Michell Instruments MDM300 I.S. User manual

MDM300
Sampling System
User’s Manual
97232 Issue 1.4
October 2016

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© 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
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MDM300 Sampling System

MDM300 Sampling System User’s Manual
iv 97232 Issue 1.4, October 2016
Contents
Safety ................................................................................................................................ v
Electrical Safety ........................................................................................................... v
Pressure Safety............................................................................................................ v
Toxic Materials............................................................................................................. v
Repair and Maintenance............................................................................................... v
Calibration................................................................................................................... v
Safety Conformity ........................................................................................................ v
Abbreviations......................................................................................................................vi
Warnings............................................................................................................................vi
1 INTRODUCTION................................................................................................1
2 INSTALLATION..................................................................................................2
2.1 Safety ............................................................................................................... 2
2.2 Unpacking the Instrument................................................................................... 2
2.3 Environmental Requirements............................................................................... 2
2.4 Preparing the Sampling System for Operation....................................................... 3
2.5 Controls, Indicators and Connectors..................................................................... 5
3 OPERATION ......................................................................................................6
3.1 Sample Gas Connection ......................................................................................6
3.2 Operating Procedure........................................................................................... 6
3.3 Sampling Hints................................................................................................... 7
4 MAINTENANCE................................................................................................10
4.1 General Maintenance Guidelines........................................................................ 10
4.2 Filter Element Replacement............................................................................... 10
Figures
Figure 1 Panel-Mount Sampling System and Flight Case .............................................1
Figure 2 Gas Port Adaptors ......................................................................................3
Figure 3 MDM300 Positioning...................................................................................3
Figure 4 MDM300 Inlet and Outlet Port Connection....................................................4
Figure 5 Mounting Posts...........................................................................................4
Figure 6 Port Connection Tightening.........................................................................4
Figure 7 Controls, Indicators and Connectors.............................................................5
Figure 8 Sample Line Connection to GAS IN Port .......................................................6
Figure 9 Filter Element Removal.............................................................................10
Figure 10 Glycol Absorption Cartridge Removal..........................................................11

MDM300 Sampling System User’s Manual
Michell Instruments v
Appendices
Appendix A Technical Specifications..............................................................................13
Appendix B Quality, Recycling & Warranty Information...................................................15
B.1 Pressure Equipment Directive (PED) 97/23/EC...............................15
B.2 Recycling Policy ..........................................................................15
B.3 WEEE Compliance........................................................................15
B.4 RoHS2 Compliance ......................................................................16
B.5 Warranty.....................................................................................16
B.6 REACH Compliance......................................................................17
B.7 Calibration Facilities .....................................................................17
B.8 Return Policy...............................................................................18
B.9 Manufacturing Quality..................................................................18
Appendix C Return Document & Decontamination Declaration........................................20
Tables
Table 1 Controls, Indicators and Connectors..............................................................5

MDM300 Sampling System User’s Manual
vi 97232 Issue 1.4, October 2016
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 subject the equipment to conditions outside of the specified operating limits.
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 will be as follows (refer to Appendix A - Technical Specifications):
Low pressure: 20 barg (290 psig)
Medium pressure: 110 barg (1595 psig)
High pressure: 340 barg (4931 psig)
!
WARNING
The flowmeter should never be pressurized.
Always expand a pressurized sample to atmospheric pressure
before it enters the flow meter.
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 www.michell.com for details of Michell Instruments’ worldwide offices contact information
Calibration
The recommended calibration interval for the MDM300 Hygrometer is 12 months. The instrument
should be returned to the manufacturer, Michell Instruments, or one of their accredited service
agents for recalibration.
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.

MDM300 Sampling System User’s Manual
Michell Instruments vii
Abbreviations
The following abbreviations are used in this manual:
AC alternating current
barg pressure unit (=100 kP or 0.987 atm) gauge
ºC degrees Celsius
ºF degrees Fahrenheit
Nl/min liters per minute
kg kilogram(s)
lb pound(s)
mm millimeters
“ inch(es)
psig pounds per square inch gauge
scfh standard cubic feet per hour
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.

MDM300 Sampling System User’s Manual
Michell Instruments 1
INTRODUCTION
1 INTRODUCTION
The MDM300 panel-mount sampling system offers a complete package for conditioning
of a sample, prior to measurement with an MDM300 or MDM300 I.S.
It is contained within an optional flight case which allows easy transport of everything
required to make the measurements. The anti-static construction of the case makes it
suitable for use in hazardous areas.
Figure 1 Panel-Mount Sampling System and Flight Case

MDM300 Sampling System User’s Manual
297232 Issue 1.4, October 2016
INSTALLATION
2 INSTALLATION
2.1 Safety
!
It is essential that the installation of the electrical and
gas supplies to this instrument be undertaken by qualified
personnel.
2.2 Unpacking the Instrument
The shipping box will contain the following:
• MDM300 Panel-Mount Sampling System
• Flight case (optional)
• 2.5mm Allen key
• 2 x 2.5mm hex bolts
• 2 x 1/8” NPT to 1/8” Swagelok®adaptors
1. Open the box. If a flight case was ordered, the sampling system
will be packaged within it.
2. Remove the sampling panel (or flight case, if ordered) from the
box, along with the fittings.
3. Save all packing materials in case it is necessary to return the
instrument.
2.3 Environmental Requirements
Refer to the user’s manual for information on acceptable environmental conditions in
which to operate the MDM300.

MDM300 Sampling System User’s Manual
Michell Instruments 3
INSTALLATION
2.4 Preparing the Sampling System for Operation
To prepare the system for operation, it is necessary to install the MDM300 into the
sampling system as follows:
4. Wrap PTFE tape (not supplied), around the ends of the 1/8” NPT to 1/8”
Swagelok®tube fittings and install into the orifice adaptors fitted to the
MDM300. Ensure that the orifice port adaptors in the MDM300 are
both large bore type (see relevant user’s manual for more details).
- I.S.
Large orice adaptor
PTFE tape here
1/8” Swagelok
tting
Adaptor
Dowty seal
h
h
h
h
Small orice
Figure 2 Gas Port Adaptors
5. Locate the MDM300 in the position shown below.
FLOWMETER (FM1)
OPTIMAL FLOW
0.2 - 0.5 L/MIN
NEEDLE VALVE
(NV1)
SAMPLE INLET
MAX 100 BARG
SAMPLE VENT
MDM300 I.S.
Sampling System
NEEDLE VALVE
(NV2)
PRESSURE GAUGE
(PG1)
BYPASS VENT
BYPASS VALVE
(NV3)
MDM300-IS SAMPLING
SYSTEM
100 200
150
250
300
50
bar
lbf/in2
Figure 3 MDM300 Positioning

MDM300 Sampling System User’s Manual
497232 Issue 1.4, October 2016
INSTALLATION
6. Connect the coiled tubes to the inlet and outlet of the MDM300. Ensure
that the 1/8” Swagelok®nuts are finger tight.
IS
Figure 4 MDM300 Inlet and Outlet Port Connection
7. Secure the instrument to the mounting posts using the supplied 2.5mm
hex bolts and allen key.
- I.S.
;;
Figure 5 Mounting Posts
8. Use a wrench/spanner to finish tightening the 1/8” Swagelok®nuts on the
inlet/outlet to ensure there are no leaks. The body of the 1/8” NPT to 1/8”
Swagelok®adaptor should be held securely with another wrench/spanner
while the nuts are tightened to prevent any movement.
- I.S.
Figure 6 Port Connection Tightening

MDM300 Sampling System User’s Manual
Michell Instruments 5
INSTALLATION
2.5 Controls, Indicators and Connectors
FLOWMETER (FM1)
OPTIMAL FLOW
0.2 - 0.5 L/MIN
NEEDLE VALVE
(NV1)
SAMPLE INLET
MAX 100 BARG
SAMPLE VENT
- I.S.
MDM300 I.S.
Sampling System
NEEDLE VALVE
(NV2)
PRESSURE GAUGE
(PG1)
BYPASS VENT
BYPASS VALVE
(NV3)
MDM300-IS SAMPLING
SYSTEM
100 200
150
250
300
50
bar
lbf/in2
h
h
h
h
h
h
h
12
h
3
4
5
6
7
8
Figure 7 Controls, Indicators and Connectors
1Outlet
Metering Valve
Usedto regulate sampleflow forsystem pressure measurements
Should be fully open for system pressure measurements
2Pressure Gauge Gauge showing the sample pressure across the sensor cell
3Sample Vent Fitted with either a silencer or Swagelok®tube fitting to enable
a vent line to be connected
4Flow Meter For flow indication
5Inlet Metering
Valve
Used to regulate sample flow for atmospheric pressure
measurements
Should be fully open for system pressure measurements
6Bypass Port Outlet from the bypass path
Can optionally be connected to a vent line during operation
7Sample Inlet For connection to the sample gas line
Refer to Section 3.1 for more information on making connections
to the system
8Bypass
Metering Valve Used for regulating the flow rate through the bypass path
Table 1 Controls, Indicators and Connectors

MDM300 Sampling System User’s Manual
697232 Issue 1.4, October 2016
OPERATION
3 OPERATION
3.1 Sample Gas Connection
Gas is introduced to the system by connecting the sample take-off line to the GAS IN
port, as shown in Figure 8.
If required, connect a vent line to the BYPASS port, and to the flowmeter vent (if fitted).
FLOWMETER (FM1
)
OPTIMAL FLOW
0.2 - 0.5 L/MIN
NEEDLE VALVE
(NV1)
SAMPLE INLET
MAX 100 BARG
- I.S.
BYPASS VENT
BYPASS VALVE
(NV3)
;
Figure 8 Sample Line Connection to GAS IN Port
3.2 Operating Procedure
1. Connect an instrument to the sample gas as detailed in Section 3.1.
2. Fully open the isolation valve.
3. Refer to the Operation Guide section in the relevant MDM300 user’s
manual for condition specific instructions on operation.
4. Depending on the sample pressure it may be necessary to use the bypass
flow control to overcome sample flow control difficulties.

MDM300 Sampling System User’s Manual
Michell Instruments 7
OPERATION
3.3 Sampling Hints
Measurement of moisture content is a complex subject, but does not need to be difficult.
This section aims to explain the common mistakes made in measurement situations, the
causes of the problem, and how to avoid them. Mistakes and bad practices can cause
the measurement to vary from the expectation; therefore a good sampling technique is
crucial for accurate and reliable results.
Transpiration and Sampling Materials
- 20
- 30
- 40
- 50
- 60
- 70
12345
Time (hours)
Dew point (ºC)
nylon
copper
polyethylene
PTFE
nickel
stainless steel
All materials are permeable to water vapor, as the water molecule is extremely small
compared to the structure of solids, even when compared to the crystalline structure of
metals. The graph to the right shows the dew point inside tubing of different materials
when purged with very dry gas, where the exterior of the tubing is in the ambient
environment.
Many materials contain moisture as part of their structure, particularly organic materials
(natural or synthetic), salts (or anything which contains them) and anything which
has small pores. It is important to ensure that the materials used are suitable for the
application.
If the partial water vapor pressure exerted on the outside of a compressed air line is
higher than on the inside, the atmospheric water vapor will naturally push through the
porous medium causing water to migrate into the pressurized air line. This effect is
called transpiration.
Adsorption and Desorption
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved
solid to the surface of a material, creating a film. The rate of adsorption is increased at
higher pressures and lower temperatures.
Desorption is the release of a substance from or through the surface of a material. In
constant environmental conditions, an adsorbed substance will remain on a surface
almost indefinitely. However, as the temperature rises, so does the likelihood of
desorption occurring.
In practical terms, as the temperature of the environment fluctuates, water molecules
are adsorbed and desorbed from the internal surfaces of the sample tubing, causing
small fluctuations in the measured dew point.

MDM300 Sampling System User’s Manual
897232 Issue 1.4, October 2016
OPERATION
Sample Tubing Length
The sample point should always be as close to the critical measurement point as possible,
in order to obtain a truly representative measurement. The length of the sample line
to the sensor or instrument should be as short as possible. Interconnection points and
valves trap moisture, so using the simplest sampling arrangement possible will reduce
the time it takes for the sample system to dry out when purged with dry gas.
Over a long tubing run, water will inevitably migrate into any line, and the effects of
adsorption and desorption will become more apparent. It is clear from the graph shown
above that the best materials to resist transpiration are stainless steel and PTFE.
Trapped Moisture
Dead volumes (areas which are not in a direct flow path) in sample lines, hold onto
water molecules which are slowly released into the passing gas; this results in increased
purge and response times, and wetter than expected readings. Hygroscopic materials
in filters, valves (e.g. rubber from pressure regulators) or any other parts of the system
can also trap moisture.
Sample Conditioning
Sample conditioning is often necessary to avoid exposure of sensitive measuring
components to liquids and other contaminants which may cause damage or affect the
accuracy over time, depending on the measurement technology.
Particulate filters are used for removing dirt, rust, scale and any other solids that may
be in a sample stream. For protection against liquids, a coalescing filter should be used.
The membrane filter is a more expensive but highly effective alternative to a coalescing
filter. It provides protection from liquid droplets, and can even stop flow to the analyzer
completely when a large slug of liquid is encountered.
Condensation and Leaks
Dewpoint > T Dewpoint < T
Maintaining the temperature of the sample system tubing above the dew point of the
sample is vital to prevent condensation. Any condensation invalidates the sampling
process as it changes the water vapor content of the gas being measured. Condensed
liquid can alter the humidity elsewhere by dripping or running to other locations where
it may re-evaporate.
The integrity of all connections is also an important consideration, especially when
sampling low dew points at an elevated pressure. If a small leak occurs in a high
pressure line, gas will leak out but vortices at the leak point and a negative vapor
pressure differential will also allow water vapor to contaminate the flow.

MDM300 Sampling System User’s Manual
Michell Instruments 9
OPERATION
Flow Rates
Theoretically flow rate has no direct effect on the measured moisture content, but in
practice it can have unanticipated effects on response speed and accuracy. The optimal
flow rate varies depending on the measurement technology.
MDM300 I.S. flow rate 0.2 to 0.5 Nl/min (0.5 to 1 scfh)
MDM300 flow rate 0.2 to 1.2 Nl/min (0.5 to 1.2 scfh)
!
WARNING
The flowmeter should never be pressurized.
Always expand a pressurized sample to atmospheric
pressure before it enters the flow meter.
An inadequate flow rate can:
• Accentuate adsorption and desorption effects on the gas passing through
the sampling system.
• Allow pockets of wet gas to remain undisturbed in a complex sampling
system, which will then gradually be released into the sample flow.
• Increase the chance of contamination from back diffusion: ambient air
that is wetter than the sample can flow from the exhaust back into the
system. A longer exhaust (sometimes called a pigtail) can also help
alleviate this problem.
An excessively high flow rate can:
• Introduce back pressure, causing slower response times and unpredictable
effects on equipment such as humidity generators.
• Result in a reduction in heating capabilities of the sensor tile during the
initialization period. This is most apparent with gases that have a high
thermal conductivity such as hydrogen and helium.

MDM300 Sampling System User’s Manual
10 97232 Issue 1.4, October 2016
MAINTENANCE
4 MAINTENANCE
4.1 General Maintenance Guidelines
Routine maintenance of the system is confined to filter element replacement and regular
recalibration of the MDM300 or MDM300 I.S. sensor. For specific details on replacing
filter elements, please see Section 4.2.
In most applications, annual recalibration ensures that the stated accuracy of the
MDM300 Advanced Dew-Point Hygrometer is maintained. The exchange sensor scheme
is the most efficient method of providing accurate annual recalibration with minimum
downtime.
Please contact Michell Instruments for more details.
Prior to recalibration being necessary, an exchange sensor can be ordered from Michell
Instruments or any authorized dealer. Once the sensor and calibration certificate has
been received it can be fitted and the original sensor returned to Michell Instruments.
For more details of recalibration of the MDM300 please see the relevant user’s manual.
4.2 Filter Element Replacement
Frequency of filter element replacement is primarily dependent upon the quantity of
contaminants present in the sample gas. If the gas is heavily laden with particulates or
liquids it is recommended to inspect the filter element on a regular basis initially, and
increase the time between inspections if the filter is found to be in good condition.
It is imperative that all filters are replaced before they become saturated. If a filter
element becomes saturated with contaminants there is a possibility that the performance
of the filter will be reduced, and contamination of the MDM300 sensor could occur.
!
Before attempting to replace the filter always disconnect the
Sampling System from the sample gas and ensure that the
system is depressurized.
To replace a particulate or coalescing filter element, proceed as follows:
1. Disconnect the U-shaped section of Swagelok®tubing from the filter drain.
SAMPLE INLET
MAX 100 BARG
- I.S.
BYPASS VENT
BYPASS VALVE
(NV3)
;
;
Figure 9 Filter Element Removal

MDM300 Sampling System User’s Manual
Michell Instruments 11
MAINTENANCE
2. Unscrew and remove the filter bowl and then the filter element. NOTE:
the filter bowl is sealed with an O-ring.
3. Discard the old used filter element and replace with a new filter element
Order codes:
MDM300-SAM-PAR - particulate element
MDM300-SAM-COA - coalescing element
4. Replace the filter bowl, ensuring the O-ring is correctly seated and
reconnect the tube to the drain port. NOTE: Tighten both securely.
To replace the glycol absorption cartridge, proceed as follows:
FLOWMETER (FM1)
OPTIMAL FLOW
0.2 - 0.5 L/MIN
NEEDLE VALVE
(NV1)
SAMPLE INLET
MAX 100 BARG
- I.S.
BYPASS VENT
BYPASS VALVE
(NV3)
Glycol
Absorption
Cartridge
h
Figure 10 Glycol Absorption Cartridge Removal
1. Loosen union bonnet nut with open end spanner/wrench. Support
body to minimize strain on pipe or tubing.
2. Unscrew union nut and remove assembly. NOTE: Union nut,
bonnet, spring and retaining ring remain together as an
assembly.
3. Gently tap filter element on side to break loose from tapered
seating area.
4. Insert new glycol absorption cartridge. Tap lightly to reseat in
tapered bore.
Order code: MDM300-SAM-PNL-GLY
5. Inspect gasket and mating surfaces on bonnet and body. Clean as
required. Replacement of the gasket is recommended.

MDM300 Sampling System User’s Manual
12 97232 Issue 1.4, October 2016
APPENDIX A
Appendix A
Technical Specifications

MDM300 Sampling System User’s Manual
Michell Instruments 13
APPENDIX A
Appendix A Technical Specifications
Enclosure
Dimensions 300 x 400 x 150mm (11.81 x 15.75 x 5.91”) (w x h x d)
Materials ABS (anti-static)
Ingress Protection IP67 / NEMA4
Sampling System
Pressure Range Low pressure: 20 barg (290 psig) Medium pressure: 110 barg (1595 psig)
High pressure: 340 barg (4931 psig)
Flow Rate MDM300 0.2 to 1.2 Nl/min (0.4 to 2.54 scfh)
MDM300 I.S. 0.2 to 0.5 Nl/min (0.4 to 1.1 scfh)
Gas Wetted Materials 316 stainless steel
Gas Connections
Depending on model:
Legris quick release - accepts 6mm O/D PTFE (LOW PRESSURE
VERSION ONLY)
1/8” Swagelok®
6mm Swagelok®
Components
Valves Inlet isolation valve, 2 x sample flow control valves,
Bypass flow control valve
Filtration Options of:
Particulate
Coalescing
Coalescing + Mini Glysorb
Pressure Gauge Depending on model:
Low pressure: 0 to 25 barg (0 to 362 psig)
Medium pressure: 0 to 137 barg (0 to 1987 psig)
High pressure: 0 to 413 barg (0 to 5990 psig)
Vent
Atmospheric pressure only - DO NOT pressurize vent
Options of:
Silencer
1/8” Swagelok®
6mm Swagelok®