Monitoring of Gas Levels in General Safety Applications with the IR1-Series

The IR1xxx and IR2xxx Series 2 sensors deploy the established non-dispersive infrared (NDIR) principle for monitoring and detecting the presence of gases. With an infrared source and specific filtering on the pyroelectric detectors mounted in the gas it is possible to identify individual gases or gas types and determine their concentrations.

The IR1xxx Series 2 is suited for consistent monitoring of gas levels in general safety applications where the size of the infrared sensor is limited and there is a need for flameproof/explosion - proof certification. They are similar to the IR1xxx Series however offer additional extras:

  • There are two height options - 16.6mm (code M) and 19.0mm (code J) for versatile fitting into instrumentation
  • An extra pin-out is provided for an embedded temperature sensor. They are classified into - thermistor (code E) with non-linearised output, or IC (code G) with linearised output
  • New dual-packaged IR detectors enable higher accuracy when compensating for changes in ambient conditions
  • Shock-resistant lamp version is offered for improved reliability in portable applications - IR11GM_1 and IR12GM_1.

The IR2xxx Series 2 and IR1xxx Series 2 share an identical design and performance standard as the IR1xxx Series 2, but are symbolized as being highly safe for methane monitoring in mining applications.

Key Features

The key features of the IR1 Series are:

  • They are configured for carbon dioxide (IR11EJ, IR11GJ, IR11EM, IR11GM, IR11GM_1, IR21EJ, IR21GJ, IR21EM, IR21GM) and hydrocarbons (IR12EJ, IR12GJ, IR12EM, IR12GM, IR12GM_1, IR22EJ, IR22GJ)
  • Sensing ranges: 0 – 0.5%, 0 – 2%, 0 – 5% vol. conc. For CO2, 0 – 100% LFL (0 – 100% vol. conc.) for hydrocarbons
  • Diffused gas sampling via mesh
  • Low power
  • Reference channel for self- compensation
  • Embedded temperature sensors - thermistor or linearised IC options
  • Special gold plated optical/gas cavity for stable signal levels
  • Operational in varying ambients of temperature, pressure and humidity
  • Fast response
  • Rugged stainless steel construction
  • Shock-resistant lamp version available
  • Low maintenance
  • Suitable for fixed or portable instrumentation
  • No moving components
  • Resistance to corrosion
  • Two size options to complement miniature catalytic and electrochemical gas sensors
  • Immunity from ‘poisoning’
  • Reliable fail-safe operation
  • Series expandable to other gases and concentration ranges
  • ATEX certified II 2G Ex d IIC Gb (IR1xxx Series) (Ta = -20 to +55 °C)
  • ATEX certified I M1 Ex ia I Ma (IR2xxx Series) (Ta = -20 to +60 °C)
  • IECEx certified Ex d IIC Gb (IR1xxx Series) (Ta = -20 to +55 °C)
  • IECEx certified Ex ia I Ma (IR2xxx Series) (Ta = -20 to +60 °C)
  • CSA certified - File 107498 (IR1xxx Series )
  • UL recognised - File E186043 (IR1xxx Series)

Operating Principle

In order to function as NDIR gas sensors, the IR1xxx and IR2xxx Series 2 need to be interfaced to a suitable transmitter for power supply and in order to process and amplify signals. Sensor outputs need linearization and compensation for ambient temperature variation using algorithms in the system software.

This is required so that sensors satisfy their full performance specification. This compensation is also facilitated with the embedded temperature sensor. Further compensation for pressure changes can also be done using in an algorithm, provided there is a suitable input from a pressure sensor.

IR1xxx Series 2

  • SIRA Certification Services, EU Notified Body No. 0518, have certified the IR1xxx Series 2 under the ATEX Directive, 94/9/EC, and the IECEx Scheme.
  • Certificate number SIRA 99ATEX1121U certifies it as a flameproof component to EN60079-0:2006 (including amendments A1 and A2) and EN60079-1:2007.
  • Instructions specific to dangerous area installations apply.
  • Certificate number IECEx SIR 04.0031U certifies it as a flameproof component to IEC60079-0 Ed. 5 and IEC60079-1 Ed. 6.
  • A component certification has been issued by the Canadian Standards Association for the IR1xxx Series 2 for use as part of an intrinsically safe portable combustible gas detector or housed in a remote sensor housing.
  • It meets the requirements of CSA standard C22.2 No. 30-M 1986. File No. 107498.
  • Underwriters Laboratories Inc. identify the IR1xxx Series 2 as components in intrinsically safe single- or multi-gas detectors for use in Class 1, Division 1, Groups A, B, C and D hazardous locations.
  • It has satisfied the requirements of UL913, fifth edition. File E186043.

IR2xxx Series 2

  • SIRA Certification Services, EU Notified Body No. 0518, have certified the IR2xxx Series 2 under the ATEX Directive, 94/9/EC, and the IECEx Scheme.
  • Certificate number SIRA 02ATEX2015U certifies it as an intrinsically safe component for mining applications, category M1, to EN60079-0:2006 (including amendments A1 and A2), EN60079-11:2007 and EN50303:2000.
  • Instructions specific to hazardous area installations apply.
  • Certificate number IECEx SIR 03.0003U certifies it as a flameproof component to IEC60079-0 Ed. 5 and IEC60079-11 Ed. 5.

Handling Precautions

Handling precautions include the following:

  • The sensors must not be allowed to fall to the floor. This may result in lamp filament breakage, damage to the pins and the gas entrance aperture.
  • Mechanical force should not be applied against the gas entrance aperture.
  • Sensors must not be immersed in water or other fluids.
  • Protect the gas entrance aperture against dust ingress and sprayed materials.
  • Anti-static handling precautions must be taken.
  • Under no circumstances should the sensor pins be soldered directly to a pcb or wires. Excessive heat could cause irrepairable damage to the pyroelectric detectors.

Fractional Absorbance Curves

Carbon Dioxide (0 - 0.5% vol. conc.)
Carbon Dioxide (0 - 2% vol. conc.)
Carbon Dioxide (0 - 5% vol. conc.)
Methane (0 - 5% vol. conc.)
Propane (0 - 2.5% vol. conc.)
Methane (0 - 100% vol. conc.)
Ethylene (0 - 3% vol. conc.)

Instructions Specific to Hazardous Area Installations

(Ref. EU ATEX Directive 94/9/EC, Annex II, 1.0.6)

  • The IR1xxx Series 2 and IR2xxx Series 2 Gas Sensing Heads are component-approved only and should not be used independently in a hazardous area without further protection.
  • The IR1xxx Series 2 and IR2xxx Series 2 Gas Sensing Heads must be protected during operation.
  • The Sensing Head shall be mounted in a protective enclosure such that an impact of 7J in accordance with EN60079-0:2006 clause 23.4.3.1 from any direction should not cause the impact head to make contact with the Sensing Head.
  • The thermal resistance of the IR1xxx Series 2 and IR2xxx Series 2 Gas Sensing Heads should not be more than 25K/W; this shall be accounted while considering its surface temperature and the temperature classification of the equipment into which it is to be incorporated.
  • The IR1xxx Series 2 and IR2xxx Series 2 Gas Sensing Heads have not been examined as a safety device (EHSR 1.5).
  • The component does not have any user-serviceable parts
  • The end-user or the installer should know the certifications of the IR1xxx Series 2 and IR2xxx Series depends on the following materials used during construction:
    • Enclosure ............................................. Stainless steel
    • Mesh ................................................... Stainless steel
    • Bushing ................................................ Epoxy resin
  • The IR1xxx Series 2 Gas Sensing Head is only certified to be used in ambient temperatures between -20 and +55 °C and must not be used outside this range.
  • The IR2xxx Series 2 Gas Sensing Head is only certified for use in ambient temperatures between -20 and +60 °C and should not be used outside this range.
  • The maximum input power of the IR1xxx Series 2 Gas Sensing Head should not be more than 2.5W.
  • The IR2xxx Series 2 is a galvanically isolating device with infallible separations between the detector and lamp circuits up to 10V.
  • The IR2xxx Series 2 has the following safety description:
    • Lamp Circuit: ........................................ Ui = 7.2 V
    • Detector Circuit: ................................... Ui = 10 V
    • Lamp + Detector Circuits ........................ Pi = 2.71 W
    • Detector Circuit .................................... Pi = 1.2 W
  • The IR2xxx Series 2 Head is dust-proof (IP5x) however offers no protection against the ingress of water. In cases where protection over IP50 is required, the apparatus into which the IR Head is installed will offer the necessary ingress protection.

Technical Specifications

The technical specifications are provided in Table 1

Mechanical
Body material stainless steel
Weight 21 g (code M), 24 g (code J)
Environmental
Ambient temperature range:
for operation for storage
Operational pressure range

-30 to +75 °C -40 to +85 °C
700 to 1300 hPa
Humidity range for operation and storage 0 to 95% non-condensing
Vibration complies with EN61779-1
Ingress protection requires extra protection depending on application
Electrical
DC supply to detectors +3 to +10 V (code G); +3 to +15 V (code E); +5 V recommended
Maximum power supply 180 mW
Lamp supply 3 to 5 V (60 mA), modulation 4 Hz, 50% duty cycle recommended Note: Applying >5 V will reduce the lamp lifetime
Warm-up time <20 s to operate, <30 min. to full specification at 20 °C

Performance Characteristics

All measurement data taken using:

  • SGX Sensortech linearisation and temperature compensation algorithms;
  • Lamp modulation 0.4 -- 5.0 V, square wave, at 4 Hz and 50% duty cycle.
  • Ambient temperature (20 °C) and pressure (1010 hPa).
  • All gases diluted in nitrogen.

This is shown in Table 2.

Sensor type IR12EM/IR12GM, IR12EJ/IR22EJ, IR12GJ/IR22GJ IR11EJ/IR21EJ, IR11GJ/IR21GJ, IR11EM/IR21 EM, IR11GM/IR21GM
Gas Methane Carbon Dioxide
Concentration range 0 - 5% vol. 1 0 - 100% vol. 0 - 0.5% vol. 1 0 - 2% vol. 1 0 - 5% vol.
Maximum response time <20 s
Limits of detector output voltage in nitrogen:
active channel
22 - 65 mV 12 - 36 mV
reference channel 9 - 29 mV
Typical % fall in active detector voltage for exposure to stated target gas (reference detector is unchanged) 12% 48% 11% 18% 22%
Sensitivity to gas over full concentration range (before linearisation) see Fractional Absorbance Curves
Maximum deviation from linearity 0.1% 1 1% 0.015% 0.1% 0.2%
Maximum variation of zero from -20 to +55 °C ±20 ppm/°C ±10 ppm/°C
Maximum variation of span from -20 to +55 °C ±0.3% vol. not available ±0.15% vol. ±0.8% vol.* not suitable
Typical resolution 0.01% 1% 0.003% vol. 0.01% vol. 0.03% vol.
Short-term drift on zero/8 hr at 20 °C ±0.01% vol. ±0.003% vol.
Short-term drift on span/8 hr at 20 °C ±0.15% vol. not available ±0.01% vol. ±0.05% vol. ±0.15% vol.
Long-term drift/month (zero) ±0.01% vol. ±0.003% vol.
Long-term drift/month (span) ±0.05% vol. not available ±0.012% vol. ±0.05% vol. ±0.20% vol.
Maximum response to 0 -- 90% change in RH at 20 °C (in target gas) ±0.25% vol. ±1.5% vol. Negligible
MTBF (lamp dependent only) >10 years for 5 V operation, >20 years for 3 V operation

Outline of the Sensor

Certain points to keep in mind include:

  • Body dimensional tolerances ±0.1 mm. Pin dimensional tolerances as indicated
  • For code J devices, this length is 19.0 mm; for code M devices it is 16.6 mm
  • IR1xxx Series 2 and IR2xxx Series 2 sensors are designed to press-fit into pcb sockets. The end-user should choose a socket to accommodate the full sensor pin length.
  • This will make sure a stable mechanical location as well as good electrical contact.
  • e2v technologies suggests the Wearns Cambion type 450- 1813-01-03-00 single-pole solder mount socket with through hole, or a suitable equivalent.

 

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