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Trace Moisture Transmitter - Michell Pura

Updated:2025-03-13

Brand: PST/Michell
Model: Pura
Description: This small transmitter is a rugged dew-point sensor for the measurement of trace moisture in ultra-high purity gases.Simple to use and install, the Pura features analog and digital outputs with option
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Product Details

Trace Moisture Transmitter - Michell Pura Description：

Product Manual

Hygrometer For Trace Moisture in Pure Gases

Features

Measures down to -120 °Cdp (-184 °Fdp) (1ppbV)

Stable and repeatable measurement

Fast response

Modbus RTU over RS485 communication

4...20 mA 2 wire

Traceable 7-point calibration certificate

1/2”, 1/4” male VCR process connections

Optional monitor/controller

MiniDIN 43650 C, M12 electrical connectors

Optional hazardous area approval

Service exchange program

This small transmitter is a rugged dew-point sensor for the measurement of trace moisture in ultra-high purity gases.

Simple to use and install, the Pura features analog and digital outputs with optional I.S. approvals, plus there is a range of VCR process connections and electrical connections. A service exchange program is also available, reducing the cost of maintenance.

Specifications

Transmitters
Product	Pura 2-wire, 3-wire & Digital Transmitters	Pura I.S. Transmitter
Performance Specifications
Measurement Range	-120...-40 °Cdp (-184...-40 °Fdp); non-standard ranges available on request
Accuracy	±1 °C from -40 to -60 °Cdp (±1.8 °F from -40 to -76 °Fdp) ± 2°C from -60 to -100 °Cdp (±3.6 °C from -76 to -148 °Fdp) ±4 °C from -100 to -120 °Cdp (±7.2 °C from -148 to -184 °Fdp (extrapolated)
Calibration	Traceable 7-point calibration certificate
Electrical Specifications
Output Signal	4...20 mA (2-wire connection, current source) 4...20 mA (3-wire connection, current sink) Pura M12: Modbus RTU over RS485 Pura 3-wire PUR-AOL-SEN-D: Michell Mnet digital	4...20 mA (2-wire connection, current source)
Output	Dew point or moisture content (ppm_V, ppb_V)
Analog Output Scaled Range	Dew point: -120...-40 °C (-184...-40 °F); Moisture content in gas: 0...127 ppm_V;
Supply Voltage	Pura 2-wire/3-wire & Pura I.S.: 12...28 V DC Pura M12: 5...28 V DC (digital)*
Load Resistance	Max 250 Ω @ 14 V (500 Ω @ 24 V)
Current Consumption	23 mA max, depending on output signal
Compliances	CE & UKCA
Operating Specifications
Operating Temperature	-40...+60 °C (-40...+140 °F)
Compensated Temperature Range	-20...+50 °C (-4...+122 °F)
Storage Temperature	-40...+60 °C (-40...+140 °F)
Operating Pressure	Minimum 10-⁷ Pa (10-⁹ torr); Maximum 24 MPa (240 barg/3481 psig)
Flow Rate	1...5 Nl/min mounted in standard sampling block; 0...10 m/sec direct insertion
Mechanical Specifications
Ingress Protection	IP66 in accordance with standard BS EN 60529:1992; NEMA 4 protection in accordance with standard NEMA 250–2003 Pura M12: IP65
Intrinsically Safe Area Certificates		ATEX/UKCA: II 1 G Ex ia IIC T4 Ga (-20...+70 °C) IECEx: Ex ia IIC T4 Ga (-20...+70 °C) TR CU: 0Ex ia IIC T4 Ga (-20...+70 °C) cQPSus: Class I, Division 1, Groups A, B, C & D, T4 Class I, Zone 0, AEx ia IIC T4 Ga, Ex ia IIC T4 Ga Tamb +70 °C
Housing Material	316 stainless steel
Dimensions	Please refer to the dimensional drawings on page 4 of this datasheet
Packaging	Pura Premium: Double bagged and sealed in UHP inert gas Pura OEM and Pura Sensor: Single bagged in 1000 gauge polythene All options: shipped individually in a profiled cardboard carton Sensor version supplied with protective guard over sensor technology for transportation and handling
Process Connection	Pura Premium (PRM): 2 x 1/4” male VCR Pura OEM (OEM): 2 x 1/4” male VCR Pura Sensor (SEN): 1/2” male VCR
Weight	PRM and OEM versions: 450 g (0.99 lb) SEN version: 180 g (0.4 lb)
Electrical Connections	Pura: MiniDIN 43650 form C Pura M12: M12 5 Pin (A coded)	MiniDIN 43650 form C
Mating Electrical Connectors	Mating connector supplied as standard Pura M12: optional 0.8, 2, 5 metre (2.62, 6.56, 16.4 foot) M12 A coded connector/cable available
Diagnostic Conditions (factory programmed)	Sensor fault: 23 mA Under-range dew point: 4 mA Over-range dew point: 20 mA
Approved Galvanic Isolators		KFD2-CR-EX1.20200 KFD2-CR-EX1.30200 KFD0-CS-EX1.50P KFD0-CS-EX2.50P KFD2-STC4-EX1.H MTL5041 MTL5040