Michell Instruments QMA401 Specifications

Process Analyzers

QMA401

Trace Moisture Analyzer

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
variety of applications where keeping moisture to a minimum is of critical importance.

Highlights

• Precision measurement from 0.1 to 2000 ppm

• Simple, low cost, on-site maintenance

• Accuracy of 0.1ppmV or 10% of reading,
whichever is greater

• Reliable measurement even in varying sample
conditions — analyzer corrects automatically for
flow variations

• Unaffected by changes in background gas
composition

• Long intervals between maintenance

• Dryer can be replaced by the user in 10 minutes

• Intuitive user interface

• Ethernet or USB digital communications

• SD card datalogging

• Optional internal sample handling and bypass loop

www.michell.com

Applications

V

• High purity gas production

• Air separation plants

• Semiconductor CVD chamber cleaning

• Semiconductor etching chambers

coolant for generators

• H

2

• Polymer chip drying

Process Analyzers

Introducing the QMA401 Trace Moisture Analyzer

Air Separation Plant

Precision Measurement

The QMA401 is the result of Michell Instruments’ continuous
improvement of Quartz Crystal Microbalance technology.
The analyzer utilizes a new generation of precision
crystal oscillators, guaranteeing high accuracy moisture
measurements which are completely insensitive to changes
in background gas composition.

While measurements at quantities of moisture <1ppm
stretch the capabilities of other technologies, the new
QMA401 offers reliability, simplicity and greatly reduced
cost of ownership from the industry-proven Quartz Crystal
technology.

Reliability

For maximum stability, all critical components of the QMA401
— 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 ±0.1ml/
min. Coupled with a pressure transducer, this system ensures
continued accuracy of measured and calculated parameters
even during fluctuations in sample pressure.

Simplicity

The QMA401 provides a highly intuitive, color, touch-screen
interface. This powerful UI makes control, logging and
configuration of analyzer parameters very simple. Both real­time trend graphing and alarm indication are immediately
visible on the main display.

Minimal & Straightforward
Maintenance

Sophisticated analyzers are often complicated and require
experience and special care in use and maintenance,
increasing cost of ownership.

The QMA401 differs through its straightforward approach to
field service, which can be carried out in-situ. The desiccant

V

dryer is easy to replace via the ‘quick release’ service panel
on the rear of the analyzer. The moisture generator has an
average life span of 3 years before replacement is required,
therefore the unit can perform reliably for many years with
just basic maintenance and housekeeping.

Integrated Sample Handling

The analyzer can be specified with an integral sample
handling system, including a pressure regulator and ‘fast
loop’ bypass, to ensure quick transit of the sample from the
point of interest to the sensor.

Use Your Preferred Communication
Media

For greater flexibility, the QMA401 offers:

• Modbus over USB and Ethernet

• Datalogging to SD card

• 2 user-configurable analog outputs

• Status and process alarms

Automatic Verifi cation

The QMA401 incorporates an automatic verification system
that uses either the internal traceable moisture generator or
an external reference supplied by the user. Carried out on the
sample 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.

www.michell.com

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.

Pole

Quartz Crystal Polyamide

Bulk adsorption of water vapor onto the coated crystal causes an
increase in the crystal’s effective mass, modifying its oscillation
frequency in a very precise and repeatable manner. The frequency
change is in direct proportion to the water vapor pressure in the
sample gas, providing a direct measurement of moisture content.

Polymer Coating

Gold Electrode

Process Analyzers

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

www.michell.com

Process Analyzers

Technical Specifi cations

Performance

Measurement technology Fast Response Quartz Crystal Microbalance

Calibrated range 0.1 to 700ppm

Measurement range 0.1 to 2000 ppm

Accuracy ±10% of reading from 1 to 2000 ppm

0.1 ppmV between 0.1 and 1 ppm

Repeatability ±5% of reading from 1 to 2000 ppm

±0.1 ppmV between 0.1 and 1 ppm

Detection limit 0.1 ppm

Available units ppmV, ppmW, mg/nm3, vapor pressure (Pa),

frost point (°C), lb/MMscf

Response speed T63 <2 mins to step change in either

direction
T95 <5 mins to step change in either
direction

Automatic calibration Internal moisture generator source

calibrated traceable to NPL and NIST

Sensitivity 0.1 ppm

greater

V

V

V

V

V

V

or 1% of reading, whichever is

V

V

Electrical Specifications

Supply voltage 85 to 264 V AC, 47/63Hz, 110 to 300 V DC

Max power consumption 111 W

Alarms 1 x System alarm, volt-free change-over

Communications Analog Outputs: 2 channels, user selectable

Data logging Direct logging to SD card or PC via

Local interface 7” color touch screen LCD

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

4-20 mA or 1 to 5 V
Digital Communications: RS485/USB Modbus
RTU, Ethernet Modbus TCP

application software

Operating Conditions

Inlet pressure 1 barg max

With optional inlet pressure regulator: 300
barg max

Outlet pressure Atmospheric

Sample flow 300ml/min total flow without bypass

Sample gas temperature 0 to +100°C

Operating environment +5 to +45°C up to 90% RH

Mechanical Specifications

Enclosure 19” Rackmount, 4U x 434mm

Gas connections 1/4” VCR(M)

Weight 13.5kg

Dimensions

442.9

440.0

177.0

186.9

40$

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: QMA401_97480_V3_UK_Datasheet_0318

464.2

428.4

© 2018 Michell Instruments