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Explanation of thermometer


Response of the thermometer is not the same according to installation requirements etc.Especially, should equivalent attention of time constant when protection tube is used because of growing

2.Protection tube

It is necessary to note it because Protection tube that uses the temperature senser of the thermometer to protect it causes damage and the measurement error if the allowable velocity,the permissible pressure,the characteristic frequency,thermal conductivity or neither corrosion resistance nor heatproof,etc.are considered

(1)Allowable velocity and permissible pressure

It becomes it as an immersion length of Protection tube and one example (an allowable velocity and permissible pressure) as shown in the next table.

【Size Protection tube and permissible pressure】
  Protection tube size *Permissible pressure
Externals Inside diameter (MPa)
Protection tubeA 16 9.5 10
Protection tubeB 20 14
Protection tubeC Small tapered vessel diameter 20 16

※The value decreases greatly not spooning the stainless steel material it

(2)Characteristic frequency and vibration frequency of whirlpool

There are following relations between flow velocity and the vibration frequency of the whirlpool.


N :Vibration frequency of Karman vortex
St:About 0.21 when there are a lot of numbers of straw Hull and numbers of reinoruzu
V :Flow velocity(m/s)
d :Protection tube diameter in point(m)
 Please set to become N/N1<0.8 when you assume the characteristic frequency of the protection tube to be N1. Because the characteristic frequency of the protection tube lowers when the temperature rises, it is [kuda] under attention.

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