Vaisala OMT355 Technical data

Vaisala Instruments Catalog 2009

Ref. B210768EN rev. A

P.O. Box 26, FI-00421 Helsinki, FINLAND

Email: [e-mail]

www.vaisala.com/OMT355

OMT355 Oxygen Transmitter for Industrial
Process Measurements

Features/Benefits

• Minimizes need for sample
conditioning equipment

• In-situ probe or sampling cell
options

• Tolerates aggressive chemicals

• Tolerates excessive amounts of

moisture even in liquid form

• Low maintenance

• Diagnostic output for preventive

maintenance

• Heated optical surfaces to prevent
condensation

Tel: [phone]

Fax: [phone]

e Vaisala SPECTRACAP® Oxygen Transmitter.

e Vaisala SPECTRACAP® Oxygen
Transmitter OMT355 is ideal for
oxygen monitoring in moist and
aggressive process gases. Typical
applications include gas generation,
inert gas blanketing, fermentation and
composting process monitoring.

Laser based measurement

e OMT355 incorporates a compact
tunable diode laser (TDL) gas
spectrometer built in the measurement
probe. This optical measurement
technology is well known for
unmatched stability and robustness.
For the first time, the SPECTRACAP®
sensor offers TDL technology in a
compact probe suitable for field use.

Direct installation

In many applications, the OMT355
can be ange-mounted directly into
a process. No sampling or sample
conditioning equipment is needed.
is feature provides real time
measurement data without sampling
or sample switching delays.

Sampling cell installation

An optional sampling cell is available

for processes with high temperatures,
elevated pressures or extremely
dicult mechanical conditions. Due to
the robustness of the SPECTRACAP®
sensor and its low sensitivity to gas
flow and pressure variations, the
sampling system can be very simple
and it can be installed near the
sampling point.

Low maintenance

A stainless steel mesh lter and an
optional porous PTFE lter protect
the OMT355 probe optics from dust
and dirt. An intelligent measurement
algorithm further minimizes
contamination eects and provides
a maintenance alert well before the
measurement performance is aected.

OMT355 with the sampling cell.

Long calibration interval

Calibration or eld checking of
the instrument can be done either
with ambient air or with zero/span
gases injected through an optional
calibration gas connector. e
calibration interval of the OMT355 is
12 months.

User friendly interfaces

For calibration and conguration, the
OMT355 features both software and
keypad user interfaces and an LCD
di sp lay.

TDL Technology

e Tunable Diode Laser (TDL)
technology used in the SPECTRACAP®
sensor is one of the most powerful
technologies in gas measurement on
the market today.
e technology is based on measuring
the attenuation of a beam of laser light
in the sample gas. For oxygen sensing
the laser is tuned to a wavelength
which is characteristic and unique for
the oxygen molecule. erefore, the
measured attenuation is an extremely
selective measure for the amount of
oxygen on the path of the laser beam.

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Vaisala Instruments Catalog 2009

Ref. B210768EN rev. A

OMT355 OXYGEN

Technical Data

Performance

Measurement range 0 ... 100 % O2
Accuracy

(including noise, linearity, and repeatability)
Temperature dependence over T range ±2 % of reading
Stability ±1 % of reading/yr
Zero drift ±0.1 % O
Response time of measurement 3 s
Diusion limited response in still air T

without lters 10 s / 20 s
with stainless steel mesh lter 10 s / 25 s
with stainless steel mesh and PTFE lters 30 s / 70 s

Pressure dependence without pressure compensation

0.8 ... 1.2 bar -2 % of reading

1.2 ... 1.4 bar -5 % of reading
Accuracy of pressure compensation ±0.25 % of reading
Background gas eects for CO

Accuracy of background gas compensation

0 ... 50 vol-% CO
0 ... 300 g/m

Operating Environment

Operating temperature range

for probe (in-line installation) -20 ... +80 °C
for electronics (housing) -40 ... +60 °C
for transmitter (ambient gas

measurement -20 ... +60 °C
Storage temperature range -55 ... +80 °C
Operating pressure range 0.8 ... 1.4 bar
Maximum pressure range for probe up to 10 bar
Compliance

IEC(EN)-61326 Electrical equipment for measurement, control

and laboratory use. EMC requirements

EN50104 Electrical apparatus for the detection and

measurement of oxygen. Performance requirements and test

methods.

EN50271 Electrical Apparatus for the Detection and

Measurement of Combustible Gases, Toxic Gases or Oxygen

Laser safety Class 3R laser product

2

3

H2O (Td = 80 °C) ±1 % of reading

and H2O, uncompensated

2

<1 % of reading for <6 vol-% CO

<1 % of reading for gas dewpoint < 30 °C

±0.2 % O

2

63/T90

±0.5 % of reading

Inputs and Outputs

Power supply

input range 11 ... 36 VDC
Power consumption

maximum 6 W

typical 3 W
Analog output 0/4 ... 20 mA, sourcing

maximum load 500 Ω
Serial output (2-wire, non-isolated) RS-485
Alarm/control relay 30 VAC/60 VDC

Mechanics

Housing material G-AlSi10 Mg (DIN 1725)
Probe material AISI 316
Housing classication IP66
Weight 2.2 kg
Mounting ange diameter 97 mm

Can be tted to standard anges. Minimum sizes:
DIN (2527B) DN50 and ANSI (150) 2.5”

/yr

Cable bushing Cable gland M20 x 1.5
Stainless steel mesh lter openings ø 310 µm

2

Wetted materials
AISI 316, EPDM or Kalrez® (optional), PTFE (optional), SiN, MgF

Options and accessories

Hydrophobic PTFE lter, pore size 8 µm

with EPDM O-rings 217055

with Kalrez
1/2” NPT conduit tting 217197
M12 male 8-pin connector for
user cable
Serial interface cable for PC 19446ZZ
USB-RJ45 Serial interface cable 219685
Sample cell with wall mounting bracket

2

with EPDM O-rings 217052

with Kalrez

For complete specications, refer to the User’s Guide.

® O-rings

® O-rings

Dimensions

Dimensions in mm 306 mm x 184 mm x 74 mm

SPECTRACAP® is a registered trademark of Vaisala.
Specications are subject to change without prior notice.
© Vaisala Oyj

2

217056

214806SP

216619

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