Michell Instruments Optidew User manual

Optidew
Chilled Mirror Hygrometer
User's Manual
97551 Issue 4.1
October 2019

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Optidew
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© Michell Instruments 2019
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Optidew User's Manual
97551 Issue 4.1, October 2019 iv
Contents
Safety .......................................................................................................................viii
Warnings...................................................................................................................viii
Electrical Safety .......................................................................................................... ix
Pressure Safety........................................................................................................... ix
Hazardous Materials (WEEE, RoHS3 & REACH) .............................................................. ix
Calibration (Factory Validation) .................................................................................... ix
Repair and Maintenance .............................................................................................. ix
Abbreviations............................................................................................................... x
1. INTRODUCTION ..................................................................................................... 1
1.1. Optidew Series.........................................................................................................1
1.2. Optidew Sensor .......................................................................................................2
1.3. Minimum Measurable Dew Points ..............................................................................3
1.4. Remote Temperature Probes.....................................................................................4
2. INSTALLATION....................................................................................................... 5
2.1. Unpacking the instruments........................................................................................5
2.2. Mounting.................................................................................................................5
2.3. Instrument Connections............................................................................................7
2.3.1. Optidew 501 ......................................................................................................7
2.3.2. Optidew 401 ......................................................................................................8
2.4. Electrical Connections...............................................................................................9
2.4.1. Electrical Supply .................................................................................................9
2.4.2. Analog and Digital Communications.................................................................... 10
2.5. Sensor Installation ................................................................................................. 13
2.5.1. Environmental monitoring ................................................................................. 13
2.5.2. Monitoring a flowing sample .............................................................................. 13
2.5.3. Environmental Chamber or Glovebox sensor mounting......................................... 14
2.6. Temperature Probe Installation ............................................................................... 14
2.6.1. Using Temperature Probes with a chamber port adapter...................................... 15
2.7. Pressure Transmitter Installation ............................................................................. 15
3. USER INTERFACE ................................................................................................. 16
3.1. Main Display .......................................................................................................... 16
3.1.1. Full Screen Mode .............................................................................................. 16
3.1.2. Main Screen ..................................................................................................... 17
3.1.3. Customizable Readouts ..................................................................................... 18

Optidew User’s Manual
Michell Instruments
3.1.4. Locking the analyzer ......................................................................................... 18
3.1.5. Menu Structure................................................................................................. 19
3.1.6. Operational Status Display................................................................................. 20
3.1.7. Sensor Status Display........................................................................................ 21
3.2. Setup Menus.......................................................................................................... 22
3.2.1. DCC................................................................................................................. 22
3.2.2. Logging ........................................................................................................... 24
3.2.3. Outputs ........................................................................................................... 25
3.2.4. Alarm .............................................................................................................. 26
3.2.5. Display ............................................................................................................ 27
3.2.6. Clock ............................................................................................................... 28
3.2.7. Inputs ............................................................................................................. 29
3.2.8. Comms Screen ................................................................................................. 30
3.2.9. Network Settings .............................................................................................. 30
3.3. Optidew 501 Transmitter without display ................................................................. 31
3.3.1. Optics Calibration ............................................................................................. 31
4. OPERATION.......................................................................................................... 32
4.1. Operating Cycle ..................................................................................................... 32
4.2. Operating Guide..................................................................................................... 33
4.2.1. Description....................................................................................................... 33
4.2.2. Operating Practice ............................................................................................ 33
4.3. Good Measurement Practice.................................................................................... 36
4.3.1. Sampling Hints ................................................................................................. 36
4.3.2. First Time Operation ......................................................................................... 39
4.4. Operational Functions............................................................................................. 39
4.4.1. DCC Function ................................................................................................... 39
4.4.2. MAXCOOL Function........................................................................................... 40
4.4.3. Frost Assurance Technology (FAST) ................................................................... 40
4.4.4. STANDBY Mode................................................................................................ 41
4.4.5. Parameter Conversions & Pressure Compensation ............................................... 41
4.4.6. Data Logging.................................................................................................... 42
5. WARNINGS AND FAULTS...................................................................................... 42
6. MAINTENANCE ..................................................................................................... 44
6.1. Mirror Cleaning ...................................................................................................... 44
6.2. Exchanging Sensors ............................................................................................... 45

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Appendices
Appendix A............................................................................................................... 46
Technical Specifications................................................................................................. 47
Appendix B............................................................................................................... 49
Modbus Register Map.................................................................................................... 50
Further Reading............................................................................................................ 58
Appendix C............................................................................................................... 59
Dimensional Drawings................................................................................................... 60
Appendix D............................................................................................................... 67
Quality, Recycling, Compliance & Warranty Information ................................................... 68
Appendix E ............................................................................................................... 69
Return Document& Decontamination Declaration ............................................................ 70
Figures
Figure 1 Optidew 501 (wall mount) and Optidew 401 (bench top)..........................................1
Figure 2 2-Stage minimum measureable dew point ...............................................................3
Figure 3 General Purpose Probe ..........................................................................................4
Figure 4 Labatory/High Temperature Probe..........................................................................4
Figure 5 Optidew 501 wall mounting points..........................................................................6
Figure 6 Optidew 501 with Touch Screen display or DCC control button..................................7
Figure 7 Optidew 501 bottom panel.....................................................................................7
Figure 8 Optidew 401 front and side panels..........................................................................8
Figure 9 Optidew 401 rear panel .........................................................................................8
Figure 10 Power Connector.................................................................................................9
Figure 11 RS458 & Analog output connector ......................................................................10
Figure 12 Analog output connector ....................................................................................11
Figure 13 Relay contact connector.....................................................................................12
Figure 14 Temperature Probe Adapter ...............................................................................15
Figure 15 Main Screen......................................................................................................16
Figure 16 Main Screen layout ............................................................................................17
Figure 17 DCC Menu ........................................................................................................22
Figure 18 Logging Screen .................................................................................................24
Figure 19 Outputs Screen .................................................................................................25

Optidew User’s Manual
Michell Instruments
Figure 20 Alarm Screen ....................................................................................................26
Figure 21 Display Screen ..................................................................................................27
Figure 22 Clock Screen .....................................................................................................28
Figure 23 Inputs Screen ...................................................................................................29
Figure 24 Comms Screen ..................................................................................................30
Figure 25 Network Settings Screen ....................................................................................30
Figure 26 Typical Operating Cycle......................................................................................32
Figure 27 Room Measurement Example .............................................................................34
Figure 28 Mirror Contaminaton Warning Symbol .................................................................35
Figure 29 Material Permeability Comparison .......................................................................36
Figure 30 Condensation in Sample Tubing..........................................................................37
Figure 31 System alarm....................................................................................................42
Figure 32 Sensor Cleaning ................................................................................................44

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viii 97551 Issue 4.1, October 2019
Safety
The instrument is designed to be completely safe when installed and operated correctly in
accordance with the information provided in this manual.
This manual contains all the required information to install, operate and maintain this product.
Prior to installation and use of this product, this entire manual should be read and understood.
Installation and operation of this product should be carried out by suitably competent personnel
only. The installation and operation of this product must be in accordance with the instructions
provided and according to the terms of any associated safety certificates. Incorrect installation
and use of this product other than those described in this manual and other than its intended
purpose will render all warranties void.
This product meets the essential protection requirements of the relevant EU directives. Further
details of applied directives may be found in the product specification.
Electricity and pressurized gas can be dangerous. This product must be installed and operated
only by suitable trained personnel.
Warnings
No user serviceable parts inside
Where this hazard warning symbol appears in the following
sections, it is used to indicate areas where potentially
hazardous operations need to be carried out and where
particular attention to personal and personnel safety must be
observed.
Where this symbol appears in the following sections it is used
to indicate areas of potential risk of electric shock.

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Michell Instruments ix
Electrical Safety
Ensure electrical safety is complied with by following the directions provided here and observing
all local operation & installation requirements at the intended location of use.
This product is completely safe when using any options and accessories supplied by the
manufacturer of this product for use with it. Refer to Section 2 (Installation) of this manual for
further details.
Pressure Safety
For this product to operate satisfactorily, pressurized gas must be connected to it. Observe all
the information contained within this manual and all local operation & installation requirements
at the intended location of use. Refer to Section 2 (Installation) of this manual for further details.
Hazardous Materials (WEEE, RoHS3 & REACH)
This product does not contain or release any prohibited chemicals listed on the SVHC (Substances of
Very High Concern) Candidate List. During the intended normal operation of this product it is not
possible for the user to come into contact with any hazardous materials. This product is designed to
be recyclable except where indicated, see relevant sections in this manual for further details.
Calibration (Factory Validation)
Prior to shipment, the instrument undergoes stringent factory calibration that is traceable to
national standards. Due to the inherent stability of the instrument, regular factory calibration is
not required, however recalibration is recommended to maintain measurement traceability.
Michell Instruments can provide a fully traceable factory calibration service for the instrument
and it is recommended that this is considered at intervals of every year of the analyzer's life.
Please contact your local Michell Instruments' office or representative for further details
(www.michell.com).
Repair and Maintenance
Apart from user-replaceable components required for routine operational maintenance described
above, the instrument must only be maintained either by the manufacturer or an accredited
service agent. Refer to www.michell.com for details of Michell Instruments’ worldwide offices
contact information.

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Abbreviations
The following abbreviations are used in this manual:
A ampere
AC alternating current
atm pressure unit (atmosphere)
bara pressure unit (=100 kP or 0.987 atm) absolute
barg pressure unit (=100 kP or 0.987 atm) gauge
°C degrees Celsius
°F degrees Fahrenheit
EU European Union
hr hour
Hz Hertz
IEC International Electrotechnical Commission
IP Internet protocol
ml/min milliliters per minute
mg/m3milligrams per cubic meter
lbs/MMscf pounds per million standard cubic feet
mA milliampere
mins minutes
mmHg millimeter of mercury
Pa pascal
ppmVparts per million (by volume)
ppmWparts per million (by weight)
%Vol percentage volume
psia pound(s) per square inch (absolute)
psig pound(s) per square inch (gauge)
RH relative humidity
RS485/232 standards defining the electrical characteristics of drivers & receivers
RTC real time clock
RTU Remote Terminal Unit
SD storage device card
UART universal asynchronous receiver/transmitter
USB Universal Serial Bus
V Volts
" Inch
Δdelta
% percentage
Ωohms

Optidew User’s Manual
Michell Instruments 1
1. INTRODUCTION
The Optidew chilled mirror hygrometer is based on the proven, fundamental condensation
temperature dew point principle, giving unmatched long-term drift-free performance.
Michell offers three highly durable sensor options, which are suitable for measuring in a wide
variety of different samples.
1.1. Optidew Series
The Optidew 501 features a compact ABS enclosure with an aluminium base plate and 4
external lugs for easy mounting to a panel or wall. It is available with a 5.7" touch screen
display, or as a "transmitter only" version.
A weatherproof version of the Optidew 501 enclosure is available with a modified connector
panel to improve ingress protection to IP65. Note that the Ethernet and SD card options are
not available in combination with the weatherproof version.
The Optidew 401 is designed to be easy to handle and transport and is ideal for laboratory
or service use. It has a 5.7” touch screen LCD fitted as standard.
Figure 1 Optidew 501 (wall mount) and Optidew 401 (bench top)

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1.2. Optidew Sensor
The new Optidew sensor is available with either a single or dual stage thermoelectric cooler and
with a choice of sensor head materials making it suitable for use in air/inert gases or in corrosive
environments. The following tables show the capabilities of each sensor type:
Single Stage
Sensor Dual Stage Sensor Harsh Environment Sensor
Approximate
maximum depression
at ambient
60 °C 70 °C 70 °C
Maximum operating
temperature 90 °C 90 °C 120 °C
Maximum
Recommended
Sensor Temperature
for FAST
21 °C 30 °C 30 °C
Lowest Measurable Dew Point
Sensor temperature
at 23°C ambient -25 °C -40 °C -40 °C
For more detailed information on the performance of the sensor across its whole operating
temperature range, see below. All versions are rated for use at pressure up to 2500 kPag (362
psig).

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Michell Instruments 3
1.3. Minimum Measurable Dew Points
The minimum dew point that can be measured is determined by the sensor temperature, and
whether the sensor can be maintained at that temperature. The following chart assumes
operation in a climatic chamber, where the air speed is sufficient to remove any excess heat
generated by the sensor.
Minimum measurable Dew Point °C
Sensor Temperature °C
Figure 2 2-Stage minimum measureable dew point

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1.4. Remote Temperature Probes
Two versions of temperature probe are available for the Optidew, a general purpose probe
rated to +90°C, and a laboratory/high temperature probe rated to +120°C.
General Purpose Probe
This 75mm probe is supplied when any of the 'standard' sensor cable options are selected. it is
intended to be installed in its' entirety into the environment to be measured.
An M12 plug is integrated into the probe itself to connect to the supplied cable.
Laboratory/High Temperature Probe
This 50mm probe is supplied when any of the high temperature cable options are selected,
however it is also designed specifically for compatibility with Michell Instruments or Rotronic
humidity calibration chambers.
The probe is fitted with a 0.5m flying lead with an M12 plug to simplify connection into a
calibration chamber. The chosen cable length option is still supplied.
Figure 3 General Purpose Probe
Figure 4 Labatory/High Temperature Probe

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Michell Instruments 5
2. INSTALLATION
2.1. Unpacking the instruments
It is recommended that all packaging is retained, in case products are returned for service or
calibration. Alternatively, if you choose to dispose of the packaging materials, ensure they are
recycled in accordance with local legislation.
Standard contents in the box:
•Calibration Certificate
•6-Way Alarm Relay Connector
•8-Way Analogue Output / RS485 Connector
•Pt100 Temperature Probe (with separate or integrated M12cable, depending on model)
•Chilled Mirror Monitor
•Chilled Mirror Sensor
•Chilled Mirror Sensor Cable
•Mains Cable
2.2. Mounting
Optidew 401
The Optidew 401 is designed to be placed on a bench or table during operation. Alternatively, it
can be used inside the optional Transport Case.
Optidew 501
The Optidew can be wall mounted using the four mounting points on each corner (see figure 2
for mounting point dimensions). It is possible to install the Optidew 501 outside, providing it is
shielded from direct sunlight and the climate is within the environmental requirements listed in
Appendix A Technical Specifications. It is highly recommended to choose the weatherproof option
if the installation will be outdoors.
Fixings
Secure using 4 off suitable screws or bolts plus washers (M4 x 15 to M6 x 15mm). Unit must be
secured to a solid surface (e.g. brick, concrete, wood min 10mm thick) or to a metal chassis plate
of minimum 3mm thickness.

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Wall Mounting Points
26 (10,2)
180 (7,1)
145 (5,7)
240 (9,4)
Figure 5 Optidew 501 wall mounting points

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Michell Instruments 7
2.3. Instrument Connections
2.3.1. Optidew 501
Number Description
1 DCC Control/ Status indicator
2 Sensor Cable connector
3 Temperature probe cable connector
4 Pressure transmitter cable connector
5 Alarm contacts connector
6 RS485 and analog output connector
7 SD Card slot (optional)
8 Ethernet port (optional)
9 Power Connector
4
3
5
6
7
8
9
1
2
Figure 6 Optidew 501 with Touch Screen display or DCC control button
Figure 7 Optidew 501 bottom panel

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2.3.2. Optidew 401
Number Description
1 Power Connector
2 Power Switch
3 SD card slot
4 Alarm contacts connector
5 RS485 and analog output connector
6 USB port
7 Ethernet port (optional)
8 Sensor Cable connector
9 Temperature probe cable connector
10 Pressure transmitter cable connector
8
10
9
4
5
6
7
2
3
1
Figure 8 Optidew 401 front and side panels
Figure 9 Optidew 401 rear panel

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Michell Instruments 9
2.4. Electrical Connections
2.4.1. Electrical Supply
The Optidew accepts a power supply of the following specification:
Voltage 100-240V AC
Frequency 50 – 60Hz
Power Consumption 30VA max
See Appendix A, Technical Specification, for full operating parameters.
Optidew 501
The wall mount is supplied with a connector wired to a 2m cable. Only use an appropriately rated
mains supply cord.
This power connector is wired as follows:
NOTE: The Optidew 501 is designed for continuous operation and therefore does not feature a
power on/off switch. As soon as power is applied, the display (or DCC button on the transmitter
version) will illuminate and the transmitter will initiate a DCC cycle.
Replacement power cables are available - contact your Michell representative.
Optidew 401
The Optidew 401 is supplied with a 2m IEC cable. The IEC socket is on the left hand side of the
instrument. There is an ON/OFF switch on the front panel. Only use an appropriately rated
detachable mains supply cord.
WARNING:
The instrument must be GROUNDED
Figure 10 Power Connector

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Fuse
This product is provided with an externally mounted fuse located next to the power connector.
The fuse is rated at 5 x 20mm medium acting: T 2.5 A H 250V.
Equipment Ratings
This product is designed to be safe at least under the following conditions: between a
temperature range of -40 to +60°C (-40 to +148°F), in maximum 80% relative humidity for
temperatures up to +31°C (+88°F) decreasing linearly to 50% RH at +50°C (+122°F).
Overvoltage Category II. Pollution Degree 2. Altitudes up to 2000m.Indoor use only but is IP65
rated.
See Appendix A, Technical Specification, for full operating parameters.
2.4.2. Analog and Digital Communications
Note: When using screened cable, the screen should only be connected to a ground point at
either the Optidew installation side, or at the receiving equipment. Failure to observe this
precaution can result in ground loops and equipment malfunction.
2.4.2.1. Digital Communications
From left to right, the first four pins of this connector are used for RS485 communications.
Pin Label Description
GND Ground
RS485 B RS485 Data B
RS485 A RS485 Data A
GND Ground
The Optidew provides Modbus RTU over RS485 or USB (Bench Top only). An Ethernet module is
optionally available for both instruments and provides Modbus TCP communication.
The Modbus register map can be found in Appendix B.
Application software is available and can be used to communicate with the instrument. Refer to
the Application Software section at the end of the manual.
Figure 11 RS458 & Analog output connector