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Paramétrages

Paramétrages

1. EP0028629 - METHODE ET APPAREIL DE DETERMINATION DE LA DENSITE D'UN LIQUIDE DE TRAITEMENT.

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Claims

1. A method of determining the density of a process liquid and comprising arranging a pair of vertically spaced pressure sensors (10) in pressure transmitting contact with said process liquid and establishing pressure transmitting communication between each of said pressure sensors (10) and a common differential pressure measuring device (13) via pressure transmitting conduits or passages (12) filled with a reference liquid, characterized in maintaining said differential pressure measuring device (13) and possibly also adjacent parts (38) of said pressure transmitting passages (12) at a substantially constant temperature differing from the temperature of the said process liquid, maintaining first parts (17) of said pressure transmitting passages (12) adjacent to said pressure sensors (10) at a temperature substantially corresponding to that of the process liquid, and positioning second parts (16, 55) of said pressure transmitting passages (12) adjacent to the differential pressure measuring device in which second parts the temperature of the reference liquid differs from the temperature of the differential pressure measuring device (13) as well as from the temperature of the process liquid, substantially symmetrically about a horizontal line (56) so that the maximum vertical spacing of said symmetrically arranged second parts (16, 55) is substantially zero or small compared to the vertical spacing of said pressure sensors (10).
  2. A method according to claim 1, characterized in positioning the said second parts (16) of the pressure transmitting passages or conduits (12) substantially horizontally.
  3. A method according to claim 2, characterized in that said second parts (16) of the pressure transmitting passages (12) are positioned substantially in the same horizontal plane.
  4. A method according to any of the claims 1-3, characterized in performming thermostatically controlled heating (25) of the differential pressure measuring device (13) to a temperature slightly exceeding the expected maximum temperature of process liquid, and in placing the parts (17) of said pressure transmitting passages (12) being adjacent to said pressure sensors (10) in good heat conducting contact with said process liquid.
  5. An apparatus for determining the density of a process liquid for use in carrying out the method according to any of the claims 1­4 and comprising a pair of mutually spaced pressure sensors (10) each connected to a common differential pressure measuring device (13) by means of pressure transmitting conduits or passages (12) filled with a reference liquid, characterized in that said differential pressure measuring device (13) is provided with thermostatically controlled means (25, 37) for maintaining the temperature of said measuring device (13) and possibly also of adjacent parts (38) of said pressure transmitting conduits (12) at a substantially constant value differing from that of the process liquid, that first parts (17) of the pressure transmitting conduits or passages (12) adjacent to said pressure sensors (10) are adapted to be positioned in heat conductive contact with the process liquid, and that second parts (16, 55) of said pressure transmitting passages or conduits (12) adjacent to the differential pressure measuring device are arranged symmetrically about a horizontal line (56), said pressure sensors (10) being positioned with a vertical spacing (H) so that the maximum vertical spacing of said symmetrically arranged second parts (16, 55) is substantially zero or small compared to the said vertical spacing of the pressure sensors (10).
  6. An apparatus according to claim 5, characterized in that said second parts (16) of the pressure transmitting conduits or passages (12) are adapted to be arranged horizontally.
  7. An apparatus according to claim 6, characterized in that said second parts (16) of the pressure transmitting conduits or passages (12) are adapted to be positioned in substantially the same horizontal plane.
  8. An apparatus according to any of the claims 5-7, characterized in that said thermostatically controlled means comprise heating means (25) and in that the walls of said second parts (16, 55) of the pressure transmitting conduits or passages (12) are of a material with a thermal conductivity which is poorer than that of the other parts of said conduits or passages.