General Description; Safety Functions - Grundfos DDI 222 Instrucciones De Instalación Y Funcionamiento

4.3 General description

The DDI 222 is a dosing pump with an EC motor (brushless DC
motor) as the drive and electronic power control. The pump is
operated via the diagonal display in a user-friendly menu
structure.
The pump incorporates an overpressure safety feature. When an
adjustable cut-off pressure is exceeded, the pump can be
switched off automatically.
The DDI 222 is available in various versions.
See also section 1. General information.
Option:
The pump can also be equipped with the following:
• diaphragm leakage sensor (MBS)
• interface for PROFIBUS.
The functions are described, but only apply to the relevant pump
version.
3b
D
2
3a
H
Fig. 2 DDI 222
Pos. Components
3a Suction valve
3b Discharge valve
2 Dosing head
D MBS pressure switch (optional)
H Drain opening
4.3.1 HV variant for liquids which are more viscous than
water
All HV-variant pumps are equipped with spring-loaded DN 20
valves with an opening pressure of 0.1 bar (or 0.8 bar for the
pressure side) and connection for PVC tube 19 x 27.
DDI 60-10 has a special dosing head.
Note that the HV-variant pump has other dimensions
than the standard pump and that other connection
Note
line dimensions might be required!

4.4 Safety functions

4.4.1 Diaphragm leakage detection (optional)
Pumps with diaphragm leakage signal have a special dosing
head with a diaphragm set and pressure switch. The pressure
switch (socket 1) is fitted and connected to the pump on delivery.
D
2
L
Fig. 3 Dosing head with diaphragm set and pressure switch
for diaphragm leakage detection
Pos. Components
2 Dosing head
D Pressure switch
Q1 Working diaphragm
Q2 Signal diaphragm (intermediate layer made from fabric)
Q3 Protection diaphragm
In the event of a leak in the diaphragm:
• Dosing medium penetrates between the working diaphragm
and the protection diaphragm and is transferred to the
pressure switch via the signal diaphragm.
• On the next pressure stroke, pressure is applied to the
pressure switch, which is activated. The pump indicates an
error but continues operating.
• The electronics operates two contacts, which can be used, for
example, to trigger an alarm signal or to switch off the pump.
• In emergency mode, the pump can continue operating for a
short time.
Warning
Danger of explosion, if dosing liquid has entered the
pump housing!
If the diaphragm is possibly damaged, don't connect
the pump to the power supply! Proceed as described
in section 10.5 Diaphragm
After a diaphragm leakage detection, the pressure
switch has to be checked. In case the diaphragm of
Caution
the pressure switch is broken or affected by the
dosing liquid, the pressure switch must be replaced.
4.4.2 Pressure control
The DDI 222 pump incorporates a pressure control function. The
pressure is calculated from the motor current consumption or is
measured directly in the dosing head if a pressure sensor is
present (Flow Monitor pump option). At a user-defined pressure,
the pump is switched off automatically.
To protect the pump and system against excessive
Caution
pressure build-up, install an overflow valve in the
discharge line.
This function protects the pump, but not the system. It is
recommended that the system is protected by an overflow valve.
This function can be enabled and disabled in the second function
level of the electronics.
L
Q1 Q2 Q3
breakage!
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