Exact measurements of the surface tension independent of a PC
The new bubble pressure tensiometer offers a selection of the most important measuring methods in conjunction with the practical control independent of a PC via an external remote control. The simple handling of the compact device thus enables easy mobile use for various applications. The measurements are precise and reproducible, yet timeconsuming settings can be presented, stored and transferred to a PC at the touch of a button. The measuring method according to Fainerman also guarantees exact surface tensions at even extremely small surface ages and the accompanying “real” bubble age.
The program offers two measuring procedures. In the first mode, the bubble frequency is reduced in stages, whereby a specified flow range is gradually passed through in order to clearly determine and represent the dependency of the dynamic surface tension from the surface age. The flow is re-adjusted at every single measuring point and is identified as measured value. The evaluation of the measurements and the necessary correction, such as for calculating the dead time, is carried out on a scientifically-founded base.
In the “constant flow” mode, the bubble frequency and, thus, the surface age, is kept constant in order to document any changes in the surfactant concentration, e.g. in the course of reactions.
Output of the measured values is optional via a printer or a data transmission software on the PC via the RS 232-interface. The measurement and the documentation of the temperature in the sample can also be carried out by means of an optional digital temperature probe. In addition to the proven PVDF-coated glass capillaries, steel capillaries (such as for highly alkaline samples) are available.
Two glass capillaries
Set of beakers to take samples
Digital temperature probe for measuring in the sample
Data transmission software for PC under WINDOWS (optional)
Double-walled thermostating vessel
Diverse types of capillary
Membrane pump for capillary rinsing
Online flow cell
Optimisation of drop sizes
Determination of surfactant consumption
Measurement of dynamic surface tensions in a time range of below one millisecond up to 20 seconds
Simple measurement of higher-viscosity and biological solutions
Exact determination of concentrations above the critical micellar concentration
As a surfactant monitor, the MPT C monitors processes with an online flow cell and extended software functions:
Surfactant content in waste and cleaning water
Washing processes and their surfactant consumption
LAUDA MPT – worldwide one of the only device that operates on the Fainerman Method
As the MPT 2, in the MPT C, the pressure is not measured inside the bubble as is customary in other devices, but in a buffer volume before the capillary. There, the pressure always corresponds to the maximum bubble pressure from which, using the known internal radius of the capillary, the surface tension can be derived.
An integrated pump produces a gas flow that is held constant at the respective specified value. For measurement, a gas, usually air, is introduced into the sample through a very narrow capillary. Depending on the gas flow rate, either a jet or individual bubbles are produced. In the jet range, the gas flow is proportional to the pressure drop along the capillary. At a certain point, the jet will split up into individual bubbles. The pressure now serves to inflate the bubble and, according to LaPlace, depends from this point forward on the surface tension and bubble radius.
The MPT is the only instrument based on the Fainerman method and allows surface tensions to be determined precisely at previously unavailable surface ages of less than one millisecond!
The measuring options of the MPT C
Extremely large dynamic range from 1 ms up to several seconds
Automatic recognition of the transition point bubble/jet range
Tabular representation of the dynamic surface tensions, number of measured points, real bubble age
Graphic representation of the dependency of the dynamic surface tensions on the bubble age, linearly or logarithmically
User-defined measuring point distance and duration of the measurement
Storage of up to 50 measured results including the accompanying parameters
Numerical description of samples determined by the user
Output of the measured values on an optional printer or PC via RS 232-interface
Plug-in boards with relay output in order to control the processes via the surface tension
Simplest handling via external remote control and the ergonomically-designed measurement desk
The ergonomic measurement desk contains the sensitive pressure sensors and the holder for the capillaries included as standard accessories, humidifier and sample beakers. A temperature probe, combined with a LAUDA thermostat guarantees the stability of the temperature. The measuring capillary can be inserted directly into the reaction vessel via a hose connection up to one metre in length or via a flow cell (bypass) for the “online” monitoring of the surfactant reactions. This enables, for example, the control of the surfactant consumption during the washing process.
The external, handy remote control Command with a large graphic display can be intuitively used without the need for any special know-how. The integrated microcontroller offers a series of useful testing methods with which, for example, it can automatically carry out a scan of the dynamic surface tensions over a range of 1 to 2000 milliseconds, thus recording the adsorption kinetics of even very fast surfactants in a complete, comprehensive manner.