Fire and Explosion prevention
Safety is always at the top of our customers’ priorities. Risks in process operation are usually identified during HAZOP assessments and mitigation strategies put in place. Process gas measurement can form an important role in providing advance warning of a hazard developing.
Oxygen, Fuel and Heat
Carbon Monoxide (CO) measurement provides an indicator of the onset of combustion. It is the primary product of combustion of a carbon based fuel – colourless and odourless, and the true indicator that conditions for combustion have been met.
The heat and fuel conditions for fire propagation may always be present in certain processes. In these cases, oxygen (O2) measurement provides assurance that combustion or explosion conditions are not met.
In addition, LEL measurement of key compounds or general VOC measurement provides indication of the fuel element of the combustion triangle.
In cases, where the hazard has a defined probability of being present, measurement systems may be required to use ATEX certified equipment as part of the measurement systems. ATEX certified equipment can be deployed when a hazard is assessed to remove, contain or nullify the ignition source. For gas analysis systems, this may include ATEX certified sample probes, sample lines, filters, pumps, flow meters and gauges as well as certified sensors or analysers.
Occupational Health
Assessment and control of exposure to substances hazardous to human health is paramount to safe working. The UK HSE provides accessible and detailed guidance for operators to refer to. It is an ongoing area of research and improvement, and as we learn more about potential hazards, develop innovative processes and use a wider range of materials, there is a need for instrumentation to provide the early warnings of exposure. As the knowledge grows, then more innovative and sensitive detection and measurement techniques need to be deployed to assess these hazards in greater detail.
Exposure to respirable dusts can lead to long-term chronic health issues as well as acute harm. The mechanisms of harm are becoming better understood after many years of observations. New mitigation measures can now be applied by Operators and their operational efficiency can be assessed by ambient particulate monitors. These instruments can provide information continuous information about changing respirable dust concentration and in some cases classify concentration into the different size fractions – PM1, 2.5. 10 or even greater detail.
Harmful process gases maybe present at negligible, low or elevated levels as a normal condition of operation. These may rise suddenly to more harmful levels under upset conditions like leakages or the risk amplified in confined spaces. Good general protection maybe afforded by deploying personal gas detectors, worn on the body of the worker, or placed in the working vicinity, during day to day operations.
Where personal gas detection is not deemed to be sufficient or reliable, because of lack of sensitivity, selectivity or specificity, then the sensing technique may need to be upgraded to that which is usually reserved for gas analysis.
FID, TDLAS, QMS can all be deployed to detect general or specific compounds.
Gas Detection
Is it safe to enter? Red light or green light?
Gas Detection systems usually consist of one or many fixed sensors which will rapidly respond to a rising or falling concentration and a way of raising an alert. They provide the instant signal for operators that a threshold has been crossed and give a “GO / NO GO” decision.
For the systems to be reliable, consideration of the chemical and physical properties of the hazardous components need to be assessed. What is the relative buoyancy of the hazard, does it rise or fall – sensors need to be in a representative position and reflect potential hazards.
Modern networking and communication protocols can simplify the connectivity of arrays of sensors, improving installation and wiring burdens. Smart controllers and annunciation can alert operators locally and remotely according to working practice.
Typical sensors can be general LEL and PID sensors, or selective for individual gases like CO, O2, CO2, NH3, NO, NO2, N2O, C2H4, H2, EtO, Cl2, HCHO, HCN, H2O2, H2S, So2, silane, benzene and specific refrigerants.
