Apparatus for determining the freezing point of a liquid
AssigneeRosemount Engineering Company Limited
InventorsJames Stewart Johnston, Trevor Howard Neve
Life of this patent
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Abstract
Apparatus for determination of the freezing point of a liquid or solution has a probe extending into the liquid with means for vibrating the probe. Fixed elements which are cooled, e.g. Peltier plates, are arranged adjacent probe so that a mantle of solid forms on these elements and grows to touch the probe, thereby changing the resonant frequency. This change in resonant frequency is sensed and used to control the cooling so that the probe remains just in contact with a surface where solid is forming, i.e. in liquid at the freezing point. The probe temperature is sensed electrically, e.g. with a resistance thermometer.
Claims7
Apparatus for the determination of the freezing point of a liquid comprising a probe for at least partial immersion in the liquid, means for vibrating said probe at a resonant frequency, an additional element adjacent said probe, said element comprising a metal block and Peltier cooling cells mounted on the block, said block having a bore within which the probe is located, means for cooling said element, means responsive to the change in resonant frequency of the probe when solid material deposited on said element comes in contact with the probe for operatively controlling the cooling means so as to establish equilibrium conditions with a mantle of solidified material on said element of constant thickness and means for measuring the temperature of the probe.
Dependencies are inferred from the claim text.