Some misunderstand of data speed of surface tensiometer for measuring surface tension

Recently, we always hear confusion from our customers about the definition of data speed for surface tensiometer. Yes! You may find various speed descriptions for commercial surface tensiometers around world. For example, it is described as "data update speed: 23 data/s (model 60) or 92 data/s (model 80)” in specification of USA KINO's surface tensiometer, while that in Kruss's is “data speed: 50Hz”. Then customers would confused that which is the correct one.

First of all, these two statements are both right, but they are from different perspective to define speed.
(1) The speed of KINO's surface tensiometer means data update speed of balance while that of Kruss's means data sampling speed.
Kruss and some other manufactures usually take data sampling speed as data speed, actually, 50Hz is used to describe sampling speed rather than data speed. Data sampling speed means acquiring speed of software from analytical balance, but not the update speed of balance. Data update speed of balance always shows more detail of measuring process, which truly makes sense. The sampling speed of KINO's surface tensiometer can reach about 100Hz or more, but it contributes quite a little (or nothing) to measuring accuracy.

In the experiment of measuring surface tesion, sampling speed is usually about 2data/s due to Kruss's video of K100 in their web ; and that is about 5data/s in the experiment of measuring contact angle based on dynamic Wilhemy plate method or Washburn method. Screenshots are shown as below:

Measurement of surface tension, Speed is about 2data/s

Measurement of contact angle; Speed is about 5data/s

Measurement of contact angle based on Washburn method; Speed is about 5data/s.

(2) About data update speed of analytical balance, KINO's balance is faster than Kruss's.
Surface tensiometer model K100 uses Sartorius from Germany, whose actual update speed is about 20 data/s, while KINO's surface tensiometer adopts METTLER TOLEDO' balance, and data update speed of balance can reach 92 data/s.

Real time data of A60 series is shown as below. You can find that the data update speed of balance is about 8data/s by calculating time interval between two measured values.

(3)What’s more important, K100 can only measure static surface tension, i.e. average values from about 10 data, so data speed make no sense for Kruss's surface tensiometer model K100, while surface tensiometer of KINO can measure dynamic surface tension which can vary with time and surface area, hereby data speed make sense.