Vapor Pressure Analyzer - VPA

Vapor Pressure Analyzer

Vapor Pressure is an important physical property of a material that defines the amount of material in the vapor phase that exists in equilibrium with the original material. All materials enter the vapor phase through sublimation (solid - gas) or evaporation (liquid - gas). The vapor pressure of a material at thermodynamic equilibrium is a fundamental property of the material and is only a function of temperature.

Knudsen Method

The Knudsen effusion method is a dynamic gravimetric technique based on the rate of escape of vapor molecules through an orifice of known dimensions in a Knudsen cell into a vacuum at a known temperature. The mass loss rate through the orifice is measured by the Surface Measurements Systems "UltraBalance" in the VPA system. Sample masses of 1 to 100 mg can typically be studied in the temperature range of 20 to 400 °C.

Temperature Controlled Incubator

The incubator provides a stable and controlled temperature environment for experiments.

• Range: 20 °C to 85 °C
• Stability: ± 0.2 °C (20 °C to 85 °C)

High Temperature Pre-Heater

• The local sample pre-heater heats the sample up to 400 °C.

Vacuum System

• The rotary pump can produce a minimum vacuum pressure of 1 x 10⁻³ Torr.
• The turbomolecular pump in combination with the rotary pump provides lower vacuum pressure down to 1 x 10⁻⁷ Torr.

Vacuum Gauge

• The final vacuum pressure is measured using a vacuum transducer operating in the range of 900 to 1 × 10⁻⁸ Torr.

Vacuum Manifold

• Primarily constructed from 316 stainless steel for chemical inertia, with KF flanges and sealed VCR connections (Cu).

Ultra Microbalance

• Measures the sample mass in real-time at a given temperature and high vacuum.
• Sample Mass: Up to 1.0g
• Mass Change: Up to ±150mg
• Resolution (Accuracy): 0.1 μg
• Peak-to-Peak Noise: ≤ 0.7 μg