Michell Instruments Pura User manual

Pura
Online Hygrometer
User’s Manual
97303 Issue 1.2, March 2016 Michell Instruments
PURA

Inside front cover (blank)

Pura Online Hygrometer User’s Manual
97303 Issue 1.2, March 2016 iii Michell Instruments
© 2016 Michell Instruments
This document is the property of Michell Instruments Ltd. and may not be copied or otherwise reproduced,
communicated in any way to third parties, nor stored in any Data Processing System without the express
written authorization of Michell Instruments Ltd.
Pura Online Hygrometer
PURA

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Contents
Safety ..............................................................................................................................................vi
Electrical Safety.........................................................................................................................vi
Pressure Safety .........................................................................................................................vi
Toxic Materials ..........................................................................................................................vi
Repair and Maintenance.............................................................................................................vi
Calibration ................................................................................................................................vi
Safety Conformity......................................................................................................................vi
Abbreviations................................................................................................................................... vii
Warnings ......................................................................................................................................... vii
Recycling Policy............................................................................................................................... viii
WEEE And RoHS Compliance............................................................................................................ viii
Calibration Facilities......................................................................................................................... viii
Manufacturing Quality...................................................................................................................... viii
Warranty ..........................................................................................................................................ix
Return Policy.....................................................................................................................................ix
1 INTRODUCTION........................................................................................................................ 1
2 DESCRIPTION........................................................................................................................... 1
2.1 Display........................................................................................................................... 2
2.2 Function Keys................................................................................................................. 4
2.3 Process Indicator Menu Structure..................................................................................... 5
2.3.1 Flowchart Reading Method .......................................................................................... 6
2.3.2 Flowchart Example ..................................................................................................... 7
3 OPERATION .............................................................................................................................. 8
3.1 Operational Requirements ............................................................................................... 8
3.1.1 Environmental Requirements – Process Indicator .......................................................... 8
3.1.2 Electrical Requirements ............................................................................................... 8
3.2 Mounting the Process Indicator........................................................................................ 8
3.3 Electrical Connections ....................................................................................................10
3.3.1 AC Power Supply Input...............................................................................................11
3.3.2 Preliminary System Test .............................................................................................12
3.3.3 DC Power Supply Input (Optional)...............................................................................13
3.4 Signal Output Connections .............................................................................................14
3.5 First Time Operation ......................................................................................................16
3.6 System Alarms...............................................................................................................17
3.6.1 Reversal of Default Alarm Switching Logic ...................................................................18
3.6.2 Set-up Alarm Levels ...................................................................................................20
3.6.3 Configure Analog Output Current Loop ........................................................................21
3.7 Change Dew-Point Temperature Range............................................................................22
3.7.1 Span and Unit Settings ..............................................................................................23
3.7.2 Configure Alarm Set-Point Limits .................................................................................24
3.7.3 Change Scale Units (to ppmV) .....................................................................................25
4 SENSOR INSTALLATION............................................................................................................27
4.1 Transmitter Connections.............................................................................................27
4.2 Installing the Sensor ......................................................................................................28
4.3 Transmitter Cable ......................................................................................................29
5 WHICH GASES TO MEASURE? ...................................................................................................31
6 MAINTENANCE.........................................................................................................................31
7 FAULT CONDITIONS .................................................................................................................31

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Michell Instruments v 97303 Issue 1.2, March 2016
Figures
Figure 2.1 Process Indicator panel layout ................................................................................1
Figure 2.2 Flowchart Example.................................................................................................7
Figure 3.1 Mounting the Process Indicator...............................................................................9
Figure 3.2 AC power supply connections ...............................................................................11
Figure 3.3 DC power supply connections ...............................................................................13
Figure 3.4 Process indicator rear panel connections................................................................14
Figure 3.5 Typical display .....................................................................................................16
Figure 3.6 Change alarm switching logic................................................................................19
Figure 3.7 Set-up alarm levels ..............................................................................................20
Figure 3.8 Configure analog output.......................................................................................21
Figure 3.9 Span and unit settings..........................................................................................23
Figure 3.10 Set-up alarm set-point limits .................................................................................24
Figure 3.11 Set-up process indicator (to read ppm
V
) ................................................................26
Figure 4.1 Transmitter connections .......................................................................................27
Figure 4.2 Dimensions - Pura Dew-Point Transmitter, Premium & OEM Versions........................28
Figure 4.3 Terminal block Removal........................................................................................29
Figure 4.4 Rear of connector terminal block...........................................................................30
Figure 4.5 Electrical Connections ..........................................................................................30
Appendices
Appendix A Technical Specifications ......................................................................................... 33
Appendix B List of Worldwide Michell Instruments’ Offices......................................................... 36
Appendix C EU Declaration of Conformity.................................................................................. 38
Tables
Table 2.1 Process Indicator front panel controls and indicators ................................................. 3
Table 2.2 Function keys .........................................................................................................4
Table 2.3 Flowchart symbols .................................................................................................. 6
Table 3.1 Summary of electrical connections ......................................................................... 15

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Safety
The manufacturer has designed this equipment to be safe when operated using the procedures detailed in this
manual. The user must not use this equipment for any other purpose than that stated. Do not apply values
greater than the maximum value stated.
This manual contains operating and safety instructions, which must be followed to ensure the safe operation
and to maintain the equipment in a safe condition. The safety instructions are either warnings or cautions
issued to protect the user and the equipment from injury or damage. Use competent personnel using good
engineering practice for all procedures in this Manual.
Electrical Safety
The instrument is designed to be completely safe when used with options and accessories supplied by the
manufacturer for use with the instrument.
Pressure Safety
DO NOT permit pressures greater than the safe working pressure to be applied to the instrument. The
specified safe working pressure is 24 MPa (240 barg / 3480 psig).
Toxic Materials
The use of hazardous materials in the construction of this instrument has been minimized. During normal
operation it is not possible for the user to come into contact with any hazardous substance which might be
employed in the construction of the instrument. Care should, however, be exercised during maintenance and
the disposal of certain parts.
Repair and Maintenance
The instrument must be maintained either by the manufacturer or an accredited service agent. Refer to
Appendix B for details of Michell Instruments’ worldwide offices’ contact information.
Calibration
The recommended calibration interval for this instrument is 12 months unless it is to be used in a mission-
critical application or in a dirty or contaminated environment in which case the calibration interval should be
reduced accordingly. The instrument should be returned to the manufacturer, Michell Instruments Ltd., or one
of their accredited service agents for re-calibration.
Safety Conformity
This product meets the essential protection requirements of the relevant EU directives. Further details of
applied standards may be found in the product specification.

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Abbreviations
The following abbreviations are used in this Manual:
AC alternating current
atm pressure unit (atmosphere)
barg pressure unit (=100 kP or 0.987 atm)
ºC degrees Celsius
ºF degrees Fahrenheit
DC direct current
ft foot (feet)
g gram(s)
Hz Hertz
“ inch(es)
lb pound
Nl/min normal liters per minute
m meter(s)
mA milliampere
max maximum
min minute(s)
MPa megapascal (Pascals x106)
m/sec meters per second
ppmVparts per million (by volume)
RS232 serial data transmission standard
Rx receive
scfh standard cubic feet per hour
scfs standard cubic feet per second
sec second(s)
Tx transmit
V Volts
ΩOhms
Warnings
The following general warnings listed below are applicable to this instrument. They are repeated in the text in
the appropriate locations.
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.

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Recycling Policy
Michell Instruments is concerned with the protection of the environment. It is our commitment to reduce
and eliminate from our operations, wherever possible, the use of substances which may be harmful to the
environment. Similarly, we are increasingly using recyclable and/or recycled material in our business and
products wherever it is practical to do so.
The product that you have purchased may contain recyclable and/or recycled parts and we will be happy to
provide you with information on these components if required.
WEEE And RoHS Compliance
The Waste Electronic and Electrical Equipment (WEEE) Directive, and the Restriction of Hazardous Substances
(RoHS) Directive place rules upon European manufacturers of electrical and electronic equipment. The
directive’s aim is to reduce the impact that electronic devices have on the environment.
Michell products are currently exempt from the RoHS directive, however all future products will be developed
entirely using compliant materials. Furthermore, Michell is taking active steps to remove non-compliant
materials and components from existing products wherever possible.
Michell is in full compliance with the WEEE Directive (Registration No. WEE/JB0235YW). Customers may be
required to return certain instruments for treatment at the end of their working life.
June 2010
Calibration Facilities
Michell Instruments’ calibration facilities are among the most sophisticated in the world and have been
recognized for their excellence.
Traceability to the National Physical Laboratory (NPL) UK is achieved through our UKAS Accreditation
(Number 0179). This covers dew point over the range -90 to +90°C (-130 to +194°F) and also Relative
Humidity.
Dew-point calibrations are also traceable to the National Institute for Standards & Technology (NIST) USA over
the range -75 to +20°C (-103 to +68°F).
NOTE: Standard traceable calibration certificates for instruments and sensors are not issued
under our UKAS accreditation. UKAS certificates are usually to special order and are clearly
identified.
Manufacturing Quality
Michell Instruments is registered with the British Standards Institute for Quality Assurance to:
BS EN ISO 9001: 2008
Rigorous procedures are performed at every stage of production to ensure that the materials of construction,
manufacturing, calibration and final test procedures meet the requirements laid down by our BSI approved
Quality System.
Please contact Michell Instruments if the product does not arrive in perfect working order.

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Warranty
Unless otherwise agreed, the Supplier warrants that, as from the date of delivery for a period of 12 months,
the goods and all their component parts, where applicable, are free from any defects in design, workmanship,
construction or materials.
The Supplier warrants that the services undertaken shall be performed using reasonable skill and care, and of
a quality conforming to generally accepted industry standards and practices.
Except as expressly stated all warranties, whether express or implied, by operation of law or otherwise, are
hereby excluded in relation to the goods and services to be provided by the Supplier.
All warranty services are provided on a return to base basis. Any transportation costs for the return of a
warranty claim shall reside with the Customer.
Return Policy
If a Michell Instruments’ product malfunctions within the warranty period, the following procedure must be
completed:
1. Notify a Michell Instruments’ representative, giving full details of the problem,
the model variant and the serial number of the product.
2. If the nature of the problem indicates the need for factory service then the
instrument should be returned to Michell Instruments, carriage prepaid,
preferably in the original packaging, with a full description of the fault
and the customer contact information.
3. Upon receipt, Michell Instruments will evaluate the product to determine the
cause of the malfunction. Then, one of the following courses of action will
be taken:
• If the fault is covered under the terms of the warranty, the
instrument will be repaired at no cost to the owner and returned.
• If Michell Instruments determines that the fault is not covered
under the terms of the warranty, or if the warranty has expired,
an estimate for the cost of the repairs, at standard rates, will be
provided. Upon receipt of the owner’s approval to proceed, the
product will be repaired and returned.

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1 INTRODUCTION
The Pura Online Hygrometer is a continuous, on-line instrument for the measurement of moisture content
in a gas, over the operating range of -120 to -40ºCdp (-184 to -40°Fdp) and equivalent units (see Technical
Specifications, Appendix A). The Pura Hygrometer utilizes the Pura Dew-Point Transmitter as the sensor,
coupled with the Pura Online Monitor as the display unit. Dual alarm relay contacts are provided which are
user-configurable, both in terms of set-point and operating mode. Current output is standard and factory set
at 4-20 mA.
2 DESCRIPTION
The controls and indicators associated with the Pura Hygrometer are located on the front panel of the Process
Indicator.
Connections to the Pura Transmitter, the RS232 communications port and the external power supply are all
made to the rear panel of the Process Indicator (refer to Sections 3 and 4).
Figure 2.1 shows the layout of these controls and Tables 2.1 and 2.2 describe their respective operational
functions.
Pura Online Hygrometer
Figure 2.1 Process Indicator panel layout

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2.1 Display
The instrument has a 4-digit display, set-up on delivery to display a dew-point temperature range of -40ºCdp
(-40ºFdp) (corresponding to a transmitter input of 20 mA), to -120ºCdp (-184ºFdp) (corresponding to a
transmitter input of 4 mA ). Negative temperature readings are signed.
Temperature units are displayed by one of the two LED’s located to the left of the display. On delivery, ºCdp
is set-up. If required, the units can be changed to ºFdp. The method of configuring the unit for ºFdp is
described in Section 3.7.
If the sensor is scaled to output ppmVthen the instrument can be set-up to read dew point in parts per
million (ppmV). This option requires the transmitter to be set-up for ppmVeither at the time of ordering, or
subsequently via Michell application software. Note: No specific ppmVLED indicator is provided on the
Process Indicator; ppmVis selected if neither the ºCdp nor the ºFdp temperature indicators are
illuminated.
Two temperature alarm indications are provided by two LEDs located on the right hand side of the display, AL1
(low) and AL2 (high). Access to the alarm relay contacts is provided on the rear panel. The connection for
these alarm relay contacts is shown in Section 3.4.
The operating temperature at which these alarm outputs operate is set-up as shown in Section 3.6.2.

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Item Description
1
ºFdp
When illuminated, this LED indicates that the displayed dew-point reading is
in degrees Fahrenheit.
Note: If neither the ºFdp or ºCdp LED is lit, ppmVis selected.
2
ºCdp
When illuminated, this LED indicates that the displayed dew-point reading is
in degrees Celsius.
Note: if neither the ºCdp nor ºFdp LED is lit, ppmVis selected.
3
Main dew-point temperature display
Flashes to alternately indicate ‘ErrL’ (error low) and temperature reading
for low temperatures under-range (lower than -120ºCdp (-184ºFdp) or
-129.9ºCdp (199.9ºFdp) for an open loop condition).
Flashes to alternately indicate ‘ErrH’ (error high) and temperature reading
for high temperature over-range.
4
AL1
When illuminated, this LED indicates that the dew-point temperature
programmed for Alarm 1 has exceeded the programmed threshold. Under
these conditions the alarm relay contacts associated with this alarm (normally
open) will change state (close) and will remain closed until the dew-point
temperature moves back within the programmed operational limit.
Alarm 1 is usually allocated to the Low Alarm setting.
These relay contacts are rated at 250 V, 3 A and are connected as shown in
Section 3.4.
Section 3.6.2 describes the setting up of AL1 trip points.
5
AL2
When illuminated this LED indicates that the dew-point temperature
programmed for Alarm 2 has exceeded the programmed threshold. Under
these conditions the alarm relay changeover contacts associated with this
alarm will change state and will remain in this state until the temperature
moves back to within the programmed operational limit.
Alarm 2 is usually allocated to the High Alarm setting.
These changeover relay contacts are rated at 250 V, 5 A and are connected
as shown in Section 3.4.
Section 3.6.2 describes the setting up of AL2 trip points.
Table 2.1 Process Indicator front panel controls and indicators

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2.2 Function Keys
The four function keys, located below the display, are used for setting up the Process Indicator.
The following set-up functions are covered in Section 3 of this Manual:
• Reversal of alarm level switching logic
• Set-up alarm level trip points for AL1 and AL2
• Selection of temperature units
• Selection of re-transmission output current loop range, either 4-20 mA or 0-20 mA
• Set-up/change operating temperature range or ppmVrange
The function key panel is shown in Figure 2.1 . Table 2.2 describes the operation of the keys.
Item Description
P‘P’ (Program) key
This key is used to access the programming menus and to select sub-
menus within the list.
‘’ Left arrow (decrement) key
This key is used to access sub-menus and, within individual sub-menus, to
decrease the numeric value of the selected parameter.
‘’ Right arrow (increment) key
This key is used to access sub-menus and, within individual sub-menus, to
increase the numeric value of the selected parameter.
SET ‘SET’ key
Depending upon the context, this key is used to access the set value of
the selected process field or as an ‘Accept’ key for new parameter values.
Table 2.2 Function keys

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2.3 Process Indicator Menu Structure
Once the Pura Hygrometer is set-up it should not require much adjustment. The dew-point transmitter is
supplied, as standard, with a linear output of 4-20 mA (corresponding to -120ºCdp (-184ºFdp) and -40ºCdp
(-40ºFdp) respectively).
As supplied, the Process Indicator is configured to accept this 4-20 mA input, to indicate the measured dew-
point temperature in ºC and to give over-range indications with a flashing display if the operational limits are
exceeded.
Alarm level set-points are pre-set. The default settings are -20ºCdp for Alarm 1 and -40ºCdp for Alarm 2.
Programming facilities within the Process Indicator permit the changing of some parameters.
These parameters, such as alarm levels, alarm switching logic, temperature units and analog re-transmission
current loop output range are set-up under a menu structure and are accessed by pressing the programming
key ‘P’on the Process Indicator’s control panel.
This Manual describes the functions relating to the
operational requirements of the Pura Hygrometer
equipment and it is not recommended that menu
structures other than those described be entered.
NOTE: If a sub-menu is entered by mistake, quit by pressing the ‘P’ key until the main display is
restored. Never try to quit with the ‘SET’ key.
Section 3 describes the set-up procedures. The flowcharts shown in Section 3 use the symbols from Table 2.3.

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Symbol Description
Display reading / Indication
Outline is shown as solid green if the display is static
Display reading / Indication
Outline is shown as solid red if the display is flashing
Display
Outline is shown as red, dashed, to indicate that the
display is alternately flashing between the two indicated values
PX 6 Indicates the requirement to press the ‘P’ program key. Any
number next to the key indicates the number of times to press
the key, e.g. 6
SET X 6
Indicates the requirement to press the ‘SET’ key. Any number
next to the key indicates the number of times to press the
key, e.g. 6
Indicates the requirement to press the increment ‘’ key.
Indicates the requirement to press the decrement ‘’ key.
Table 2.3 Flowchart symbols
2.3.1 Flowchart Reading Method
Figure 2.2 shows a typical flowchart for setting up the alarm switching levels and shows how to change the
default settings for AL1 from -20ºCdp to -25.5ºCdp and for AL2 from -40ºCdp to -50ºCdp.
This, and all subsequent flowcharts in other sections, should be read from top to bottom, left to right.
Further details on alarm settings are given in Section 3.

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2.3.2 Flowchart Example
SET SET
SET SET
SET
Set x2 for Alarm 2 only
Current
Value
Current
Value
New
Value
New
Value
Main Display
P
P to exit if setting
Alarm 1 only
P to exit
without
setting
Main display
P
P to exit
without
setting
P
The following is a flowchart example showing
the set-up of alarm levels. For actual set-up
instructions see Section 3.6.2.
The alarm set-point levels are set-up from the
program menu as follows:
To set-up both alarm set-points
1. Press the ‘SET’ key once. ‘ALr1’ will be
displayed shown with a green outline to
indicate that the display is static. (To set
Alarm 2, press the ‘SET’ key two times and
follow the Alarm 2 branch instead).
2. Press the ‘’ key to display the current Alarm
1 set-point (-20ºC in this example). This is
shown with a red outline and is flashing.
3. Use the ‘’ and ‘’ keys to set the required
value (-25.5ºC in this example). This is
shown with a red outline and is flashing.
4. To exit to the main display without
saving any new setting, press the ‘P’
key.
5. Press the ‘SET’ key once to store the new (or
existing) value for Alarm 1 and to enter the
set-up menu for Alarm 2. ‘ALr2’ will now
be displayed. This is shown with a green
outline and is static. Press the ‘P’ key to exit
if setting Alarm 1 only.
6. Press the ‘’ key to display the current Alarm
2 set-point (-40ºC in this example). This is
shown with a red outline and is flashing.
7. Use the ‘’ and ‘’ keys to set the required
value (-50ºC in this example) This is shown
with a red outline and is flashing.
8. Press the ‘SET’ key once to store the new
value for Alarm 2. The display will then
return to the main dew-point temperature
display.
Figure 2.2 Flowchart Example

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3 OPERATION
3.1 Operational Requirements
The following operational requirements are required:
3.1.1 Environmental Requirements – Process Indicator
Operating temperature range: 0 to +50ºC (+32 to +122ºF)
Humidity: 90% RH (non-condensing)
Altitude: Up to 2000m
3.1.2 Electrical Requirements
Supply voltage: 100 V to 240 V AC (+10%, -15%), 50/60 Hz, 6 VA
Transmitter supply: 12 V to 28 V DC (25 mA max)*
*Current loop excitation supply, 24 V DC (supplied by the Process Indicator)
3.2 Mounting the Process Indicator
The Process Indicator is designed for panel mounting and requires a panel cut-out of 46 x 92mm (1.8 x 3.6”).
The recommended panel thickness is 2 to 5mm (0.08 to 0.2”).
To mount the unit, proceed as follows (refer to Figure 3.1):
1. Pass the Process Indicator (1) through the front of the panel (2).
2. Support the Process Indicator and insert the hook on the underside of the
clamp (3) into the slot (4) located on top of the Process Indicator casing.
3. Tighten the fixing screw (5) finger tight, against the back of the panel.
4. Insert the hook on the second clamp (6) into the slot located on the underside
of the instrument casing and tighten the fixing screw, finger tight, against the
back of the panel.
5. Ensure that the Process Indicator is sitting flush to the front of the panel (2)
and tighten the fixing screws evenly against the back of the panel.
Caution: Do not overtighten the screws as
this could cause the case to crack.

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Pura Online
Pura Online
1
2
4
3
5
6
Figure 3.1 Mounting the Process Indicator

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3.3 Electrical Connections
Electrical connections to the Pura Hygrometer system are as follows:
• AC power supply, 100 V to 240 V AC (+10%, -15%), 50/60 Hz, 6 VA. A low
voltage (24 V DC) option is also available.
• Transmitter current loop input, 4-20 mA (24 V DC loop power provided by
Process Indicator).
• Alarm 1 (Low), potential free contacts, single pole make. Contacts rated at
250 V, 5 A.
• Alarm 2 (High), potential free contacts, single pole changeover. Contacts rated
at 250 V, 5 A.
• Re-transmitted dew-point input signal 4-20 mA or 0-20 mA.

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3.3.1 AC Power Supply Input
It is essential that the connection of electrical supplies to
this instrument be undertaken by competent personnel
Connect the AC power supply to the Process Indicator (1) as shown in Figure 3.2 . Refer also to Table 3.1 which
gives a summary of all the connections to the rear panel of the Process Indicator.
14 15 16 17 18 19 20 21 22 23
2345678910 11
2
1
4
3
Process Indicator
viewed from underneath
Figure 3.2 AC power supply connections
1. Ensure that no power is connected to the mains lead.
2. Connect the blue (white - US standard) (neutral) lead (2) to terminal 23 on the
rear panel of the Process Indicator.
3. Connect the brown (black - US standard) (live) lead (3) to terminal 24 on the
rear panel of the Process Indicator.
4. Strip back the insulation on the free end of the power cable and wire to an
appropriate power supply plug (brown lead to live supply terminal, blue lead to
neutral supply terminal).
5. Check that the wiring has been completed correctly before connecting to a
mains power supply.