SIGMA
Handheld Combustion Gas Analyzer

Product Description

SIGMA

A compact, handheld, economical combustion gas analyzer with the
power and performance of a much larger, bulkier and heavier unit.

MRU’s new Sigma up to 4 gas handheld analyzer, originally introduced in Europe in early 2007, is the product of a design breakthrough for MRU engineers. MRU has successfully harnessed the power and performance of an analyzer normally available only in a much larger package to create the very compact and comfortable Sigma handheld analyzer. Despite its small size (about 3” x 8” x 2”) and light weight (just over 1½ lbs) Sigma is capable of measuring up to 4 gases (O₂, CO, NO, & either NO₂ or SO₂) simultaneously.

Plus, it is loaded with additional performance features*:

Menu guided software, function push buttons.

Efficient CO sensor purging using 2nd pump

Rechargeable MiMh battery (8 hours) line voltage power supply

Universal power supply: 90 -24 Vac, 50 – 60 Hz

Automatic self-diagnosis of hardware and software

Stack draft and differential temperature measurement

Memory for storage of 100 measurements

Ergonomic design

Choice of probe lengths

Choice of probe temperatures to 2,000o F

Bluetooth for wireless data transfer to a PC

RS232 cable for transfer data transfer to PC/PDA

RS232/USB converter for data transfer to PC/PDA

Ambient air temperature probe

12” long combustion air temperature probe with 8’ cable

IR thermal printer

Condensate trap and filters for protection against particulates

Robust, ABS transport case with compartment for accessories

Belt clip and magnet for fastening

Large, backlit LCD display

User selectable zoom: 4 or 8 values displayed

Choice of fuel types

Calculated values: CO2, dew point, losses, efficiency, excess air.

* Some features listed are options

Sigma is small in size, but big on features and performance.

SIGMA: Basic Analyzer

1 Zero setting active (flashing) 2 Battery condition (displayed in evey menu) 3 Status line

SIGMA: Display close-up with 4 readings

1 Belt clip 2 Magnet 3 Gas outlet 4 Handle strip 5 Battery compartment

SIGMA: View of the back of the analyzer

SIGMA: Probe

SIGMA: Special Set
(Includes basic Sigma, CO sensor, NO sensor, IR thermal printer and ABS transport case)

O2	Standard	Standard	Standard	Standard	Standard	Standard	Standard
CO (H2 Comp.)	X	X	X	X	X	X	X
NO		X	X	X	X	X	X
NO2			X	X
SO2				X	X
CO high)						X*
CO very high							X*

* Requires low range CO sensor purging (for protection against high CO in sample gas.

Technical Specifications

Measured Value

SIGMA

Electrochemical Sensors

O₂

Range	0 – 21.0 Vol-%
Accuracy	± 0.2 Vol-% abs.

CO (H₂ Comp.)

br> 10 % reading > 4,000 ppm

Range	0 – 4,000 ppm, overload up to 10,000 ppm
Accuracy	± 20 ppm or 5 % reading ≤ 4,000 ppm

CO high (option # 61506)

Range	0 - 4,000 ppm, overload up to 20,000 ppm
Accuracy	± 100 ppm or 5 % reading ≤ 4,000 ppm 10 % reading > 4,000 ppm

NO (option # 61505)

Range	0 – 1,000 ppm, overload up to 5,000 ppm
Accuracy	± 5 ppm or 5 % reading ≤ 1,000 ppm 10 % reading > 1,000 ppm

NO₂(option # 61507)

Range	0 - 200 ppm, overload up to 1,000 ppm
Accuracy	± 5 ppm or 5 % reading ≤ 200 ppm 10 % reading > 200 ppm

SO₂ (option # 61508)

Range	0 - 2,000 ppm, overload up to 5,000 ppm
Accuracy	± 10 ppm or 5 % reading ≤ 2,000 ppm 10 % reading > 2,000 ppm

Stack gas temperature TA

Range	0 - 650 °C using stainless steel sampling tube
Range	0 – 1,100 °C using Inconel steel sampling tube
Accuracy	± 2 °C ≤ 200 °C 1 % reading > 200 °C

Combustion air temperature TL

Range	0 - 100 °C
Accuracy	± 1 °C

Draft

Range	± 100 hPa
Accuracy	± 0,03 hPa or 1% reading

Differential pressure (option #61509)

Range	± 100 hPa
Accuracy	± 0,03 hPa or 1% reading
Calculated values	(depend on fuel)

CO₂

Range	0 - CO2 max
Accuracy	± 0.3 Vol-% abs.

Dewpoint

°C

Losses qA

0 – 99.9 %

Efficiency ή

0 - 120 %

Measured values as

mg/Nm3, referenced to O2 , mg/KWh, NOx as mg/Nm3 NO2

General Specifications

Operation temperature

+ 5 - + 45 °C, max. 95 % humidity, not condensing

Storage temperature

- 20 - + 50 °C

Power supply

internal: 4 x Mignon NiMh battwery, 8 h operation external: universal grid power, 90 - 260 Vac / 6 - 9 Vdc

Weight

approx. 2.6 lbs (1.2 kg)

Dimensions

3” x 8 ¼” x 2” (80 x 210 x 55 mm) ( W x H x D)

ELECTROCHEMICAL CELL OPERATIONAL PRINCIPLE

The measurement principle of the analyzer is based on electrochemical cell (EC) technology. Temperatures are measured by Type K (NiCrNi) and Platinum RTD PT 2000 thermocouples.

The oxygen content of the sample gas is measured with a 2 electrode electrochemical sensor. Toxic gases like carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and hydrogen sulphide (H₂S) are measured with 3 electrode sensors.

Electrochemical sensors operate based on gas diffusion technology, the advantage of which is that the signal generated is directly proportional and linear to the volume concentration (% or ppm) of the analysis gas components.

The 3 electrodes are: S (sensing electrode), C (counter electrode) and R (reference electrode).

Item   1 Sample gas 2 Particle filter 3 Sensing electrode 4 Reference electrode 5 Counter electrode 6 Contact pin 7 Electrolyte reservoir 8 Bilk electrolyte 9 Capillary diffusion barrier

When the gas being measured contacts the sensing electrode, it reacts on the electrode surface either through oxidation (for example CO, H₂S, SO₂, NO, H₂) or reduction (like CO, H₂S, SO₂, NO, H₂)

CO sensor example:

CO reacts at the sensing electrode as follows:

CO + H₂O -> CO₂ + 2H⁺ + 2e^-

and at the counter electrode, oxygen from air will be re-oxidized to water:

½ O₂ + 2H⁺ + 2e^- -> H₂O

The current generated (A-range) is measured and analysed by the microprocessor.

NOTE: Electrochemical sensors must be re-hydrated with ambient air after measurements, and thus are not suitable for continuous measurements.

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