BEKO TECHOLOGIES launched the METPOINT OCV device in 2009 to measure remaining oil vapour content in compressed air down to 0.001 mg/m3 or, in ISO8573-1 terms, better than Class 1. BEKO are now seeing the first results of the installations that have been made. In the first few installations BEKO received calls into their service department saying “this unit can’t be working properly!” A customer who has invested a great deal of money in a 100% oil free compressor is inevitably going to be disappointed even suspicious when his system readings are not what he believed that he would be seeing.
So what is happening? BEKO have examples of both oil free compressors and lubricated compressors with oil removal filtration giving cause for concern immediately after the installation of a METPOINT. The first example is of a pharmaceutical company checking their air quality direct from an oil free compressor. The initial readings were 0.01 ppm which meets ISO8573 Class 1 but is not what was expected from an oil free compressor. However the concern that the user had was that the readings fluctuated and at one point rose to 0.5 ppm. At this point the customer believed that the instrument was malfunctioning…nothing had changed in his system and therefore it “must” have been the instrument. In fact after investigation it was discovered that not only would the instrument readings vary from day to day depending on traffic density and prevailing winds but that the location of the storage and handling of lubricants on the site has to be given some thought as this affected the readings on the instrument.
The customer is now happy that the unit is working correctly and that whilst his oil free compressor is also working well the inlet air quality cannot be controlled. The customer is considering installing an activated carbon tower to be absolutely sure that his compressed air quality will be of the highest standard independent of inlet conditions.
The second example, of a company using oil injected screw compressors and filters to provide technically oil free air, is more complex. The company suffered a power outage and it is well known that if a screw or vane compressor is stopped incorrectly, that is whilst on load then there will be a momentary spike in oil carry over. The service providers for the compressor quite correctly changed the separator and the carbon filter but were still seeing high readings and again there was the call to BEKO for help in the belief that the product was malfunctioning. BEKO attended site and checked the instrument and found that it was functioning perfectly. The reason for the reading was that a small amount of oil vapour had passed all the defences during this system disturbance and would cause a small but more than normal reading until either the oil worked out of the system or the pipe work downstream of all the filters was removed and cleaned. There are many more variables and risks of failure in the second system. Temperature has a big effect on the efficiency of filters, maintenance is more critical and the sheer number of components required to reach the required quality of compressed air are some of the risks. Again this customer was very happy to have information and based on the above and the higher number of risks is seriously looking at investing in oil free compressors to minimise these risks.
What does all the above tell us? Quite simply that whilst BEKO TECHNOLOGIES believe completely in the quality and reliability of oil free compressors and also that technically oil free air can be achieved from lubricated and filters, a new user of a METPOINT OCV oil vapour meter will nearly always see higher readings than expected. This is simply because the environment cannot always be controlled. Ambient air typically contains 140 million particles per m3 and as more than 75% of these particles are below 2 microns they will pass straight through a compressor intake filter which is usually 3-5 microns. Hydrocarbons will be present in our cubic metre of air to the levels of 0.05 to 0.5 mg/m3 and as a vapour will pass straight through coalescing filters.
What BEKO are pleased about is that the METPOINT is giving customers good information from which they can make management decisions about their compressed air system. To manage we must measure!
