Adjusting The Dosing Flow Via The Stroke Length; Adjustment Of The Stroke Rate With A Frequency Converter; Opening And Reactivating The Integral Relief Valve - Grundfos DMX 221 Installation And Operating Instructions Manual

1. Install a transparent hose with dosing medium in
the inlet valve, or use the scaled pulsation
damper, if installed on the inlet side.
2. For pumps with level control unit, deactivate the
function.
3. Start dosing.
4. Set the dosing flow to 15 %.
5. Turn the adjusting knob slowly towards the zero
point until the dosing flow stops.
The medium level stops falling in the transparent
hose.
6. Stop dosing.
7. Unscrew the locking screw below the stroke-
length adjusting knob.
8. Without changing the position of the adjusting
knob, remove the plug placed in the middle of the
adjusting knob.
9. Unscrew the screw in the adjusting knob together
with the spiral spring.
10. Gently and without turning it, pull off the adjusting
knob.
11. Fit it back in such a way that the arrow on the
adjusting knob is pointing to zero on the dial.
12. Refit the spiral spring and the screw in the
adjusting knob. Tighten the screw until the spring
is slightly preloaded.
Even when turning the adjusting knob to 100 %,
the spiral spring must remain preloaded.
13. Screw in the locking screw below the stroke-
length adjusting knob.
Related information
3.2 Safety instructions and requirements for startup
9.6 Dosing curves
3.7 Adjusting the dosing flow via the stroke
length
Make sure the pump was installed and started up
correctly.
Only adjust the stroke length while the
pump is running.
• To increase the dosing flow, turn the adjusting
knob slowly to the left.
• To decrease the dosing flow, turn the adjusting
knob slowly to the right.
14
Related information
3.2 Safety instructions and requirements for startup
5.1.1 DMX 221 components
5.1.2 Functional principle of the pump
9.6 Dosing curves
3.8 Adjustment of the stroke rate with a
frequency converter
If a frequency converter is connected, the dosing flow
can be adjusted by changing the stroke rate. This can
only be done in the range of 10-100 % of the
maximum stroke rate.
For more information, read the installation and
operating instructions of the frequency converter.
Related information
11.2 Pumps with VFD
3.9 Opening and reactivating the integral
relief valve
• Make sure the pump was installed and started up
correctly.
• Make sure the pump is running during this task.
WARNING
Chemical hazard
Death or serious personal injury
‐
Wear protective clothing when working
on the dosing head, connections or
lines.
‐
Collect and dispose of all chemicals in
a way that is not harmful to persons or
the environment.
A
Fig. Knob positions
1. To open the relief valve, turn the relief-valve knob
to position B.
The relief valve is open. Dosing medium and air
can flow out through the overflow line.
2. To reactivate the relief valve, turn the relief-valve
knob to position A.
The relief valve is reactivated and will open at the
set opening pressure.
Related information
3.3 Starting up the pump
3.10 Setting the opening pressure of the integral
relief valve
B