Cox — Precision Turbine Flow Meters

Cox is built to aerospace test-stand standards, and three things combine to get there. Each meter reads its rotor with a radio-frequency (RF) carrier pickoff that senses the blades without magnetically dragging on the rotor, so the rotor spins essentially friction-free and stays linear well down into low flow. It turns on low-friction hybrid ceramic ball bearings. And every meter ships with a multi-point wet calibration traceable to NIST. The dual-rotor Cox Exact holds ±0.1% of reading with a flow computer, at ±0.02% repeatability; the single-rotor Precision (CPT) reaches its rated accuracy across its calibrated range with flow-computer correction.

The dual-rotor Exact (CDL remote / CDX integral) hydraulically couples two counter-rotating helical rotors. Averaging the two cancels swirl — so it usually needs no flow straightener — and extends turndown dramatically: 120:1 on the smallest meter up to 500:1 on the larger ones, with the viscosity curve blending over a 60:1 range. That span often replaces a costly multi-meter manifold, and the ratio between the two rotors doubles as a built-in bearing-health check. The single-rotor Precision (CPT, 1/2–2 in) is the lighter-cost choice for steadier service, with expanded mechanical linearity that limits viscosity/temperature drift. For ultra-low flow, the Precision LoFlo (CLF, 3/8 in) comes in six flow-range variants. Rule of thumb: variable viscosity or the widest single-meter range → Exact; stable conditions or budget → CPT; very small rates → LoFlo.

A conventional magnetic pickoff tugs on the rotor each time a blade passes, which loads the rotor and hurts low-flow accuracy. Cox’s RF pickoff senses the blades through a radio-frequency field with no magnetic pull, so the rotor turns nearly friction-free — a big part of how a turbine meter holds linearity at low flow. The pickoff is embedded and immune to vibration, which is why Cox meters go onboard vehicles and aircraft. Magnetic (MAG) pickoffs are available where an application calls for one.

A turbine meter’s output shifts with viscosity, and viscosity shifts with temperature. Cox characterizes each meter across multiple viscosities to build a Universal Viscosity Curve (UVC); a flow computer then tracks process temperature and applies that curve, so the reading holds as the fluid warms or cools. The dual-rotor Exact reduces the dependence further by self-compensating hydraulically. Tell us the fluid and its temperature range and the meter is calibrated to match.

Every Cox meter ships with a 10-point MIL-PRF-7024 wet calibration and a unique K-factor, run on primary-standard calibrators at an NVLAP-accredited lab and traceable to NIST (calibrator uncertainty ±0.05% of reading, ±0.02% repeatability). Calibrations use blended solvent and oil to simulate your actual fluid; multi-viscosity UVC and custom-fluid calibrations are available when the process fluid differs from the standard. Recalibrate on the interval your quality system or custody-transfer standard requires.

The meter outputs pulses; the flow computer turns them into rate, total, and viscosity-corrected flow. The EC80 is the embedded rate-and-total processor — Strouhal-Roshko viscosity/temperature compensation with a 4-20 mA or EIA-485 output, well suited to OEM and panel builds. The FC-5000 is the full-featured unit — Strouhal-Roshko compensation, batching, BTU/energy, and wider protocol and I/O — when you need batching, energy metering, or system integration; its communications are standard, while the scaled-output form, relay function, and mounting are specified at order-time, so we configure it to your needs at time of quote. The FC30 is a compact single-channel panel-mount flow computer — 40-point linearization, Strouhal-Roshko temperature compensation, batching, and serial communications, factory-programmed to your application.

Yes — the hybrid ceramic ball bearings are the enabler: harder, lighter, and more dimensionally stable across temperature than steel, and they run in non-lubricating fluids, so they handle cryogenics through hot oils. The Precision CPT covers −450 to +450 °F; the Exact’s standard range is −150 to +330 °F (wider on request), with a 3000 psig standard pressure rating. Wetted parts are stainless (316 body, 17-4 PH rotors), which is why Cox is a routine choice for aerospace fuel-flow and high-pressure test stands.

Cox is handled under authorized Badger Meter distribution: send your application and calibration requirements to Prater Technical, we configure the meter, flow computer, and calibration to your fluid, and we ship to you with the calibration documentation. Engineered builds — special calibrations, custom fittings, high-pressure or cryogenic service — are all configured at time of quoting.