Posts Tagged ‘ lower explosive limit ’

List of Safety Precautions for Shutdown Activities of Chemical Plants

safety precautions for shutdown activities of chemical plantsThere are two kinds of chemical plant shut down, i.e. planned shutdown and emergency or unplanned shutdown. An example of planned shutdown is as preparation for Turn Around or yearly preventive maintenance programs. Emergency plant shutdown can be triggered by many factors, such like electric power failure, machinery failure, instrumentation trouble and many more.

In both shutdown cases, there are safety precautions for shutdown activities of chemical plants that need to be taken into account. Such safety precautions are required to prevent potential hazards that commonly appear during plant shut down.

In fact, many people may underestimate chemical plant safety in shutdown condition. Of course there may no pumps running, no reactions occur or production process. But various potential hazards such as over pressure, fire and explosion still exist, which could present real danger to the plant and people inside it. (more…)

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Understanding LEL of Common Combustible Gases

by Lukman Nulhakiem

LEL-of-common-combustible-gasesThere are many common combustible gases found in chemical plant. These combustible gases have one similarity. They can be ignited when their concentration in air are within their flammability limits.

What are flammability limits? Flammability limits or commonly known as explosive limits are defined as concentration of combustible gas in mixture with air in which they can be ignited and exploded in the presence of source of ignition.

The lowest concentration of a combustible gas in mixture with air where it still can be ignited is called by Lower Explosive Limit (LEL) or Lower Flammable Limit (LFL). Whereas, the highest concentration of a combustible gas in mixture with air where it still can be ignited is called by Upper Explosive Limit (UEL) or Upper Flammable Limit (UFL). (more…)

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Combustible Gas Detectors – Overview

Combustible gas detectors are ones of the basic safety equipments required when there is combustible gas inside the plant site. Auto-ignition temperature and Lower Explosive Limit (LEL) describe the potential dangers of combustible gases.

Auto-ignition temperature is the lowest temperature at which combustible gas could be ignited spontaneously (self-sustained combustion), without the presence of source of ignition. Meanwhile, Lower Explosive Limit or LEL is the lowest concentration of combustible gas in the air that will propagate flame when exposed to a source of ignition.

There are two types of combustible gas detectors in market. The first type is electrocatalytic (catalytic bead), which is also referred to passive type of gas detector. The second type is infrared detector, which uses infrared absorption as detecting technology. It is the active type. (more…)

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