HygroSmart I7000XP
Interchangeable Sensor for RH
& Temperature
User’s Manual
97481 Issue 1
January 2015
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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© 2015 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.
HygroSmart I7000XP
Interchangeable Sensor
For Michell Instruments' contact information please go to
www.michell.com
HygroSmart I7000XP User’s Manual
Contents
Safety ................................................................................................................................ v
Electrical Safety
Toxic Materials ............................................................................................................. v
Repair and Maintenance ............................................................................................... v
Calibration ................................................................................................................... v
Safety Conformity ........................................................................................................ v
Abbreviations ......................................................................................................................vi
Warnings ............................................................................................................................vi
1 INTRODUCTION ................................................................................................1
2 INSTALLATION ..................................................................................................2
2.1 Unpacking the Instrument ................................................................................... 2
2.2 Choice of the Site of Installation .......................................................................... 2
2.3 Connections ....................................................................................................... 3
2.3.1 Electrical Connections .................................................................................... 3
2.3.2 Power Supply ................................................................................................ 3
3 MAINTENANCE ..................................................................................................4
3.1 Replacing the HygroSmart I7000XP Interchangeable Sensor .................................. 4
3.2 Recalibration Service ........................................................................................... 4
........................................................................................................... v
Figures
Figure 1 Operating Graph .........................................................................................2
Figure 2 Electrical Connections .................................................................................3
Figure 3 HygroSmart I7000XP Sensor Pin Connector ..................................................4
Figure 4 Hygrosmart I7000XP Operating Conditions ...................................................7
Figure 5 Hygrosmart I7000XP Dimensions .................................................................7
Appendices
Appendix A Technical Specications ...............................................................................6
A.1 Operating Conditions .....................................................................7
A.2 Dimensions ...................................................................................7
Appendix B Quality, Recycling & Warranty Information .....................................................9
B.1 Pressure Equipment Directive (PED) 97/23/EC .................................9
B.2 Recycling Policy ............................................................................9
B.3 WEEE Compliance ..........................................................................9
B.4 RoHS2 Compliance ......................................................................10
B.5 Warranty .....................................................................................10
B.6 REACH Compliance ...................................................................... 11
B.7 Calibration Facilities ..................................................................... 11
B.8 Return Policy ............................................................................... 12
B.9 Manufacturing Quality .................................................................. 12
Appendix C Recommended Practices in Humidity Measurements.....................................14
Appendix D Return Document & Decontamination Declaration ........................................ 19
iv 97481 Issue 1, January 2015
HygroSmart I7000XP User’s Manual
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.
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
Michell Instruments’ contact information please go to www.michell.com.
Calibration
Refer to details in Section 3.2 regarding recalibration of the HygroSmart 17000XP interchangeable
sensor.
Safety Conformity
This product meets the essential protection requirements of the relevant EU standards and directives.
Michell Instruments v
HygroSmart I7000XP User’s Manual
Abbreviations
The following abbreviations are used in this manual:
A ampere
°C degrees Celsius
°F degrees Fahrenheit
mA milliampere
mm millimeter
m/sec meters per second
RH relative humidity
s second
T temperature
V volt
Warnings
The following general warning listed below 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.
vi 97481 Issue 1, January 2015
HygroSmart I7000XP User’s Manual
INTRODUCTION
1 INTRODUCTION
The HygroSmart I7000XP sensor is designed to accurately and reliably measure
relative humidity and temperature in a wide spectrum of industrial and heavy industrial
applications.
The sensor incorporates the latest HygroSmart 3 technology, providing excellent
performance across a wide customer measurement range and giving rapid eld
interchangeability to minimize customer maintenance costs, on all Michell HygroSmart
based probes and transmitters.
Michell Instruments 1
HygroSmart I7000XP User’s Manual
INSTALLATION
2 INSTALLATION
2.1 Unpacking the Instrument
2.2 Choice of the Site of Installation
On delivery please check that all the following components are present in the packing
box:
• HygroSmart I7000XP interchangeable sensor
• Certicate of calibration
• User’s manual
The installation site choice for the sensor, or the transmitter which incorporates the
sensor, must be made bearing in mind the effectiveness of air circulation. The point at
which the sensor is installed must be typical of the surrounding environment where the
measurements of relative humidity are to be taken.
The following should be avoided in keeping with good instrumentation practice:
• Installation location not representative of measuring conditions
• Installation location adjacent to high power sources
The operating envelope of the measurement probe is detailed in the following operating
graph:
RH%
100
75
50
25
Maximum mixing ratio
250g water/kg dry air
-40 0 5025 70 85
Figure 1
2 97481 Issue 1, January 2015
Temp °C
Operating Graph
HygroSmart I7000XP User’s Manual
INSTALLATION
2.3 Connections
2.3.1 Electrical Connections
HygroSmart I7000XP
Pin
1 Not Connected
2 Power Supply 3 Power Supply +ve
4 Output Voltage RH
5 Output Temperature PT100
6 Output Temperature PT100
7 Output Temperature PT100
PT100
5
6 7
1 2 3 4
2.3.2 Power Supply
The power supply required to power the system is:
• 5 V DC ± 0.1 V
Figure 2
Electrical Connections
Michell Instruments 3
HygroSmart I7000XP User’s Manual
MAINTENANCE
3 MAINTENANCE
3.1 Replacing the HygroSmart I7000XP Interchangeable Sensor
Figure 3
The following steps should be taken to carry out the replacement of the HygroSmart
I7000XP sensor:
1. Switch off the power supply to the transmitter.
2. Unscrew the protection lter mounted on the measurement probe body.
NOTE: Be careful not to apply any force to the lter protection
cage.
3. Taking care not to bend the male pins on the sensor electrical connector,
remove the HygroSmart I7000XP to be replaced and insert the new
component.
3.2 Recalibration Service
HygroSmart I7000XP Sensor Pin Connector
The HygroSmart I7000XP interchangeable sensor can be returned to any Michell Service
Center (see www.michell.com for details) for recalibration. Alternatively, an optical
advanced RH & temperature calibration system can be provided for on-site recalibration.
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APPENDIX A
Appendix A
Technical Specications
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HygroSmart I7000XP User’s Manual
APPENDIX A
Appendix A Technical Specications
Performance Specications
RH Measurement Range 0 to 100% RH
RH Accuracy at 23°C (73°F) ±1% RH (5 to 95% RH)
RH Resolution 0.1% RH
RH Measurement Response Time <10 seconds
RH Element & Hybrid Technology HygroSmart 3
RH Long Term Stability ±1% RH per year
Temperature Technology PT100 1/3 DIN
Temperature Measurement Range -40 to +85°C (-40 to +185°F)
Temperature Accuracy ±0.2°C
Temperature Resolution Innite
Electrical Specications
Output Signal
Temperature Output Signal
Digital Output Signal I
Supply Voltage Range +5 V DC ±1 V
Power Consumption 300uA @ 5 V
White housing: 0-1 V
Black housing: 0.2-1 V
Standard: 3-wire PT100
Optional: no output
2
C interface
Operating Specications
Operating Temperature -40 to +85°C (-40 to +185°F)
Storage Temperature -40 to +85°C (-40 to +185°F)
Mechanical Specications
Housing Material NORYL PPO UL94 V0
Dimensions L=33mm, ø14mm (L=1.3”, ø0.5”)
Weight 3g (0.1oz)
Electrical Connections 7 pins
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APPENDIX A
A.1 Operating Conditions
RH%
100
75
A.2 Dimensions
50
Maximum mixing ratio
250g water/kg dry air
25
-40 0 5025 70 85
Figure 4
Hygrosmart I7000XP Operating Conditions
Temp °C
(0.69”)
17.5mm
Figure 5
Michell Instruments 7
(1.30”)
33mm
12mm
(0.47”)
14mm
(0.55”)
Hygrosmart I7000XP Dimensions
HygroSmart I7000XP User’s Manual
APPENDIX B
Appendix B
Quality, Recycling
& Warranty
Information
8 97481 Issue 1, January 2015
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APPENDIX B
Appendix B Quality, Recycling & Warranty Information
B.1 Pressure Equipment Directive (PED) 97/23/EC
The above Directive has been implemented in United Kingdom Law by the Pressure Equipment
Regulations 1999.
The Regulations require that all pressure equipment and assemblies within the scope of the Pressure
Equipment Directive must be safe when placed on the market or put into service.
Michell Instruments’ products have been assessed and, as referenced against the Classication Charts
detailed in Annex II of the Directive, do not fall into the requirements for CE marking compliance
with the Pressure Equipment Directive.
Article 3, paragraph 3 states that any product containing a pressurized uid that does not qualify for
compliance should, nevertheless, be constructed with Sound Engineering Practice (SEP).
Michell Instruments attests here that its products have been designed, manufactured & tested to
assure safe operation, and in accordance with Sound Engineering Practices.
B.2 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.
To protect natural resources and to promote material reuse, please separate batteries from other
types of waste and recycle responsibly. If batteries are not properly disposed of, these substances
can cause harm to human health and the environment.
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. For further information
please see the following sections.
B.3 WEEE Compliance
Directive 2012/19/EU 4 July 2012 on Waste Electronic and Electrical Equipment (WEEE)
The Waste Electronic and Electrical Equipment (WEEE) Directive places rules upon European
manufacturers of electrical and electronic equipment. The directives’ aim is to reduce the impact
that electronic devices have on the environment.
Michell Instruments is in full compliance with the WEEE Directive and is registered with an approved
recycler (Registration No. WEE/JB0235YW) and treats the requirement of the directive and the
protection of the environment with the utmost importance. All Michell Instruments’ products are
appropriately marked indicating their requirement for recycling.
It may be required to return certain instruments for treatment at the end of their working life.
Feb 2013
Michell Instruments 9
HygroSmart I7000XP User’s Manual
APPENDIX B
B.4 RoHS2 Compliance
Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011
The Restriction of Hazardous Substances (RoHS) Directive places rules upon European manufacturers
of electrical and electronic equipment. The directives’ aim is to reduce the impact that electronic
devices have on the environment.
According to the EC Directive 2002/95/EC, Michell Instruments’ products qualify as Category 9,
Control and Monitoring Equipment. Under the 2002/95/EC Directive, Category 9 products are exempt
from compliance with the Directive.
However, the careful design of all Michell Instruments’ products takes into consideration the
requirements of the Directive and, wherever possible, compliance is achieved. All future products
will be developed entirely using compliant materials. Furthermore, Michell Instruments is taking
active steps to remove non-compliant materials and components from existing products wherever
these may occur. Presently, none of the non-compliant materials are known to occur in Michell
Instruments’ products.
The new Directive 2011/65/EU (RoHS2) entered into force on 21 July 2011 and required all Member
States to transpose the provisions into their respective national laws by 2 January 2013.
Under the provisions of the RoHS2 EU Directive 2011/65/EU (Article 3, [24]) denes ‘Control and
Monitoring Equipment’ specically as ‘monitoring and control instruments designed exclusively for
industrial or professional use’.
RoHS2 EU Directive 2011/65/EU states the closing date for compliance of any Control and Monitoring
Equipment product sold into the EU market place as 22nd July 2017.
However, the careful design policy of all Michell Instruments’ products continues to attain compliance
in the shortest practical timescales and strives to ensure that less than 0.1% of total mass per
product, of all non-compliant materials, appear within them. Michell Instruments continues to
monitor suppliers and material sources to ensure that compliance of goods provided is maintained.
January 2013
B.5 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 be 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.
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APPENDIX B
B.6 REACH Compliance
Regulation (EC) No. 1907/2006
Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)
Michell Instruments is a manufacturer of moisture measurement and gas analysis instrumentation
and is a ‘downstream’ user of chemicals, as described by the EU Council Directive 76/769/EEC. The
products we supply are not raw chemical products (goods).
Under normal and reasonably foreseeable circumstances of application, the goods supplied to you
shall not contain or release any prohibited chemicals. No listed SVHC (Substances of Very High
Concern) appear within products manufactured by Michell Instruments. Therefore the 0.1% mass
per product, or total usage of 1 tonne/year, will never be exceeded. For these reasons we are neither
required by obligation for registration nor for the creation of material safety data sheets (MSDS) for
our products.
Our continued review of the SVHC Candidate List and latest additions is to ensure we remain
compliant.
Michell Instruments maintains a hazardous material register in which MSDS data sheets are collated,
and we will check that our suppliers will comply to REACH requirements for all materials and
substances we use in the processes of our manufacturing.
In the unlikely event that any chemicals of concern appear in our products in quantities greater than
0.1% of total mass per product we will immediately inform you by correspondence according to the
REACH Article 33 requirements. Our current appraisal is, however, that we do not expect or foresee
such an incidence.
January 2013
B.7 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 certicates for instruments and sensors are not
issued under our UKAS accreditation. UKAS certicates are usually to special order and
are clearly identied.
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HygroSmart I7000XP User’s Manual
APPENDIX B
B.8 Return Policy
If a Michell Instruments’ product malfunctions within the warranty period, the following procedure
must be completed:
1. Notify a Michell Instruments’ distributor, 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.
B.9 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 nal test procedures meet the requirements laid down
by our BSI approved Quality System.
Please contact Michell Instruments (www.michell.com) if the product does not arrive in perfect
working order.
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APPENDIX C
Appendix C
Recommended Practices
in Humidity Measurements
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HygroSmart I7000XP User’s Manual
APPENDIX C
Appendix C Recommended Practices in Humidity Measurements
The following text is reproduced with kind permission from the National Physical Laboratory. It is originally published in
the booklet,
Denition of Relative Humidity
Relative Humidity – The ratio of the actual vapor pressure to the saturation vapor pressure over a plane
liquid water surface at the same temperature, expressed as a percentage. This is commonly understood when
the term ‘X percent relative humidity’ is used.
A Guide to the Measurement of Humidity.
For actual vapor pressure, e, and saturation vapor pressure, e
e
s
relative humidity (in %) = ––– x 100
e
s
USAGE: The phrase ‘relative humidity’ is commonly abbreviated RH although this is not a recognized
abbreviation. Values of relative humidity are commonly expressed in units of percent relative humidity (% RH).
Recommended practices in humidity measurements
General practical recommendations
• Where relative humidity is of interest, a direct measurement of relative humidity is usually
best. Where an absolute measure of humidity is needed, choose dew point, vapor pressure
or similar measurements.
• Establish the measurement requirements at the purchasing stage in order to have the
right instrument for the job.
• Allow hygrometers to equilibrate in any new environment. This is particularly necessary
after changes in temperature due to transportation or storage. Depending on the instrument
and on how great the change in conditions, this may require from only a few minutes to
many hours.
• Follow Michell Instruments’ care instructions for the instrument. Some instruments need
routine cleaning or other maintenance. Before using any solvent cleaner, check with Michell
Instruments that this will not harm the sensor or other materials of construction.
• Wherever possible, ensure that hygrometers are calibrated under the conditions of use,
i.e. at similar values of humidity and temperature, and (if relevant) in similar conditions of
pressure, airow, etc.
• Keep a record of calibrations and any adjustments to the hygrometer. This will show the
long-term stability of the instrument and allow the associated uncertainty to be assessed.
• Check instruments, if possible, at intervals between calibrations, by comparison with
another (stable) instrument, to monitor for long-term drift. Routine checks are also useful
before and after subjecting an instrument to transportation or other stress, which might
lead to a shift in its performance. Where the check is against two (or more) instruments
this is even better: not only does this add condence, but in the event of one instrument
drifting among a set of three, it can be seen which reading is most suspect.
• Cleanliness of the environment will affect different hygrometers in different ways. Dust
and airborne droplets should be avoided or ltered out if possible. Contaminants can come
from the most surprising sources, ordinary urban pollution, for example.
• The readings given by some types of hygrometer are sensitive to gas type. For any
Instrument which reads in terms of mass per unit volume, e.g. in grams per cubic metre,
it must be conrmed whether the calibration is valid for the gas in use.
• Avoid using instruments in direct sunlight or near any other source of heat, unless they
are suitably shielded to prevent measurement errors.
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APPENDIX C
Sampling in general
• Relative humidity measurements should be carried out at a representative temperature.
Failure to allow temperature equilibration will lead to a false indication of the relative
humidity.
• Variations in vapor pressure from place to place can occur where an environment is subject
to any addition or removal of water. If so, care must be taken over where to make a
measurement in order to obtain a representative result.
• Sources and sinks of water vapor should be avoided in any sampling system. Invasion of
stray water can be minimised by attention to leaks, hygroscopic materials, droplets and
condensation. The lower the humidity, the more critical these precautions are.
• Hygroscopic materials should be avoided. Many materials contain moisture as part of their
structure, particularly organic materials (whether natural or synthetic), salts (or anything
which contains them), and anything which has small pores. Temperature changes can
increase the tendency of these materials to affect the humidity of the surrounding air.
• Condensation in a sampling process can invalidate humidity measurements by reducing
the water content of the gas being measured. What is more, condensed liquid may alter
the humidity elsewhere by dripping or running to other locations and evaporating there.
In these circumstances, measurement results may be misleading if hygrometer location is
not considered carefully.
• Water droplets or mist must be avoided. These can result in overestimates of the humidity
of the air between the droplets. Such results may exceed 100% RH, or may be impossible
to interpret meaningfully. Droplets of liquid also damage some electrical types of humidity
sensor. Filtering the air sample can eliminate droplets.
• If pumps are used for sampling gas, these should be located after the hygrometer, to avoid
contaminating the measurement environment. Where possible, oil free pumps should be
used, or lters employed. Oscillations in pressure due to pumping can sometimes be
reduced or buffered using a needle valve or a reservoir of large volume.
• Special treatments such as ltration can change the amount of moisture in a gas. Some
drying agents take out other gases, too.
• When sealing any sensor or probe into a port or manifold in a duct or chamber, leaks
through the probe or electrical cable should be considered. These are not always sealed
against passage of ambient air.
• Where sampling involves a step change in temperature, pressure or gas ow rate, relative
to the process being sampled, results may need to be converted or interpreted. For
example ‘pressure dew point’ will differ from the value found after expanding the gas
sample to atmospheric pressure. Care should be taken to distinguish between ‘gauge’ and
absolute values of pressure.
Dew point in general
• The measuring environment and all parts of the sampling pathway must be kept above
the dew point if condensation is to be avoided. Electrical trace heating or other heating
methods should be used if necessary. An excess temperature of 10°C above the dew point
is usually a safe margin.
• For measurements in the region below 0°C it must be clear whether the condensate is dew
or frost. Failure to distinguish between these can result in errors of about 1°C for every
10°C below zero.
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HygroSmart I7000XP User’s Manual
APPENDIX C
Relative humidity in general
Recommendations specic to ranges of measurements
• Due care must be taken of temperature. The effect of temperature on humidity is highly
signicant. Failure to take this into account can sometimes lead to errors so large that the
measurement is meaningless. In many situations, the largest single source of uncertainty
in a humidity measurement is the effect of temperature differences from place to place
in the process, room or chamber. The importance of considering the temperature effects
carefully cannot be overstated when relative humidity is the parameter of interest.
• Care must be taken when expressing uncertainties, changes or fractional differences in
relative humidity. For example, the difference between 50% RH and 52% RH is 2% RH.
This can also be expressed as a difference of 4% of value. It is important to distinguish
clearly between these two kinds of statement.
• Ambient humidity - Avoid using hygrometers near the body, which is a source of heat and
moisture. Do not breathe close to the measurement.
• High humidity, above the ambient range - Sample lines should be maintained above the
dew point of the gas being measured, to avoid condensation. Electrical trace heating is
often the most practical method.
• Low humidity, and very dry gases - If possible, prepare for measurements by ushing
sample lines and hygrometers with dry gas, or by evacuating to low pressure. Drive
off stray residual water by baking assemblies if possible (but not instruments – unless
designed for this!). The lower the moisture content to be measured, the more dramatically
the required drying time multiplies.
• Avoid hygroscopic materials. At low humidity (anything much below a dew point of 0°C)
the amounts of water given off by organic and porous materials can dramatically affect
the value of humidity. The lower the level of moisture, the more signicant the effects.
• Choose impermeable materials, to avoid inward diffusion of moisture through sampling
tubes and enclosures. Steel and other metals are practically impermeable. PTFE (‘Teon’)
is only slightly permeable and will usually be satisfactory for dew points above -20°C, and
sometimes below this level. Materials such as PVC and rubber are relatively permeable
and so totally unsuitable at low humidity, and not really satisfactory in any humidity range.
• Surface nish of pipework is important for very dry gases. Even the tiny quantities of
water adsorbed on the surfaces of non-hygroscopic materials can have signicant effect.
Polished or electropolished steel is recommended for the best results.
• Clean environments are always best for humidity measurements, but this is especially
critical at very low humidity. Even ngerprints harbour water. High purity cleaning agents
are recommended: Analytical Reagent (AR) quality solvents for oil-based contaminants,
and puried water (distilled or de-ionised) for salts. Cleaning should be followed by
thorough drying by a clean method.
• Sample tubing should be as short in length as possible. The surface area should be
minimised by using the narrowest tubing that the ow conditions will permit.
• Avoid leaks. Minimising the number of connections (elbows, tees, valves, etc.) helps with
this.
• Adequate ow of the gas sample should be ensured, to minimise the inuence of sources
of stray water in the ow path.
• ‘Dead ends’ should be avoided, as they cannot easily be ushed.
• Back-diffusion of moisture should be minimised, e.g. by fast ow rates of gas, long exhaust
tubes after the sensor, or by valves which isolate the low-humidity region from ambient air.
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APPENDIX C
Practical recommendations for specic types of hygrometer
Relative humidity capacitive sensor
• Care should be taken to avoid mechanical shock (impact) or thermal shock (sudden
temperature changes). Sensors should be protected from steam or water sprays, and from
direct sunlight.
• Where a sensor is at risk of exposure to dust, droplets, or the occasional knock during
handling, the appropriate guard or lters for the sensor head should be used.
• Any temptation to breathe on the sensor, or to wave it over cups of tea, etc. should be
resisted. Filters and saturation guarding may protect the sensor, but these actions carry a
risk of damage by condensation or other contamination.
• Protective lters can slow the response time of sensors. This can be avoided by removing
any lter, but the benet must be weighed against the risk of damage to the sensor.
• Sensors should not normally be submerged in liquids. In the case of a resistive (electrolytic)
sensor, water or other liquids would certainly damage the sensor beyond repair.
• Salt solutions are especially commonly used for calibration of electrical sensors, and should
be provided with traceability directly or via a calibrated hygrometer. Protection of sensors
from direct contact with salt or solution is most important as contamination would destroy
or seriously impair the sensing element.
Michell Instruments 17
HygroSmart I7000XP User’s Manual
APPENDIX D
Appendix D
Return Document &
Decontamination Declaration
18 97481 Issue 1, January 2015
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APPENDIX D
Appendix D Return Document & Decontamination Declaration
Decontamination Certicate
IMPORTANT NOTE: Please complete this form prior to this instrument, or any components, leaving your
site and being returned to us, or, where applicable, prior to any work being carried out by a Michell
engineer at your site.
Instrument Serial Number
Warranty Repair? YES NO Original PO #
Company Name Contact Name
Address
Telephone # E-mail address
Reason for Return /Description of Fault:
Has this equipment been exposed (internally or externally) to any of the following?
Please circle (YES/NO) as applicable and provide details below
Biohazards YES NO
Biological agents YES NO
Hazardous chemicals YES NO
Radioactive substances YES NO
Other hazards YES NO
Please provide details of any hazardous materials used with this equipment as indicated above (use continuation sheet
if necessary)
Your method of cleaning/decontamination
Has the equipment been cleaned and decontaminated? YES NOT NECESSARY
Michell Instruments will not accept instruments that have been exposed to toxins, radio-activity or bio-hazardous
materials. For most applications involving solvents, acidic, basic, ammable or toxic gases a simple purge with dry
gas (dew point <-30°C) over 24 hours should be sufcient to decontaminate the unit prior to return.
Work will not be carried out on any unit that does not have a completed decontamination declaration.
Decontamination Declaration
I declare that the information above is true and complete to the best of my knowledge, and it is safe for Michell
personnel to service or repair the returned instrument.
Name (Print) Position
Signature Date
F0121, Issue 2, December 2011
Michell Instruments 19
http://www.michell.com
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