Dosing system DDA

The DDA7.5-16 antiscalant dosing system consists of a compact diaphragm dosing pump with speed-controlled stepper motor drive and intelligent control electronics. Thanks to the stepper motor, the dosing pumps always operate at full stroke length for optimum dosing accuracy. The stepper motor drive enables low-pulsation and continuous dosing, even at low dosing volume flows.

The flexible mounting plate allows wall and floor mounting without additional mounting accessories. The control cube can be rotated to three different positions (left/front/right). The dosing pump is operated via a rotary/push wheel. The dosing pump has an LCD display with plain text display and 4-color status backlighting (white/green/yellow/red). The operating display is protected from environmental influences by a hinged protective cover.

The “FlowControl” function monitors the dosing process and displays typical dosing errors (e.g., air bubbles, cavitation, overpressure, etc.) in the menu area as plain text messages.

The DDA7.5-16 has an integrated volume flow measurement with an accuracy of +/-1.5% (during trouble-free operation). The volume flow is displayed or can be forwarded via an analog signal.

If dosing errors (e.g., fluctuating back pressure, air bubbles, etc.) cause deviations from the target dosing volume flow, the “AutoFlowAdapt” function compensates for these by regulating the speed of the stepper motor.

The dosing head consists of:

• Double valves for maximum dosing accuracy
• Ventilation spindle for easy commissioning or ventilation
• Pressure sensor for dosing monitoring “FlowControl” and “AutoFlowAdapt”

Features:

• Suction stroke speed reduction (anti-cavitation), 50% (max. Q: 3.75 l/h) or 25% (max. Q: 1.88 l/h), especially for higher viscosity or outgassing media
• 2-stage operating lock against unauthorized access
• Additional information (e.g., current mA input signal)
• Counter for dosed volume (resettable), operating hours

Inputs/outputs:

• Input for pulse signal, analog signal 0/4-20mA, ext. stop
• Input for two-stage level monitoring
• 2 configurable output relays (30 V AC/DC) for alarm, warning, stroke signal, operation, timer for time interval/weekly timer
• Analog output for dosing volume flow, system pressure, etc.
• Input/output for Profibus-DP box (accessory)

Multifunction valve for direct mounting on the pump pressure connection. The valve has 4 functions:

• The valve keeps the back pressure constant to enable optimum dosing accuracy in systems with varying pressure or pressureless systems.
• Anti-siphon effect The valve prevents unwanted siphoning when the suction side pressure at the pump is higher than or equal to the system pressure.
• Pump protection The valve protects the pump from impermissibly high operating pressures by opening the internal pressure relief valve at values above 11 bar.
• Manual pressure relief. Pulling the corresponding button relieves the pressure in the pump head so that pressureless suction can be resumed or the pump head can be vented. If both buttons are pulled simultaneously, the pump head and the entire pressure line are relieved.