Michell Instruments Pura User manual

Pura
Advanced Online Hygrometer
User Manual
°Cdp
°Fdp
Pura
Advanced Online


Setup
97074 Issue 10
December 2021

Please ll out the form(s) below for each instrument that has been purchased.
Use this information when contacting Michell Instruments for service purposes.
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Order Code
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Installation Location
Tag Number
Product Name
Order Code
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Installation Location
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© 2021 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 Advanced Online Hygrometer
For Michell Instruments' contact information please go to
www.michell.com
°Cdp
°Fdp
Pura
Advanced Online


Setup

Pura Advanced Online Hygrometer User Manual
iv 97074 Issue 10, December 2021
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
1 INTRODUCTION ................................................................................................1
1.1 Features ............................................................................................................ 1
2 INSTALLATION ..................................................................................................2
2.1 Unpacking the Instrument ................................................................................... 2
2.1.1 Unpacking Pura Advanced Online Hygrometer ................................................. 2
2.1.2 Unpacking Pura SEN (transmitter, no block version) ......................................... 3
2.1.3 Unpacking Pura OEM-single bag, PRM-double bag versions .............................. 4
2.1.4 Unpacking Monitor ........................................................................................ 4
2.2 Pura Advanced Online Components ...................................................................... 5
2.3 Pura SEN ........................................................................................................... 6
2.4 Pura OEM, PRM .................................................................................................. 6
2.5 Monitor .............................................................................................................. 7
2.6 Monitor Panel Layout .......................................................................................... 7
2.7 Transmitter Mounting ......................................................................................... 8
2.7.1 Sensor Block Connection (Recommended Method) .......................................... 8
2.7.2 Direct Pipeline Connection ............................................................................. 9
2.7.3 Pura OEM & PRM Connection ....................................................................... 10
2.8 Sensor Cables .................................................................................................. 11
2.8.1 Self-Assembly ............................................................................................. 11
2.8.2 Cable Selection for Self-Assembled Cables ..................................................... 11
2.8.3 Wiring Connection Between the Transmitter and the Monitor .......................... 12
2.9 Mounting the Monitor ....................................................................................... 13
2.10 Electrical Connections ....................................................................................... 14
2.10.1 High Voltage Power Supply Input ................................................................. 14
2.10.2 Low Voltage Power Supply Input (Optional) .................................................. 15
2.11 Pressure Transducer Connection (Optional) ........................................................ 15
2.12 Transmitter Connections .................................................................................... 16
3 OPERATION ....................................................................................................17
3.1 Set-Up Security Feature .................................................................................... 17
3.1.1 Selecting the Engineering Units .................................................................... 18
3.1.2 Conguring the Alarms ............................................................................... 18
3.1.3 Hysteresis, Make/Break Delay & Delay Type .................................................. 19
3.1.4 Analog Output Scaling ................................................................................ 20
3.1.5 Display Brightness Adjustment ..................................................................... 20
3.2 Pressure Compensation ..................................................................................... 21
3.3 Using a Pressure Transducer ............................................................................. 21
3.3.1 Manual Pressure Input Calibration ................................................................ 21
3.3.2 Automatic Pressure Input Calibration ............................................................ 22
3.4 Using a Fixed Pressure Input in Single Channel Mode .......................................... 22

Pura Advanced Online Hygrometer User Manual
Michell Instruments v
Figures
Figure 1 Unpacking – Monitor and Pura SEN, no block version ....................................2
Figure 2 Unpacking – Monitor and Pura OEM / PRM ...................................................3
Figure 3 Unpacking – Pura OEM & PRM – Single / Double Bag ....................................4
Figure 4 Unpacking – Monitor ...................................................................................4
Figure 5 Components ...............................................................................................5
Figure 6 Pura SEN ...................................................................................................6
Figure 7 Pura OEM, PRM ..........................................................................................6
Figure 8 Control Layout and Functions ......................................................................7
Figure 9 Sensor Block Connection .............................................................................8
Figure 10 Connector Terminal Block Removal ............................................................11
Figure 11 Cable Assembly ........................................................................................11
Figure 12 Cable Connections ....................................................................................12
Figure 13 Connector Installation ...............................................................................12
Figure 14 Mounting the Monitor ...............................................................................13
Figure 15 High Voltage Power Supply Connections .....................................................14
Figure 16 Low Voltage Power Supply Connections ......................................................15
Figure 17 Electrical Connection Detail .......................................................................15
Figure 18 Transmitter Connections............................................................................16
Figure 19 Location of the Lockout switches ...............................................................17
Figure 20 Installation Location .................................................................................25
Figure 21 Installation Location .................................................................................25
Figure 22 Material Permeability Comparison ..............................................................27
Figure 23 Dead volume ............................................................................................28
Figure 24 Pura SEN .................................................................................................32
Figure 26 Monitor Dimensions ..................................................................................32
Figure 25 Pura PRM & OEM ......................................................................................32
Appendices
Appendix A Technical Specications .............................................................................. 31
Appendix B Setup Codes .............................................................................................34
Appendix C Quality, Recycling & Warranty Information ................................................... 37
Appendix D Return Document & Decontamination Declaration ........................................ 39
Tables
Table 1 Cable Connections ..................................................................................... 12
Table 2 Operation Access Levels ............................................................................. 17
Table 3 Engineering Unit Selection .........................................................................18
4 MAINTENANCE ................................................................................................23
4.1 Maintenance and Calibration ............................................................................ 23
4.2 Fault Conditions ............................................................................................... 23
5 MEASUREMENT GUIDE ....................................................................................24
5.1 Sampling Considerations ................................................................................... 24
5.2 Sampling Hints ................................................................................................. 27

Pura Advanced Online Hygrometer User Manual
vi 97074 Issue 10, December 2021
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 specied 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. For
contact information visit the website at www.michell.com
Calibration
Periodic re-calibration is recommended in order to maintain the highest quality of measurement in
your application. Michell Instruments recommends that you have your Pura transmitter re-calibrated
annually unless it is used in a mission-critical application or in a contaminated environment, in which
case the calibration interval should be reduced accordingly.
Michell Instruments can oer a variety of re-calibration and exchange transmitter schemes to suit
your specic needs. A local representative will be pleased to provide detailed, custom advice.
Safety Conformity
This product meets the essential protection requirements of the relevant EU & UKCA directives.
Further details of applied standards may be found in Appendix C.

Pura Advanced Online Hygrometer User Manual
Michell Instruments vii
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
dp dew point
ft foot (feet)
g gram(s)
Hz Hertz
“ inch(es)
lb pound
l/min liters per minute
m meter(s)
µm micro-meter
mA milliampere
max maximum
min minute(s)
MPa megapascal (Pascals x106)
Nl/min normal liters per minute
Nm Newton meter
ppmV parts per million (by volume)
rh relative humidity
scfh standard cubic feet per hour
V Volts
Ω Ohms
Warnings
The following general warning is applicable to this instrument. It is 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.
Where this symbol appears in the following sections it is
used to indicate areas of potential risk of electric shock.

Pura Advanced Online Hygrometer User Manual
viii 97074 Issue 10, December 2021

Pura Advanced Online Hygrometer User Manual
Michell Instruments 1
INTRODUCTION
1 INTRODUCTION
The Pura Advanced Online Hygrometer is an instrument designed for the continuous
online measurement of moisture content in non-corrosive gases, over an operational
range of -120 °C...-40 °C (-184 °F...-40 °F) dew point and equivalent units (see Appendix
A, Technical Specications).
The system comprises a programmable monitor congured to accept a unique Michell
Mnet data string from the Pura transmitter. The zero and span of the monitor are
set to cover the dew-point range -120 °C...-40 °Cdp (-184 °F...-40 °Fdp) at operating
pressures up to 24 MPa (240 barg/3480 psig).
Two alarm outputs are provided for connection to external systems which are user-
congurable both in terms of setpoint and operating mode. Current output is standard
and factory set at 4...20 mA (or optionally set at 0...20 mA or 0...10 V).
The monitor has a pressure input channel for any industry standard 2-wire pressure
transmitter. In addition to providing a pressure measurement, the pressure signal can
be used to provide real-time pressure compensation on the primary channel when
displaying ppm values. The customer can also set a xed pressure compensation value.
The pressure input only aects the ppmV or ppbV units. For dew point, the displayed
value is a pressure dew point.
1.1 Features
The Pura Advanced Online Hygrometer is simple to use and install, and can be congured
to meet specic needs.
• ¼” male VCR process connections for PRM and OEM version
½” male VCR process connection for Pura SEN version
• Dew-point, ppmV or ppbV moisture content
• Michell Mnet – sensor digital string signal
• Sensor block compliant with clean room standards
• Measurement range -120 °C...-40 °Cdp (-184 °F...-40 °Fdp)
• Up to ±1 °Cdp accuracy
• Calibration certicate (NPL, NIST)

Pura Advanced Online Hygrometer User Manual
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INSTALLATION
2 INSTALLATION
!
It is essential that the connection of electrical and gas supplies
to this instrument be undertaken by competent personnel.
2.1 Unpacking the Instrument
2.1.1 Unpacking Pura Advanced Online Hygrometer
The Pura Advanced Hygrometer instrument and accessories are packed in a box and the
method of unpacking is shown as follows:
Figure 1 Unpacking – Monitor and Pura SEN, no block version

Pura Advanced Online Hygrometer User Manual
Michell Instruments 3
INSTALLATION
Figure 2 Unpacking – Monitor and Pura OEM / PRM
2.1.2 Unpacking Pura SEN (transmitter, no block version)
Unpack the dew-point transmitter from the rectangular cardboard box.
NOTE: The transmitter sensing element is protected while in transit by a red
cover containing a small desiccant capsule. This plastic item is not required
for the operation of the transmitter.
NOTE: Keep the electrical connector in a safe place until the transmitter is
ready for wiring.

Pura Advanced Online Hygrometer User Manual
497074 Issue 10, December 2021
INSTALLATION
2.1.3 Unpacking Pura OEM-single bag, PRM-double bag versions
Figure 3 Unpacking – Pura OEM & PRM – Single / Double Bag
2.1.4 Unpacking Monitor
The monitor (2) is packed, together with its xing clamps (1) as shown below.
1
°Cdp
°Fdp
Pura
Advanced Online


Setup
2
Figure 4 Unpacking – Monitor

Pura Advanced Online Hygrometer User Manual
Michell Instruments 5
INSTALLATION
2.2 Pura Advanced Online Components
On delivery, please check that all the following standard components are present in the
packing box. Report any shortages immediately.
2
3
1
4
5
7
°Cdp
°Fdp
Pura
Advanced Online


Setup
6
Figure 5 Components
1. PURA Monitor
2. Clamps
3. Sensor cable assembly
4. Pura Transmitter (SEN) OR
Pura Transmitter (OEM) or (PRM)
Leak test certicate included
5. Screwdriver
6. Power cable
7. Calibration certicate

Pura Advanced Online Hygrometer User Manual
697074 Issue 10, December 2021
INSTALLATION
2.3 Pura SEN
NOTE: For environmental and operating conditions, refer to Appendix A,
Technical Specications.
Electrical connector
Transmitter cover
Transmitter label
Hexagonal nut
Process connection
Sensing element
Figure 6 Pura SEN
2.4 Pura OEM, PRM
NOTE: For environmental and operating conditions, refer to Appendix A,
Technical Specications.
NOTE: OEM and PRM version transmitters are protected in transit by putting
in a plastic bag lled with nitrogen. Pura OEM transmitter has single bag
protection, Pura PRM transmitter has double bag protection.
Electrical connector
Transmitter cover
Transmitter label
Sensor block
Gas inlet
(see note below) Gas outlet
NOTE: The Pura has a uni-directional connection and must be
connected so the upstream ow is connected to the inlet port
of the Pura block (marked with a silver label).
INLET
Figure 7 Pura OEM, PRM

Pura Advanced Online Hygrometer User Manual
Michell Instruments 7
INSTALLATION
2.5 Monitor
The instrument has a 5-digit display, set up on delivery to display a dew-point temperature
range of -120 °C...-40 °Cdp (-40 °F...-184 °Fdp).
Dew-point temperature units are displayed by the last LED located to the far right of
the display. On delivery, °Cdp is set up. If required, the units can be changed to °F. The
method of conguring the unit for °F is described in Section 3.1.1.
Optionally, the instrument can be set up for parts per million ppmV or parts per billion
ppbV. This option requires the hygrometer to be set up for ppmV or ppbV (see Section
3.1.1).
Four alarm indications are provided by four LEDs located on the bottom of the display.
These are marked SP1, SP2, SP3, SP4. Access to the alarm relay contacts is provided
on the rear panel. The connection for these alarm relay contacts is shown in Figure 18 .
NOTE: Every display is factory tted with 2 alarm relays as standard.
Refer to Section 3, Operation, for information on how to congure the alarms.
2.6 Monitor Panel Layout
Pura
Advanced Online


Setup
1
2
3
4


 
Item Function
1Increases the value of the displayed parameter; navigates through each
displayed parameter
2Decreases the value of the displayed parameter; navigates through each
displayed parameter
3LED annunciations for Alarm Setpoints 1...4
4Saves programming settings, moves between programming steps
Figure 8 Control Layout and Functions

Pura Advanced Online Hygrometer User Manual
897074 Issue 10, December 2021
INSTALLATION
2.7 Transmitter Mounting
2.7.1 Sensor Block Connection (Recommended Method)
!
The following procedure must be carried out by a qualied
installation engineer.
!
WARNING: Under no circumstances should the sensing element
be handled with the ngers.
To mount the transmitter into the sensor block, proceed as follows – refer to Figure 9.
1. Remove the red protective cover (2) from the tip of the transmitter
(1).
2. Fit the 1/2” VCR gasket (3) over the threaded part of the transmitter
body.
3. Screw the transmitter (1) into the sensor block (4) and tighten the
gas line nut 1/8 (one eighth) of a turn using a second spanner/
wrench. NOTE: Use the ats of the hexagonal nut and not
the sensor body.
4. Fit the transmitter cable/connector assembly to the plug located
on the base of the transmitter and tighten the xing screw (see
Figure 13).
Figure 9 Sensor Block Connection

Pura Advanced Online Hygrometer User Manual
Michell Instruments 9
INSTALLATION
2.7.2 Direct Pipeline Connection
The transmitter may be directly mounted into a pipe or duct .
!
CAUTION: Do not mount the transmitter too close to the
bottom of a bend where any condensate in the pipeline might
collect and saturate the probe.
The pipe or duct will require a 1/2” VCR male process connection thread to match the
transmitter body thread. For circular pipework, to ensure the integrity of a gas tight
seal, a mounting ange will be required on the pipework in order to provide a at
surface to seal against.
Procedure
!
The following procedure must be carried out by competent
personnel.
!
WARNING: Under no circumstances should the lter guard be
handled with the ngers.
1. Ensure that the red protective cover has been removed from the
tip of the transmitter.
2. After rst checking that the pipeline has a wide enough bore to
accept the transmitter’s process connection screw the transmitter
into the pipe. Tighten enough to obtain a gas tight seal. (Torque
will depend upon the pipeline material.)
Michell Instruments recommends the use of Swagelok® retained gasket assemblies,
containing silver plated, stainless steel 1/2” VCR gaskets, when connecting the Pura
into a gas line.
NOTE: Do not overtighten or the thread on the pipework may be stripped.

Pura Advanced Online Hygrometer User Manual
10 97074 Issue 10, December 2021
INSTALLATION
2.7.3 Pura OEM & PRM Connection
The Pura OEM and PRM have been assembled and packaged within a Class 100 clean-
room environment. To maintain this level of cleanliness the packaging should only be
unpackaged within the same, or cleaner, environment.
Michell Instruments recommends the use of Swagelok® retained gasket assemblies,
containing silver plated, stainless steel ¼” VCR gaskets, when connecting the Pura into
a gas line. The distance between the inlet and outlet gas connection ports is set at a
pitch of 120 mm (4.7”).
!
CAUTION: Over tightening the nuts can cause irrecoverable
damage to the seals and seatings.
1. Install the sealing gasket onto the VCR connections on either the
Pura or the connecting gas lines. Ensure that the Pura is installed
into the gas line with reference to the gas ow direction and the
inlet port, as indicated on the Pura body.
2. Tighten the female nut rmly, nger tight.
3. Hold the Pura transmitter stationary with a spanner/wrench and
tighten the gas line nut 1/8 of a turn using a second spanner/
wrench.
4. Repeat this operation on the remaining gas connection port.

Pura Advanced Online Hygrometer User Manual
Michell Instruments 11
INSTALLATION
2.8 Sensor Cables
2.8.1 Self-Assembly
For guidance on type of cable, refer to Section 2.8.2, Cable Selection for Self-Assembled
Cables.
Assembly Instructions
1. Remove the screw from the rear of the DIN connector housing.
2. Lever the terminal block from the connector housing by inserting a small
screwdriver in the notch on the front face of the terminal block.
3. Ensure the small sealing O-ring and washer and retained with the screw.

O-ring
and washer
Figure 10 Connector Terminal Block Removal
4. Cable should be assembled according to Figure 11 .
Figure 11 Cable Assembly
2.8.2 Cable Selection for Self-Assembled Cables
It is recommended to use 3-core screened cable. For short runs, a cable with individual
conductor sizes of 24 AWG / 0.21 mm2 would be a typical choice.

Pura Advanced Online Hygrometer User Manual
12 97074 Issue 10, December 2021
INSTALLATION
2.8.3 Wiring Connection Between the Transmitter and the Monitor
The diagram below shows the identity of the connector terminals.
YELLOW
GREEN
BLUE
RED
PIN 3
PIN 2
RED
+Power YELLOW
Signal (A)
GREEN
Signal (B)
PIN 1
BLUE
Ground 1
2
3
4YELLOW Signal (A)
BLUE Ground
GREEN Signal (B)
RED +Power
Figure 12 Cable Connections
The sensor cable connections are shown in the table below and in the gure above.
Connection Red wire Blue wire Green wire Yellow wire
Monitor Pin 1 Pin 2 Pin 3 Pin 4
Transmitter Pin 3 GND Pin 1 Pin 2
Table 1 Cable Connections
When installing the connector, and to ensure that full ingress protection is achieved, the
securing screw (with the O-ring and washer) must be tightened to a minimum torque
setting of 3.4 Nm (2.5 ft-lbs). The sensor cable used must be a minimum diameter of
4.6 mm (0.2”).
4
8
L
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c
a
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B
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:
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+
2
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4
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6
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N
O-ring
and washer

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m
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r
R
a
n
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e
:
-
1
0
0
/
+
2
0
SEN Version
OEM & PRM Versions
Figure 13 Connector Installation