The presence of oil mist in compressed air is a significant problem. Inhalation of either mineral or synthetic oil can cause respiratory irritation, dizziness, nausea and even unconsciousness. The presence of oil mist results in the pipes of a compressed air system being coated with oil. This increases the risk of fire, especially when used with enriched oxygen, and can be difficult and costly to clean up afterwards.
With the advent of synthetic oils the detection of oil mist has become more difficult. This is ironically due to some of the benefits of using synthetic oils in the first place. The presence of oil vapor mistrackers is much greater. Their higher operating temperatures are less likely and therefore the presence of carbon monoxide is less likely.
Mineral oil is essentially a natural product derived from crude oil. Produced as part of the distillation of crude oil, it comprises a mixture of numerous light oil fractions (typically in the range C15 to C50, alkanes and cycloalkanes).
Synthetic oil is a synthesized product made from methane, carbon monoxide and carbon dioxide. By controlling the quality of the feedstocks and the synthesis process, the oil produced is much more uniform in composition (commonly poly-alpha-olefins or esters) and has fewer impurities than mineral oils. The key benefits are greater resistance to oxidation and thermal breakdown, longer service life, and better chemical and shear stability.
All compressors require lubrication to minimize frictional heating and wear of their moving parts, the majority are oil lubricated. During normal operation, movement of the compressor leads to the deposition of a thin oil. The high speed of motion and the great forces required to compress the air, resulting in some of the oil being atomised. As a result all compressed gas at the output of the
compression chamber wants to contain some oil mist. Under normal conditions this oil mist is then removed by the coolers and filters on the output of the compressor, typically a mixture of coalescing and charcoal filters.
Other sources of oil can be mistaken as the result of filter carry over. Under certain fault conditions the oil collected by a filter is re-atomised back into the air flow.
In the respect of oil mist creation, both synthetic and mineral oils behave much the same way.
A properly maintained compressor should never generate oil above statutory levels in its filtered output.
There are also a number of mechanisms that can cause oil to appear in the output of a compressor:
4.1. Poor maintenance practices on the compressor filters.
In a timely manner, they may fail to remove the oil from the gas flow or even become a source of oil mist in their own right. In the case of coalescing filters, they can re-entrain oil mist if the gas flow is prone to sudden high flow pulses.
Particulate or charcoal filters can not be blocked by the filter. These situations will result in oil mist being carried into the compressor output.
If the filter media is not exhausted, it may occur.
4.2. High compressor output temperatures.
The output of a compressor's chamber always wants to contain a quantity of oil mist. The quantity of this contamination is dictated by the temperature in the compression chamber and the volatility of the oil used. Under normal operating conditions the temperature of the gas is lower than the flash point of the oil. The filtration on the output is intended to remove this level of contamination.
If the discharge temperature of the compressor rises, more oil mist wants to be present at the compression chamber output. If the temperature rises significantly, the oil will break down and produce significant quantities of contaminants. Any increase of contamination will have the effect of consuming the filters at a higher rate than expected and result in their early failure. Oil mist can be used over these exhausted filters.
There may be many causes of increased discharge temperature at the compression chamber:
Lack of cooling, or possibly of the cooling system.
Overloading the compressor, by running the compressor outside its specified operating limits. For example, by running the compressor for a higher output pressure than it was designed for.
Running the compressor in an environment where the ambient temperature is higher than it was designed for.
Insufficient oil delivered to the moving parts of the compressor will result in greater friction and higher operating temperatures.
A build-up of carbon offsets on the valve seats, which results in a reduction in the operating and operating temperature of the compressor. Carbon residues can therefore create hot spots in the compression chamber that can ignite oil vapor if the flash point is exceeded.
In extreme cases the temperature of the gas may be high. This produces large volumes of contaminants.
4.3. Failure of seals.
The seals on a compressed and compressed air filter are compressed.
The filters will quickly be overwhelmed and oil mist will be introduced into the compressor output.
In the gas to pass straight to the compressor output.
It is also stated that the other contaminants want to be produced as a result of these failures.
So can I use the OilControl - OilGuard - OilMonitor as a monitor on my compressor which uses synthetic oil?
Yes, as many of the mechanisms that generate oil mist and oil vapor. The online sensor for the contaminant can give an indication that the problem may be due to the compressor. This measurement can be used as a prompt to stop the compressor line.
It should be noted that the Oil Control is substitute for regular preventative compressor and filter maintenance. The first line of defense against oil is that the compressor and filters are operating correctly!
TPS oil monitor according to ISO 8573-5: 2010
Inline measurement of residual oil content in compressed air
According to ISO 8573-5: 2010 all hydrocarbons with 6 or more carbon atoms per molecule in compressed air- Oil vapore + Oil aerosol - need to be measured! The TPS OilControl (Compressed Gas Oil monitor) is capable of completing the residual oil with a minimum detection limit of 0.001mg / Nm3.
The Oil Monitor is easy to install and it is capable of expanding the range of CO2, CO, O2 and other possibilities up to ISO 8573-1.
Because it is the ideal monitor to install and monitor your compressed air quality.
The complete set is delivered including a sample take-off point, a measurement system and a monitor system, providing you with a 4..20mA output or other options.
The system only needs 230VAC, 50HZ power supply to start your measurement.