Abstract
Measurement of surface tension by ring or plate method is usually carried out at an atmospheric pressure to avoid the complexity of the apparatus used. We have developed an apparatus with a ring for measuring the surface tension of the liquid under pressure. The present apparatus has a load cell to detect force from the surface tension and also a device to control the distance between the ring and the surface of test liquid by making use of gravitational force. The overall uncertainty in surface tension with this apparatus is estimated to be less than ±5%. Measurements for R134a at 283 K and 288 K reveal that the deviation of present data from the reference is within ±2.5% and the data reproducibility is also within ±2.5%.
