BS EN 116 Diesel and domestic heating fuels - Determination of cold filter plugging point - Stepwise cooling bath method
10 Procedure
10.1 Position the spacer (6.3) in the jacket (6.2). The jacket shall be free from moisture/ice; this shall be checked immediately before the positioning.

10.2 Pour the filtered test sample (see Clause 8) into the test jar to the mark (45 ml).

10.3 Check that the cooling bath with the positioned jacket is at a temperature at (−34 +/- 0.5) °C.

10.4 Place the test jar with its stopper (6.4), and the pipette with filter unit (6.5) and suitable thermometer (6.8.1) into the jacket as shown in Figure 6.

Ensure that the bottom of the filter unit rests on the bottom of the test jar. Check that the thermometer does neither touch the wall of the test jar nor the filter unit. The lower end of the thermometer is (1.5 +/- 0.2) mm above the bottom of the test jar.

10.5 Connect the pipette to the vacuum system.

10.6 Start the test now according to the manufacturer's instruction. The cooling bath shall be brought at the appropriate temperature as indicated in Table 1. Most apparatus will automatically carry out the test procedure.

10.7 When the temperature of the test portion reaches an integer value, the first aspiration cycle is started by connecting the pipette via the valve unit to the vacuum regulator, causing the test portion to be drawn into the pipette. When the pipette is filled to the 20 ml mark, it is connected via the valve unit to the atmosphere, thus allowing the test portion to return to the test jar.

10.8 The aspiration cycle is repeated for each 1° C decrease of the test portion's temperature until the temperature is reached at which the pipette is not filled to the 20 ml mark within 60 s. Record the temperature at which this last filtration was commenced as CFPP (see also Clause 12).

A small minority of samples may exhibit anomalous aspiration behaviour, which may be detected by examining the aspiration times recorded in the test print-out for signs of an unexpected reduction in the time to fill the pipette, after which the aspiration time again continues to increase progressively, until the failure limit of 60 s is reached.

10.9 If after cooling in accordance with 10.7, the test portion fills the pipette to the 20 ml mark in less than 60 s, but does not flow back to the bottom filling mark when the pipette is vented to atmosphere via the valve unit (see 6.7) before the start of the next aspiration, record the temperature at the commencement of the filtration as the CFPP (see also Clause 12).

11 Calibration
11.1 General
The following components of the test equipment shall be calibrated at regular intervals. Unless otherwise stated, a calibration is recommended every half year.

11.2 Thermometers
The calibration of temperature measuring devices, including Pt 100 (6.8.1 and 6.8.2) shall be checked at regular intervals (i.e. at least once a year) by means of reference thermometers traceable to national or international SI standards.

11.3 Cooling unit
The individual cooling bath temperatures shall be checked with a certified thermometer.

11.4 Vacuum unit
The vacuum shall be checked by means of a manometer traceable to national or international SI standards.