Vaisala HUMICAP HMT330 SERIES User manual

USER'S GUIDE
Vaisala HUMICAP
®
Humidity and
Temperature Transmitter Series
HMT330
M210566EN-D

PUBLISHED BY
Vaisala Oyj Phone (int.): [phone]
P.O. Box 26 Fax: [phone]
FIN-00421 Helsinki
Finland
Visit our Internet pages at http://www.vaisala.com/
© Vaisala 2006
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 ............................................................................ 9
About This Manual ................................................................... 9
Contents of This Manual ....................................................... 9
General Safety Considerations ........................................... 10
Feedback............................................................................. 10
Product Related Safety Precautions .................................... 11
ESD Protection ....................................................................... 11
Recycling ................................................................................ 12
Trademarks ............................................................................. 12
License Agreement ................................................................ 12
Warranty .................................................................................. 13
CHAPTER 2
PRODUCT OVERVIEW................................................................................ 15
Introduction to HMT330 ......................................................... 15
Basic Features and Options................................................ 16
Probe Options ..................................................................... 19
Warmed Probe HMT337 ..................................................... 20
CHAPTER 3
INSTALLATION............................................................................................ 21
Mounting the Housing ........................................................... 21
Standard Mounting without Mounting Plate ........................ 21
Wall Mounting with Wall Mounting Kit................................. 22
Mounting with DIN Rail Installation Kit ................................ 23
Pole Installation with Installation Kit for Pole or Pipeline .... 24
Mounting Rain Shield with Installation Kit ........................... 26
Panel Mounting Frame........................................................ 27
Wiring ...................................................................................... 28
Cable Bushings ................................................................... 28
Grounding the Cables ......................................................... 29
Grounding the Transmitter Housing.................................... 30
Signal and Power Supply Wiring......................................... 31
Connections to 24 VAC Power Supply ............................... 32
Probe Mounting ...................................................................... 34
General Instructions for Probes with Cable ........................ 35
HMT333 for Ducts and Tight Spaces .................................. 37
HMT334 for High Pressure and Vacuum Applications........ 37
HMT335 for High Temperatures ......................................... 40
HMT337 for High Humidity Applications ............................. 40
Temperature Probe (Optional) ............................................ 40
HMT338 for Pressurized Pipelines...................................... 41
Tightening the Clasp Nut..................................................... 42

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Optional Modules....................................................................44
Power Supply Module..........................................................44
Installation ......................................................................45
Warnings ........................................................................46
Galvanic Isolation for Output ...............................................48
Third Analog Output ............................................................48
Installation and Wiring ....................................................49
Relays..................................................................................50
Installation and Wiring ....................................................50
Selecting the Activation State of the Relay ....................50
RS-422/485 Interface ..........................................................52
Installation and Wiring ....................................................52
8-Pin Connector...................................................................55
CHAPTER 4
OPERATION .................................................................................................57
Getting Started........................................................................57
Display/Keypad (Optional).....................................................57
Basic Display .......................................................................57
Graphic History....................................................................58
Menus and Navigation.........................................................59
Language Setting ...........................................................60
Rounding Setting............................................................61
Display Backlight Setting................................................61
Display Contrast Setting.................................................61
Keypad Lock (Key guard)...............................................62
Menu PIN Lock...............................................................62
Factory Settings .............................................................63
MI70 Link Program for Data Handling ..................................63
Serial Line Communication ...................................................63
User Port Connection ..........................................................64
Service Port Connection......................................................65
Terminal Program Settings..................................................66
List of Serial Commands .....................................................68
Getting Measurement Message from Serial Line ................70
Stopping Continuous Outputting ....................................70
S ................................................................................70
Outputting Reading Once...............................................70
SEND ........................................................................70
SEND D.....................................................................71
Formatting Serial Line Message..........................................72
TIME and DATE .............................................................72
FTIME and FDATE.........................................................72
FST.................................................................................73
General Settings .....................................................................74
Changing Quantities and Units............................................74
Using Display/Keypad ....................................................74
Using Serial Line ............................................................75
FORM........................................................................75
UNIT ..........................................................................76

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Pressure Compensation Setting ......................................... 77
Using Display/Keypad .................................................... 77
Using Serial Line ............................................................ 77
PRES and XPRES .................................................... 77
User Port Serial Settings..................................................... 78
Using Display/Keypad .................................................... 78
Using Serial Line ............................................................ 79
SERI ............................................................................... 79
SMODE .......................................................................... 80
INTV ............................................................................... 80
ECHO............................................................................. 81
Data Filtering ....................................................................... 81
FILT................................................................................ 82
Device Information .............................................................. 82
? ..................................................................................... 83
HELP.............................................................................. 83
ERRS ............................................................................. 84
VERS ............................................................................. 84
Resetting Transmitter by Using Serial Line......................... 85
RESET ........................................................................... 85
Locking Menu/Keypad by Using Serial Line ....................... 85
LOCK ............................................................................. 85
Data Recording....................................................................... 87
Selecting Data Recording Quantities .................................. 87
DSEL.............................................................................. 87
View Recorded Data ........................................................... 88
DIR ................................................................................. 88
PLAY .............................................................................. 89
Deleting the Recorded Files................................................ 90
DELETE/UNDELETE ..................................................... 90
Analog Output Settings ......................................................... 91
Changing Output Mode and Range .................................... 91
Analog Output Quantities .................................................... 93
AMODE/ASEL................................................................ 93
Analog Output Tests ........................................................... 95
ITEST ............................................................................. 95
Analog Output Fault Indication Setting ............................... 96
AERR ............................................................................. 96
Operation of Relays ............................................................... 97
Quantity for Relay Output.................................................... 97
Measurement-Based Relay Output Modes......................... 97
Relay Setpoints .............................................................. 97
Hysteresis ...................................................................... 98
Relay Indicating Transmitter Error Status ........................... 98
Enabling/Disabling Relays ................................................ 100
Setting Relay Outputs ....................................................... 100
RSEL............................................................................ 101
Testing Operation of Relays.............................................. 103
RTEST ......................................................................... 103

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Operation of RS-485 Module ...............................................104
Networking Commands .....................................................104
SERI .............................................................................104
ECHO ...........................................................................105
SMODE ........................................................................105
INTV .............................................................................106
ADDR ...........................................................................106
SEND............................................................................107
OPEN ...........................................................................107
CLOSE .........................................................................107
Sensor Functions .................................................................108
Chemical Purge (Optional) ................................................108
Automatic Chemical Purge (Interval Purge).................109
Manual Chemical Purge ...............................................109
Chemical Purge in Power Up .......................................109
Starting and Configuring Chemical Purge.........................110
Using Buttons on Motherboard.....................................110
Using Display/Keypad (Optional) .................................110
Using Serial Line ..........................................................111
PURGE....................................................................111
PUR.........................................................................112
Sensor Heating..................................................................113
Setting Humidity Sensor Heating .................................113
XHEAT ....................................................................113
CHAPTER 5
MAINTENANCE..........................................................................................115
Periodic Maintenance...........................................................115
Cleaning ............................................................................115
Changing the Probe Filter .................................................115
Changing the Sensor ...........................................................116
Error States .......................................................................117
CHAPTER 6
CALIBRATION AND ADJUSTMENT .........................................................119
Opening and Closing the Adjustment Mode......................119
Relative Humidity Adjustment.............................................121
Using Push-Buttons...........................................................121
Using Display/Keypad .......................................................122
Using Serial Line ...............................................................123
CRH..............................................................................123
Relative Humidity Adjustment after Sensor Change ........124
Using Display/Keypad .......................................................124
Using Serial Line ...............................................................124
FCRH............................................................................124
Temperature Adjustment .....................................................125
Using Display/Keypad .......................................................125
Using Serial Line ...............................................................125
CT.................................................................................126
CTA ..............................................................................126

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Analog Output Adjustment.................................................. 127
Using Display/Keypad ....................................................... 127
Using Serial Line ............................................................... 127
ACAL............................................................................ 127
Feeding Adjustment Information........................................ 128
Using Display/Keypad ....................................................... 128
Using Serial Line ............................................................... 128
CTEXT ......................................................................... 128
CDATE ......................................................................... 128
CHAPTER 7
TECHNICAL DATA .................................................................................... 129
Specifications ....................................................................... 129
Performance...................................................................... 129
Relative Humidity ......................................................... 129
Temperature (+ Operating Pressure Ranges) ............. 130
Optional Temperature Probe ....................................... 130
Calculated Variables .................................................... 131
Accuracies of Calculated Variables .................................. 131
Accuracy of Dewpoint Temperature °C ....................... 131
Accuracy of Mixing Ratio g/kg (Ambient Pressure 1013
mbar)............................................................................ 132
Accuracy of Wet Bulb Temperature °C ........................ 132
Accuracy of Absolute Humidity g/m³ ............................ 132
Dewpoint Temperature (HMT337 Warmed Probe
Option)............................................................................... 133
Operating Environment ................................................ 133
Inputs and Outputs....................................................... 134
Mechanics .................................................................... 134
Transmitter Weights ..................................................... 135
Technical Specifications of Optional Modules .................. 135
Power Supply Module .................................................. 135
Analog Output Module ................................................. 135
Relay Module ............................................................... 136
RS-485 Module ............................................................ 136
Options and Accessories ............................................. 136
Dimensions (in mm) ............................................................. 139
HMT331............................................................................. 140
HMT333............................................................................. 140
HMT334............................................................................. 141
HMT335............................................................................. 141
HMT337............................................................................. 142
HMT338............................................................................. 142
Temperature Probe ........................................................... 142
Technical Support ................................................................ 143
Return Instructions .............................................................. 143
Vaisala Service Centers....................................................... 144

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APPENDIX A
PROBE INSTALLATION KITS AND INSTALLATION EXAMPLES .........145
Duct Installation Kits (for HMT333/337/335).......................145
Duct Installation Kit for Temperature Probe (for HMT337)146
Pressure Tight Swagelok Installation Kits (for HMT337)..147
RH Probe Installation.........................................................147
Temperature Probe Installation .........................................147
Examples of Vapor Tight Installations with Cable Gland .148
RH-Probe Installations (for HMT333/337) .........................148
T- Probe Installations (HMT337) .......................................149
Example of Climate Chamber Installation .........................150
Example of Installation Through Roof ...............................151
Ball Valve Installation Kit for HMT338 ................................152
Meteorological Installation Kit (for HMT337) .....................154
APPENDIX B
CALCULATION FORMULAS.....................................................................155
List of Figures
Figure 1 Transmitter Body ......................................................................17
Figure 2 Inside of Open Transmitter .......................................................18
Figure 3 Probe Options...........................................................................19
Figure 4 Standard Mounting ...................................................................21
Figure 5 Mounting with Wall Mounting Kit ..............................................22
Figure 6 Dimensions of Plastic Mounting Plate ......................................22
Figure 7 Mounting with DIN Rail Installation Kit .....................................23
Figure 8 Vertical Pole..............................................................................24
Figure 9 Horizontal Pole .........................................................................24
Figure 10 Mounting with Metal Wall Mounting Plate ................................25
Figure 11 Dimensions of Metal Mounting Plate (mm) ..............................25
Figure 12 Mounting Rain Shield with Installation Kit ................................26
Figure 13 Panel Mounting with Frame......................................................27
Figure 14 Panel Mounting Dimensions.....................................................27
Figure 15 Cable Bushings.........................................................................28
Figure 16 Grounding the Screen of Electrical Cable ................................29
Figure 17 Screw Terminal Block on Motherboard ....................................31
Figure 18 Connections to 24 VAC Power Supply.....................................33
Figure 19 Measurement Error at 100 %RH ..............................................34
Figure 20 Horizontal Mounting of Sensor Head........................................35
Figure 21 Vertical Mounting of Sensor Head............................................36
Figure 22 HMT344 Probe .........................................................................38
Figure 23 Tightening the Nut ....................................................................38
Figure 24 Cleaning of Tightening Cone ....................................................39
Figure 25 HMT338 Probe .........................................................................41
Figure 26 Sealing of Fitting Body into Process.........................................42
Figure 27 Tightening the Clasp Nut ..........................................................42
Figure 28 Power Supply Module...............................................................44
Figure 29 Galvanic Output Isolation Module.............................................48
Figure 30 Third Analog Output .................................................................48
Figure 31 Relay Module............................................................................51
Figure 32 RS-485 Module.........................................................................52

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Figure 33 4-Wire RS-485 Bus .................................................................. 53
Figure 34 Wiring of Optional 8-Pin Connector.......................................... 55
Figure 35 Basic Display............................................................................ 58
Figure 36 Graphical Display ..................................................................... 58
Figure 37 Main Menus .............................................................................. 60
Figure 38 Service Port Connector and User Port Terminal on Mother
Board ........................................................................................ 64
Figure 39 Connection Example Between PC Serial Port and User Port.. 64
Figure 40 Starting Hyper Terminal Connection ........................................ 66
Figure 41 Connecting to Hyper Terminal ................................................. 67
Figure 42 Hyper Terminal Serial Port Settings......................................... 67
Figure 43 Device Information on Display ................................................ 82
Figure 44 Current/Voltage Switches of Output Modules .......................... 91
Figure 45 Measurement-Based Relay Output Modes .............................. 97
Figure 46 FAULT/ONLINE STATUS Relay Output Modes ...................... 99
Figure 47 Relay Indicators on Display.................................................... 100
Figure 48 Decrease of Sensor Gain ....................................................... 108
Figure 49 Purge Buttons on Motherboard .............................................. 110
Figure 50 Chemical Purge Settings........................................................ 110
Figure 51 Performing Chemical Purge ................................................... 111
Figure 52 Changing the Sensor.............................................................. 116
Figure 53 Error Indicator and Error Message......................................... 117
Figure 54 Adjustment and Purge Buttons .............................................. 120
Figure 55 Adjustment Menu ................................................................... 120
Figure 56 Selecting Point 1 Reference Type.......................................... 122
Figure 57 Accuracy over Temperature Range ....................................... 130
Figure 58 Accuracy in Dewpoint Measurement...................................... 133
Figure 59 Transmitter Body Dimensions ................................................ 139
Figure 60 HMT331 Probe Dimensions ................................................... 140
Figure 61 HMT333 Probe Dimensions ................................................... 140
Figure 62 HMT334 Probe Dimensions ................................................... 141
Figure 63 HMT335 Probe Dimensions ................................................... 141
Figure 64 HMT337 Probe Dimensions ................................................... 142
Figure 65 HMT338 Probe Dimensions ................................................... 142
Figure 66 Optional Temperature Probe Dimensions.............................. 142
Figure 67 Duct Mounting Installation Kit................................................. 145
Figure 68 Duct Mounting Installation Kit for T-Probe ............................. 146
Figure 69 Swagelok Installation Kit for RH-probe .................................. 147
Figure 70 Swagelok Installation Kit for T-Probe ..................................... 147
Figure 71 Cable Installation with Cable Gland ....................................... 148
Figure 72 Probe Head Installation with Cable Gland ............................. 148
Figure 73 Vapor Tight Installation........................................................... 149
Figure 74 Wall Mounting Installation ...................................................... 149
Figure 75 Climate Chamber Installation (not Available from Vaisala).... 150
Figure 76 Example of Installation through Roof ..................................... 151
Figure 77 Installing Sensor Head through Ball Valve Assembly ............ 152
Figure 78 Meteorological Installation Kit for Outdoor Installation........... 154

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List of Tables
Table 1 Quantities Measured by HMT330.............................................15
Table 2 Optional Quantities Measured by HMT330 ..............................16
Table 3 HMT338 Probe Dimensions .....................................................41
Table 4 Connecting the Twisted Pair Wires to the Screw Terminals ....52
Table 5 4-Wire (Switch 3: On) ...............................................................53
Table 6 2-Wire (Switch 3: Off) ...............................................................54
Table 7 Wiring of 8-Pin Connector ........................................................55
Table 8 Periods for Trend and Max/Min Calculations ...........................59
Table 9 Graph Information Messages in Cursor Mode .........................59
Table 10 Default Serial Communication Settings for the User Port ........64
Table 11 Fixed Communication Settings for Service Port.......................65
Table 12 FORM Command Modifiers......................................................75
Table 13 Multiplication Factors ................................................................78
Table 14 Selection of Output Modes .......................................................80
Table 15 Filtering Levels..........................................................................81
Table 16 Error Messages ......................................................................118
Table 17 Indicator Led Functions ..........................................................120
Table 18 Calculated Variables (Typical Ranges) ..................................131
Table 19 Transmitter Weights (in kg/lb).................................................135

Chapter 1 _________________________________________________________ General Information
VAISALA _____________________________________________________________________ 9
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 HUMICAP®Humidity and Temperature
Transmitter Series HMT330.
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, advantages,
and the product nomenclature of HMT330.
- Chapter 3, Installation, provides you with information that is
intended to help you install the product.
- Chapter 4, Operation, contains information that is needed to
operate this product.
- Chapter 5, Maintenance, contains information that is needed in
basic maintenance of the product.
- Chapter 6, Calibration and Adjustment, provides information and
instructions concerning calibration and adjustment of HMT330.
- Chapter 7, Technical Data, provides the technical data of the
product.

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- Appendix A, Probe Installation Kits and Installation Examples,
presents the installation kits available for HMT330 and provides
some installation examples.
- Appendix B, Calculation Formulas, presents the equations used in
HMT330 to calculate values of dewpoint, mixing ratio, absolute
humidity and enthalpy in normal pressure.
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.
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 ____________________________________________________________________ 11
Product Related Safety Precautions
The Vaisala HUMICAP®Humidity and Temperature Transmitter
Series HMT330 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 or lead to malfunction.
ESD Protection
Electrostatic Discharge (ESD) can cause immediate or latent damage
to electronic circuits. Vaisala products are adequately protected
against 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.

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Recycling
Recycle all applicable material.
Dispose of batteries and the unit according to statutory regulations.
Do not dispose of with regular household refuse.
Trademarks
HUMICAP®is a registered trademark of Vaisala. Microsoft®,
Windows®, Windows NT®, Windows®2000 and Windows®XP are
registered trademarks 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.

Chapter 1 _________________________________________________________ General Information
VAISALA ____________________________________________________________________ 13
Warranty
Vaisala hereby represents and warrants all Products
manufactured by Vaisala and sold hereunder to be
free from defects in workmanship or material
during a period of twelve (12) months from the date
of delivery save for products for which a special
warranty is given. If any Product proves however to
be defective in workmanship or material within the
period herein provided Vaisala undertakes to the
exclusion of any other remedy to repair or at its
own option replace the defective Product or part
thereof free of charge and otherwise on the same
conditions as for the original Product or part
without extension to original warranty time.
Defective parts replaced in accordance with this
clause shall be placed at the disposal of Vaisala.
Vaisala also warrants the quality of all repair and
service works performed by its employees to
products sold by it. In case the repair or service
works should appear inadequate or faulty and
should this cause malfunction or nonfunction of the
product to which the service was performed Vaisala
shall at its free option either repair or have repaired
or replace the product in question. The working
hours used by employees of Vaisala for such repair
or replacement shall be free of charge to the client.
This service warranty shall be valid for a period of
six (6) months from the date the service measures
were completed.
This warranty is however subject to following
conditions:
a) A substantiated written claim as to any alleged
defects shall have been received by Vaisala
within thirty (30) days after the defect or fault
became known or occurred, and
b) The allegedly defective Product or part shall,
should Vaisala so require, be sent to the works
of Vaisala or to such other place as Vaisala may
indicate in writing, freight and insurance
prepaid and properly packed and labelled,
unless Vaisala agrees to inspect and repair the
Product or replace it on site.
This warranty does not however apply when the
defect has been caused through
a) normal wear and tear or accident;
b) misuse or other unsuitable or unauthorized use
of the Product or negligence or error in storing,
maintaining or in handling the Product or any
equipment thereof;
c) wrong installation or assembly or failure to
service the Product or otherwise follow
Vaisala's service instructions including any
repairs or installation or assembly or service
made by unauthorized personnel not approved
by Vaisala or replacements with parts not
manufactured or supplied by Vaisala;
d) modifications or changes of the Product as well
as any adding to it without Vaisala's prior
authorization;
e) other factors depending on the Customer or a
third party.
Notwithstanding the aforesaid Vaisala's liability
under this clause shall not apply to any defects
arising out of materials, designs or instructions
provided by the Customer.
This warranty is expressly in lieu of and excludes
all other conditions, warranties and liabilities,
express or implied, whether under law, statute or
otherwise, including without limitation any implied
warranties of merchantability or fitness for a
particular purpose and all other obligations and
liabilities of Vaisala or its representatives with
respect to any defect or deficiency applicable to or
resulting directly or indirectly from the Products
supplied hereunder, which obligations and
liabilities are hereby expressly cancelled and
waived. Vaisala's liability shall under no
circumstances exceed the invoice price of any
Product for which a warranty claim is made, nor
shall Vaisala in any circumstances be liable for lost
profits or other consequential loss whether direct or
indirect or for special damages.

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Chapter 2 ___________________________________________________________ Product Overview
VAISALA________________________________________________________________________ 15
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features, advantages, and the product
nomenclature of HMT330.
Introduction to HMT330
Vaisala HUMICAP®Humidity and Temperature Transmitter Series
HMT330 provides reliable humidity measurement in wide range of
applications. Analog outputs can be chosen between current and
voltage signals. Alternatively, digital outputs RS-232 (standard) or
RS-422/485 (optional) can be selected. The quantities measured and
calculated by HMT330 are presented in Table 1 below. The quantities
available as an option are presented in Table 2 below.
Table 1 Quantities Measured by HMT330
Quantity Abbreviati
on
Metric Unit Non Metric
Unit
Relative humidity (RH) RH %RH %RH
Temperature (T) T ºC ºF

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Table 2 Optional Quantities Measured by HMT330
Quantity Abbreviati
on
Metric Unit Non Metric
Unit
Dewpoint / Frostpoint
Temperature (Td/f)
TDF ºC ºF
Dewpoint Temperature (Td) TD ºC ºF
Absolute humidity (a) A g/m3gr/ft3
Mixing ratio (x) X g/kg gr/lb
Wetbulb temperature (Tw) TW ºC ºF
Humid air volume/ dry air
volume
(by volume or by weight) (H2O)
H2O ppmv/ppmwppmv/ppmw
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
Basic Features and Options
- Several probes for various applications
- User friendly display
- Calculated output quantities available
- Different probe mounting kits, sensor protection options and probe
cable lengths
- Transmitter mounting kits for multiple installation purposes
- Chemical purge for applications where interfering chemicals in the
measuring environment pose a risk
- Warmed probe and sensor heating for high humidity conditions
(HMT337)
- Optional modules: isolated power supply, power supply module,
RS-422/485-module, additional analog output module and relay
module
- Additional temperature sensor (HMT337)

Chapter 2 ___________________________________________________________ Product Overview
VAISALA________________________________________________________________________ 17
0503-001
Figure 1 Transmitter Body
The following The following numbers refer to Figure 1 above:
1 = Signal + powering cable gland
2 = Cable gland for optional module
3 = Cable gland for optional module
4 = Cover screw (4 pcs)
5 = Display with keypad (optional)
6 = Cover LED

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0508-010
Figure 2 Inside of Open Transmitter
The following numbers refer to Figure 2 above:
1 = Service port (RS-232)
2 = DIP switches for analog output settings
3 = Power supply and signal wiring screw terminals
4 = Relay/RS-422/485 module (optional)
5 = Grounding connector
6 = Power supply module (optional)
7 = Analog output relay module (optional)
8 = Humidity probe cable
9 = Temperature probe cable (optional)
10 = Output isolation module (optional)
11 = Adjustment buttons (chemical purge buttons) with indicator
led