The Pendant Drop Interfacial Tension system measures interfacial tension at reservoir pressure and temperature to 10,000 psi and 350 °F.
The cell has interchangeable needle tips to achieve a wide measurement range. The lower limit is 10-3 dynes/cm. The Temco system can be
provided with a vibration free table, heating system, metering pumps, camera, and image and analysis software.
Investigations of surface and interfacial tension require a viewable environmental
chamber, temperature and pressure control, a metering pump for drop formation, and
observation equipment. During the last several years, Temco has developed a system
to meet the special requirements for high pressure and temperature testing of interfacial
tension. The pendant drop visual cell is a through windowed cell. The cell has an
external band heater for rapid heating. The cell is also insulation wrapped to maintain
a constant, uniform temperature throughout the test period. A needle is installed
into the cell for the injection of the liquid phase into the cell. A pendant drop
or clinging bubble will form on the tip of the needle. The cell is designed so that
the injected phase can enter from the bottom or the top of the visual cell.
To observe and record the pendant drop dimensions, a camera system is used with
an external light source. The image of the drop is captured within the computer
and software for data analysis and collection. The software is discussed later in
this literature. The formation of the pendant drop is controlled with a precision-metering
pump. For high pressure applications, either hand pumps or computer controlled pumps
can be provided. The entire system is provided with transfer vessels for the storage
of test fluids, a back pressure system for the maintenance of the pressure, and
a vibration free table to maintain the stability of the pendant drop.
Surface tension is derived form drop shape. Given fluid density, the value of SW / SE is an entry into a
lookup table which yeilds surface tension.