Michell Instruments QMA601 Specifications

Process Analyzers

QMA601

Process Moisture Analyzer

Fast, high-precision moisture measurements for hazardous areas.

The next generation Advanced Quartz Crystal Microbalance analyzer from Michell Instruments
is designed to provide reliable, fast and accurate measurement of trace moisture content in a
wide variety of process applications where keeping moisture levels as low as possible is of critical
importance.

Highlights

• Fast and reliable measurement from 0.1 to
2000ppm

• Accuracy of ±0.1ppmV at <1ppmV and 10% of
reading from 1 to 2000ppm

• Maintenance-free for 3 years

• Built-in verification of customer process gas

• IECEx, ATEX, TC-TR Ex certified for Exd flameproof,
CSA

• Intuitive, color HMI with touch-screen keypad; no
‘hot work’ permit required

• 14 internal alarms

• 21 predefined carrier gases and 3 user-defined
gases

• Proven Michell Instruments quality: 40 years of
expertise in moisture measurement built into the
design

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US certified for explosion proof

Applications

• Glycol dehydration of natural gas

• Molecular sieve dehydration of natural gas

• Natural Gas transmission and storage

• Refinery catalytic reforming — recycle gas
monitoring

• Ethylene and propylene production

• LNG production / revaporization

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Process Analyzers

40 Years of Experience with Moisture Measurement

The control of moisture is critical for the operational safety and efficiency of the plant equipment in upstream through to
downstream processes. We at Michell Instruments have been developing expert moisture-sensing instruments and systems for
40 years. Over this time, we have developed the world’s largest range of moisture and hydrocarbon dew-point analyzers for the
oil, natural gas, refining and power industries. We have gained extensive knowledge of applications in these industries, with
thousands of installations in sites across the globe.

Introducing the QMA601
Process Moisture Analyzer

Precision Measurement

• High accuracy with lower detection limit of 0.1 ppm

• Wide range of 0.1 to 2000ppm

• Sensitivity of 0.01ppm

The QMA601 is the result of Michell Instruments’ continuous
effort to improve Quartz Crystal Microbalance technology. The
new analyzer utilizes a new generation of precision crystal
oscillators guaranteeing a highly accurate measurement
which is completely insensitive to changes in background
gas composition.

While other moisture technologies are being stretched at
sub-ppm trace moisture levels, the new QMA601 can offer
reliability, simplicity and greatly reduced cost of ownership
from trusted and proven Quartz Crystal technology.

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Reliability

For maximum stability, all critical components of the QMA601
— the moisture generator, sensor and flow control devices
— are precisely temperature controlled. This ensures that
fluctuations in sample gas or environmental temperature
have no influence on the measurement.

The analyzer utilizes a mass flow controller to ensure precise
control of the sample and reference gas flows to ±0.1 ml/
min. Coupled with a pressure transducer, this system ensures
continued accuracy of measured and calculated parameters
even during fluctuations in sample pressure.

Simplicity

Human Machine Interface (HMI)

The QMA601 provides a highly intuitive, menu driven color
interface, utilizing a capacitive touch-screen keypad. This
powerful HMI makes control, logging and configuration of
analyzer parameters very simple. The main display also
incorporates real-time trend graphing and alarm indicators
based on the NAMUR 102 standard. This allows operation
and interrogation of the analyzer in the field with no need
for a ‘hot work’ permit.

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Easy Integration into Existing Control Systems

The QMA601 is equipped with two analog outputs,
configurable for either current or voltage scaling. It also
provides both Modbus RTU Protocol over RS485 and Modbus
TCP for easy connection to a SCADA or other user-defined
data acquisition system.

Dedicated remote application software is also available.

Integrated Sampling System

The instrument can be supplied with a high quality, in-house
designed, sample conditioning system that is optimized
for the application, as well as for the requirements of the
analyzer.

Reduced Cost of Ownership

Minimum Maintenance

Sophisticated instruments are often complicated and
require experience and special care in use, increasing
cost of ownership. The QMA601 differs through its very
uncomplicated approach to field service; the desiccant dryer
is easy to replace via its mounting on the sampling panel.
The moisture generator has an average life span of 3 years
before replacement is required. The analyzer will therefore
perform reliably for many years with just basic maintenance
and housekeeping.

Automated Verification

The QMA601 incorporates an automatic or manual
verification system that can use either the internal traceable
moisture generator or an external reference supplied by the
user. Carried out on the process gas flow, these periodic
validation-checks of sensor performance can be initiated on
demand, or automatically (at user-defined intervals and time
of day), providing a verification of analyzer performance
and automatically adjusting out any change. The moisture
generator at the core of the system is supplied with a
calibration traceable to NPL and NIST.

Ease of Installation

Available with a choice of either AC or DC powered versions.*
No barrier unit or safety earth are required, saving the user
both cost and inconvenience.

*CSAUS version 24V DC only

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Technology:

Quartz Crystal Microbalance

The Quartz Crystal Microbalance (QCM) technology for moisture measurement is
based on monitoring the frequency modulation of a hygroscopic-coated quartz
crystal with specific sensitivity to water vapor.

Bulk adsorption of water vapor onto the coated crystal causes an increase in
effective mass. This change in mass modifies the oscillation frequency in a very
precise and repeatable manner and the frequency change is in direct proportion
to the water vapor pressure. The moisture concentration can therefore be
measured as a change in the oscillation frequency, with respect to a reference
crystal.

The sorption process is fully reversible with no long-term drift effect, giving a
highly reliable and repeatable measurement.

Process Analyzers

Pole

Quartz Crystal Polyamide

Our products are also backed up
by global service and support. With
locations on 6 continents and 56
countries, Michell Instruments offers
an extensive network of factory
trained application engineers ready to
analyze your application and deliver
the solution. This allows us to assure
customer satisfaction throughout the
product’s lifetime.

If you can’t find a product to fit your
application contact your local Michell
Instruments office, or visit our website

www.michell.com/uk - we’re here to

help.

Polymer Coating

Gold Electrode

The QMA601 Process Moisture Analyzer is designed to provide highly reliable,
fast and accurate measurement of moisture content in a wide variety of
carrier gases. Utilizing Quartz Crystal Microbalance technology, the analyzer
incorporates automatic (or manual) verification using an integrated moisture
generator reference source and, with its intuitive touch-screen operated color
HMI, provides easy operation.

The Moisture Specialists:

We have the solution for your moisture sensing needs

With 5 proprietary moisture sensing technologies, Michell Instruments will tailor
our solutions to best fit the specifics of the your application, as well as the project
budget.

Capacitive humidity sensors:

For quick and easy pipeline integrity measurement in low pressure town gas.

Michell Ceramic Sensor technology:

3rd generation of metal oxide for natural gas applications at high pressure (CNG)
and economical, easy gas processing applications.

Chilled Mirror:

For precise reference measurements at highest accuracy and NPL or NIST
traceability.

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Quartz Crystal Microbalance:

For fast, precise measurement at low ranges in changing backgrounds.

TDLAS:

For fast, precise and low maintenance measurement in both sweet and sour gases
from 1000ppm

to 1ppmv.

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Process Analyzers

Technical Specifications

Measuring technology Fast Response Quartz Crystal Microbalance
Calibrated range* 0.1 to 700ppm
Measurement range 0.1 to 2000ppm
Accuracy ±10% of reading from 1 to 2000ppm

Repeatability ±5% of the reading from 1 to 2000ppm

Limit of detection
Available units ppmV, ppmW, mg/Nm3, vapor pressure (Pa), dew

Response speed

Automatic calibration Internal moisture generator source calibrated

Sensitivity

Electrical Specifications

Supply voltage 85 to 264 V AC, 47/63Hz or 24 V DC (ATEX /

Alarms 1 x system alarm, volt-free change-over (FORM

Analog signals 2 x 4–20 mA or 1–5 V (selectable)

Digital communications

Data logging Available on analyzer (Limited number of values)

Local interface
Electrical connections M20 entries for cable glands

*Applies only to standard 30-30 second cycle variant. Contact Michell
Instruments for further details

±0.1ppmV between 0.1 & 1ppm

±0.1ppmV between 0.1 & 1ppm

0.1ppm

point (°C/°F), lb/MMscf

T63 <2 mins to step change in either direction
T95 <5 mins to step change in either direction*

traceable to NPL & NIST

0.01ppm

IECEx)
24 V DC only (CSAUS)

C)
3 x process alarms, selectable for various
parameters, volt-free changeover
(FORM C)

Maximum load resistance 500 Ω for 4–20 mA
and minimum load of 1M Ω for 1–5 V

RS485 ModBus RTU
Modbus TCP

or via Application Software

7” colour LCD with intuitive HMI

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or 1% of reading, whichever is greater

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Operating Conditions

Inlet pressure 3 barg (43.5 psig)
Outlet pressure 2 barg (29 psig)
Sample flow 300ml/min total flow
Sample gas temperature 0 to +100°C (+32 to +212°F)
Operating environment

Mechanical Specifications

Type GUB Flameproof Exd
Enclosure

Gas connections 1/8” NPT
Weight 35kg (77lb) without sampling system
Sample system enclosure 316L stainless steel

Certifications

Hazardous area
certifications

Analyzer only

Analyzer in sampling

system

Lid & body

Glass window

ATEX

IECEx

CSAc

CSAUS

TC-TR

+5 to +45°C (+41 to +113°F) up to
90% RH
–20 to +55°C (–4 to +131°F) up to 95% RH
(fitted with heater/thermostat and/or enclosure
cooling as appropriate to maintain +5 to +45°C
(+41 to +113°F) internal temperature)

Cast copper-free aluminum LM25
(EN AC-42000), less than 0.6 magnesium
Heat resistant, explosion proof, polyester coated,
IP66, NEMA 4

II 2 GD Ex d IIB+H2 T6 Gb, Ex tb IIIC T85°C
Db, Tamb -40°C to +60°C

Ex d IIB+H2 T6 Gb, Ex tb IIIC T85°C Db, Tamb

-40°C to +60°C

Class I, ZONES, Ex d IIB+H2 T6 Gb, Tamb -20°C
to +55°C

Class I, Div 1, Group BCD T6, Tamb -25°C to
+55°C

1Ex d IIB+H2 T4 Gb X, 1Ex tb IIIC 130°C Db X
and
1Ex d IIB+H2 T3 Gb X, 1Ex tb IIIC 195°C Db X

Michell Instruments Ltd 48 Lancaster Way Business Park, Ely, Cambridgeshire, CB6 3NW
Tel: [phone], Fax: [phone], Email: [e-mail], Web: www.michell.com/uk

Michell Instruments adopts a continuous development programme which sometimes necessitates specification changes without notice.
Issue no: QMA601_97490_V4_UK_Datasheet_0518

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