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.
Chapter 1 _________________________________________________________ General Information
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 Dewpoint Transmitter DMT142.
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 Dewpoint Transmitter DMT142.
- Chapter 3, Functional Description, describes the advanced
functionality of Dewpoint Transmitter DMT142, including the
auto-calibration, sensor purge and sensor warming functions.
- Chapter 4, Installation, provides you with information that is
intended to help you install Dewpoint Transmitter DMT142.
- Chapter 5, Serial Commands, contains the operating instructions
for the serial interface of Dewpoint Transmitter DMT142.
- Chapter 6, Maintenance, provides information that is needed in
basic maintenance of Dewpoint Transmitter DMT142, and contact
information for Vaisala Service Centers.
- Chapter 7, Troubleshooting, describes the error states and provides
contact information for technical support.
- Chapter 8, Technical Data, provides the technical data of Dewpoint
Transmitter DMT142.
Version Information
Table 1 Manual Revisions
Manual Code Description
M210397EN-A Vaisala DRYCAP® Dewpoint
Transmitter DMT142 Advanced User
Manual, April 2003
M210397EN-B Vaisala DRYCAP® Dewpoint
Transmitter DMT142 User's Guide,
October 2005
Td measurement and operating
pressure range specification revised
New sampling cell, installation flange
and connection cable options added
M210397EN-C Vaisala DRYCAP® Dewpoint
Transmitter DMT142 User's Guide,
March 2006; this manual
Corrected wiring diagrams
Chapter 1 _________________________________________________________ General Information
General Safety Considerations
Throughout the manual, important safety considerations are
highlighted as follows:
WARNING
CAUTION
NOTE
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 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: manuals@vaisala.com
Product Related Safety Precautions
The Dewpoint Transmitter DMT142 delivered to you has been tested
for safety and approved as shipped from the factory. Note the
following precautions:
Chapter 1 _________________________________________________________ General Information
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 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 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 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.
This chapter introduces the features and advantages of Dewpoint
Transmitter DMT142.
Introduction to Dewpoint Transmitter DMT142
Vaisala DRYCAP® dewpoint transmitter DMT142 is designed for a
wide range of OEM applications. The excellent stability and reliability
of its performance is based on advanced DRYCAP® polymer sensor
technology. The DRYCAP® technology has low maintenance needs
due to its excellent long term stability and durability against
condensation. The DMT142 transmitter is easy to install and the
mechanics have been designed for harsh environments requiring
protection against dust, dirt and splashed water.
The Basic Features and Options
- Small size to fit in tight installations.
- Analog outputs: 4 ... 20 mA or 0 - 1 V/0 - 5 V versions.
- Low maintenance requirements due to excellent long term stability.
- DRYCAP® polymer sensor with automatic auto-calibration and
sensor purge ensures long term stability.
- Sensor warming keeps the sensor dry in abnormally high humidity
situations.
- Field check suitability with DM70 hand-held meter.
- RS232 serial line connection for service use with DMT142RS
cable.
- Optional sampling cells with different installation options available
as DMT142 installation accessories.
3
4
2
1
5
678
0507-093
Figure 1 Dewpoint Transmitter DMT142 Components
The following numbers refer to Figure 1 above:
1 = Serial line connector (for service use)
2 = DRYCAP® sensor protected with sintered filter
3 = Sealing washer
4 = Protective cap for probe
5 = G1/2" ISO 228/1
6 = Protection plug for serial line connector
7 = Cable connector
8 = Connection cable (optional)
This chapter describes the advanced functionality of Dewpoint
Transmitter DMT142, including the auto-calibration, sensor purge and
sensor warming functions.
Advanced DRYCAP® Technology
Dewpoint Transmitter DMT142 utilizes an advanced, patented
measurement technology to ensure 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 DMT142 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 auto-calibration the transmitter outputs the Td value
prior to the procedure.