Appts. for determining filtration point of doped diesel fuels - by continuous automatic detection of refrigeration-created pressure drop

摘要

Appts. includes a reservoir filled with a refrigerant. The temp. at which the refrigerant solidifies is considerably below that at which the liq. to be analysed loses its characteristic of filterability, and there is a device for cooling the refrigerant. A tube of a conductive metal is immersed in the refrigerant. Its inlet and outlet ends are not submerged and it is isolated electrically. There is a pump delivering the liq. to be analysed to the inlet of the tube, at a constant rate of flow and an arrangement for retaining crystals at the tube emerging from the refrigerant. Electrical connections are provided to join the two ends of the tube to the terminals of an electrical power supply, and there are in the circuit, a switching mechanism and a pressure monitoring device. The latter operates the switch to feed the current to the electrically conducting tube when the difference between the pressure, measured just in front of the crystal retaining arrangement and that measured just beyond it, passes a first predetermined value. When this difference in pressure reaches a second predetermined value, the pressure sensitive device cuts off the current. Just beyond the crystal retaining arrangement there is a thermocouple for measuring the temp. of the liq. being analysed and an instrument for recording the values measured. The arrangement for retaining crystals may be a gauze with a fine mesh or a helicoidal capillary tube. Appts. is esp. used with a doped gas oil or diesel fuel. The device gives the same index of filterability for a modern diesel fuel both before and after doping. The arrangement separates the functions of refrigerating the gas oil and of establishing a pressure difference so that the temp. of the threshold of filterability can be measured automatically, accurately and continuously.