Guide

TEMA type letters explained.

Three letters, read from the front of the exchanger to the rear, say a great deal about how it is built.

The order

Front end, shell, rear end.

The first letter names the front end (stationary head), the second the shell, and the third the rear end. Each position has its own set of letters, so the same letter can mean different things in different places: N, for example, is both a front end and a rear end.

On the reference exchanger

A, E, and T, where they sit.

A side elevation of the reference exchanger with its three zones marked: A, the front end with the channel and its removable cover, on the left; E, the one pass shell, in the middle; and T, the rear end with the pull-through floating head inside the shell cover, on the right. — **Front end.** A: channel and removable cover
**Shell.** E: one pass shell
**Rear end.** T: pull-through floating head

Two examples

AET and AES.

The reference exchanger is an AET. Its channel has a removable cover (A), its shell is a single pass (E), and its bundle ends in a pull-through floating head (T).

The example that PlutoGen is given on its page asks for an AES: the same front end and shell, with a floating head with a backing device (S) at the rear.

The last letter

What the rear end letter tells you.

The rear end letter shows how the tube bundle is held. L, M, and N belong to fixed tubesheet exchangers, U to U-tube bundles, and P, S, T, and W to floating head designs.