Di/Da-Designation of connections

The shut-off valves and other connections for reciprocating compressors are named according to the following rule:

Di19 / Da25 / TT

Inside diameter of the connection in mm, rounded up/down as necessary

Di19 / Da25 / TT

Outside diameter of the connection in mm (if suitable for welding), rounded up/down as necessary
Daxx: connection not suitable for welding
DaKlemm: with compression fitting

Di19 / Da25 / TT

Maintenance connections (position and quantity, not for bushes)
T: top
R: right
L: left
TT: 2 connections on top of the valve
RL: 1 on the right, 1 on the left
TX: 1 connection on top of the valve
XX: no maintenance connection

If necessary for differentiation, the hole spacing of the flange connection is also indicated in mm, e.g. "LA52".

Model of valve Di19/Da25/S/TT. For designation, the diameters are rounded up/down as necessary. The real values are 19.15 mm and 25.4 mm.
Model of valve Di19/Da25/S/TT. For designation, the diameters are rounded up/down as necessary. The real values are 19.15 mm and 25.4 mm.

Sometimes (especially with screw compressors) another designation is used: Brazing-welding designation of connections.

For the actual valve bodies and also for individual bushes, there is a more detailed nomenclature (Nomenclature of valve bodies, Nomenclature of brazing and welding bushes).