PURPOSE: To measure density without any variation in liquid level by providing a diffuser below the lower measurement limit of the liquid level in a vaporiza tion can, sending the liquid out of the vaporization can be a circulation pump and letting part of the circulating liquid flow in the diffuser, and measuring the differential pressure by the diffuser.
CONSTITUTION: The liquid in the vaporization can 4 is sent out by the circulation pump 1 and returned to the vaporization can 4, where it is vaporized. Further, a branch pipe 2 is provided at the exit of the circulation pump 1 and the diffuser 3 is provided at a level below the lower measurement limit of the liquid level in the vaporization can. The liquid is run through the branch pipe 2 and diffuser 3 and returned to the vaporization can 4. At this time,the liquid run through the diffuser 3 is reduced in flow rate to suppress the influence of dynamic pressure and the pressure difference of the liquid is detected by a differential pressure gauge 5. The differential pressure is therefore measured without being affected by variation in the liquid level in the vaporization can, so the concentration is measured accurately.
YOSHIOKA SETSUO
HITACHI ENG CO LTD