| | Droplet Size
This tutorial deals with oil droplet size. Oil droplet size is one of the most important factors in determining the oil separation performance of all mechanical separators.
1. Oil droplet size distribution
It is the relative proportion of small droplets that is important in predicting separation performance. A mixture with some small droplets may be effectively treated providing that most of the contaminant exists as larger droplets. Our company normally uses the volumetric mean droplet size as the input to predicting performance.
2. Oil droplet size distribution for different applications
Oil droplet size distributions can be measured on site by skilled laboratory technicians. Consult Ultraspin for help. Oil droplets are often similar in size for similar applications. The following information can be used as a rough, first cut guide. |
| | 150 micron | - No emulsifying chemicals e.g. no cleaners, detergents or radiator coolant
- Little or no mechanical emulsification, no pumps
- Non emulsifying oil types
- No solids or sludge
| e.g. Some fuel depots, storm water run-off from fuel storage sites |
| | 60 micron | - Low usage of “quick break” detergents or cleaners
- No other emulsifying chemicals e.g. no radiator coolant
- Low level of mechanical emulsification e.g. diaphragm pumps
- Non emulsifying oil types
- No solids or sludge
| e.g. Run-off from service station forecourts, some vehicle wash bays |
| | 25 micron | - Medium usage of general detergents and cleaners
- Low concentrations of other emulsifying chemicals e.g. radiator coolant
- Medium level of mechanical emulsification e.g. large centrifugal pump
- Mildly emulsifying oil types
| e.g. Most workshops, automated vehicle washes |
| | Less than 25 micron | - High usage of all types of detergents and cleaners
- High level of mechanical emulsification e.g. small centrifugal pumps
- Emulsifying oil types
| e.g. Some workshops, parts washing water, manual vehicle wash bays |
| | What changes oil droplet size distribution? |
| | Mechanical | | - Reduce or eliminates upstream restrictions
- Reduce pressure drops
- Use low shear pumps
- Avoid all forms of unnecessary fluid agitation.
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| | Chemical | | - Avoid oil types that contain emulsifiers and detergents (consult oil data sheet )
- Prevent highly emulsifying chemicals from entering the system (eg Glycol)
- Avoid use of soluble solvent bases cleaners
- Avoid the use of ‘aggressive’ water based cleanser and detergents
- Limit the use of high pH fluids
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| | Congratulations! You have made it to the end of our web tutorials! This should mean that you are now able to buy oily water separators with more confidence and understand the basics of oily water science. |
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