Pura

 Pure Gas Dew-Point Transmitter / On-Line
In many high purity gas applications, such as the semiconductor industry, the residual moisture content of the gas is critical to satisfactory operation of a process. Historically trace moisture measurement has been problematic, demanding the use of complex moisture analyzers or expensive analytical techniques. Now Michell has brought to market a simple, economical and very effective solution for on-line measurement of dew-point temperatures down to -120°C (equivalent to less than 1 part per billion).

The Pura transmitter benefits from Michell's experience and expertise in the production and calibration of impedance dew-point sensors. Incorporation of industry standard materials and manufacturing processes gives the first low cost transmitter suitable for large-scale integration into a semiconductor fabrication plant or high purity gas line.

Product Features

  • Measurement Range down to -120°C dew point (1 ppbV)
  • Stable and repeatable measurement
  • High integrity sampling system
  • Analogue and digital output
  • Simple installation
  • VCR process connections
  • Compact design
  • Optional display / alarm unit
Pura

Technical Specification
SENSOR
Sensor Type Michell Ceramic Moisture Sensor
Range -120 to -40°C dew point (calibrated -100 to -40°C )
Accuracy ±1°C from -40 to -60°C; ±2°C from -61 to -100°C; ±4°C from -101 to -120°C (estimated)
Resolution 0.1°C from -40 to -79.9°C; 1°C from -80 to -100°C; 1 to 3°C from -100 to -120°C
Pressure Rating Minimum 10-9 torr; Maximum 24 MPa p.s.i.g.
Gas Flow Rate 1 to 5 Nl/min
ELECTRONICS
Power Supply Nominal 24VDC, 10 V min to 28 V max, current max 25 mA
Output 4-20 mA output adjustable from 1 to 80°C span using interface software (supplied)
Max load = 100 Ω + 50 Ω x (V supply-8)
Output Error Status Standard output error conditions as supplied: 23 mA = sensor fault; 20 mA = over range; 4 mA = under range
MECHANICAL
Sensor Block Cold drawn stainless steel, 0.1-0.2 Ra µm electro-polished internal finish
Gas Connection Ports Premium and OEM versions: ¼" male VCR connections
Pura Sensor version: ½" male VCR connection
Installation Profile Premium and OEM versions: 120.00mm 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 Dimensions Premium and OEM versions: 120 x 35 x 150 mm
Pura Sensor version: 132 x 35 dia mm
Weight Premium and OEM versions: 450 g
Pura Sensor version: 180 g
Packaging Pura: Double bagged and sealed in UHP inert gas
Pura OEM and Pura Sensor: Single bagged in 1000 gauge polythene
All options: shipped individually in profiled sponge protection and carton
Sensor version supplied with protective guard over sensor surface for transportation and handling

Applications
Semi-Conductor / Electronics

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