Vaisala DMT143 User Manual
USER'S GUIDE
Vaisala DRYCAP®
Dewpoint Transmitter
DMT143
M211435EN-E
PUBLISHED BY
Vaisala Oyj
Street address: Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
Mailing address: P.O. Box 26, FI-00421 Helsinki, Finland
Phone: +358 9 8949 1
Fax: +358 9 8949 2227
Visit our Internet pages at www.vaisala.com.
© Vaisala 2014
No part of this manual may be reproduced, published or publicly displayed in any form
or by any means, electronic or mechanical (including photocopying), nor may its
contents be modified, translated, adapted, sold or disclosed to a third party without prior
written permission of the copyright holder. Translated manuals and translated portions
of multilingual documents are based on the original English versions. In ambiguous
cases, the English versions are applicable, not the translations.
The contents of this manual are subject to change without prior notice.
This manual does not create any legally binding obligations for Vaisala towards
customers or end users. All legally binding obligations and agreements are included
exclusively in the applicable supply contract or the General Conditions of Sale and
General Conditions of Service of Vaisala.
_________________________________________________________________________________
Table of Contents
CHAPTER 1
GENERAL INFORMATION ............................................................................ 5
About This Manual ................................................................... 5
Contents of This Manual ....................................................... 5
Version Information ............................................................... 6
Related Manuals ................................................................... 6
Documentation Conventions ................................................. 6
Safety ......................................................................................... 7
ESD Protection ...................................................................... 7
Recycling .................................................................................. 7
Regulatory Compliances ......................................................... 8
Trademarks ............................................................................... 8
License Agreement .................................................................. 8
Warranty .................................................................................... 8
CHAPTER 2
PRODUCT OVERVIEW .................................................................................. 9
Introduction to DMT143 ........................................................... 9
Basic Features and Options .................................................. 10
Transmitter Parts .................................................................... 11
Model with G1/2” ISO228/1 Thread .................................... 11
Model with NPT Thread ...................................................... 12
Loop-Powered Display ........................................................... 13
Connection Cables ................................................................. 14
Sampling Accessories ........................................................... 14
CHAPTER 3
FUNCTIONAL DESCRIPTION ..................................................................... 15
DRYCAP® Technology ........................................................... 15
Auto-Calibration .................................................................. 15
Sensor Purge ...................................................................... 16
Sensor Warming in High Humidities and Freezing Conditions
............................................................................................ 16
DMT143 Startup Sequence .................................................... 17
Alarm LED ............................................................................... 18
CHAPTER 4
INSTALLATION ............................................................................................ 19
Transmitter Configuration Before Installation .................... 19
Selecting the Location ........................................................... 20
Installing the Transmitter ...................................................... 20
Wiring ...................................................................................... 22
Power Supply Requirements ............................................... 23
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Sampling from a Process ...................................................... 26
Sampling Accessories ........................................................... 26
DMT242SC Sampling Cell .................................................. 26
DMT242SC2 Sampling Cell with Swagelok Connectors ..... 26
DSC74 Sampling Cell with Quick Connector and Leak Screw
............................................................................................. 27
DSC74B Two-Pressure Sampling Cell ................................ 28
DSC74C Two-Pressure Sampling Cell with Coil ............ 30
DM240FA Duct Installation Flange ................................ 32
CHAPTER 5
OPERATION ................................................................................................. 33
Transmitter Start-Up ............................................................... 33
Operation with DM70 Hand-Held Dewpoint Meter ............... 34
Serial Communication ............................................................ 35
Connecting to the Serial Interface ....................................... 35
Installing the Driver for the USB Service Cable ............. 35
Terminal Application Settings .............................................. 36
List of Serial Commands ....................................................... 38
Device Information ................................................................. 39
Show Device Information..................................................... 39
Show Analog Output Mode ................................................. 39
Show Firmware Version ...................................................... 40
Show Firmware Information ................................................ 40
Show Currently Active Errors .............................................. 40
Show Serial Number ............................................................ 40
Show Command List ........................................................... 41
Configuring Analog Output ................................................... 42
Set Analog Output Parameters and Scaling ........................ 42
Set Analog Output Error Notification ................................... 43
Extend Analog Output Range .............................................. 44
Test Analog Output .............................................................. 44
Enable or Disable Analog Output ........................................ 45
Serial Line Output Commands .............................................. 45
Start Measurement Output .................................................. 45
Stop Measurement Output .................................................. 45
Set Output Interval ............................................................... 46
Output a Reading Once ....................................................... 46
Configuring Measurement Parameters ................................ 47
Set Measurement Output Format ........................................ 47
Set Measured Gas Type...................................................... 49
Set Measurement Filtering .................................................. 49
Set Pressure Compensation Value ..................................... 50
Select Unit ........................................................................... 51
View User Adjustment Parameters ..................................... 51
Set User Adjustment Parameters ........................................ 52
Configuring Serial Line Operatio n ........................................ 53
Set Serial Line Operating Mode .......................................... 53
Set Serial Line Settings ....................................................... 53
Set Transmitter Address ...................................................... 54
Set Serial Line Response Time ........................................... 55
Other Commands.................................................................... 55
Opening the Transmitter in POLL Mode.............................. 55
Closing the Connection to a Transmitter in POLL Mode ..... 55
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Configure the Alarm LED .................................................... 56
Show Transmitter Uptime .................................................... 57
Reset Transmitter ................................................................ 57
Restore Factory Settings ..................................................... 57
CHAPTER 6
MAINTENANCE ........................................................................................... 59
Periodic Maintenance ............................................................ 59
Cleaning .............................................................................. 59
Calibration ........................................................................... 59
Changing the Filter .............................................................. 60
Field Check Using the DM70 Hand-Held Dewpoint Meter .. 61
Repair Maintenance ............................................................... 63
CHAPTER 7
TROUBLESHOOTING ................................................................................. 65
Solving Typical Problems...................................................... 65
Error Messages ...................................................................... 66
Unknown Serial Settings ....................................................... 66
Technical Support .................................................................. 67
Product Returns ..................................................................... 67
CHAPTER 8
TECHNICAL DATA ...................................................................................... 69
Specifications ......................................................................... 69
Spare Parts and Accessories ................................................ 72
Dimensions in mm ................................................................. 73
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List of Figures
Figure 1 DMT143 Parts – Model with ISO Thread ................................. 11
Figure 2 DMT143 Parts – Model with NPT Thread ................................ 12
Figure 3 Nokeval 301 Loop-Powered Display ........................................ 13
Figure 4 DMT143 Startup Sequence ...................................................... 17
Figure 5 Removing the Transport Protection Cap .................................. 20
Figure 6 Installing the Transmitter with Sealing Ring ............................. 21
Figure 7 Tightening with a Wrench ......................................................... 21
Figure 8 DMT143 Digital and Analog Connectors .................................. 22
Figure 9 Wiring the Digital Connector ..................................................... 22
Figure 10 Wiring the Analog Connector .................................................... 22
Figure 11 Example of Current Consumption During Purge ...................... 24
Figure 12 Example of Current Consumption During Auto-Calibration ...... 25
Figure 13 Sampling Cells DMT242SC2 (left) and DMT242SC (right) ...... 27
Figure 14 DSC74 Sampling Cell with Access or ies ................................... 28
Figure 15 DSC74B .................................................................................... 29
Figure 16 Removing the Leak Screw ........................................................ 29
Figure 17 Default Assembly of DSC74C .................................................. 30
Figure 18 Alternative Assembly of DSC74C (for Tight Spaces) ............... 31
Figure 19 DM240FA with DMT143 ........................................................... 32
Figure 20 Measurement Settings Menu .................................................... 34
Figure 21 PuTTY Terminal Application ..................................................... 37
Figure 22 Removing the Filter .................................................................. 60
Figure 23 Comparing Dewpoint Readings on MI70 .................................. 62
Figure 24 Dewpoint Accuracy vs. Measurement Conditions .................... 70
Figure 25 DMT143 Dimensions – Model With ISO Thread ...................... 73
Figure 26 DMT143 Dimensions – Model With NPT Thread ..................... 73
List of Tables
Table 1 Manual Revisions ....................................................................... 6
Table 2 Related Manuals ......................................................................... 6
Table 3 Output Parameters of the DMT143 ............................................ 9
Table 4 Alarm LED States ..................................................................... 18
Table 5 Connector Pinouts .................................................................... 22
Table 6 Default Serial Interface Settings ............................................... 36
Table 7 List of Serial Commands .......................................................... 38
Table 8 FORM Command Parameters .................................................. 48
Table 9 FORM Command Modifiers ...................................................... 48
Table 10 Pressure Conversion Coefficients ............................................ 50
Table 11 Selection of Output Modes ....................................................... 53
Table 12 Troubleshooting Table .............................................................. 65
Table 13 Error Messages ........................................................................ 66
Table 14 Measured Parameters .............................................................. 69
Table 15 Operating Environm ent ............................................................. 70
Table 16 Outputs ..................................................................................... 70
Table 17 General ..................................................................................... 71
Table 18 Spare Parts and Accessories for DMT143 ............................... 72
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Chapter 1 _________________________________________________________ General Information
CHAPTER 1
GENERAL INFORM ATION
This chapter provides general notes for the manual and the DMT143.
About This Manual
This manual provides information for installing, operating, and
maintaining DMT143.
Contents of This Manual
This manual consists of the following chapters:
- Chapter 1, General Informati on, provides general notes for the manual
and the DMT143.
- Chapter 2, Product Overview, introduces the DMT143 transmitter and
its features.
- Chapter 3, Functional Description, describes the advanced
functionality of DMT143, including the auto-calibration, sensor purge,
and sensor warming functions.
- Chapter 4, Installation, provides you with information that is intended
to help you install the DMT143.
- Chapter 5, Operation, contains information that is needed to operate
the DMT143.
- Chapter 6, Maintenance, provides information that is needed in basic
maintenance of the DMT143.
- Chapter 7, Troubleshooting, describes common problems, their
probable causes and remedies, and provides contact information for
technical support.
- Chapter 8, Technical Data, provides the technical data of the
DMT143.
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Manual Code
Description
M211435EN-E
February 2014. This manual. Startup sequence
hand-held indicator.
M211435EN-D
June 2013. Updated wiring instruc t io ns .
M211435EN-C
January 2013. Previous version. Updated
SDELAY commands.
M211435EN-B
June 2012. Updated section Alarm LED on page
dimension drawings.
M211435EN-A
First version.
Manual Code
Manual Name
M211434EN
DMT143 Quick Guide
M211634EN
Nokeval 301/302 Display Wiring Diagram
Version Information
Table 1 Manual Revisions
length changed (appl icab le f r om software version
1.1.5 onward), updated sensor warming information
and instructions related to connecting an MI70
command descriptions for ASEL, FORM, SERI, and
18. Updated section Configure the Alarm LED on
page 56
. Updated technical specification and
WARNING
CAUTION
Related Manuals
Table 2 Related Manuals
Documentation Conventions
Throughout the manual, important safety considerations are highlighted
as follows:
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 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.
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Chapter 1 _________________________________________________________ General Information
Do not modify the unit. Improper modification can damage the product
or lead to malfunction.
The transmitter body does not have
not designed to be opened. Opening the transmitter will void the
warranty.
Recycle all applicable material.
Dispose of the unit
with regular household refuse.
Safety
The DMT143 delivered to you has been tested and approved as shipped
from the factory. Note the following precautions:
CAUTION
CAUTION
Recycling
user serviceable parts inside, and is
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. It is possible to damage the product,
however, by delivering electrostatic discharges when touching the
exposed connectors on the back of the product.
To make sure you are not delivering high static voltages yourself, avoid
touching the exposed pins of the connectors.
according to statutory regulations. Do not dispose of
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Regulatory Compliances
DMT143 is in conformity with the provisions of the following EU
directives:
- EMC-Directive
- RoHS-Directive
Conformity is shown by compliance with the following standards:
- EN 61326-1: Electrical equipment for measurement, control, and
laboratory use – EMC requirements – for use in industrial locations.
- EN 550022: Information technology equipment – Radio disturbance
characteristics – Limits and methods of measurement.
Trademarks
DRYCAP® is a registered trademark of Vaisala Oyj.
All other trademarks are the property of their respective owners.
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
Visit our Internet pages for standard warranty terms and conditions:
www.vaisala.com/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.
8 ____________________________________________________________________ M211435EN-E
Chapter 2 ___________________________________________________________ Product Overview
Parameter
Abbreviation
Metric Unit
Non-Metric
Unit
Dewpoint/frost point temperature
Tdf
ºC
ºF
Dewpoint/frost point temperature,
converted to atmospheric pressure
Tdfatm
ºC
ºF
ppm moisture, by volume
H20
ppm
ppm
When dewpoint is below 0 °C, the transmitter outputs frostpoint for Td.
CHAPTER 2
PRODUCT OVERVIE W
This chapter introduces the DMT143 transmitter and its features.
Introduction to DMT143
Vaisala DRYCAP® Dewpoint Transmitter DMT143 is a small and
lightweight dewpoint transmitter suitable for a wide range of OEM
applications. The DMT143 is easy to install and the mechanics have been
designed for harsh environments requiring protection against dust, dirt
and splashed water.
NOTE
DMT143 uses a DRYCAP® polymer sensor for dewpoint measurement.
DRYCAP® technology has low maintenance needs due to its excellent
long term stability and durability against condensation. The calibration
interval of the DMT143 is two years.
Table 3 Output Parameters of the DMT143
Dewpoint temperature in atmospheric pressure (T
atm) is a calculated
d/f
parameter that presents the dewpoint the gas would have at atmospheric
pressure. For this calculation to provide accurate results, it is important to
have the correct pressure setting stored in the transmitter. This setting is
specified on the order form, and it can be changed using the RS-485 line
or DM70 hand-held dewpoint meter.
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Basic Features and Options
- Dewpoint measurement range -60 ... +60 °C (-76 ... +140 °F).
- Dewpoint measurement accuracy up to ±2 °C (±5.4 °F) Td in air or N2.
- Operating pressure range 0 ... 50 bara (725 psia).
- Configurable for optimum dewpoint measurement accuracy:
- Dewpoint measurement in SF6 or air.
- Pressure compensation (fixed pressure setting or live pressure
input through RS-485).
- Analog output: one output channel, selectable from:
- 0 ... 1 V
- 0 ... 5 V
- 1 ... 5 V
- 4 ... 20 mA
- Digital output: RS-485 (non-isolated).
- LED for dewpoint level alarm and transmitter diagnostics.
- DRYCAP® polymer sensor:
- Autocalibration ensures accuracy in changing measurement
conditions.
- Sensor warming keeps the sensor dry in high humidity.
- Sensor purge ensures long term stability.
- NIST traceable (certificate included).
- Field check suitability with DM70 hand-held dewpoint meter.
- Optional accessories:
- Stainless steel grid filter for vacuum applications.
- Sampling cells with various installation options.
- Loop-powered external display.
- Connection cable for DM70 hand-held dewpoint meter.
- Plastic shipping case for avoiding contamination during
shipping.
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Chapter 2 ___________________________________________________________ Product Overview
When the transmitter is
transport protection cap that keeps the sensor dry. The transport
protection cap should be left on the transmitter during storage. Remove
the transport protection cap before installing the transmitter.
The following numbers refer to Figure 1 above:
1 = Transmitter body. Type label is applied here.
2 = Digital output: non-isolated RS-485.
3 = Alarm LED.
4 = Analog output.
5 = Sealing ring.
Must be used with the G1/2” ISO228/1 connection thread.
6 = 24 mm nut.
7 = Connection thread: G1/2" ISO228/1.
8 = DRYCAP® sensor protected with sintered filter.
Transmitter Parts
NOTE
delivered, the filter is protected by a yellow
Model with G1/2” ISO228/1 Thread
1202-120
Figure 1 DMT143 Parts – Model with ISO Thread
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The following numbers refer to Figure 2 above:
1 = Transmitter body. Type label is applied here.
2 = Digital output: non-isolated RS-485.
3 = Alarm LED.
4 = Analog output.
5 = 30 mm nut.
6 = Connection thread: NPT 1/2".
7 = DRYCAP® sensor protected with sintered filter.
Model with NPT Thread
1202-121
Figure 2 DMT143 Parts – Model with NPT Thread
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Chapter 2 ___________________________________________________________ Product Overview
The loop resistance of the display must be included in the loop resistance
calculation for the complet
display, refer to the manufacturer’s documentation.
Loop-Powered Display
DMT143 can be connected to a loop-powered external LED display. The
display provides a reading of the output parameter. The display is
powered by the 4 ... 20 mA current signal, so there is no need for an
external power supply.
Two models are available:
- Nokeval 301
- Nokeval 302 (with alarm relays)
The display is delivered at its default settings. Configure the display
functions and scaling according to the documentation delivered with the
display. For a wiring example, see Nokeval 301/302 Display Wiring
Diagram (document code M211634EN). For the order codes of the
displays, see section Spare Parts and Accessories on page 72.
Figure 3 Nokeval 301 Loop-Powered Display
NOTE
e current loop. For the loop resistance of the
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1102-053
USER'S GUIDE ____________________________________________________________________
Connection Cables
Vaisala supplies shielded cables with M8 female straight threaded
connector. Standard cables are available in four lengths:
- 0.3 m (1.0 ft)
- 3 m (9.8 ft)
- 5 m (16.4 ft)
- 10 m (32.8 ft)
Heavy duty cables are available in two lengths:
- 1.5 m (4.9 ft)
- 3 m (9.8 ft)
Also available are the following cables for service and field check use:
- USB service cable
- MI70 connection cable
For the order codes of the cables, see section Spare Parts and Accessories
on page 72.
Sampling Accessories
DMT143 is compatible with various sampling accessories. For more
information on performing sampling, and a description of the accessories,
see section Sampli ng Ac cess ori es on page 26.
For the order codes of the sampling accessories, refer to section Spare
Parts and Accessories on page 72.
14 ___________________________________________________________________ M211435EN-E
Chapter 3 _______________________________________________________ Functional Description
CHAPTER 3
FUNCTIONAL DESCRIPTION
This chapter describes the advanced functionality of DMT143, including
the auto-calibration, sensor purge, and sensor warming functions.
DRYCAP® Technology
Vaisala DRYCAP® dewpoint measurement technology ensures accurate
measurement with excellent long term stability. This results in very low
maintenance requirements for the transmitter. The lasting performance is
achieved with microprocessor technology and software that automatically
performs self-diagnostic functions in addition to the normal dewpoint
measurement. The self-diagnostic procedures that are conducted are
called auto-calibration, sensor purge, and sensor warming.
Auto-Calibration
The auto-calibration feature of the DMT143 transmitter is an automatic
procedure which greatly reduces the possible drift in the dry end of the
dewpoint measurement. It is performed at one hour intervals, and when
the power is switched on. During auto-calibration the sensor is warmed
for a short period (< 1 min) and the sensor capacitance values are
evaluated at the elevated temperature. The possible dry end drift is then
corrected to correspond to the calibrated values. During the autocalibration the transmitter outputs the Td value prior to the procedure.
Auto-calibration is carried out only if several criteria for the
measurement environment are fulfilled. This ensures the reliability of the
adjustments, and maintains the excellent long term stability that the
patented technology offers. These criteria include for example a stable
enough moisture level in the measured atmosphere. If the conditions are
not fulfilled, the auto-calibration function is postponed until satisfactory
conditions are reached.
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Sensor Purge
Sensor purge is also an automatic procedure that minimizes the drift at
the wet end readings of the dewpoint measurement. Sensor purge is
performed once a day or when the power is switched on. The sensor is
heated for several minutes which will then evaporate all excess
molecules out of the sensor polymer. This, together with the autocalibration results in a very small drift of the sensor due to the very linear
behaviour of the polymer technology. During the sensor purge the
transmitter outputs the Td value prior to the procedure.
Sensor Warming in High Humidities and Freezing Conditions
DMT143 has a sensor warming feature that improves the sensor’s
performance in high humidities and freezing conditions. Sensor warming
does not interrupt the transmitter’s Td value output.
NOTE
In high humidity, sensor warming prevents the sensor and filter from
becoming wet. High humidity may be present when the dewpoint
temperature rises close to the gas temperature.
Sensor warming is switched on automatically when the humidity in the
measured gas increases to a level where dew can start to form. The
advantage of sensor warming is the rapid response of dewpoint
measurement. A wet sensor and filter would otherwise result in a
dewpoint equal to ambient temperature (that is, RH = 100 %).
If in spite of sensor warming the sensor gets soaked, it will recover fully
back to normal operation after it dries out.
In freezing conditions, DMT143 uses sensor warming to maintain the
sensor temperature above 0 °C.
When measuring in temperatures below 0 °C, the supply voltage must be
24 ... 28 VDC. For more information on DMT143 supply voltage
requirements, see section Power Supply Requirements on page 23.
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Chapter 3 _______________________________________________________ Functional Description
The transmitter always performs this sequence when starting
the transmitter continuously powered to optimize its measurement
performance and availability.
Normal output Normal output
2 s
O
utput f r oz en
40 s 3 ... 5 m in
Time
Purge*
3 min
Autocal**
<2 min
* Purge will repeat ev er y 24 hour s
** Autocal will repeat every 60 m inutes (is pos tponed if envir onm ent is not s uitable)
Startup
DMT143 Startup Sequence
When the transmitter is powered up, it will perform the sequence
(applicable from software version 1.1.5 onward) shown in Figure 4
below. After a two-second startup, the transmitter will measure normally
for forty seconds, after which it will perform the sensor purge and autocalibration functions. This can take up to five minutes, during which time
the output is frozen: it will display the last measured values before the
sensor purge began.
The auto-calibration function may be postponed if the measurement
environment is not suitable. For example, the environment may be
changing rapidly or have too high humidity.
Normal operation and output is typically achieved no later than six
minutes after startup. The sensor purge will repeat every 24 hours, and
auto-calibration every hour. The output will again be frozen for their
duration.
1401-033
Figure 4 DMT143 Startup Sequence
NOTE
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up. Keep
USER'S GUIDE ____________________________________________________________________
LED Color
Meaning
Not lit
Power off or LED functionality disabled.
Green
Power on, normal measurement.
Green and blinking
Purge or autocalibr ati on in progres s , m eas urem ent
frozen.
Red
Dewpoint above limit.
Red and blinking
Transmitter error. See section Error Mess ages on
page 66.
Alarm LED
The alarm LED at the back of the transmitter provides a visual indication
of the transmitter’s status. The alarm LED functionality is preset at the
factory according to order form. You can configure it as follows:
- You can change the alarm limit using the DM70 hand-held dewpoint
meter. See section Operation with DM70 Hand-Held on page 34.
- You can use the ALARM command on the serial line to change the
alarm limit, enable/disable the dewpoint alarm, or turn on/off the LED
completely. See section Configure the Alarm LED on page 56.
Table 4 Alarm LED States
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Chapter 4 ________________________________________________________________ Installation
CHAPTER 4
INSTALLATION
This chapter provides you with information that is intended to help you
install the DMT143.
Transmitter Configuration Before Installation
You may wish to configure your transmitter before physically installing
it. For easy access to the serial line, use the USB service cable and a
terminal program on a PC. Instructions for using the serial line and the
serial commands are provided in Chapter 5, Operation, on page 33.
Some configuration settings can also be changed using the D70 handheld indicator. See section Operation with DM70 Hand-Held on page 34.
Examples of configurable settings for analog output:
1. Analog output parameter and scaling.
2. Analog output error level.
Examples of configurable settings for RS-485 output:
1. By default, DMT143 transmitters are configured for single
transmitter operation. Serial operation mode is STOP and
address is 0.
To configure transmitters for operation on a common line, you
must give each transmitter a unique address (range 0 ... 255) and
set their serial operation mode to POLL.
2. The default serial line settings may not be right for your RS-485
line.
3. You may need to change the transmitter’s serial output format to
suit your needs.
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Selecting the Location
It is important that the point of installation represents well the gas to be
measured. Temperature changes do not affect the dewpoint measurement,
but pressure changes will have an effect on the measurement. All leaks in
the system must be eliminated to avoid ambient humidity affecting the
measurement.
Direct installation to the measured gas is the recommended installation
method if the temperature of the gas is suitable for DMT143 and no
additional filtering is needed due to very dusty or oily gas. Oil as such is
not harmful for the DRYCAP® sensor, but response time may be slower
if there are oil particles in the system, or if oil is collected to the filter
over a longer period of time. The maximum measurement pressure is
50 bara / 725 psia (absolute pressure) for direct measurement.
If the gas temperature is higher than the specified maximum operating
temperature of the transmitter, gas sampling and cooling it to ambient
temperature (for example, 20 °C / 68 °F) is recommended. Note that the
dewpoint temperature must be clearly lower than the ambient
temperature to avoid condensation in the sampling line. Sampling from
the process is easy by using Vaisala sampling cell options; see section
Sampling Accessories on page 26.
The DMT143 is light in weight, which means that it can be installed in a
sample pipeline in the sampling cells without the need of any additional
mechanical support. You can use a standard G1/2" T-shaped pipe fitting
(not available from Vaisala) when installing DMT143 into a pipeline.
Installing the Transmitter
1. Remove the yellow transport protection cap from the transmitter.
1202-122
Figure 5 Removing the Transport Protection Cap
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Chapter 4 ________________________________________________________________ Installation
2. Model with parallel thread (G1/2" ISO 228/1) requires a sealing
ring for a tight connection. Use the sealing ring that is provided
with the transmitter. Make sure the threads on the mounting point
match your transmitter.
For the model with NPT thread, do not use a sealing ring.
1202-123
Figure 6 Installing the Transmitter with Sealing Ring
3. Tighten the connection by turning with a wrench (max. 50 Nm).
Wrench size is 24 mm for ISO threaded transmitter, 30 mm for
NPT threaded model.
1202-124
Figure 7 Tightening with a Wrench
4. Connect the signal and power cable to the DMT143. Refer to the
following sections for wiring instructions and power supply
requirements.
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