Vaisala DRYCAP DMT345 User manual

USER'S GUIDE
Vaisala DRYCAP
®
Dewpoint
Transmitters
DMT345 and DMT346
M210762EN-D

PUBLISHED BY
Vaisala Oyj Phone (int.): [phone]
P.O. Box 26 Fax: [phone]
FI-00421 Helsinki
Finland
Visit our Internet pages at http://www.vaisala.com/
© Vaisala 2009
No part of this manual may be reproduced in any form or by any means, electronic or
mechanical (including photocopying), nor may its contents be communicated to a third
party without prior written permission of the copyright holder.
The contents are subject to change without prior notice.
Please observe that this manual does not create any legally binding obligations for
Vaisala towards the customer or end user. All legally binding commitments and
agreements are included exclusively in the applicable supply contract or Conditions of
Sale.

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Table of Contents
CHAPTER 1
GENERAL INFORMATION..........................................................................13
About This Manual.................................................................13
Contents of This Manual.....................................................13
Version Information.............................................................14
Related Manuals.................................................................14
Feedback.............................................................................14
Safety.......................................................................................15
General Safety Considerations...........................................15
Product Related Safety Precautions...................................15
ESD Protection....................................................................15
Recycling ................................................................................16
Regulatory Compliances.......................................................16
Transmitters with LAN or WLAN Interface..........................16
Transmitters with WLAN Interface ......................................17
Patent Notice ..........................................................................17
Trademarks.............................................................................18
License Agreement................................................................18
Warranty..................................................................................18
CHAPTER 2
PRODUCT OVERVIEW................................................................................19
Introduction to DMT345 and DMT346...................................19
Basic Features and Options................................................20
Operating Principle..............................................................21
Structure of the Transmitter ................................................22
Probes and Cooling Set......................................................24
CHAPTER 3
INSTALLATION............................................................................................25
Selecting Location .................................................................25
Mounting the Housing ...........................................................25
Standard Mounting without Mounting Plate........................25
Wall Mounting with Wall Mounting Kit.................................26
Mounting with DIN Rail Installation Kit................................28
Pole Installation with Installation Kit for Pole or Pipeline ....29
Mounting Rain Shield with Installation Kit...........................30
Panel Mounting Frame........................................................31
DMT345 Probe Mounting.......................................................32
Installation with Flange........................................................32
DMT346 Probe and Cooling Set Mounting...........................33
Description of the Cooling Set.............................................34
Parts of the Cooling Set.................................................35
General Probe and Cooling Set Mounting Instructions.......36

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Probe and Cooling Set Mounting with Process Shut
Down ..............................................................................38
Probe and Cooling Set Mounting with Process Running38
Removing the Transmitter for Maintenance...................38
Wiring.......................................................................................39
Cable Bushings ...................................................................39
Cable Grounding .................................................................40
Transmitter Housing Grounding..........................................41
Signal and Power Supply Wiring.........................................41
Connections to a 24 VAC Power Supply.............................43
Optional Modules ...................................................................45
Power Supply Module .........................................................45
Installation......................................................................45
Warnings ........................................................................46
Galvanic Isolation for Output...............................................49
Third Analog Output ............................................................50
Installation and Wiring....................................................50
Alarm Relays.......................................................................51
Installation and Wiring....................................................51
Selecting Relay Activation State ....................................52
RS-422/485 Interface ..........................................................53
Installation and Wiring....................................................53
LAN Interface.......................................................................56
WLAN Interface...................................................................57
Attaching the WLAN Antenna ........................................58
Data Logger Module............................................................58
8-Pin Connector...................................................................60
CHAPTER 4
OPERATION.................................................................................................63
Getting Started........................................................................63
Display/Keypad.......................................................................63
Basic Display.......................................................................63
Graphic History....................................................................64
Menus and Navigation.........................................................66
Changing the Language.................................................67
Rounding Setting............................................................67
Display Backlight Setting................................................68
Display Contrast Setting.................................................68
Keypad Lock (Keyguard)................................................68
Menu PIN Lock...............................................................68
Factory Settings...................................................................69
Display Alarms.....................................................................69
Configuring a Display Alarm...........................................70
MI70 Link Program for Data Handling ..................................71
Serial Line Communication...................................................72
User Port Connection..........................................................72
Service Port Connection......................................................73
Connection Cables.........................................................73
Installing the Driver for the USB Cable ..........................74
Using the Service Port....................................................74
LAN Communication..............................................................75
IP Configuration...................................................................75
Using Display/Keypad....................................................76
Using Serial Line............................................................77

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Wireless LAN Configuration................................................78
Using Display/Keypad....................................................79
Using Serial Line............................................................80
Telnet Settings....................................................................81
Web Configuration for LAN and WLAN...............................81
Terminal Program Settings .................................................82
Opening a Serial/USB Connection.................................83
Opening a Telnet Session (LAN/WLAN)........................84
List of Serial Commands.....................................................85
Getting Measurement Message from Serial Line................87
Starting Continuous Outputting......................................87
R................................................................................87
Stopping Continuous Outputting....................................87
S................................................................................87
Formatting Serial Line Message .........................................88
FTIME and FDATE.........................................................88
FST ................................................................................88
General Settings.....................................................................89
Changing Quantities and Units ...........................................89
Using Display/Keypad....................................................89
Using Serial Line............................................................90
FORM.............................................................................90
UNIT...............................................................................91
Pressure Compensation Setting .........................................92
Using Display/Keypad....................................................92
Using Buttons on Motherboard......................................93
Using Serial Line............................................................93
XPRES and PRES....................................................93
Date and Time.....................................................................94
Using Display/Keypad....................................................94
Using Serial Line............................................................95
User Port Serial Settings.....................................................95
SERI...............................................................................96
SMODE..........................................................................96
INTV...............................................................................97
ECHO.............................................................................97
Data Filtering.......................................................................98
FILT................................................................................98
Device Information..............................................................98
? .....................................................................................99
HELP............................................................................100
ERRS...........................................................................100
VERS ...........................................................................101
Resetting the Device.........................................................101
Locking Menu/Keypad by Using Serial Line .....................101
LOCK ...........................................................................101
Data Recording.....................................................................102
Selecting Data Recording Quantities................................102
DSEL............................................................................102
View Recorded Data.........................................................103
DIR...............................................................................103
PLAY............................................................................104
Deleting Recorded Files....................................................105
UNDELETE..................................................................106
Analog Output Settings.......................................................106
Changing Output Mode and Range..................................106
Analog Output Quantities..................................................108

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AMODE/ASEL..............................................................109
Analog Output Tests..........................................................110
ITEST ...........................................................................110
Analog Output Fault Indication Setting..............................111
AERR............................................................................111
Operation of Relays..............................................................112
Quantity for Relay Output..................................................112
Measurement-Based Relay Output Modes.......................112
Relay Setpoints............................................................112
Hysteresis.....................................................................113
Relay Indicating Transmitter Error Status .........................114
Enabling/Disabling Relays.................................................115
Indication Led Operation...................................................115
Setting Relay Outputs .......................................................116
RSEL............................................................................117
Testing Operation of Relays..............................................118
RTEST..........................................................................118
Operation of the RS-485 Module.........................................119
Networking Commands................................................119
SERI.............................................................................119
ECHO...........................................................................120
SMODE ........................................................................120
INTV .............................................................................120
ADDR ...........................................................................121
OPEN [nn]....................................................................121
CLOSE .........................................................................121
SDELAY .......................................................................122
Sensor Functions .................................................................122
AutoCal..............................................................................122
Automatic AutoCal........................................................123
Manual AutoCal............................................................123
Sensor Purge.....................................................................124
Manual Sensor Purge...................................................124
Interval Purge...............................................................125
Power-Up Purge...........................................................125
PUR.........................................................................125
PURGE....................................................................126
Sensor Warming................................................................126
CHAPTER 5
MAINTENANCE..........................................................................................127
Periodic Maintenance...........................................................127
Cleaning ............................................................................127
Changing the Cooling Set Filter ........................................127
Error States .......................................................................127
Technical Support ................................................................129
Return Instructions ..............................................................129
Vaisala Service Centers.......................................................130
CHAPTER 6
CALIBRATION AND ADJUSTMENT.........................................................131
Calibration.............................................................................131
User Calibration and Adjustment.......................................131
Opening and Closing Adjustment Mode............................132

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Adjustment Information.....................................................132
CTEXT and CDATE.....................................................132
Two-Point Relative Humidity Adjustment..........................133
Using Display/Keypad.......................................................133
Using Serial Line...............................................................134
FCRH...........................................................................134
One-Point Dewpoint Adjustment........................................136
One-Point Dewpoint Adjustment Using Display/Keypad ..136
One-point Dewpoint Adjustment Using Serial Line...........137
Adjusting Temperature........................................................138
Adjusting Temperature Using Display/Keypad .................138
Adjusting Temperature Using Serial Line .........................139
CT ................................................................................139
Adjusting Analog Outputs...................................................140
Adjusting Analog Outputs Using Display/Keypad.............140
Adjusting Analog Outputs Using Serial Line.....................141
ACAL............................................................................141
CHAPTER 7
TECHNICAL DATA....................................................................................142
Specifications.......................................................................142
Performance......................................................................142
Technical Specifications of Optional Modules ..................146
Power Supply Module..................................................146
Analog Output Module.................................................146
Relay Module...............................................................146
RS-485 Module............................................................147
LAN Interface Module ..................................................147
WLAN Interface Module...............................................147
Data Logger Module ....................................................147
Options and Accessories....................................................148
Dimensions (mm/inch).........................................................149
APPENDIX A
EXAMPLE INSTALLATION OF DMT346..................................................151
APPENDIX B
CALCULATION FORMULAS ....................................................................153

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List of Figures
Figure 1 Transmitter Body......................................................................22
Figure 2 Inside the Transmitter...............................................................23
Figure 3 Probes, Cooling Set .................................................................24
Figure 4 Standard Mounting...................................................................26
Figure 5 Mounting with Wall Mounting Kit..............................................26
Figure 6 Dimensions of the Plastic Mounting Plate (mm/inch)...............27
Figure 7 Mounting with Metal Wall Mounting Plate................................27
Figure 8 Dimensions of the Metal Mounting Plate (in mm) ....................28
Figure 9 Mounting with DIN Rail Installation Kit.....................................29
Figure 10 Vertical Pole Installation...........................................................29
Figure 11 Horizontal Pole Installation.......................................................30
Figure 12 Mounting the Rain Shield with Installation Kit..........................30
Figure 13 Panel Mounting Frame.............................................................31
Figure 14 Panel Mounting Dimensions (mm/inch) ...................................32
Figure 15 DMT345 Probe Dimensions (mm/inch)....................................32
Figure 16 Flange Installation Kit...............................................................33
Figure 17 DMT346 Probe Dimensions (in mm)........................................33
Figure 18 Cooling Set Dimensions (in mm)..............................................34
Figure 19 Measurement Ranges With and Without the Cooling Fins......35
Figure 20 Parts of the Cooling Set (Dimensions in mm)..........................35
Figure 21 Mounting Flange Dimensions (in mm) .....................................36
Figure 22 Installing the Probe Through Process Wall..............................37
Figure 23 Installing Probe Through Thick Walls.......................................37
Figure 24 Cable Bushings........................................................................39
Figure 25 Grounding the Screen of Electrical Cable................................40
Figure 26 Screw Terminal Block on the Motherboard..............................41
Figure 27 Connections to 24 VAC Power Supply.....................................44
Figure 28 Power Supply Module ..............................................................45
Figure 29 Galvanic Output Isolation Module............................................49
Figure 30 Third Analog Output.................................................................50
Figure 31 Third analog output selection...................................................51
Figure 32 Relay Module ...........................................................................52
Figure 33 RS-485 Module ........................................................................53
Figure 34 4-Wire RS-485 Bus Connections, Part A.................................55
Figure 35 4-Wire RS-485 Bus Connections, Part B.................................56
Figure 36 LAN Interface Module...............................................................57
Figure 37 WLAN Interface Module...........................................................58
Figure 38 Data Logger Module.................................................................59
Figure 39 Wiring of Optional 8-Pin Connector..........................................60
Figure 40 Basic Display............................................................................64
Figure 41 Graphical Display.....................................................................64
Figure 42 Graphical Display with Data Logger.........................................65
Figure 43 Main Views...............................................................................67
Figure 44 Display Alarm Active ................................................................70
Figure 45 Display Alarms .........................................................................70
Figure 46 Modifying an Alarm Limit..........................................................71
Figure 47 Service Port Connector and User Port Terminal on the
Motherboard.............................................................................72
Figure 48 Connection Example Between PC Serial Port and User Port..73
Figure 49 Network Interface Menu...........................................................76
Figure 50 IP Configuration Menu..............................................................77
Figure 51 Wireless LAN Settings..............................................................79
Figure 52 Entering Network SSID ............................................................80
Figure 53 Selecting the Wireless Network Type ......................................80
Figure 54 Web Configuration Interface for WLAN....................................82

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Figure 55 Opening a Serial Connection....................................................83
Figure 56 Opening a Telnet Connection...................................................84
Figure 57 Pressure Set Buttons on Motherboard.....................................93
Figure 58 Following Device Information on the Display ...........................99
Figure 59 Current/Voltage Switches of Output Modules ........................107
Figure 60 Measurement-Based Relay Output Modes............................112
Figure 61 FAULT/ONLINE STATUS Relay Output Modes.....................115
Figure 62 Relay Availability ....................................................................116
Figure 63 Following AutoCal on the Display...........................................123
Figure 64 Performing Manual Purge.......................................................124
Figure 65 Activating Start-up Purge........................................................125
Figure 66 Error Indicator and Error Message.........................................128
Figure 67 Inserting the Sensor in Reference Humidity 1........................133
Figure 68 Waiting for Readings to Stabilize............................................134
Figure 69 Following Stabilization............................................................136
Figure 70 Proceeding with T d/f Adjustment............................................137
Figure 71 Completing T d/f Adjustment....................................................137
Figure 72 Dewpoint Measurement Accuracy Graph DMT345................143
Figure 73 Dewpoint Measurement Accuracy Graph DMT346................144
Figure 74 DMT345/346 Transmitter Body Dimensions ..........................149
Figure 75 WLAN Antenna Dimensions...................................................150
Figure 76 Cooling Set Installation...........................................................151
Figure 77 Insulation with Mineral Wool...................................................152

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List of Tables
Table 1 Manual Revisions.....................................................................14
Table 2 Related Manuals ......................................................................14
Table 3 Output Quantities and Their Abbreviations for Vaisala
DRYCAP®Dewpoint Transmitter DMT345 ..............................19
Table 4 Optional Output Quantities and Their Abbreviations for Vaisala
DRYCAP®Dewpoint Transmitter DMT345 ..............................20
Table 5 Output Quantities and Their Abbreviations for Vaisala
DRYCAP®Dewpoint Transmitter DMT346 ..............................20
Table 6 Connecting Twisted Pair Wires to Screw Terminals...............54
Table 7 4-Wire (Switch 3:On)................................................................55
Table 8 2-Wire (Switch 3:Off)...............................................................56
Table 9 Observartion Periods and Resolution ......................................59
Table 10 8-Pin Connector Wiring............................................................60
Table 11 Periods for Trend and Max/Min Calculations...........................65
Table 12 Graph Information Messages...................................................66
Table 13 Default Serial Communication Settings for User Port..............73
Table 14 Communication Settings for the Service Port ..........................75
Table 15 IP Settings for the LAN and WLAN Interfaces .........................76
Table 16 Wireless LAN Settings..............................................................79
Table 17 Measurement Commands........................................................85
Table 18 Formatting Commands.............................................................85
Table 19 Data Recording Commands.....................................................85
Table 20 Purge Commands ....................................................................86
Table 21 Autocalibration Commands......................................................86
Table 22 Calibration and Adjustment Commands...................................86
Table 23 Setting and Testing the Analog Outputs ..................................86
Table 24 Setting and Testing the Relays................................................86
Table 25 Other Commands.....................................................................86
Table 26 Modifiers...................................................................................90
Table 27 Multiplication Factors................................................................94
Table 28 Selection of Output Modes.......................................................97
Table 29 Filtering Levels.........................................................................98
Table 30 Error Messages......................................................................128
Table 31 Indicator Led Functions..........................................................132
Table 32 Dewpoint Specifications DMT345..........................................142
Table 33 Temperature Specifications DMT345.....................................143
Table 34 Relative Humidity Specifications DMT345.............................143
Table 35 Mixing Ratio Specifications DMT345 .....................................143
Table 36 Dewpoint Specifications DMT346..........................................144
Table 37 Mixing Ratio Specifications DMT346 .....................................144
Table 38 Operating Environment Specifications (Both Models) ...........144
Table 39 Inputs and Outputs Specifications (Both Models)..................145
Table 40 Mechanics Specifications (Both Models) ...............................145
Table 41 Options and Accessories........................................................148

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Chapter 1 ________________________________________________________ General Information
VAISALA_______________________________________________________________________ 13
CHAPTER 1
GENERAL INFORMATION
This chapter provides general notes for the manual and the product.
About This Manual
This manual provides information for installing, operating, and
maintaining Vaisala DRYCAP® Dewpoint Transmitters DMT345 and
DMT346.
Contents of This Manual
This manual consists of the following chapters:
- Chapter 1, General Information, provides general notes for the manual
and the product.
- Chapter 2, Product Overview, introduces the features and advantages
of the Vaisala DRYCAP® Dewpoint Transmitters DMT345 and
DMT346.
- Chapter 3, Installation, provides you with information that is intended
to help you install this product.
- Chapter 4, Operation, contains information that is needed to operate
this product.
- Chapter 5, Maintenance, provides information that is needed in basic
maintenance of the product. Possible error states and situations, their
probable causes and remedies are described in this chapter. This
chapter also contains contact information for Vaisala Technical
Support and Vaisala Service Centers.
- Chapter 6, Calibration and Adjustment, provides you with instructions
on how to calibrate and adjust Vaisala DRYCAP® Dewpoint
Transmitters DMT345 and DMT346.
- Chapter 7, Technical Data, provides the technical data of the product.

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- Appendix A, Example Installation of DMT346, illustrates an example
installation of DMT346 transmitter into a process.
- Appendix B, Calculation Formulas, contains the formulas used for the
calculated output quantities.
Version Information
Table 1 Manual Revisions
Manual Code Description
M210726EN-A May 2006 - First version
M210726EN-B June 2007 - New options added: Data logger
module and USB-RJ45 cable. Support for
Chinese language.
M210726EN-C May 2008 – New options added: LAN Interface,
WLAN Interface. Display Alarm feature added.
M210726EN-D June 2009 – Added PuTTY terminal application
instructions, revised description of the MI70 Link
software. Removed instructions for
HyperTerminal. Removed Humicap 180L2 sensor
option.
Related Manuals
Table 2 Related Manuals
Manual Code Manual Name
M010091EN-E Vaisala DRYCAP®Hand-Held Dewpoint Meter
DM70 User's Guide, March 2006
M210185en-B Humidity Calibrator HMK15 User's
Guide
Feedback
Vaisala Customer Documentation Team welcomes your comments and
suggestions on the quality and usefulness of this publication. If you find
errors or have other suggestions for improvement, please indicate the
chapter, section, and page number. You can send comments to us by e-
mail: [email protected]

Chapter 1 ________________________________________________________ General Information
VAISALA_______________________________________________________________________ 15
Safety
General Safety Considerations
Throughout the manual, important safety considerations are highlighted
as follows:
WARNING Warning alerts you to a serious hazard. If you do not read and follow
instructions very carefully at this point, there is a risk of injury or even
death.
CAUTION Caution warns you of a potential hazard. If you do not read and follow
instructions carefully at this point, the product could be damaged or
important data could be lost.
NOTE Note highlights important information on using the product.
Product Related Safety Precautions
The DMT345/46 Dewpoint and Temperature Transmitter delivered to
you has been tested for safety and approved as shipped from the factory.
Note the following precautions:
WARNING Ground the product, and verify outdoor installation grounding
periodically to minimize shock hazard.
CAUTION Do not modify the unit. Improper modification can damage the product,
lead to malfunction, or make the product noncompliant with applicable
legislation.
ESD Protection
Electrostatic Discharge (ESD) can cause immediate or latent damage to
electronic circuits. Vaisala products are adequately protected against

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ESD for their intended use. However, it is possible to damage the product
by delivering electrostatic discharges when touching, removing, or
inserting any objects inside the equipment housing.
To make sure you are not delivering high static voltages yourself:
- Handle ESD sensitive components on a properly grounded and
protected ESD workbench. When this is not possible, ground yourself
to the equipment chassis before touching the boards. Ground yourself
with a wrist strap and a resistive connection cord. When neither of the
above is possible, touch a conductive part of the equipment chassis
with your other hand before touching the boards.
- Always hold the boards by the edges and avoid touching the
component contacts.
Recycling
Recycle all applicable material.
Dispose of batteries and the unit according to statutory regulations. Do
not dispose of with regular household refuse.
Regulatory Compliances
Transmitters with LAN or WLAN Interface
This equipment has been tested and found to comply with the limits for a
Class B digital device, pursuant to Part 15 of the FCC Rules. These limits
are designed to provide reasonable protection against harmful
interference in a residential installation. Operation is subject to the
following two conditions: (1) this device may not cause interference, and
(2) this device must accept any interference, including interference that
may cause undesired operation of the device.
This equipment generates, uses and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is
no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television

Chapter 1 ________________________________________________________ General Information
VAISALA_______________________________________________________________________ 17
reception, which can be determined by turning the equipment off and on,
the user is encouraged to try to correct the interference by one or more of
the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.
Transmitters with WLAN Interface
This device has been designed to operate with a 2 dBi half-wave antenna.
Antennas with a gain greater than 2 dB are strictly prohibited for use with
this device. The required antenna impedance is 50 ohms.
To reduce potential radio interference to other users, the antenna type and
its gain should be so chosen that the equivalent isotropically radiated
power (e.i.r.p.) is not more than that permitted for successful
communication.
This Class [B] digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe [B] est conforme à la norme NMB-
003 du Canada.
Patent Notice
The Vaisala DRYCAP®Dewpoint Transmitters DMT345 and DMT346
are protected by, for example, the following patents and their
corresponding national rights:
Finnish patents 98861 and 99164, French patents 6650303 and 9504397,
German patents 69418174 and 19513274, Japanese patents 3585973 and
2801156, UK patents 0665303 and 2288465, U.S. patent 5607564.

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Trademarks
DRYCAP® is a registered trademark of Vaisala Oyj.
Windows® is a registered trademark of Microsoft Corporation in the
United States and/or other countries.
License Agreement
All rights to any software are held by Vaisala or third parties. The
customer is allowed to use the software only to the extent that is provided
by the applicable supply contract or Software License Agreement.
Warranty
For certain products Vaisala normally gives a limited one-year warranty.
Please observe that any such warranty may not be valid in case of
damage due to normal wear and tear, exceptional operating conditions,
negligent handling or installation, or unauthorized modifications. Please
see the applicable supply contract or Conditions of Sale for details of the
warranty for each product.

Chapter 2 __________________________________________________________ Product Overview
VAISALA_______________________________________________________________________ 19
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features and advantages of the Vaisala
DRYCAP®Dewpoint Transmitters DMT345 and DMT346.
Introduction to DMT345 and DMT346
The DMT345 and DMT346 transmitters incorporate the advanced
Vaisala DRYCAP®technology, which enables reliable and accurate
dewpoint measurement. Both transmitters also feature the AutoCal
function which provides excellent long term stability of the
measurement.
The DMT345 is designed for measurement of relative humidity in
temperatures up to 180 °C. The transmitter outputs dewpoint/frostpoint
(Td/f), mixing ratio (x), volume concentration (ppm), relative humidity
(RH), and temperature (T).
The DMT346 is a high-performance instrument for measurement of
dewpoint and mixing ratio in temperatures up to 350 °C.
DMT346 also outputs sensor saturation rate (SSR) and temperature (TS=
TSensor) of the cooled Vaisala DRYCAP® sensor. Because the sensor is
cooled, these values do not represent true process conditions, hence they
cannot be used for process control. Nevertheless, they provide a valuable
aid for calibration and for checking the cooling effect.
For quantities measured by DMT345, see Table 3 below. For the optional
calculated quantities measured by DMT345, see Table 4 on page 20.
For quantities measured and calculated by DMT36, see Table 5 on page
20.
Table 3 Output Quantities and Their Abbreviations for Vaisala
DRYCAP®Dewpoint Transmitter DMT345
Quantity Abbreviation Metric Unit Non Metric Unit
Dewpoint/frost point temperature (Td/f ) TDF ºC ºF
Mixing ratio (x) X g/kg gr/lb
Relative humidity RH RH %RH %RH

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Quantity Abbreviation Metric Unit Non Metric Unit
Temperature T T ºC ºF
Table 4 Optional Output Quantities and Their Abbreviations
for Vaisala DRYCAP®Dewpoint Transmitter DMT345
Quantity Abbreviation Metric Unit Non Metric Unit
Parts per million H2O ppmv/ ppmwppmv/ ppmw
Absolute humidity (a) A g/m3gr/ft3
Absolute humidity in standard pressure and
temperature (NTP) ANTP g/m3gr/ft3
Wet bulb temperature (Tw) TW ºC ºF
Water vapor pressure (Pw ) PW hPa lb/in2
Water vapor saturation pressure (Pws) PWS hPa lb/in2
Enthalpy (h) H kJ/kg Btu/lb
Difference of T and Td/f (∆T) DT ºC ºF
Table 5 Output Quantities and Their Abbreviations for Vaisala
DRYCAP®Dewpoint Transmitter DMT346
Quantity Abbreviation Metric Unit Non Metric Unit
Dewpoint temperature (Td/f) TDF ºC ºF
Mixing ratio (x) X g/kg gr/lb
Sensor saturation rate SSR % -
Sensor temperature TS ºC ºF
Basic Features and Options
DMT345/346 has the following basic features and options:
- Dewpoint measurement with AutoCal and sensor purge features.
- Sensor warming in high humidities.
- Two analog outputs and a serial interface, optional third analog
output.
- Installation accessories
- DMT345: mounting flange,
- DMT346: cooling set for high temperature applications.
- User friendly multilingual display option.
- Different sensor protection options and probe cable lengths 2 m, 5 m
or 10 m.
- USB connectivity for service connections via the optional
USB-RJ45 cable
- Optional modules:
- galvanic isolation for outputs