Explosive Air
Have you considered your air compressor as a potential bomb?
If you have not, then you better!
Although air compressors are built to withstand high pressures,
and will have all the necessary relief valves to take care of
normal occurring overpressures, explosion involving fire
propagation is another matter.
How can a fire occur in an air compressor?
In order to understand the phenomenon of explosion, we
have to understand the nature of fire, because, after all, an
explosion is a very rapid propagation of fire.
A fire will only start whenever three conditions are met - fuel,
oxygen and heat.
An air compressor when operating will have a very rich supply of
oxygen already in place - pressurized oxygen.
Where do we get the fuel?
If you use oil lubricated air compressors, the lubricating oil
can become the source of fuel. It can also be in the form of
carbon dust. Carbon is formed when oil is heated to high
temperatures.
How is it possible to have high temperatures to ignite the
combustible mixture?
There can be a lot of reasons - lack of lubrication due to oil
deterioration, reduced lubricating quality of the oil, oil pump
mechanism fault, oil filter choked, worn out parts leading to
lessen oil pressures, etc. Whenever there is a hotspot sufficient
to ignite the combustible mixture an explosion will occur. That
is the extreme case.
Let’s see what can happen that can lead to that extreme case of
an explosion.
All the above reasons for lubrication failure or deterioration
will gradually cause the machine to operate poorly, wear out the
moving parts, cause oil spills and carry over of the oil in the
air passages and increased heat built-up.
Now comes the cooling part. Is there a lack of cooling? If the
high temperatures due to rubbing of parts from the above are not
cooled down sufficiently, the heat will build up. The
intercoolers play a very important role in removing the heat?
There are also many other reasons for the lack of cooling.
When the heat transfer surfaces have been coated by films of
scale or carbon it will definitely affect the cooling process.
The heating surfaces may have been reduced due to choked passages
for the cooling medium in the heat exchanger. The cooling medium
itself may be too hot probably due to a fault in another machine
like the cooling tower where the heat can be taken away to the
atmosphere.
The flow of coolant can sometimes be the culprit. When the
cooling pump fails, or the driving belt snaps there will be a
lack of coolant flow. One must also find out whether the valves
for coolant have been accidentally closed or not.
Very often, the effects build upon one another in a vicious cycle
- poor heat transfer leads to more heat that carbonizes more oil
which coats the heat transfer surfaces more…which leads to
worse heat transfer…
Therefore use oil lubricated air compressors with caution. If
your air compressors have been running for a long time, chances
are, your air compressor pipelines may have already accumulated a
sizable amount of oil carried over together with the air flow
during operation.
Does your air compressor work non-stop? Is the inter-cooler or
the after-cooler efficient? Is your compressed air hot? These are
the questions you have to ask yourself.
The oil film in the pipes turns to carbon with heat. The
oxygen-rich and moist atmosphere inside the pipes can turn the
oil into acids that can further deteriorate the oil to form other
organic compounds, perhaps some highly flammable products.
It just needs a spark or a hot spot to ignite this.
Boom!!
Did I frighten you?
What you need is good preventive maintenance. An air compressor
working at peak condition with good cooling, good lubricating
pressures, and good lubricant and good parts should give
trouble-free performance throughout its lifetime.
Sometimes the compressor may have reached the point of no return
- coated coolers leading to high temperatures that lead to more
coated cooling surfaces that lead to higher temperatures… In
this case it is safer to discard the compressor altogether and
obtain an entirely new compressor unit. It could be more
economical - and safer!
If you do that, do ensure that preventive maintenance is done
regularly to keep the unit at peak operating conditions all the
time.
An explosion in an air compressor can have grave consequences.
Don’t take any chances. Perform regular preventive maintenance or
buy a new unit before an explosion occurs.
Until next time
Locate good air compressors for your garage and workshop here:
Eastwood
Many years of working experience in Marine, Facilities,
Construction has given the author material for writing e-books
and articles related to engineering, and management.
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Tags: air compressor, carbon, compressed air, cooling, explosion, fire, hotspot, lubrication, oil, safety