D_GR
Take Measuring Air to the Next Level With Our D_GR Tester
Dissolved gas in liquids can adversely affect equipment performance, product quality, and safety. A few examples can include reduced response time of hydraulic controls in military aircraft and space launch vehicles, formation of defects in paper sheets produced in paper-making operations, printing defects, and the adverse effect of dissolved air on the carbonation of beverages.
The DG_R_SM is a piston and cylinder device with unique and proprietary features that set it well above prior testing devices in this class. The piston and cylinder geometry of the DG_R_SM expands a liquid sample to release dissolved gas and then compresses the gas-liquid mixture to determine the volume of the released gas using thermodynamic gas laws.
The DGR dissolved gas tester offers significant improvements over the use of older technology, which can suffer from the use of mercury-based pistons, glass components, and very long testing times, to mention only a few.
Applications
- Hydraulic systems
- Critical control systems
- Rocket launchers
- Military aircraft
- Beverage carbonation
- Polymeric resins
- Cutting tool coolant systems
- Printing inks
- Food and pharmaceuticals
- Fine paper
- Any process or product that can be improve through the availability of dissolve air information.
Measurement of Dissolved Gas: The DG_R_SM Solution
The DG_R_SM is a piston and cylinder device with unique and proprietary features that set it well above prior testing devices in this class. The piston and cylinder geometry of the DG_R_SM expands a liquid sample to release dissolved gas and then compresses the gas-liquid mixture to determine the volume of the released gas using thermodynamic gas laws. Unlike competing testers in this class, the DG_R_SM does not rely upon inaccurate volumetric measurement of the released dissolved gas, and it does not use unsafe mercury pistons. Additionally, it is much faster and it can be fully automated. Finally, it provides full prediction of the dissolved gas content at various pressures and temperatures using Henrys Law calculations.
Control is fully automated with field tuning as necessary through a convenient operator interface.
Dissolved gas range 0.05% to 18%
Measurement accuracy at 0.05% dissolved gas: 0.045% to 0.055%
Measurement accuracy at 18% dissolved gas: 17.6% to 18.4%
Testing time less than 4 minutes, user adjustable as needed.
Wetted parts 303 SS and Buna rubber seals.
How it Works
The D_GR tester is pictured in Figure 1. Figures 2 and 3 are open cross sections which illustrate the action of key internal components.
As shown in Figures 2 and 3, the tester has two axially-connected cylinders: the fixed-volume Sample Cylinder, and the variable-volume Vacuum Cylinder. The volume of the Vacuum Cylinder is controlled by the position of the Vacuum Piston. When the Vacuum Piston is fully extended, which is the position illustrated in Figure 2, the Vacuum Cylinder volume is zero. Conversely, when the Vacuum Piston is fully retracted, as shown in Figure 3, the volume of the Vacuum Cylinder is at its maximum.
Referring to Figure 2, with the Vacuum Piston fully extended and the Feed Valve and Overflow Valve opened, the liquid to be sampled flows through the Sample Cylinder. Closure of the Feed and Overflow Valves isolates a sample in the Sample Cylinder.
Referring to Figure 3, the Vacuum Piston is then retracted, thereby generating a high vacuum on the sample. The high vacuum causes the dissolved gas in the liquid to be released into the gas phase which then is dispersed as “entrained gas” in the liquid phase. The thin liquid layer with a high surface-to-volume ratio, illustrated in Figure 3, significantly increases the rate of release of dissolved gas when compared with older technology in the “piston and cylinder” class of testers. Additionally, a high-frequency low-amplitude pulsation of the Vacuum Piston further increases the release rate.
After the dissolved gas has been released, the Vacuum Piston is fractionally extended to establish a starting pressure. The Compression Piston, which has been fully contained within the Vacuum Piston, is then extended into the liquid sample in order to compress the entrained gas. The pressure change is measured with the Pressure Transducer and the volume change is determined by the distance travelled by the Compression Piston. The entrained gas content, calculated using a gas law, represents the amount of gas which was originally dissolved in the liquid.
