| |
|
 |
Catalysts are like some ten year olds.
They never get into trouble. It is just
that wherever they go, intensity of
activity increases. |
|
Causes of fire -
|
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Ignition caused by uncontrolled acceleration
of an initially slow oxidation reaction. |
|
Oxidation
can lead to ignitions when heat of reaction
cannot be dissipated. |
|
Presence
of metallic swarf in oil rapidly accelerates
oxidations - leading to ignition. |
|
A
serious problem in lubricating reciprocating
compressors is the formation of carbonaceous
deposits on the valves in the air discharge
system, on the inter coolers and after
coolers and also in pubation dampers.
Not only does this reduce the efficiency,
but is now generally accepted as the
major cause of fires and explosions
in compressor systems. Any malfunctioning
of valves, cooling systems, etc. leading
to high air discharge temperature could
suddenly bring a previously passive
carbonaceous deposit into a critical
explosive condition.
|
|
Flash
point of an oil only indicates the rolability
of the lighter components, but giving
little or no indication of the extent
of rolability of the higher ends. It
is therefore of little guide by itself
to suitability of the oil for air compressors. |
|
|
|
For
an oil to pass as rapidly and completely
as possible through the high temperature
zone, it is clear that the lowest viscosity
grade consistant with the lubrication
requirements and the minimum of heavy
ends should, in principle, be chosen. |
|
Rust
catalyses oxidation. |
|
In refrigeration compressors: |
| |
| Carbonic acid
formed by reaction between CO2
and H2O can corrode or rust metals. |
| Ammonium Hydroxide
NH4OH from H2O and NH3 is specially
active towards copper and brass. |
| Sulphur and
sulphuric acid are active towards
most metals. |
| Organic halids
may be hydrolyzed to form halogen
acids attacking most metals. |
| CO2 AND NH3
have negligible solubility in
lubricating oils. |
| Iron and methyl
chloride have high solubility
in lubricating oils. |
|
|
In gear systems: |
| |
Antifoam additives promote disruption
of bubble films promoting collapse of
foams and escape of air thus released
(through breather). However, some antifoam
additives tend to retard release of
air submerged in the body of the oil
thus increasing the volume of air in
circulation. With increase in pressure
the entrained air can cause pitting
of ger surfaces. |
| |
If
silicons are used in excess they affect
air release property of oils. |
| |
Zinc
soaps are very effective emulsifiers
and the metal itself, in the form of
galvanized plating reacts readily with
organic acids. For this reason, galvanized
plating should never be used in lubrication
system. |
| |
Free
water, if present in oils is known to
remove some of the rust inhibitors from
the oil. |
| |
Dissolved
free water can cause significant reduction
in the fatigue life of ball bearings
and stressed alloy steel components.
Tests have shown that 0.01.1 of dissolved
water in a lubricant decreases the fatigue
life by 32-48.1 which is relevant for
installations in ball bearings and gears. |
|
Any
communication from management down the
line should aim at AIDA model - |
| |
| Gain attention. |
| Hold interest |
| Arouse desire
and |
| Elicit action |
|
|
Care of Coolants |
| |
| Add oil to
water with continuous stirring. |
| Make up the
emulsion strength periodically. |
| Monitor and
control pH of emulsion. |
| Do not use
hard water. |
| Remove chips
and fires periodically. |
| Aerate emulsion
periodically. |
| Keep emulsion
under circulation during machine
downtime - weekends. |
| Clean system
while changing it. |
| Add bactericide
when required. |
|
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