BS EN 116 Diesel and domestic heating fuels - Determination of cold filter plugging point - Stepwise cooling bath method
5 Reagents and materials
5.1 Hydrocarbon solvents, technical grade, e.g. Heptane.

5.2 Light hydrocarbon solvent, technical grade, e.g. Isopentane.

5.3 Lintless filter paper, with particle retention of (5 +/- 1) µm.

5.4 Certified reference materials.
Certified reference materials may be obtained from the European Commission's Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Brussels.

6 Apparatus
The equipment, as detailed in 6.1 to 6.11, shall be arranged as shown in Figure 1. Unless otherwise stated, all dimensions in the figures are given in mm.

IMPORTANT - Parts of the apparatus made of copper, zinc or brass can interact with bio-components like fatty acid methyl ester (FAME). Care shall be taken and parts made from alternative materials are available.

6.1 Test jar, cylindrical, of clear glass, flat bottomed, with an outside diameter of (34 +/- 0.5) mm, a wall thickness of (1.25 +/- 0.25) mm and a height of (120 +/- 5) mm, having a permanent mark at the 45 ml level.

Test jars of the required dimensions may be obtained by selection from jars conforming to ISO 3016 which specifies wider tolerances.

6.2 Jacket, watertight, cylindrical, flat bottomed, to be used as an air bath, having an inside diameter of (45 +/- 0.25) mm, an outside diameter of (48 +/- 0.25) mm and a height of (115 +/- 3) mm.

6.3 Spacer, made from POM-C , except for the stainless steel rods with 2 mm diameter, to be placed into the jacket (6.2), conforming to the dimensions as shown in Figure 2.

6.4 Stopper, of oil-resistant plastic and non-thermal conductive material, having three holes to accommodate the pipette (6.5), the thermometer (6.8) and to allow venting of the system and able to ensure that pipette and thermometer are safely positioned in the test jar.

6.5 Pipette with filter unit:
6.5.1 A pipette of clear glass with a calibration mark corresponding to a contained volume of (20 +/- 0.2) ml at a point (149 +/- 0.5) mm from the bottom of the pipette (see Figure 3). It shall be connected to the filter unit (6.5.2).

6.5.2 A filter unit as in Figure 4, with ISO general purpose metric screw threads according to ISO 261, further consisting of a filter holder as in Figure 5 and a disc, 15 mm diameter, stainless steel wire mesh gauze with a nominal aperture size of 45 μm in basket weave (not twill). The nominal diameter of the wire shall be 32 μm and the tolerance for the size of an individual aperture shall be as follows:
1) no aperture size shall exceed the nominal size by more than 22 μm;
2) the average aperture size shall be within +/- 3.1 μm of the nominal size;
3) not more than 6 % of the apertures shall be above the nominal size by more than 13 μm.

The requirements for the wire mesh are taken from ISO 3310-1, to which reference may be made for methods for testing the gauze.

6.6 An automated detection system comprising one sensor to record the filling of the pipette, prior to the subsequent aspiration cycle at a volume of (20 +/- 0.2) ml, called the 20 ml mark, and a second sensor positioned (85 +/- 4) mm from the bottom of the pipette, called bottom filling mark.

6.7 A valve unit that connects the pipette either to the vacuum regulator to allow sample sucking into the pipette, or to the atmosphere to allow backflow of the sample to the test jar. The connecting line between the valve unit and the pipette should have a maximum length of 2 m, and an internal diameter comprised between 4 mm and 6 mm.

6.8 The following thermometers, conforming to the essential dimensions set out in Annex A, shall be used:
6.8.1 A platinum resistance thermometer with digital display shall be used for measuring the sample temperature with a resolution of 0.1 °C and an accuracy of 0.5 °C (see Figure 6 and 10.4 for the positioning).

6.8.2 A platinum resistance thermometer with digital display shall be used for measuring the cooling bath temperature.

6.9 Cooling bath.
It shall be of a shape and size suitable for containing the jacket (6.2) in a stable and upright position at the required depth.

The jacket (6.2) may be fixed permanently in the lid.

The bath temperature shall be maintained at the required value by a refrigeration unit or by the use of suitable freezing mixtures, ensuring a homogenous temperature in the bath by stirring or other means of agitation for liquid baths.

The bath temperature given in Table 1 shall be used, for different levels of cold filter plugging point. These may be obtained by separate cooling baths or by adjusting the refrigeration unit. If a refrigeration unit is used it shall be capable of changing the bath temperature within 2 min 30 s.

If several testing units are placed in one large cooling bath, the distance between the jacket wells shall be at least 50 mm.

6.10 Vacuum source, vacuum pump or water pump powerful enough to ensure an air flow rate in the vacuum regulator of (15 +/- 1) l/h during the entire aspiration cycle.

For Vacuum control either follow 6.10.1 or 6.10.2.

6.10.1 Vacuum regulator with glass bottles, comprising of:
A vacuum pump or water pump with a suction performance of 60 l/h to 100 l/h. A performance of less than 60 l/h will not be sufficient to ensure the required vacuum if several test units are operated simultaneously. A performance higher than 100 l/h can lead to turbulence in the water filled bottle and negatively influence the constancy of the vacuum.

A glass bottle, at least 350 mm high, with a capacity of not less than 5 l, is partially filled with water. It shall be closed by a stopper with three holes of convenient diameter for glass or stainless steel tubes. Two tubes shall be short and shall not go below the water level. The third tube shall be long enough for one end to be approximately 200 mm beneath the surface of the water while the other end reaches a few centimetres above the stopper. The depth of the immersed part shall then be adjusted to obtain the required depression 2 kPa +/- 0.05 kPa on the manometer.

A second empty 5 l bottle shall be fitted in the line to serve as vacuum reservoir in order to ensure a constant depression. The arrangement is shown in Figure 7.

With this vacuum regulation up to 10 test units may be operated simultaneously. A prerequisite is that each test unit has a separate line from the valve unit to the vacuum regulator, and that a line length of 5 m is not exceeded. Commercially available silicone tubing with an internal diameter of 4 mm to 6 mm may be used for the supply lines.

6.10.2 Electronic vacuum regulator (for automatic method), able to guarantee the requested vacuum of 2 kPa +/- 0.05 kPa over the whole aspiration cycle.

6.11 Time measuring device, having a resolution of 0.2 s and an accuracy of 0.1 % over a period of 10 min.