Reference thermocouple junctions are maintained at a constant temperature by an insulated housing which surrounds the junctions. A heating element is contained within the housing. Temperature sensing elements disposed within and outside the housing control the heating element. The thermocouple junctions, internal sensing element and heating element can be secured to a metal block within the housing.
An improved oven (10) for maintaining the junctions of a plurality of reference thermocouples at a common and contant temperature. The oven (10) is characterized by a cylindrical body (12) defining a heat sink having an axially extended cylindrical cavity (14), a singularized heating element comprising a unitary cylindrical heating element consisting of a resistence heating coil (20) wound about the surface of a metallic spool (18) having an axial bore (22) defined therein and seated in the cavity, an annular array of radially extended bores (30) defined in the cylindrical body (12) and a plurality of reference thermocouple junctions (32) seated in the bores in uniformly spaced relation with the heating element, and a temperature sensing device (28) seated in the axial bore for detecting temperature changes as they occur in the spool and circuit (46) for applying a voltage across the coil in response to detected drops in temperatures of the spool.
A cold junction compensation device for a thermocouple, comprising a thermostatically interface casing (1) receiving directly the wires (3, 3') of the thermocouple (2) and ensuring the interconnection of these latter with an extension cord (4). The interface casing (1) contains moreover a cold junction compensation circuit (5).
A liquid sample is placed in a closed vessel. A thermocouple junction is submerged in the liquid sample. The pressure of the liquid is decreased, or the thermocouple junction is heated, until boiling from the thermocouple junction is detected. The pressure or temperature is then varied until the boiling just ceases. The pressure and temperature at cessation of boiling define the boiling point free of spurious liquid superheating effects.
The invention relates to a device for correcting error in temperature readings caused by thermocouple-to-extension wire ambient temperature fluctuations. The device creates an isothermal mass which raises the temperature of terminals to higher than ambient temperature. The isothermal mass consists of a self heating thermistor surrounded by thermal conductive epoxy inside an isothermal mass which contains the terminals. The isothermal mass is enclosed within insulating discs using a closure casing to complete the assembly. Using these higher than ambient temperature terminals for the connection between a thermocouple and extension wires, any error due to ambient temperature fluctuations is minimized.
A temperature regulator is provided which includes a temperature sensor, a temperature regulating unit, a cold junction temperature measuring device and a double-wall insulating partition. Temperatures measured by the temperature sensor are compensated with the temperatures measured by the cold junction temperature measuring device. Since the double-wall insulating partition insulates the cold junction measuring device from the heat generated inside the temperature regulating unit, the cold junction measuring device can correctly measure the temperature of the cold junction.
