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10 Gas Detection Flexible Gas Monitoring

The X-zone 5000 from Dräger (Germany) combines the advantages of mobile and stationary gas measurement, making it ideal for situations with increased security needs - for example for maintenance of industrial plants. The monitoring device is placed at locations where a gas leak is likely to occur. It can constantly monitor these areas and provide a pre-warning before sending people to a danger zone. The X-zone 5000 itself cannot measure the gases. For gas measurement, the portable gas detector in the size of a mobile phone , the X-5000, is plugged into the field monitor and communicates with it automatically. This way, the X- 5000 detects up to six explosive, flammable or toxic gases and warns if one of them is present in the ambient air. This particular type of device combination is patented by Dräger.

The X-zone 5000 works without an external power supply and without interruption for up to 120 hours. It can take in gases from all sides and warns both optically and acoustically within a radius of 360 degrees. Even in noisy and confusing areas, the alarms of 108 decibels can be perceived clearly. In comparison: a starting airplane reaches a volume of about 120 decibels.

The Dräger X-zone 5000 monitors a perimeter of approximately 25 meters. The user can expand this radius greatly by interlinking multiple devices, via a wireless connection or cable. Up to 25 field monitors automatically connect to form an ’alarm chain’ and exchange information over a distance of up to 100 meters. In case of danger, the detecting device sends its signal to the connection network, causing all devices to sound the alarm. The source of danger is easily identified: the triggering device glows red, the other devices are red and green.

To monitor the air in tight and small spaces such as industrial tanks, the X-zone 5000 has a pump that supplies the air from the respective container, with the

monitoring device inside the container sending alarm signal to a device stationed outside. Besides its own warning, the X-zone5000 can also trigger alarms in other danger areas allowing the device can initiate security measures, such as switching on a ventilation system.

The X-zone 5000 includes a Zone 0 hazardous approval and can therefore be used in the explosive environments. It works in temperature ranges between -20 degrees C and +50 degrees C, and operates in accordance with IP 67 certification resistance to dust and water.

The X-zone 5000 is capable of working on battery power without interruption for up to 120 hours. If you do not change the workspace of the device, no calibration or adjustments are required. The device is then tested once before first-time use with the help of the bump test station or the workshop Solution E-Cal.

Reader Reply Card No. 22

New Developments for Photo Ionisation Detector

Pathfinder Fixed Gas Detection System Transmitter

he IR-29 fixed gas detection system transmitter from GfG utilises an innovative closed-path infrared gas detection technique for integrated general hydrocarbon, volatile organic chemical (VOC),

carbon dioxide (CO2), and water vapour measurement. Transmitters can be configured for measurement of a single hazard; or the transmitter can be equipped with multiple detectors that allow the transmitter to measure and interpret readings for multiple hazards at the same time.

The patented GfG (Germany) infrared detection technique includes use of a highly efficient gold film mirrored surface overlaid on the inner walls of the optical sensing chamber. The infrared light used to provide gas measurements

is automatically focused as a function of the configuration of the walls of the chamber directly on the signal detectors, omitting the need for lenses, optical splitters and parabolic focusing mirrors.

Alphasense (UK), an independent gas sensor technology company, has been working with Owlstone to apply their Advection Diffusion Spectrometry (ADS) technology for chemical detection, on a new development based on the Alphasense PID modules giving enhanced selectivity through the use of the Ion Mobility Spectroscopy (IMS) - ADS technology.

Utilising existing PID technology and linked to a sensor module that has been produced featuring a chip, fan for gas sampling, the micro-controller with associated electronics uses UV as the preferred ionisation source. The sensor module/chip, has embedded firmware, is mounted to a rigid circuit board as part of the newly developed Owlstone IMS- ADS module.

Gas flow through the chip must be regulated and at least two signals will be output (peak height and peak width), a third signal (kurtosis) is possible but will require additional work to the sub-module. Signal outputs could be analogue, PWM or serial. End-users will have no need to see raw spectra, as all processing will be performed on-board.

Arthur W Burnley, Sales and Marketing Director for Alphasense, stated, “Successful development of this new sensor technology will open a range of exciting commercial opportunities for Alphasense. We are very happy to be working with Owlstone in what will prove to be a mutually rewarding partnership, and we are anticipating that this device will be available for sale in Q3 of 2011. Alphasense is a centre of excellence for gas sensor technology and the PID-Plus is just one of several new and exciting product introductions planned for 2011. Further developments from Alphasense include expansion of our existing NDIR, Catalytic and Electro-Chemical sensors (measuring as low as 10ppb) plus the addition of Mixed Metal Oxide sensors and more.”

Reader Reply Card No. 25

Lenses, optical splitters and focusing mirrors are a potential source of noise in an optical measurement system. They are also very expensive hardware components that increase both the size and price while reducing the signal strength of the detector. Removal of these expensive components reduces the price while substantially improving the performance of the IR-29 compared to other infrared transmitter designs. Removal of these elements also permits significantly lower step-change resolution for the measured gases, allowing the compact IR-29 to provide readings of VOC and hydrocarbon gases from the low parts-per-million range, through the explosive range, and all the way up to 100% volume concentrations.

The inclusion of multiple detectors and the ability to discriminate between infrared absorbance at multiple wavelengths substantially increases the specificity and quality of readings. While the sensitivity of the IR-29 to methane and propane is excellent, the sensitivity of the transmitter to toxic VOCs and large hydrocarbon molecules is even better than its sensitivity to methane.

As the detection technique is based on infrared absorbance, the IR-29 does not require the presence of oxygen to detect gas, can be used for high range measurement up to 100% volume gas, and is not subject to damage due to exposure to sensor poisons such

as H2S or atmosphere contaminated with silicone vapours. The IR-29 is extremely stable and maintains calibration and accuracy for long periods of time without needing adjustment. The IR-29 has no elements that deteriorate in normal operation and so can be expected to last for many years in continuous operation.

Reader Reply Card No. 23

Safe, Accurate and Simple Methane Leak Detection

Sensit’s (USA) Portable Methane Detector (PMD) is fast becoming an industry standard for Master Meter Operators, Leak Survey Contractors and Natural Gas Distribution and Transmission companies carrying out above ground leak surveys and below ground leak pinpointing and vehicle leak surveys. This unit can also carry out Bar Hole Tests and Tick-Style leak detection.

Sensit’s PMD has an exceptionally high sensitivity and can detect a leak at 1 ppm – allowing you to detect the leak faster and easier. The instrument’s large, graphic display, with automatic backlight sensor, is easy to read. The PMD includes a powerful 1.5 liter per minute pump to allow for rapid sensing. This instrument is methane selective, its can filter out other gases within the ppm range, allowing it to do its job and not allow other gases to contaminate the instrument’s readings.

The PMD is intrinsically safe, it can be used both indoors and outdoors. This flexible instrument allows for walking or vehicle operation, it has an easy connection for auxiliary pumps to allow for mobile measurements. Users will also appreciate the simplicity of calibrating the PMD, using Sensit’s Smart-Cal Calibration Station.

Reader Reply Card No. 24

AET October / November 2011

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