I'm looking for standard levels of silicon in oil used for compressors used in the drilling industry. In particular, for machines with approximately 500 hours of use.
Can anyone help me with this?

Hi CDB,
As you know from grade school geography (boy that was a long time ago) 27% of the earth is made up of silica. So depending on where you are drilling you may be in a very heavy silicon area or otherwise. Silica in it's natural state can be an incredably hard material. Not what you want in your compressor. As you have probably gathered the less silicon you have in your compressor the longer it will last. Some proponants would suggest that 50 PPM would be acceptable for their maintenance and life cycle expectations. If you monitor the relationship between the silicon (as a contaminent) and iron and copper (as wear), if your compressor has antifriction bearings with bronze gearing retainers. So when you see an expotential increase of iron and copper wear then it's time to set your base line acceptable silicon levels, somewhere below that point.
If you post your compressor type and generic mining environment we could probably give some additional experiences.
regards.......

CDB,
what Alan said is correct, however you need to know your silicon base line. Remember that Si is also an aditive. An esay tip, as Alan said earth is 27% Si, but there are other elements also. Look always for Aluminum, if is sand dust will have Si and Al. And remember, allways compare the Si increment with your base line.

Dear CDB

Normally the silicon levels in fresh hydraulic oils used in mobile drilling compressor oil if they are using a silicon defoamer should be around 20 ppm.

That being the baseline you can set your rejections limits for used oil.

Your elemental baselines should correlate with the profile of the new oil. Send a sample of your new oils to a lab for elemental analysis and set your baselines from that. Increases or decreases in particular elemenst then will indicate contamination ingression, wear and additive depeltion.