IEC 61520 pdf download Metal thermowells for thermometer sensors – Functional dimensions
This International Standard specifies functional dimensions for metal thermowells for thermo-meter sensors of nominal diameters ranging from 3 mm to 8 mm for use in process control.
2Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply:
protective parts machined from solid bar stock. The various types of thermowells are asfollows:
– type A: threaded type;
– type B: extended threaded type;
– type C: flanged type;
– type D: weld-in type.
insertion length u
portion of the thermowell which can be in contact with the medium
insertion length U(differs from U only on type d thermowells)
portion of the thermowell which is inserted into any means of attachment.This insertion lengthis usually the reference length for any stress and resonance calculations.This dimension isusually determined by the user of the thermowell
tip thickness x
the minimum thickness of the well at the tip. May be “v” or “w” shaped
3.1Type A: threaded type
Figure 1 illustrates the external configuration of type A thermowells.The immersion length Umay be either cylindrical or tapered.