Pyxis CR Series LPR Corrosion Rate Sensors

Pyxis CR-200, CR-300 and CR-301 are inline sensors that measure the general corrosion rate (0.001-995 MPY, 0.001 MPY resolution) and a localized (pitting) corrosion index (0.001-100) in real time using linear polarization resistance (LPR). They compensate for sample conductivity (10-10,000 µS/cm, and 10-50,000 µS/cm for the CR-301) and give 4-20 mA and RS-485 Modbus output; the CR-301 has a titanium and PEEK body for -10 to 240 °C and up to 34.5 bar. Mikron Proses (Üsküdar, Istanbul) provides application consulting on selecting the right CR model and electrode material.

Corrosion monitoring · Cooling tower and process water → Send us your requirement

For the wider picture of cooling water control, see cooling tower automation; for other Pyxis sensors, see online measurement and automation systems.

LPR measurement and how it differs from corrosion coupons

The LPR method makes an instantaneous electrochemical measurement through the electrodes and gives a real-time corrosion rate in MPY (1 mil = 1/1,000 inch). The manufacturer notes that this value may be linear with the weight-loss corrosion rate of a coupon exposed for a long period, but it is not necessarily the same number; LPR data should be used to correlate with coupons and for real-time adjustment of the water treatment program. In addition to general corrosion, the CR series measures electrochemical noise, and an index for localized corrosion (pitting) is calculated from it.

CR-200 and CR-300: the standard family

The CR-200 is a battery-powered (3.6 V ER26500) wireless sensor with Bluetooth 4.1 output over 10 m line of sight. It removes the need to run power and signal cables to each test point, stores up to 6 months of data at a 30-minute sampling interval, and transfers the data as a CSV file through the uPyxis app. Battery life is up to 1 year.

The CR-300 is a fixed-mount sensor powered by 24 VDC from an existing controller, PLC or DCS network. General and localized corrosion data are provided on both 4-20 mA and RS-485 Modbus outputs, and the supplied MA-CR Bluetooth adapter allows wireless configuration through the uPyxis app. Both models have a 304 stainless steel enclosure, are installed in a 1-inch NPT flow cell and work up to 7 bar.

CR-301: high temperature and pressure

The CR-301 uses a titanium and PEEK (polyether ether ketone) body with an integrated cooling fin design. It operates from -10 to 240 °C and up to 34.5 bar, is rated IP68 and mounts in a 3/4-inch NPT connection. Typical applications listed by the manufacturer are geothermal process, district energy heating and oil and gas process or produced water. Outputs and configuration logic (4-20 mA and RS-485 Modbus, uPyxis with the MA-CR adapter) are the same as for the CR-300.

Configuration with the uPyxis app

All three models are configured in the uPyxis mobile or desktop app, which offers more than 20 commonly measured metallurgies with preloaded general corrosion scale, localized corrosion index scale and alloy factor selected by UNS code. Covered metallurgies include aluminum, copper, brass, carbon steel, 304 and 316 stainless steel and duplex stainless steel. The user can edit these values, for an expanded scale of up to 995 MPY and alloy factors from 0 to 3. A copper electrode pair and a mild steel electrode pair, plus 2.0 MPY and 0.1 MPY calibration check caps, are included with the sensor.

The right model (wireless, wired or high temperature) and electrode material depend on the number of measurement points, the existing automation infrastructure and the temperature and pressure conditions. Send us your requirement and we will select the model and electrode combination together.