Heidolph Intelligent Hei-VAC Control Operating Instructions Manual page 75

Commissioning
➜
Vacuum hose made of PTFE, plugged on hose nipple, fixed with union nut:
With built-in controller the vacuum port is not visible. The vacuum hose
may not be kinked.
Make sure there is sufficient space inside the housing, or use a stable,
curved hose nozzle for connection.
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