PUR-2W-M12

Supported Applications

The Pura Transmitters are ultra-pure moisture transmitters designed for the measurement of trace moisture in ultra-high purity gases. The PUR-2W-M12 is the Pura M12 Transmitter in its 2-wire, 4-20 mA configuration, providing a rugged dew-point sensor for continuous in-line monitoring. Because the sensing element measures dew-point moisture content directly, it is well suited to processes where even trace levels of water vapour must be controlled.

Typical media handled by the Pura platform include ultra-high purity gases and UHP inert gas, as well as Natural Gas, LPG, Hydrogen, Nitrogen, Air, Inert Gases and Hydrocarbons. The M12 connector and compact form factor allow the transmitter to be installed close to the sample point, either through a sample block or by direct pipeline connection.

Operating Conditions & Performance

The PUR-2W-M12 covers a standard measurement range of -120...-40 °Cdp, with non-standard ranges available on request. Measurement accuracy is specified as ±1 °C from -40 to -60 °Cdp, ±2 °C from -60 to -100 °Cdp, and ±4 °C from -100 to -120 °Cdp (extrapolated). Each unit ships with a traceable 7-point calibration certificate.

The transmitter provides a 4-20 mA output signal from a 2-wire connection operating as a current source. Supply voltage is 12...28 V DC, with a load resistance of Max 250 Ω @ 14 V and a current consumption of 23 mA max, depending on output signal.

• Operating temperature: -40...+60 °C
• Ambient temperature: -20...+50 °C
• Storage temperature: -40...+60 °C
• Maximum pressure: 24 MPa
• Enclosure rating: IP66 in accordance with standard BS EN 60529:1992, with NEMA 4 protection in accordance with standard NEMA 250-2003

Wetted parts are constructed from 316 stainless steel with a cold-drawn, electro-polished internal sample block finish, and the housing is 316 stainless steel. Compliance marks include CE & UKCA.

Configuration Options

Within the PUR-2W-M12 series the base-model options differ mainly in how the sensor is packaged and connected, allowing the same core M12 2-wire transmitter to suit different integration needs.

• PRM — Double Bagged
• OEM — Single Bagged
• SEN — Sensor only, no block

These options carry different weights and process interfaces. The PRM and OEM versions weigh 450 g, while the SEN version weighs 180 g. Dimensional configurations reflect this: the SEN version presents a 1/2" VCR connection, whereas the PRM and OEM versions mount to a 1/4" VCR sample block. The Range character further distinguishes units, with code A designating the -120 to -40°C dp range.

Key Product Differences

The lineup is built from the base model PUR-2W-M12 (Pura M12 Transmitter 2-wire 4-20 mA), extended by a base-model character and a range character. A worked ordering example is PUR-2W-M12-AA, described as a Pura Transmitter M12 2 wire 4-20mA, Double Bagged, with -120 to 40 °C range.

• PUR-2W-M12-BA — OEM (Single Bagged) build with the range A dew-point range.
• PUR-2W-M12-CA — SEN (Sensor only, no block) build with the range A dew-point range.

This ordering structure was introduced under the ordering code change effective 1st July 2025 and directly cross-references the previous base model code PUR-TX-2W-M12, whose product description was intentionally left unchanged to allow quick cross-referencing between new and old specifications.