPR seals and a Nylon guard for Skydrol, Fyrquel, HFD-R); water-based and fire-resistant / emulsion hydraulic fluids (H212–H913); plain water and other general liquids (H204–H905, brass or stainless — no aluminum); air and compressed gas (H270–H971, multi-pressure SCFM scale); API oil and corrosive liquids (H231X–H841X, T316 stainless); and corrosive air and gas (H237X–H847X, T316 stainless). Aluminum or brass bodies run to 3,500 psi, T303 stainless to 6,000 psi. Tell Prater Technical the fluid, flow range, line pressure, and port, and the family and model fall out quickly.

No. Phosphate-ester fire-resistant fluids (Skydrol, Fyrquel, HFD-R) attack the Viton seals and polycarbonate guard used on the petroleum and water meters. The phosphate-ester series (H294–H898) is built with EPR pressure seals and a Nylon guard specifically for compatibility — both are required. Running a phosphate-ester fluid through a standard petroleum meter degrades the seals and crazes the guard, so match the series to the fluid rather than just the port size.

Plain water corrodes an aluminum body, so the Water & Other Liquids series (H204–H905, for plain water, coolant, and general liquids) is built in brass or T303/T316 stainless only. The Water-Based series (H212–H913, for water-glycol, fire-resistant, and water/oil emulsion hydraulic fluids) is a different case: the glycol content protects an aluminum body, so it is offered in aluminum, brass, or stainless — though the factory recommends a brass body for emulsions below 20% oil. Both calibrate to a specific gravity of 1.0; pick stainless for higher pressure or aggressive water chemistry.

The metal-body meters are ±2% of full scale with ±1% repeatability; the transparent EZ-View direct-read meters are ±5% of full scale. The one exception is the smallest body: ¼-inch meters are ±7% of full scale. Accuracy holds in any orientation with no straight-run requirement, but the factory recommends 200-mesh (74-micron) filtration upstream to keep grit off the piston and cone. If you need a tighter number than a rotameter delivers, that is a different meter — say so and we will steer you to the best-fit option.

Both mount on any H-series meter; the difference is switching versus a signal. A Flow-Alert flow switch trips at an adjustable high- or low-flow setpoint over the full range — micro-switch (F1 single, F2 double, SPDT 10 A @ 250 VAC) for relay/PLC inputs, or reed-switch (RS1/RS2, normally open or closed) for low-power logic — in a NEMA 12/13 enclosure. The MR transmitter adds a non-contact magnetic sensor with an integral 8-digit rate-plus-totalizer display and a field-selectable analog output (0–5 V, 0–10 V, or 4–20 mA), and can drive an F6700 (AC) or F6750 (DC) remote digital display with linearization, alarms, and optional Modbus/Profibus communications. Use Flow-Alert to trip an alarm or interlock; use the MR when you need a reading and an output.

Two stainless series families cover it: API oil and corrosive liquids (H231X–H841X) and corrosive air and gas (H237X–H847X), both built in T316 stainless for the wetted parts. For the harshest duty, add the Hostile-Environment option (HE) — a cylindrical Pyrex® glass guard, T316 stainless indicator, bumpers, end-caps and scale support, and a Teflon-coated Alnico magnet — rated continuous −20…+400°F and intermittent to +500°F. Specify the fluid or gas and the environment and we build the corrosion path to suit.

Hedland is a Badger Meter line that Prater Technical Partners sells as an authorized distributor — authorized for sale nationwide, with distributor catalog unit prices published on our webstore. Badger also runs a 24-hour Quick-Ship program on the most common petroleum, water, brass, and EZ-View configurations, and an Accelerated Delivery program on the rest. Tell us the fluid, flow range, pressure, port, and any switch or transmitter output, and we configure the part number, add Flow-Alert or MR electronics if needed, and ship.