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Michell Instruments PURA User Manual

Online hygrometer
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Pura
Online Hygrometer
User Manual
97303 Issue 2
January 2022

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  • Page 1 Pura Online Hygrometer User Manual 97303 Issue 2 January 2022...
  • Page 2 Please fill out the form(s) below for each instrument that has been purchased. Use this information when contacting Michell Instruments for service purposes. Product Name Order Code Serial Number Invoice Date Installation Location Tag Number Product Name Order Code Serial Number...
  • Page 3 © 2022 Michell Instruments This document is the property of Michell Instruments Ltd and may not be copied or otherwise reproduced, communicated in any way to third parties, nor stored in any Data Processing System without the express written authorization of Michell Instruments Ltd.

  • Page 4: Table Of Contents

    INSTALLATION ....................3 Unpacking the Instrument ................... 3 2.1.1 Unpacking Pura Online Hygrometer ..............3 2.1.2 Unpacking Pura SEN (transmitter, no block version) ......... 4 2.1.3 Unpacking Pura OEM-single bag, PRM-double bag versions ......5 2.1.4 Unpacking the Monitor .................. 5 Pura Online Components ..................
  • Page 5 Pura Online Hygrometer User Manual Change Dew-Point Temperature Range .............. 31 3.4.1 Span and Unit Settings ................32 3.4.2 Configure Alarm Set-Point Limits ..............33 3.4.3 Change Scale Units (to ppm ) ..............34 MEASUREMENT GUIDE ..................36 General Operational Guidelines ................. 36 Maintenance and Calibration ................
  • Page 6 Unpacking – Monitor and Pura SEN, no block version ........3 Figure 3 Unpacking – Monitor and Pura OEM / PRM ...........4 Figure 4 Unpacking – Pura OEM & PRM – Single / Double Bag ........5 Figure 5 Monitor Unpacking Method ................5 Figure 6 Components ....................6...

  • Page 7: Safety

    Michell Instruments can offer a variety of re-calibration and exchange transmitter schemes to suit your specific needs. A local representative will be pleased to provide detailed, custom advice.

  • Page 8: Abbreviations

    Pura Online Hygrometer User Manual Abbreviations The following abbreviations are used in this Manual: alternating current pressure unit (atmosphere) barg pressure unit (=100 kP or 0.987 atm) ºC degrees Celsius ºF degrees Fahrenheit direct current dew point foot (feet) gram(s) Hertz “...

  • Page 9: Introduction

    Pura Online Hygrometer User Manual INTRODUCTION INTRODUCTION The Pura Online dew-point hygrometer is an instrument designed for the continuous online measurement of water dew point in gaseous sample streams, in a diverse range of applications. The system comprises a programmable monitor configured to accept a 4...20 mA current loop signal from the Michell ceramic metal-oxide dew-point transmitter.

  • Page 10: Features

    Pura Online Hygrometer User Manual INTRODUCTION Features The Pura Online Hygrometer is simple to use and install, and can be configured to meet specific needs. • ¼” male VCR process connections for PRM and OEM version ½” male VCR process connection for Pura SEN version •...

  • Page 11: Installation

    Unpacking the Instrument 2.1.1 Unpacking Pura Online Hygrometer The Pura Hygrometer instrument and accessories are packed in a box and the method of unpacking is shown as follows: Unpacking – Monitor and Pura SEN, no block version Figure 2...

  • Page 12: Unpacking Pura Sen (Transmitter, No Block Version)

    Pura Online Hygrometer User Manual INSTALLATION Unpacking – Monitor and Pura OEM / PRM Figure 3 2.1.2 Unpacking Pura SEN (transmitter, no block version) Unpack the dew-point transmitter from the rectangular cardboard box. NOTE: The transmitter sensing element is protected while in transit by a red cover containing a small desiccant capsule.

  • Page 13: Unpacking Pura Oem-Single Bag, Prm-Double Bag Versions

    Pura Online Hygrometer User Manual INSTALLATION 2.1.3 Unpacking Pura OEM-single bag, PRM-double bag versions Unpacking – Pura OEM & PRM – Single / Double Bag Figure 4 2.1.4 Unpacking the Monitor The monitor (2) is packed, together with its fixing clamps (1) as shown below.

  • Page 14: Pura Online Components

    Pura Online Hygrometer User Manual INSTALLATION Pura Online Components On delivery, please check that all the following standard components are present in the packing box. Report any shortages immediately. Components Figure 6 Pura Monitor Clamps Sensor cable assembly Pura Transmitter (SEN) OR...

  • Page 15: Pura Sen

    NOTE: For environmental and operating conditions, refer to Appendix A, Technical Specifications. NOTE: OEM and PRM version transmitters are protected in transit by putting in a plastic bag filled with nitrogen. Pura OEM transmitter has single bag protection, Pura PRM transmitter has double bag protection. Electrical connector...

  • Page 16: Monitor

    Pura Online Hygrometer User Manual INSTALLATION Monitor The controls and indicators associated with the Pura Online are located on the front panel of the Process Indicator. Connections to the Pura Transmitter, the RS485 communications port and the external power supply are all made to the rear panel of the Process Indicator (refer to Sections 3 and 4).

  • Page 17: Monitor Controls And Indicators

    Pura Online Hygrometer User Manual INSTALLATION 2.5.2 Monitor Controls and Indicators Item Description °F units indicator Indicates that the displayed dew-point reading is in degrees Fahrenheit. °C units indicator Indicates that the displayed dew-point reading is in degrees Celsius. Note: if neither the °Cdp nor °Fdp LED is lit, ppm is selected.

  • Page 18: Electrical Connections

    Pura Online Hygrometer User Manual INSTALLATION 2.5.3 Electrical Connections Electrical connections to the Pura Online system are as follows: Required: • AC power supply, 100 to 240 V AC (-15 %, +10 %), 50/60 Hz, 6 VA. A low voltage (24 V DC) option is also available.

  • Page 19: Table 2 Summary Of Electrical Connections

    Pura Online Hygrometer User Manual INSTALLATION Figure 10 Monitor Rear Panel Connections Terminal Wire Colour Signal Supply Information Blue 0 V (GND) Transmitter Cable Screen Green 4...20 mA loop return Transmitter loop supply +24 V DC w.r.t. terminal 1 (+ve)

  • Page 20: Ac Power Supply Input

    Pura Online Hygrometer User Manual INSTALLATION 2.5.4 AC Power Supply Input It is essential that the connection of electrical supplies to this instrument be undertaken by competent personnel. Connect the AC power supply to the monitor as shown in Figure 11 . Refer also to Table 4 which gives a summary of all the connections to the rear panel of the monitor.

  • Page 21: Dc Power Supply Input (Optional)

    Pura Online Hygrometer User Manual INSTALLATION 2.5.5 DC Power Supply Input (Optional) Connect the DC power supply to the monitor as shown in Figure 12 . Refer also to Table 4 which gives a summary of all the connections to the rear panel of the monitor.

  • Page 22: Transmitter Connection

    Pura Online Hygrometer User Manual INSTALLATION 2.5.6 Transmitter Connection Connect the transmitter cable to the monitor as shown below: 1 0 1 2 2 2 0 2 1 1 9 2 7 1 8 1 6 1 1 4 1...

  • Page 23: Signal Output Connections

    2.5.7 Signal Output Connections The Pura Online system has four possible signal outputs: Alarm 1 (ALr1), Alarm 2 (ALr2), the re-transmitted input signal (4...20 mA or 0...20 mA current loop signal depending upon instrument configuration) and the digital communications interface.

  • Page 24: Mounting The Monitor

    Pura Online Hygrometer User Manual INSTALLATION 2.5.8 Mounting the Monitor The monitor is designed for panel mounting and requires a panel cut-out of 46 x 92mm (1.8 x 3.6”). The recommended panel thickness is 2 to 5mm (0.08 to 0.2”).

  • Page 25: Preparation Of The Transmitter Cable

    Refer to wiring schematics later on in this document for connection examples. Note: The sensor cable is supplied as standard. Replacement pre-wired cables can be obtained by contacting your local Michell Instruments representative or assembled by the user according to instructions in the following section. Michell Instruments...

  • Page 26: Sensor Cable Assembly

    Pura Online Hygrometer User Manual INSTALLATION 2.6.2 Sensor Cable Assembly For guidance on type of cable refer to Section 2.6.3. Assembly Instructions Remove the screw from the rear of the DIN connector housing. Lever the terminal block from the connector housing by inserting a small screwdriver in the notch on the front face of the terminal block.

  • Page 27: Cable Selection For Self-Assembled Cables

    2.6.4 Maximum Loop Resistance vs Supply Voltage Maximum Load of Pura – Including Cable Resistance Figure 18 NOTE: Cable resistance of the entire loop must be considered when calculating loop resistance.

  • Page 28: Wiring Connection Between The Transmitter And The Monitor

    Pura Online Hygrometer User Manual INSTALLATION 2.6.5 Wiring Connection Between the Transmitter and the Monitor When installing the connector, and to ensure that full ingress protection is achieved, the securing screw (with the O-ring and washer) must be tightened to a minimum torque setting of 3.4 Nm (2.5 ft-lbs).

  • Page 29: Transmitter Mounting

    Pura Online Hygrometer User Manual INSTALLATION Transmitter Mounting 2.7.1 Sensor Block Connection (Recommended Method) The following procedure must be carried out by a qualified installation engineer. WARNING: Under no circumstances should the sensing element be handled with the fingers. To mount the transmitter into the sensor block, proceed as follows – refer to Figure 21.

  • Page 30: Direct Pipeline Connection

    Michell Instruments recommends the use of Swagelok retained gasket assemblies, ® containing silver plated, stainless steel 1/2” VCR gaskets, when connecting the Pura into a gas line. NOTE: Do not overtighten or the thread on the pipework may be stripped.

  • Page 31: Pura Oem & Prm Connection

    2.7.3 Pura OEM & PRM Connection The Pura OEM and PRM have been assembled and packaged within a Class 100 clean- room environment. To maintain this level of cleanliness the packaging should only be unpackaged within the same, or cleaner, environment.

  • Page 32: Operation

    The span will require changing if the instrument is to be ranged in °F, if a different transmitter is employed, if the user chooses to re-range the Pura transmitter. The instrument must also have been installed as detailed in Section 2 and connected to a sample gas supply that is representative of the process being monitored.

  • Page 33: First Time Operation

    Pura Online Hygrometer User Manual OPERATION First Time Operation Prior to operation, the instrument must be connected to the correct electrical power supply and the relevant analog and alarm outputs connected to external systems as required and as described above.

  • Page 34: System Alarms

    (-40ºCdp) and the numeric section of the display gives an indication of the actual measured reading. System Alarms The Pura Hygrometer has two alarm outputs. As supplied, the default alarm set-points and the alarm switching logic are as follows (the default temperature units are degrees Celsius): •...

  • Page 35: Reversal Of Default Alarm Switching Logic

    Pura Online Hygrometer User Manual OPERATION 3.3.1 Reversal of Default Alarm Switching Logic As stated in Section 3.3, the switching logic for the alarm channels may, if required, be individually reversed. Starting at the default state, the method of reversing the switching logic for both alarms is as follows: Figure 32 shows the operational key sequence.

  • Page 36: Figure 22 Change Alarm Switching Logic

    Pura Online Hygrometer User Manual OPERATION Main Display (Change Alarm 2 Switching Logic) Main Main Display Display Figure 22 Change alarm switching logic 97303 Issue 2, January 2022...

  • Page 37: Set-Up Alarm Levels

    Pura Online Hygrometer User Manual OPERATION 3.3.2 Set-up Alarm Levels The alarm set-point levels are set-up Main display from the program menu as follows (to exit to the main display without saving any new settings press the ‘ ’ Set x2 for Alarm 2 only...

  • Page 38: Configure Analog Output Current Loop

    Pura Online Hygrometer User Manual OPERATION 3.3.3 Configure Analog Output Current Loop The Pura Hygrometer is provided with an analog current loop output module which buffers and re-transmits the current loop input signal from the dew-point transmitter. By default, the re-transmission output is set as a 4...20 mA current loop (to exactly follow the...

  • Page 39: Change Dew-Point Temperature Range

    Pura Online Hygrometer User Manual OPERATION Change Dew-Point Temperature Range The default temperature unit for the Pura Hygrometer is degrees Celsius. This is indicated by the º LED indicator. The default settings associated with this temperature scale are as follows: •...

  • Page 40: Span And Unit Settings

    Pura Online Hygrometer User Manual OPERATION 3.4.1 Span and Unit Settings To change the span and unit settings, Main Display (°C) proceed as follows. Figure 34 shows the operational key sequence. 1. Press the ‘ ’ key once, the display will read ‘...

  • Page 41: Configure Alarm Set-Point Limits

    Pura Online Hygrometer User Manual OPERATION 3.4.2 Configure Alarm Set-Point Limits The following procedure is used to set limits Main display to which the alarm levels can be set (usually after re-configuring the instrument’s range for Fahrenheit readings). Figure shows operational sequence.

  • Page 42: Change Scale Units (To Ppm )

    Note: The dew-point transmitter must first be programmed to provide an output proportional to ppm by using the Michell application software. Contact Michell Instruments for information (for contact details see Appendix B). Press the ‘ ’ key once, the display will read ‘...

  • Page 43: Figure 27 Set-Up Process Indicator (To Read Ppm )

    Pura Online Hygrometer User Manual OPERATION Main Display, e.g. °C Main Display, ppm(v) Set-up process indicator (to read ppm Figure 27 Michell Instruments...

  • Page 44: Measurement Guide

    MEASUREMENT GUIDE MEASUREMENT GUIDE The Pura Online Hygrometer is designed to operate in a flowing gas stream and is suitable for the measurement of the moisture content of a wide variety of gases. In general, if the gas (in conjunction with water vapor) is not corrosive to ceramics or base metals then it will be suitable for measurement by the Pura Online.
  • Page 45 Generally, if the sample gas (in conjunction with water vapor) is not corrosive to base metals, it will be suitable for measurement by the Pura Online system. Gases containing entrained solids should be filtered before application to the sample block.

  • Page 46: Maintenance And Calibration

    Maintenance and Calibration Routine maintenance of the Pura Online Hygrometer is confined to regular re-calibration. For most applications, annual re-calibration ensures that the stated accuracy of the Pura Online Hygrometer is maintained. Specialist calibration instrumentation is required to calibrate the transmitter and a true calibration can only be performed by exposure of the dew-point sensor to a reference gas of known dew point.

  • Page 47: Maintenance

    All calibrations are traceable to national standards either via the National Physical Laboratory (UK) or the National Institute of Standards and Technology (USA). The Pura transmitter can be returned to Michell Instruments either directly or via the authorized distributor, for calibration.
  • Page 48 Pura Online Hygrometer User Manual APPENDIX A Appendix A Technical Specifications 97303 Issue 2, January 2022...

  • Page 49: Appendix A Technical Specifications

    Pura Online Hygrometer User Manual APPENDIX A Appendix A Technical Specifications Monitor Equipment Use Process indicator – dew-point measurement 48 x 96 x 86mm (1.9 x 3.8 x 3.4”) Horizontal, Housing & Mounting DIN 43700 Plastic housing for panel mounting.
  • Page 50 Pura Online Hygrometer User Manual APPENDIX A Transmitter Measurement Range (dew -120...-40 °C (-184...-40 °F) dew point point) Accuracy (dew point) ±1 °C from -40 up to -60 °C ±2 °C from -60 up to -100 °C ±4 °C from -100 up to -120 °C (estimated) Repeatability 0.5 °C (0.9 °F) dew point...
  • Page 51 Pura Online Hygrometer User Manual APPENDIX B Appendix B Quality, Recycling, Compliance & Warranty Information Michell Instruments...

  • Page 52: Appendix B Quality, Recycling, Compliance & Warranty Information

    APPENDIX B Appendix B Quality, Recycling, Compliance & Warranty Information Michell Instruments is dedicated to complying to all relevant legislation and directives. Full information can be found on our website at: www.michell.com/compliance This page contains information on the following directives: •...
  • Page 53 Pura Online Hygrometer User Manual APPENDIX C Appendix C Return Document & Decontamination Declaration Michell Instruments...

  • Page 54: Appendix C Return Document & Decontamination Declaration

    Has the equipment been cleaned and decontaminated? NOT NECESSARY Michell Instruments will not accept instruments that have been exposed to toxins, radio-activity or bio-hazardous materials. For most applications involving solvents, acidic, basic, flammable or toxic gases a simple purge with dry gas (dew point <-30°C) over 24 hours should be sufficient to decontaminate the unit prior to return.
  • Page 55 Pura Online Hygrometer User Manual NOTES Michell Instruments...
  • Page 56 www.ProcessSensing.com http://www.michell.com...

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