Filter loss study: loss of hydrocarbons from filter when sampling and storing oil mist and oil vapour samples
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The main purpose of the thesis was to find the best way of storing samples of aerosol from drilling mud on filter.The patterns of loss depend on the properties of the base oil and the concentration of the sample. Most sample is lost during aspiration for high volatility samples, but the degree of loss during storage has similar patterns. Lower concentration samples loose more than higher concentration samples during aspiration.Filters should be taken out of the cassette before weighing rather than weighing the whole cassette with filter.Storage on cellulose acetate plus glass fibre filter combination and on double glass fibre filter have similar patterns, but more sample is lost during aspiration with a double glass fibre filter than with a cellulose acetate plus glass fibre filter combination for EDC Pearl and Sipdrill 2.0. Samples should be stored at refrigerator temperature for higher concentrations (ca. 70 mg/m3) and at room temperature for low concentrations (ca. 20 mg/m3). Plugs do not make much difference.How long a sample can be stored depends on the volatility of the sample, as high volatility (low viscosity) samples tend to lose more during aspiration.