Selection and installation of thermocouple and thermal resistance points

A, thermocouple and thermal resistance selection:

1, the normal temperature range of the measured object selection of under 300 ℃ heat resistance.

2, the normal temperature range of the measured object in the selection of more than 300 ℃ thermocouple.

2, installation and maintenance of the thermocouple and thermal resistance practice

1, to grasp the method of the installation of the thermocouple and thermal resistance;

2, learn how to use the thermocouple, heat resistance temperature measurement;

3, thermocouple, heat resistance and secondary instrument connection.

3, thermocouple and thermal resistance of the installation requirements of

installation of thermal resistance and thermocouple, thermocouple installation should be paid attention to the use of some of the details; For temperature measurement accurate, safe and reliable and convenient maintenance, and shall not affect the equipment operation and production operations. Should satisfy the following requirements, in the choice of thermocouple and thermal resistance of the installation site and insertion depth to pay attention to the following 2 points:

1, with a protection casing thermocouple and thermal resistance of heat transfer and heat loss, in order to reduce the measurement error, thermocouple and thermal resistance should have enough insert depth:

( 1) When measuring the original insertion depth of more than 1 m, shall be installed vertically, as far as possible or add racks and protect casing.

( 2) If is need to measure the temperature of flue gas, although the flue diameter of 1000 mm, the thermocouple or heat resistance insertion depth of 500 mm.

( 3) For thermocouple temperature center fluid, usually should be measuring end is inserted into the pipe center ( Vertical or inclined installation) 。 As the current body of pipe diameter is 100 mm, the thermocouple or heat resistance insertion depth should choose 50 ~ 100 mm ( Should take into account the installed base or flange size) ;

( 4) For high temperature and high pressure and high velocity of temperature measurement, Such as main steam temperature) , in order to reduce the protection to protect fluid resistance and prevent casing pipe under the action of fluid fracturing, the way protecting tube shallow inserted or use hot thermocouple. Shallow inserted type thermocouple protection tube, its depth into the steam pipe should be no less than 75 mm; Heat sets the standard of thermocouple insertion depth is 100 mm;

2, in order to make the measurement end of the thermocouple and thermal resistance and had good heat exchange between the measured medium, should choose reasonable location of measuring points, try to avoid the valve, elbow and pipe of elements and equipment installed near the thermocouple or heat resistance.

4, the installation method of thermocouple and thermal resistance

1, first of all should be good measuring thermocouple and thermal resistance of flanged or threaded screw tooth size, form a complete set of processing good flanged or threaded base.

2, according to the flange or the size of the thread base, the need to measure the hole in the pipeline.

3, flange welding or teeth. The flange seat insert has open hole or thread base, the tower flange or thread base with measured pipe welding.

4, bolt or the thermocouple or heat resistance thread precession has good welding base.

5, according to the wiring diagram of the thermocouple or heat resistance box connected line, and connected to the corresponding display instrument dial photogenic. Pay attention to the junction box is in contact with the medium of the pipe wall being measured phase, to ensure that the terminal box does not exceed 100 ℃ temperature range. Junction box of the outlet hole should prevent bad sealing, water vapor dust deposition such as shorting terminal.

6, the location of the thermocouple or heat resistance installation, should consider convenient maintenance and maintenance.

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