Demulsification value reflects the ability of the oil to shed water from an emulsion. It is commonly applied to turbine oils (especially steam turbines) and may also be relevant to other applications where there is a risk of oil/water emulsions forming.
The test involves passing steam through the test sample until the resulting water/oil emulsion doubles in volume. The sample is then maintained at a specified temperature and time taken for water to separate out of the emulsion is measured.
Demulsification Value is reported in seconds (<300 s is typically satisfactory, while values above 600 s may give cause for concern). If the sample failed to separate fully after 1200 s, the amount of oil in ml that has separated will be reported (e.g. “9 ml, where 20 ml is required for total separation).
The test is carried out to a procedure based on the IP19 test method.