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Xentaur LPDT User Manual

Loop powered dewpoint transmitter
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  • Page 2 Check the Internet for updates; the latest revision of this manual is available in Adobe Acrobat format at: http://www.xentaur.com Document No.: LDO.01.D.2000 Rev.0 6/1/99 Copyright © 1999 by Xentaur Corporation...
  • Page 3 LPDT User’s Manual Xentaur reserves the right to change or modify the product specification and / or appearance at any time without notice. Therefore, the information in this document is subject to change without notice and does not represent a commitment on the part of Xentaur Corporation.
  • Page 4 Examine the LPDT package for damage or mishan- dling. If any damage is evident notify the carrier and request an inspection. Unpack the box, it should contain: The LPDT with sensor in desiccant container, connectorized cable, and this manual. PLEASE READ THIS MANUAL IN WHOLE, PRIOR TO INSTALLING OR REMOVING THE SENSOR FROM ITS SHIPPING CONTAINER.
  • Page 5 This warranty is effective from the date of delivery to the original purchaser. The equipment must be determined by Xentaur to have been defective for the warranty to be valid. This warranty applies as follows: •...

  • Page 6: Table Of Contents

    LPDT User’s Manual LPDT User’s Manual Table of Contents 1.0 Overview of the LPDT ..........1 2.1 Precautions using the sensor .........3 2.2 Sensor Technical Specifications ........4 2.3 Sensor Installation & Sampling Techniques ....4 2.3.1 In-situ Installation ............5 2.3.2 Extractive Installation ..........7 2.4 Troubleshooting unexpected readings ......9...
  • Page 7 LPDT User’s Manual Appendix H: Uncertainty in LBS & ppmV calculations ..43 Appendix I: Sensor Response Time ........44 Appendix J: Return Authorization Request ......45...

  • Page 8: Overview Of The Lpdt

    The LPDT uses the Xentaur HTF™ sensor which is encap- sulated in sintered stainless steel, thus it is capable of com- ing into contact with a wide variety of environments.
  • Page 9 LPDT User’s Manual page 2...

  • Page 10: Precautions Using The Sensor

    Section 2: Sensor and Sampling Techniques 2.1 Precautions using the sensor The Xentaur HTF™ Al sensor is designed and field proven to be highly reliable, rugged and maintenance free. However the user should consider the following precau- tions: • To avoid the need for prolonged dry-down (when expecting to measure dewpoints dryer than -65ºC), do...

  • Page 11: Sensor Technical Specifications

    LPDT User’s Manual tive. • Do not disassemble the porous metal filter encapsula- tion, as this will damage the sensor and void your fac- tory warranty. • Prior to installation of the probe, ensure that no contam- inants are present in the system (e.g. oil, liquid water).

  • Page 12: In-Situ Installation

    Section 2: Sensor and Sampling Techniques diameter of tubing, number of interconnecting fittings, dead space in tubing and manifolds; will influence the measure- ment value and response time. The high capacitance HTF™ sensors can be installed either directly in the line to be sampled (in-situ), or in a slip stream of a sample system (extractive).
  • Page 13 LPDT User’s Manual • Under a pressurized system removal of the sensor with- out the installation of isolation valves can be dangerous. If in-situ installation is required, bypass mounting is prefer- able; make sure to install the sensor at the upper surface of...

  • Page 14: Extractive Installation

    If the resources to make your own sample system are avail- able, the following two diagrams may be used as a guideline to configure a simple system. Exhaust 4-20mA loop cable LPDT oint Transmitter Think Safety www.xentaur.com Safety shut-off Valve...
  • Page 15 LPDT User’s Manual It is generally recommended to measure at ambient pressure for the following reasons: • The readings will not be affected by variations in line pressure. • The risk of exposing the sensor to liquid water is signif- icantly reduced.

  • Page 16: Troubleshooting Unexpected Readings

    Section 2: Sensor and Sampling Techniques • Do not install any devices upstream of the sensor, such as other measuring systems, flow meters etc., which are not absolutely necessary as these are potential leak sources. • Installation of a coalescing and / or particulate filter ahead of the sensor is desirable to prevent any liquid or particulate contamination of the sensor.
  • Page 17 LPDT User’s Manual Troubleshooting unexpected readings (table spans 2 pages) Symptom Possible Cause Reading is not Condensation in sample system. changing 1. Water vapor in the system. Slow Response 2. Flow rate too low. 3. Sample pipe too large and/or too long.
  • Page 18 MOMENTARILY with the sensor in a known dry condition. Polarity is not important, but the contact MUST be very brief or the sensor may be damaged. Remove (unscrew) the sensor. Short the center contact of the LPDT sensor connection to the case, if the instrument reads...
  • Page 19 LPDT User’s Manual page 12...

  • Page 20: Precautions Using The Lpdt

    If weather proofing is required consult your representa- tive for an optional cover. 3.1.1 Electromagnetic Compatibility Considerations The LPDT has been designed and verified by testing to meet the requirements of the EC Council EMC Directive 89/336/EEC, for Industrial, Scientific & Medical equip- ment.

  • Page 21: Instrument Technical Specifications

    RS-232, however to interface to a PC or other RS-232 device an optional adapter is required. In the digital mode the LPDT can be remotely operated and the dewpoint as well as temperature page 14...

  • Page 22: Installation

    Sample Cell, if you do not have the ability to provide an appropriate sample cavity mounting. If the ¾”x16 thread is used then the LPDT will seal against the wall of the sample cell with the provided Viton A O-ring. If the 14mm x 1.25 spark plug thread is used then an addi-...

  • Page 23: Electrical Installation

    The provided cable is terminated with a connector which has a retainer, the retainer may be used to secure the connector to the LPDT thus avoiding accidental disconnection. The LPDT will draw 4mA to 20mA from the power supply depending on the dewpoint being measured.

  • Page 24: Operating The Instrument

    To accommodate a variety of installation possibilities, the LPDT front panel may be rotated (360°) by gently pressing down on the spring loaded face plate and turning it to the desired position.
  • Page 25 LPDT User’s Manual not to change any parameter inadvertently. 3. °C°F appear simultaneously, to indicate the sensors’ attenuation in decibels. 4. Values larger than ±1999 or smaller than ±0.01 are dis- ±3 played in powers of 10 . As required, either a “10 ”...

  • Page 26: Push Buttons

    Section 3: Instrument 3.4.3 Push Buttons Three push buttons are located on the front panel. XENTAUR LPDT x10¯³ HILO TEMP ˚C˚F DEWPOINT G/M³ MODE button UP button DOWN button Each button is marked with an icon engraved above it. In general the MODE button navigates through the different user options “Modes”;...

  • Page 27: Viewing Dewpoint Mode

    LPDT User’s Manual 3.4.4.1 Viewing Dewpoint Mode In this mode the user can view the dewpoint, this is indi- cated by the presence of the ‘DEWPOINT’ legend on the lower left of the display. The available engineering units in which to view the moisture content are °C, °F, PPM, LBS and G/M ;...

  • Page 28: Start Calibration (Spancheck™) Mode

    Section 3: Instrument 3.4.4.3 Start Calibration (SpanCheck™) Mode The instrument is calibrated at the factory with the sensor it is shipped with and does not need to be re-calibrated prior to installation. Instrument calibration is recommended in approximately 12 month intervals, and the XTR65W sensor should be re-cali- brated after prolonged exposure to liquid water.
  • Page 29 The display may show alternating as an indication that the measured capacitance is too low to be from a saturated sensor, in this case make sure that the sensor is fully engaged into the LPDT, and repeat the page 22...
  • Page 30 Section 3: Instrument calibration procedure. 7. Install the sensor in the sample cell or adapter fitting or put it back into the packaging container for later use. The instrument will retain the calibration even if the power is turned off. Under certain conditions, an over (super) saturated sensor may need to be completely dried out before a calibration is performed.

  • Page 31: Viewing Serial Number Mode

    LPDT User’s Manual taken that the sensor temperature is not below the tempera- ture of the hand, as in such case condensation could occur and super saturate the sensor. For the same reason, avoid exhaling directly onto the sensor. 3.4.4.4 Viewing Serial Number Mode In this mode the user can view the serial number of the sen- sor calibrated and shipped with the instrument.
  • Page 32 Section 3: Instrument diagram of the SetUp State. The setup state provides nine capabilities, each one con- trolled from its own mode. Depressing the MODE button navigates through the modes in the following order: lect Alternate Display Units ‹ Select Sensor Type ‹ Measured Attenuation of Sensor at a Low Dewpoint ‹...
  • Page 33 LPDT User’s Manual tainer is labeled with the proper values. 5. Calibration Adjustment : In this mode the user can enter a sensor specific Adjustment Value to improve the instruments’ accuracy in the range of -50°C to -10°C, this adjustment has very little or no effect outside this range.
  • Page 34 Section 3: Instrument f. Observe the display, if the buttons are not being pressed; the display will every few seconds show for a short duration the dewpoint as being computed at the moment (utilizing the current cal-adjust value in the computation).

  • Page 35: Troubleshooting The Instrument

    LPDT User’s Manual the current loop output, refer to appendix G. 9. Lock/Unlock the instrument : This mode is used to block access to parameter settings, protecting the instru- ment from unauthorized or inadvertent changes of parameters. Attempting to change settings while instru-...
  • Page 36 Section 3: Instrument DISPLAY EXPLANATION REQUIRED ACTION PROM check sum failed. RAM write/read test failed. cycle power Unidentified power-up failure. if problem persists, EEPROM C heck S um F ailed. return to your representative for service. A/D converter failure. Ref erence voltage for A/D out of spec. check input voltage 10-33VDC Lo w supply voltage.
  • Page 37 Under these circumstances the unit display will be blank and the instrument will not draw any current when powered up. The fuse is not user replaceable, therefore the LPDT must be sent to your representative for servicing. page 30...

  • Page 38: Appendix A: Operating State User Interface Flowchart

    Appendices Appendix A: Operating State User Interface flowchart 30 seconds anywhere Power ON initialization other than calibration and sign on message without a key press XENTAUR LPDT a flashing 1sec. PSI legend means pressure correction is Viewing XENTAUR LPDT being applied,...

  • Page 39: Appendix B: Set-Up State User Interface Flowchart

    LPDT User’s Manual Appendix B: Set-Up State User Interface flowchart CAUTION! These parameters are set properly at the factory, to correspond to the shipped sensor. Do not modify them unless you are replacing the sensor. page 32...
  • Page 40 Appendices User Interface Flow Diagram - Set-Up State (continued from previous page page 33...

  • Page 41: Appendix C: Lpdt Mechanical Drawing

    LPDT User’s Manual Appendix C: LPDT Mechanical Drawing 1.750" oint Transmitter Think Safety www.xentaur.com page 34...

  • Page 42: Appendix D: Lpdt Electrical Connections

    Appendices Appendix D: LPDT Electrical Connections Methods of Using and Interfacing the LPDT Operation with Wall Transformer Operation with Relay Option Board Dewpoint viewed on Instrument Display Dewpoint viewed on Instrument Display and available as 4-20mA output 10-33VDC Relay Option Board...

  • Page 43: Appendix E: Sensor/Spancheck™ Theory Of Operation

    LPDT User’s Manual Appendix E: Sensor/SpanCheck™ Theory of Operation The Sensor is constructed as a capacitor whose dielectric consists of porous Aluminum Oxide as well as the gas that has entered in the pores of the Aluminum Oxide. The plates...
  • Page 44 This is refered to as SpanCheck™. The advantages of this unique capability of Xentaur sensors and instruments are obvious in time and cost savings for re-calibration, as well as ease of sensor replacement.
  • Page 45 LPDT User’s Manual page 38...

  • Page 46: Appendix F: Pressure Correction

    As all Xentaur dewpoint meters, the LPDT is equipped with the necessary software to perform pressure correction. However, for the lack of space, the LPDT does not have a Pressure Correct button. Therefore the user can not set or enable Pressure Correction, this must be done at the factory.

  • Page 47: Appendix G: Current Vs. Dewpoint

    LPDT User’s Manual Appendix G: Current vs. Dewpoint The current being pulled by the LPDT, varies with the dew- point being measured by the LPDT. To use the current to calculate the value of the dewpoint measurement, one must know the settings of the low and high ends of the analog output range, then: ×...
  • Page 48 It is available at www.xen- taur.com. If you are not certain how to carry out such calcu- lations send, by e-mail to xentaur@xentaur.com or by fax to (516) 345-5349, your system specifics, and some one will get back to you with appropriate analog output settings.
  • Page 49 LPDT User’s Manual Relationship of 4-20mA output and instrument reading in ppmV or LBS 289.1 LBS = 0˚C = 6063.8 ppmV 49.3 LBS = -20˚C = 1019.3 ppmV 1.97 LBS = -50˚C = 38.83 ppmV 0.56 LBS = -60˚C = 10.66 ppmV...

  • Page 50: Appendix H: Uncertainty In Lbs & Ppmv Calculations

    Appendices Appendix H: Uncertainty in LBS & ppmV calculations 1000 0.25 0.05 Measured Dewpoint ˚C page 43...

  • Page 51: Appendix I: Sensor Response Time

    LPDT User’s Manual Appendix I: Sensor Response Time page 44...

  • Page 52: Appendix J: Return Authorization Request

    Return Authorization Request Appendix J: Return Authorization Request Xentaur must approve and assign a return authorization number (RAN) to any instrument being returned. The RAN must appear on all paperwork and packag- ing. The issuance of a RAN does not automatically imply that the instrument is covered by our warranty.
  • Page 53 LPDT User’s Manual page 46...
  • Page 54 Xentaur Corporation, 3661 Horseblock Road, Medford, NY 11763 USA Tel: (516) 345-3434...

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