Gas Detection from Past to Present

Testing for gasses has come a long way since the days when Victorian miners would take a canary down a mineshaft as an early warning indicator of toxic gases such as carbon monoxide, methane or carbon dioxide.

The 19th Century scientist John Scott Haldene investigated mine explosions, which spurred him on to experiments with animals. He demonstrated that canaries show signs of distress when breathing in carbon dioxide.

This led to the Coal Mines Act 1911 which made it mandatory to use canaries in mines and surprisingly, this practice continued in Britain until 1987 by which time more sophisticated methods and testing equipment had been developed.

Fast forward to the 21st Century and gas detection equipment has evolved beyond recognition as modern-day gas leakage detectors, flue gas analysers and intrinsically safe testing equipment.

Gas leakage detectors

The most common form of gas leakage detector is for combustible gasses and start from as low as £40 for occasional testing equipment.

For example, the Extech FG100 Combustible Gas Leak Detector will test for combustible gases like liquefied natural gas (LNG) and liquefied propane gas (LPG) from 500 to 6,500 parts per million (ppm). Featuring sensitive detection circuitry, it provides both audible and visual alarms with continuous operation up to four hours and has separate LED indicators for gas leakage and static electricity.

For more intensive use by gas or HVAC professionals, the Kane LS1/B Leak Seaka combustible gas leak detector detects any combustible hydrocarbon gas in concentrations above 10 ppm. A long flexible gooseneck probe with illuminated tip can be manoeuvred into difficult to access spaces. A built-in thumbwheel allows the user to filter out the effects of background gas, locating the leak source in under one second. The sensitivity of the instrument may be adjusted to maintain accuracy.

At the top end of the market for gas leakage detectors is the Testo Gas Detector which measures natural gas, methane and propane limits with instant audible response if lower explosion limits are reached. Gas concentrations are measured by a semiconductor sensor and displayed to a resolution of 1 ppm.

Flue gas analysers

New Flue Gas Regulations came into force in April 2014 to measure and record the carbon monoxide (CO) level in the flue gas when a condensing boiler is commissioned. The CO level in the chimney flue gases and the combustion (CO/CO2) ratio is measured by using a flue gas analyser.

Starting with the Anton Sprint eVo 1 Multifunction Flue Gas Analyser, the Anton Sprint eVo range features advanced menu driven software to produce a total of 10 separate reports which can be printed on site, including flue gas analysis, differential temperature, let-by/tightness test, working pressure, operating pressure and five separate CO room safety test reports in according to BS7967. Printouts include serial number and calibration due date for the instrument used to carry out the test.

At the middle of the range, the Kane 450 commercial and domestic boiler analyser performs all combustion, temperature, pressure and CO tests needed on all boilers including high efficiency boilers, with an optional gas leak-detection wand. A simple rotary switch dial allows quick changes to settings to perform tests on different kinds of gases. Infrared output allows instant printing of information on a thermal printer, while torchlight facilitates testing in areas of low lighting.

At the top end of the range, the Testo 320-2 flue gas analyser kit has a wide measurement range for eliminating malfunctions and emergencies, monitoring legal limit values or for daily routine work when servicing heating systems. The testo 320 has two measurement sensors for O2 and CO, as well as a temperature sensor integrated into the flue gas. It calculates all relevant flue gas measurement parameters such as CO2 value, degree of effectively and flue gas loss. Direct draught or pressure measurements are additionally available. It offers several measurement menus, for example for flue gas, draught, differential pressure and ambient CO measurement.

Intrinsically safe testing equipment

Testing for gasses is one thing, but where explosive gasses are routinely present, it makes sense to use intrinsically safe testing equipment. Intrinsic safety devices are purpose built to stop potential dangerous sparks or other damaging heating effects when working in volatile environments. These tools are essential for those who work in hazardous environments such as gas platforms.

For example, the Fluke 725Ex intrinsically safe multifunction process calibrator has full certification for testing machinery in explosive atmospheres. It is also compatible with Fluke’s range of 700PEx pressure modules which are also made for use in explosive gas environments, which enable pressure measurements to 300 psi or 200 bar, allowing calibration of pressure transmitters. A pressure switch test function is also included which allows capture of sets, reset and deadband values.

Similarly, the Beamex MC2-IS Intrinsically Safe Calibrator connects to almost 20 available Beamex intrinsically safe pressure modules. It can be used in combination with various appliances and systems to measure pressure, current, voltage and frequency with built-in voltage, frequency and pulse generation plus mV measurement/simulation, resistance measurement/simulation, RTD measurement/simulation and TC measurement/simulation.

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