Thermowell straight/ reduced/ tapered

what are the fundamental differences between three different types thermowell

• 7MT21, for screwing in, straight, cylindrical process connection
• 7MT22, for screwing in, reduced, cylindrical process connection
• 7MT23, for screwing in, tapered, cylindrical process connection

I read somewhere that thermowell tapered can be used for larger flow,

Where can I read the technical characteristics or a comparison of these three types.

danw

A Google search for

applying different styles of thermowells, straight vs tapered

brought up a dozen articles by major vendors who discuss selection criteria for thermowell shank/stem, basically strength for vibration resistance (not resonating) and response time.

Very worthwhile velocity charts at

Velocity charts for thermowells

Here's a typical case with assumed dimensions for a pipe mounted device.

The calculations are only as good as your numbers, and details of the flow conditions, but the case you've mentioned is not overly high risk..

You bet, thermowells are far more than a challenge at times.

The following dimensional summary involving failures, flow tests, and a peronal experience.

It may be of interest for your current selection methods. They can be addressed reliably but only with revised standards at some point.

added:

Thermowell dimension in cm's.

Cases 1 Power plant application (published record 1981)

Cases 2,3 Power plant applications (published record 1989) 

Cases 4,5 Flow Test (publically available 2017)

Case 6 Plant Experience (personal) where a flow meter was being upgraded