HL-DU: Liquid Dosing Unit

Precision and flexibility for liquid dosing

The automatic liquid dosing unit HL-DU combines high functionality with versatility and is ideal for a wide range of applications in chemical laboratory process engineering. The HL-DU can be used to precisely dispense up to five liquids, including spikes and reference materials.

The dosing unit can be configured for a wide range of vessels, with or without caps and lids, including laboratory beakers, sample tubes and microwave digestion vessels. All steps, such as removing and placing caps and lids (optional), liquid dispensing and transferring the vessel to an automation handling device, are fully automated. Additional options make it possible to fulfill almost any specific customer requirement.
 

Robust and highly precise pump technology

In the HL-DU, membrane dosing pumps are preferably used. Their chemical-resistant materials are suitable for almost all aggressive fluids such as acids, alkalis or solvents. In addition to maximum product purity and the fact that they are free of metal, they are characterized by a low dead volume, which significantly improves dosing accuracy. For particularly precise applications, such as dosing standards, calibrated models are available.

Alternatively, syringe pumps can be used to meet specific dispensing volumes and accuracy requirements.

A wide range of options for individual requirements

The HL-DU offers numerous expansion options:

• Capping/decapping unit HL-CU: Various types of lids, including screw caps, watch glass lids and snap-on caps, can be automatically removed and replaced. Sensors monitor the precise placement of the lids.
• Magnetic stirrer: Enables efficient mixing of different vessel sizes and sample volumes. The stirring speed can be precisely adjusted to ensure optimal results.
• Exhaust system: For applications with corrosive acid vapors, an integrated exhaust system can be installed to remove vapors locally and protect the system.

Liquid Level Detection

An extremely accurate ultrasonic sensor can be integrated to determine the fill level precisely. This enables the sample vessel to be refilled accurately to a defined target volume. At the same time, the achievement and maintenance of the target volume can be monitored and documented.

Alternatively, the SparkPoint Vision module offers additional functionalities: in addition to determining the fill level, it can also be used to analyze other fluid characteristics such as turbidity or the detection of particulate matter.

Gravimetric monitoring of dosing

Liquid dispensing can be monitored gravimetrically if desired. Various scale options are available for this purpose, ranging from precise standard scales to high-precision models. The latter are shielded and mounted vibration-free to minimize the effects of air movement or vibration and thus ensure highly accurate measurement results.

The balances can also be used to determine the actual weight of the sample prior to dispensing. To do this, the tare weight of the sample vessel is determined in advance and subtracted from the total weight. The necessary liquid addition is then calculated to achieve either a target weight or a dilution factor. The liquid is then added volumetrically in the dosing station. For verification purposes, the sample can be weighed again after the dosing process and the actual dilution factor determined.