Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D2780-92 – Standard Test Method Technical Guide
This article provides an overview of ASTM D2780-92, a standard test method for the solubility of fixed gases in liquids, covering its scope, procedure, and significance.
📐 Overview and Scope
ASTM D2780-92 is a standard test method for determining the solubility of fixed gases in liquids. It is applicable to gases and liquids that are non-reactive and compatible with borosilicate glass, mercury, stainless steel, PTFE, and FPM under test conditions. This method also covers the determination of the concentration of fixed gases in solutions which are not saturated with the gas. The values stated in SI units are to be regarded as the standard, with the values in parentheses for information only. This standard does not purport to address all safety concerns; it is the responsibility of the user to establish appropriate safety and health practices.
⚙️ Test Procedure and Apparatus
The test method involves saturating a liquid specimen with a fixed gas under specified conditions of temperature and pressure. The saturation step may be eliminated if it is desired to determine the concentration of fixed gas in a liquid sample suitably presented for analysis. A portion of the solution of gas in liquid is transferred to a gas extraction apparatus in which the fixed gas is quantitatively removed from the liquid. The separated gas is transferred to a gas buret in which its volume is determined.
The apparatus includes an Ambient Pressure Saturator, which comprises a gas supply and pressure regulator, gas dispersion element, heating mantle, and temperature measurement and control devices. For saturation at higher pressures, an Elevated Pressure Saturator is used, which consists of a 2.5 L stainless steel bomb with a thermostatic control jacket, capable of pressures up to 608 kPa (6 atm). The following table summarizes the key features:
| 🟦 Feature | 🔧 Ambient Pressure Saturator | ⚡ Elevated Pressure Saturator |
|---|---|---|
| Pressure Range | Ambient pressure | Up to 608 kPa (6 atm) |
| Key Components | Gas supply, dispersion element, heating mantle, temperature control | 2.5 L stainless steel bomb, thermostatic jacket, valves, pressure gauge |
| Application | Saturation at atmospheric pressure | Saturation at higher pressures |
📊 Key Measured Properties and Significance
The solubility of fixed gases in liquids is an important engineering parameter in the design of hydraulic systems. It is a measure of the amount of gas which can be released from solution when the system undergoes changes in pressure and temperature. Theoretical considerations permit approximate values of gas solubility to be computed, but this test method provides a physical measurement. Dissolved gases are separated physically from a liquid and measured volumetrically. The test method permits subsequent analysis of separated gases by any appropriate method, such as gas chromatography, as referenced in Practice E 260.
💡 Tip: Ensure that the liquid specimen is properly saturated under specified conditions to achieve accurate solubility measurements. The apparatus must be compatible with the test materials to avoid contamination. Using the appropriate saturator for the required pressure range is crucial.
⚠️ Warning: For specific hazard statements, refer to sections 6.1, 6.2, 8.3, 8.4.2, and 9.3 of the standard. When using toxic or flammable gases, provide suitable collection and disposal means as the use of such gases in the ambient pressure saturator is not recommended without proper precautions.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D2780-92?
This standard covers the determination of solubility of fixed gases in liquids for non-reactive gases and liquids compatible with borosilicate glass, mercury, stainless steel, PTFE, and FPM under test conditions.
💡 What are the key apparatus used in this test?
The test uses an Ambient Pressure Saturator or an Elevated Pressure Saturator, along with a gas extraction apparatus and buret for volumetric measurement. The choice depends on the required saturation pressure.
⚡ How is the gas solubility measured?
The liquid is saturated with gas under controlled conditions, then transferred to an extraction apparatus where the gas is quantitatively removed and its volume determined in a gas buret. The volume measurement provides the solubility data.
📌 What safety precautions are necessary?
Users must establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For toxic or flammable gases, ensure proper collection and disposal. Refer to specific hazard statements in the standard.