intermediate position and damping

Do I always need dampers when using a swivel unit with intermediate position?

Pneumatic turning (0-180°) can be extended in function with a mid-position-module, called intermediate-positions, enabling a stop @ 90°.

Technical view:  an additional module is mounted to the swivel-unit, just instead of the normally placed side-plate.
Inside the intermediate-position-module a pneumatic driven piston moves 2 piston-rods to limit the range of the siwvel unit´s piston-gears!
So there is a direct mechanical limitiation on the gear. Repeat accuracy therefore depends on the gear backlash (0,05°).

As penetration depth of the piston rods can be adjusted (+/- 20°, at ZWP-9-SES +/- 10°), final putting into operation is easy. 

Final answer to the question "Mid position with or without damping?" really depends on your application.

Example 1
Take over of payload is in the middle position (90°) e.g. to check the actual location situation of the workpiece. According the result (e.g. by camera) turning starts to left (0°) or right position (180°).
In this application case, swiveling back to mid-position is done without any load - no dampers are needed.

Example 2
Working on the payload is done in position 0 and 180°. A possible scrap shall be given over in the middle (90°).
In this case, we recommend choosing a swivel unit, enabling to mount a hydraulic shock absorber.

Why? Expected is a fast turning to the mid with the mass of the workpiece. A mounted damper will work "against" a hard impact to the system.

But to clearly show the depending relationship to your application:
If there is enough remaining time in the cycles, you could also use restrictors to slow down the turning process...

By the way: Intermediate positions for our swivel units are available in corresponding sizes.

Please find here some examples (CAD-data) of swivel units with mounted intermediate position: