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3 replacing the rolling diaphragm and springs, 3 replacing the rolling diaphragm and springs -11 – ARI Armaturen STEVI BBD 415 DN 25-50 EN User Manual

Page 11

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Rev. 0040321000 0714

Page 2-11

Operating and Installation Instructions

Straight-through blow-down valves - STEVI

®

BBD 415

7.3 Replacing the rolling diaphragm and springs

- Remove the actuator (refer to section 10.1).
- Dismantle the actuator (refer to section 10.2).
- Remove the following units: stem (pos. 50.1) / diaphragm plate (pos. 50.11) / rolling

diaphragm (pos. 50.10) / diaphragm flange (pos. 50.9).

- Loosen the flange nut (pos. 50.14).
- Remove the diaphragm flange (pos. 50.9).
- Replace the rolling diaphragm (pos. 50.10) and reassemble.
Note:
When this unit is assembled, a hole must be bored in the rolling diaphragm (pos. 50.10)
and aligned with the camber of the diaphragm plate (pos. 50.11) as well as with the flat of
the stem.
- Insert the unit into the actuator.
- The camber of the diaphragm plate (pos. 50.11) that is aligned with the hole in the rolling

diaphragm (pos. 50.10) must also be exactly positioned over the air connection in the
diaphragm base (pos. 50.7) (Fig. 6 and Fig. 7).

Note:
The flat of the stem (pos. 50.1) should still be easily accessible after the valve and actuator
have been assembled (Fig. 6 and Fig. 7).
- Align the compression springs (pos. 50.15) centrally on the diaphragm plate (pos. 50.11).
- Make sure the compression springs are properly positioned!
- Fit the diaphragm cover (pos. 50.18) over the springs (pos. 50.15) and screw together

(for tightening torques refer to section 7.7).

- To assemble the actuator, refer to section 7.5.

ATTENTION !
Refer to sections 10.0 and 11.0 before dismantling the valve.
- If the rolling diaphragm is replaced, the springs must be replaced at the same

time.