Adjusting And Locking The Stroke Length; Notes For Stroke-Length Adjustment - Grundfos DMI 208 Installation And Operating Instructions Manual

8.4 Adjusting and locking the stroke length

Adjust the stroke length only while the
pump is running!
Adjust the stroke length manually by
Caution
turning the knob!
Follow the notes for stroke-length
adjustment for the relevant pump type!
1. Remove the covering cap from the front of the
stroke-length adjustment knob.
2. Use a screwdriver to loosen the locking screw by
approximately 2 turns.
3. Increase/reduce the dosing flow while the pump is
running.
4. Slowly turn the adjustment knob to the left/right to
set the desired dosing volume.
5. Depending on the application, tighten the locking
screw so that the adjustment knob can still be
turned/cannot be turned any more.
6. Replace the covering cap.

8.5 Notes for stroke-length adjustment

In general, keep the stroke length
setting as high as possible, and adjust
Note
the flow rate using the stroke
frequency.
8.5.1 For automatic deaeration
Do not set the stroke length to less than
40 %.
Caution
Set lower flow rates by reducing the
stroke frequency!
• Dosing flow between 40 % and 100 %:
– ideal operating range: quick deaeration, only
brief interruption in dosing.
– Over 80 %, the flow rate only increases very
slightly.
• Dosing flow between 20 % and 40 %:
– deaeration is slower and unsteady.
• Dosing flow less than 20 %:
– automatic deaeration impossible or limited.
3
8.5.2 With Plus system
Refer to the following table with
minimum stroke settings for various
pump types and dosing media at an
Caution
ambient temperature of approximately
25 °C. For higher temperatures,
increase the stroke setting.
Type
stroke setting
Degassing media*
(e.g. chlorine bleaching agents)
3
DMI 0.3-10 Plus
3
DMI 0.8-16 Plus
3
DMI 1.0-10 Plus
3
DMI 1.1-16 Plus
3
DMI 1.6-10 Plus
3
DMI 3.0-10 Plus
3
DMI 3.6-16 Plus
3
DMI 4.0-8 Plus
3
DMI 6.0-8 Plus
Non-degassing media* (e.g. PAC)
3
DMI 0.3-10 Plus
No restriction to the stroke
Other types
setting
* Except for H O , peracetic acid and other highly
2 2
degassing media, use a dosing head with
automatic deaeration for degassing media.
Maximum
Minimum
counter
pressure
1.5 bar (e.g.
100 %
injection unit)
100 % 16 bar
80 % 10 bar
80 % 16 bar
60 % 10 bar
20 % 10 bar
40 % 16 bar
20 % 6 bar
10 % 8 bar
10 % 10 bar
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