Beschreibung
Gas analysis based on the NDIR technique is an established method to determine the concentrations of gases in complex mixtures. The RITTER »MultiGas« sensors use new optical components for optimal analysis results: Up to 3 optical filters analyse the gas which flows through the sensor as one gas stream. The optional oxygen, pressure, and humidity sensors are in-line with the same single gas stream.
The individual internal modules are sealed by means of O-ring connections.
In order to achieve an optimum adaptation to the required measuring range, the lengths of the modular measurement cells (= cuvettes) can be implemented in the range of 5 mm (large measurement range in percentage level) up to 250 mm (small measurement range in ppm level).
Cuvettes with a length ≥ 20 mm are coated with a resistant gold layer in order to improve the reflection properties for low concentration level detection. Cuvettes used with aggressive gases are gold-coated as well.
The other internal mechanical parts are made out of aluminium, optionally out of stainless steel.
For fast response applications the measuring system delivers a stable result within t90 ≈ 3 seconds.
The entire unit can be disassembled for easy maintenance/service.
Anwendungen
Specifications
General features
| Messverfahren: | Innovative NDIR Sensor (non-dispersive infrared sensor) |
| Detectable gases: | CO2 CO N2O CH4 CnHm* CF4 SF6 H2O |
| Number of simultaneously detectable gases: | max. 3 per sensor unit |
| Measurement ranges: | See below |
| Volumenstrom-Bereich: | 5 ~ 300 ltr/h – For higher flow rates the sensor can be operated in bypass |
| Max. gas inlet pressure: | 300 mbar |
| Pressure loss (without additional optional sensors): | 10 @ 100 / 35 @ 200 / 70 @ 300 (mbar @ ltr/h) |
| Temperature compensation: | Yes |
| Datenerfassungs-Software: | Yes |
| Lifetime of IR radiation source: | > 40 000 h |
| Measurement cuvette: | Aluminium, with measurement ranges ≤1% gold-plated inside |
| Cuvette sealing: | Viton O-ring |
| Gehäuse: | High-quality table-top casing, aluminium |
| Dimensions (W x H x L): | 171 x 86 x 290 mm |
| Gewicht: | approx. 2 kg |
| Gas connections: | PVDF screw-type tube connection for tube Øi 4mm, Øo 6 mm |
Measuring response
| Linearity error: | < ± 1% F.S. |
| Repeatability: | ± 0.5% F.S. |
| Long term stability zero: | < ± 2% F.S. / week |
| Long term stability span: | < ± 2% F.S. / month |
| Temperature influence of zero point: | < 1% F.S. / 10K |
| Temperature influence of span: | < 2% F.S. / 10K |
| Cross sensitivity: | < 2% F.S. |
| Pressure influence: | < 1.5% / 10hPa of reading |
| Aufwärmzeit: | 2 min |
| Ansprechzeit (t90): | ≈ 3 sec |
| Sampling frequency by software: | ≤ 10 Hz |
| Detection limit: | See below |
| Resolution: | 0.5 x detection limit |
| Water vapour: | No influence with measurements of CO2 and CH4 |
Electrical features
| Spannungversorgung: | 24 VDC inkl. Steckernetzteil 100 ~ 240 VAC / 24 VDC |
| Average power consumption: | < 1W |
| Schnittstelle: | USB (standard), RS232 (option) – incl. data transmission cable 1 m |
| Analogue voltage output (option): | 0-2V / 0-5V / 0-10V |
Climatic conditions
| Max. Betriebstemperatur: | +15 ~ +45 °C |
| Storage temperature: | –20 ~ +60 °C |
| Betriebsdruck: | 800 ~ 1200 hPa (mbar) |
| Ambient humidity: | 0 ~ 95% rel. humidity // Condensing inside of sensor must be prevented! |
* Analysis of CnHm*
The calibration of sensors for CnHm will be performed with propane. Aromatic hydrocarbons are also measured but with a different weighting. This means that the sensitivity of the sensor is significantly smaller with these gases than with other hydrocarbons.
Tabelle der Messbereiche
Messbereiche / Messbereichs-Endwert (F.S.) 100 Vol.% 50 Vol.% 30 Vol.% 20 Vol.% 10 Vol.% 5 Vol.% 1 Vol.% 5.000 ppm 2.000 ppm 1.000 ppm 500 ppm 300 ppm 100 ppm 50 ppm 10 ppm CO2 CO N2O CH4 CnHm* CF4 SF6 H2O Messbereiche auf Anfrage
Infrarot-Modul NDIR Ultraviolett-Modul NDUV Ultraviolett-Modul NDUV / UVRAS
* Kalibrierung mit Propan
Table of Detection Limits (= 3 σ) in Percent of Full Scale
Nachweisgrenzen / % vom Messbereichs-Endwert (F.S.) 100 Vol.% 50 Vol.% 30 Vol.% 20 Vol.% 10 Vol.% 5 Vol.% 1 Vol.% 5.000 ppm 2.000 ppm 1.000 ppm 500 ppm 300 ppm 100 ppm 50 ppm 10 ppm CO2 < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,3% < 0,3% CO < 0,2% < 0,2% < 0,2% < 0,2% < 0,2% < 0,2% < 0,2% < 0,3% < 0,5% < 0,5% N2O < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,3% CH4 < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,1% < 0,3% < 0,5% CnHm* < 0,1% < 0,1% < 0,1% < 0,2% < 0,2% < 0,2% < 0,2% < 0,5% < 0,5% CF4 < 0,2% < 0,2% < 0,2% SF6 < 0,1% < 0,1% < 0,1% < 0,2% < 0,5% < 0,3% < 0,3% H2O Messbereiche auf Anfrage
Infrarot-Modul NDIR Ultraviolett-Modul NDUV Ultraviolett-Modul NDUV / UVRAS
* Kalibrierung mit Propan
Definition der Nachweisgrenze
Die Nachweisgrenze ist der kleinste Messwert, der mit einer bestimmten Unsicherheit ermittelt werden kann. Diese Unsicherheit beinhaltet die Auflösung, das Rauschen und die Stabilität des Gassensors für ein bestimmtes Gas und einen bestimmten Messbereich. Zur Ermittlung der Nachweisgrenze werden mehrere Einzelmessungen unter identischen Messbedingungen durchgeführt. Mit den erhaltenen Werten der Einzelmessungen wird die Standardabweichung "Sigma" (σ) berechnet. Die in der Tabelle angegebenen Werte entsprechen dem dreifachen Betrag von Sigma.
Recalibrations
The following recalibration intervals are recommended for IR sensors: