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Michell Instruments

PUR Gas Trace Moisture Transmitter

Designed to measure trace moisture in ultra high purity gases down to -120°Cdp w/ optional hazardous area approval

Have questions? We're here to help!
Have questions? We're here to help!

This small transmitter is a rugged, self-contained hygrometer designed specifically for the measurement of trace moisture content in ultra high purity gases. 
Simple to use and install, the Pura is available in 2-wire, 3-wire and hazardous area versions and is fully configurable to meet specific needs.

• Measurement range down to -120°Cdp (1ppbV)
• Stable and repeatable measurement
• Analogue and digital output
• Simple installation
• VCR process connections
• Optional display / alarm unit
• Compact design
• Fast response
• Optional Hazardous Area Approval
• Service exchange program

Sensor
Sensor TypeMichell Advanced Ceramic Moisture Sensor
Range-120 to -40°Cdp (calibrated from -100 to -40°C)
Accuracy ±1°C from -40 up to -60°Cdp
±2°C from -60 up to -100°Cdp
±4°C from -100 to -120°Cdp (estimated)
Operating PressureMinimum 10-7 Pa (10-9 torr)
Maximum 24 MPa (240 barg)
Operating Temperature-40 to +60°C
Flow Rate1 to 5 Nl/min
Electronics/Electrical
PowerNominal 24 V DC, 10-28 V DC maximum current 25 mA 2 or 3-wire configuration
Output PUR-TX-2W: 4 to 20mA 2-wire
PUR-TX-3W: 4 to 20mA 3-wire
PUR-AOL-SEN only: Digital String (RS485)
Cable with DisplayPUR-OL & PUR-IS-OL: 2m (standard) / 5 or 10m (optional)
PUR-AOL: 2m (standard) / 5 or 10m (optional)
Mechanical
Sensor BlockPremium and OEM version: Cold drawn stainless steel, 0.1 - 0.2 Ra µm electro-polished internal finish
Pressure Connections Premium and OEM version: ¼" male VCR connection
Pura Sensor version: ½" male VCR connection
Installation ProfilePremium and OEM version: 120mm pitch, drop in across gas port face seals
Zero pipe clearance required
2 off M4 x 0.7, 7mm deep mounting holes in block, diagonally opposed at 20 x 20mm pitch
Pura Sensor version: fits into user's ½" VCR configured port
Overall DimensionsPremium and OEM version: 120 x 35 x 150mm (w x d x h)
Pura Sensor version: 132 x Ø35mm
WeightPremium and OEM versions: 450g
Pura Sensor version: 180g
PackagingPura Premium: Double bagged and sealed in UHP inert gas
Pura OEM & Pura Sensor: Single bagged in 1000 gauge polythene
All options: shipped individually in profiled sponge protection and carton
Pura Sensor version supplied with protective guard over sensor surface for transportation and handling
Service ExchangeAvailable on the Pura Sensor (SEN) ½" VCR connection
Monitors
Advanced Online Monitor:
Measurement Units°F, °Cdp; ppmV and ppbV with user-selectable range and resolution
Secondary Measurement VariablePressure via external transducer 0-30 MPa (300 variable barg)
Completely user-configurable for any industry standard transducer
Automatic compensation for ppmV and ppbV
Power SupplyUniversal 85 to 265 V AC; 95 to 370 V DC
Ingress ProtectionIP54 (NEMA 12); IP66 (NEMA 4X) for front panel only with optional cover
Operating Temperature0 to +50°C
Relays 2 off 10 A / 240 V c/o fully user-configurable: can accommodate full range for selected engineering unit + sensor fault alarm functions
Display Resolution5 Digit
Outputs: Analogue4-20 mA fully user-configurable and scaleable for range
Outputs: DigitalRS232: provides 2-way communication - full data access to user and total availability of all set-up options
Online Monitor:
Measurement UnitsSimple display defined by 2-wire sensor input
Secondary Measurement VariableppmV with no line pressure correction input available with PUR-TX-2W & PUR-IS-2W
Power Supply100 to 240 V AC (+10, -15%) 50/60 Hz
Ingress ProtectionIP65 front panel (IP20 rear panel)
Operating Temperature0 to +50°C
RelaysAlarm 1 relay: single pole make contact, rating 3 A @ 250 V AC
Alarm 2 relay: changeover contacts, rating 5 A @ 250 V AC
Display Resolution4 Digit
Outputs: Analogue0-20 or 4-20 mA fully user-configurable and scaleable for range
Outputs: DigitalRS232: provides 2-way communication - full data access to user and total availability of all set-up options
Options
Advanced Online Monitor:
Power Supply18 to 36 V AC; 9 to 60 V DC
Relays 1 or 2 further 5 A relays (max 4 in total) n/o type fully user configurable: can accommodate full range + full unit choice + sensor fault alarm functions
Outputs: Analogue0-10 V fully user-configurable and scaleable for range
Outputs: DigitalRS485
Online Monitor:
Power Supply24 V DC
Relays1 further optional relay - refer to factory
Outputs: Analogue0 to 10 V output using 500 Ω shunt resistant

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