Recently Parkes Scientific, along with eralytics worked to gather preliminary data showing the extreme bias that can result from insufficient shaking even when strictly following ASTM D6377-2020. These findings were presented to the CCQTA September 2020 meetings during the General Forum.
The published application note regarding this issue can be accessed with the following link: Application Note - ERAVAP Shaker Speed (PDF)
Below are the conclusions from the application note.
- A higher shaking speed leads to a higher VPCR.
- The difference between a VPCR result obtained with a shaking speed of 1.5 c/s and 4.5 c/s can be as large as 7.7 kPa (1.12 psi).
- Applying shaking speeds of 4.5 c/s or above eventually lead to the formation of a thermodynamic equilibrium vapor pressure.
- A VPCR result obtained at higher shaking speed (4.5 c/s or above) is closer to (or at) the actual thermodynamic equilibrium vapor pressure, meaning this result is more accurate.
- The measurement time for ASTM D6377 can be reduced significantly by increasing the shaking speed.
- For ERAVAP a shaking speed of 4.5 c/s (= “36” in the method parameters) was found to be the optimum setting for ASTM D6377 measurements.