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Compressor/Manifold Unit
The Compressor/Manifold Unit is an innovative design that combines a high-pressure (15 bar or 1500 kPa) compressor with a manifold. The unit is exceptionally quiet and is packaged in a small, conveniently sized metal enclosure, allowing countertop placement and operation.
The Compressor/Manifold Unit has two separate, independent pressure outputs, allowing it to run two pressure chambers simultaneously. The system has regulators for independently controlling a low-pressure output and a high-pressure output.
Electronic pressure transducers and digital readouts accurately monitor each pressure output. The low-pressure regulator is electronically controlled, and continuously monitors and adjusts the pressure in the low-pressure side to maintain a set pressure. The high-pressure regulator is manually controlled, yet easy to operate and accurately maintain a set pressure.
The unit incorporates several pressure-release mechanisms for safe operation. Each pressure output has its own manual exhaust valve, allowing the user to release pressure in either output line. An emergency stop button immediately releases pressure in both output lines.
Units are available for operation with either 110V-60Hz or 220V-50Hz AC power.
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Specifications:
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Compressor/manifold system components The Compressor/Manifold Unit consists of a number of components which provide power to the unit, control the operation of the low-pressure and high-pressure outlets, allow routine maintenance, and enable safe operation of the system.
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POWER, MAINTENANCE, AND SAFETY FEATURES
Power switch The power switch controls the supply of electricity to the compressor/manifold unit. Turning the switch on supplies power to the compressor motor, the pressure transducers and digital displays, and the compressor-motor cooling fan.
Emergency stop The emergency stop is a safety relief valve which immediately releases the air pressure in the compressor/manifold unit. Pressing the emergency stop button releases pressure from both the high-pressure and low-pressure sides, and from any extractor chambers connected to the pressure outlets.
Air filter and water trap The air filter and water trap clean and dry the air prior to being drawn into the compressor. Particulate matter is filtered out and water vapor is removed.
Storage tank drain The storage tank drain is used to release air pressure and to drain water from the pressure tank.
LOW-PRESSURE SIDE
Low-pressure regulator The low-pressure regulator is used to regulate the pressure in the low-pressure output line. The regulator provides air pressure in the range of 0 to 6 bars (0 to 600 kPa). The regulator is electronically controlled and maintains a constant set pressure by continuously monitoring and adjusting the pressure in the line. Slight changes in pressure, such as those caused by temperature changes or by volume changes as water is displaced from soil samples, are detected, and the regulator reacts to adjust the pressure automatically.
Pressure display The pressure of the regulated air is monitored with an electronic pressure transducer. An LED display provides a continuous readout of the pressure in units of bars.
Extractor chamber exhaust valve The extractor chamber exhaust valve is used to release the air pressure in the low-pressure side and from inside the extractor chamber. When the valve is closed, the chamber can be pressurized. When the valve is opened, air in the chamber is exhausted and pressure is released, allowing the extractor chamber to be opened safely.
Pressurized air outlet The air outlet provides access to the regulated supply of air pressure from the low-pressure side. A quick-connect fitting allows connection of a low-pressure hose, which is connected to a low-pressure extractor chamber. The outlet fitting automatically closes and seals when no pressure hose is connected.
HIGH-PRESSURE SIDE
High-pressure regulator The high-pressure regulator is used to regulate the pressure on the high-pressure output line. The manual regulator provides regulated air pressure in the range of 5 to 15 bars (500 to 1500 kPa).
Pressure display The pressure of the regulated air is monitored with an electronic pressure transducer. The LED display provides a continuous readout of the pressure in units of bars.
Extractor chamber exhaust valve The extractor chamber exhaust valve is used to release the air pressure in the high-pressure side and from inside the extractor chamber. When the valve is closed, the chamber can be pressurized. When the valve is opened, air in the chamber is exhausted and pressure is released, allowing the extractor chamber to be opened safely.
Air outlet The air outlet provides access to the regulated supply of air pressure from the high-pressure side. A quick-connect fitting allows connection of a high-pressure hose, which is connected to a high-pressure extractor chamber. The outlet fitting automatically closes and seals when no pressure hose is connected.
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Compressor/extractor operation
1. Plug in and turn on the compressor/manifold unit. Plug the power cable at the back of the unit into an electrical outlet and turn the unit on with the power switch on the front panel. Turning the unit on supplies electrical power to all system components. The compressor motor turns on and begins pressurizing the storage tank. A pressure controller monitors the pressure in the tank, pressurizing the tank to approximately 250 psi (17 bars or 1700 kPa). A fan inside the compressor/manifold enclosure starts automatically to circulate air inside the enclosure and keep the compressor cool. Power is supplied to the pressure transducers and digital displays, and to the electronically controlled low-pressure regulator.
2. Install the porous plate and samples to be analyzed inside the extractor chamber. A porous ceramic plate is placed inside the chamber and an outflow tube is connected. The outflow tube, a short length of small-diameter plastic tubing, is connected to the pressure plate and to a tube fitting on the inside of the chamber. The outflow fitting vents to ambient air pressure, and carries water released from the soil sample. A short length of tubing can also be connected to the tube fitting on the outside of the chamber to facilitate in draining or collecting the outflow water.
3. Close and seal the extractor chamber. Ensure that the lid is properly oriented by matching the alignment markers on the top of the lid and the side of the extractor chamber. The lid is locked securely in place by aligning and tightening the six clamping bolts. Unused outflow-tube connections can be sealed by connected a short length of outflow tubing to the fittings, and sealing the tubing with a tubing clamp.
4. Reset the pressure regulators. Reset the pressure regulators to zero pressure by rotating the regulator handles counter-clockwise. This will ensure that the pressure output line does not begin pressurizing prematurely when the exhaust valves are closed.
5. Reset the extractor exhaust valves. The extractor exhaust valves are reset by turning the valve switches counter-clockwise to the "Pressurize" position. This enables the pressure outputs to be controlled and pressurized using the pressure regulators.
6. Reset the emergency stop button. The emergency stop is reset by pulling the emergency stop button out, away from the compressor/manifold front panel. Resetting the valve allows the system to be pressurized. If the emergency stop is not properly and safely reset, the high- and low-pressure sides can not be pressurized.
7. Connect the compressor/manifold unit to the extractor chamber. A pressure hose is connected to a pressurized-air outlet fitting on the compressor/manifold, and to the pressure hose connection on the extractor chamber.
8. Pressurize the chamber. Pressure in the extractor chamber is controlled by the pressure regulator. Pressure is increased by turning the regulator handle clockwise, and decreased by turning the handle counter-clockwise. The digital display provides a continuous readout of the pressure. Pressure is increased slowly until the desired pressure is reached. The large chamber volume, the volume of air in the air hose, and the high compressibility of air can cause a lag time between the time when the regulator is set and when the air pressure in the system equilibrates. By adjusting the regulator slowly, allowing the air pressure to equilibrate in the entire compressor/extractor system, and monitoring the pressure shown on the LED display, the desired pressure can be set accurately and over-pressurization avoided. If the desired pressure is exceeded, the pressure can be reduced by turning the regulator handle slowly counter-clockwise, and allowing the pressure to equilibrate.
9. Release pressure and open the chamber. When the test being run in the chamber is finished, the pressure is released and the chamber is opened. Pressure is released quickly by turning the exhaust valve clockwise to the "Exhaust" setting. Pressure can also be released slowly by turning the regulator counter-clockwise, reducing the pressure in the system. Using the exhaust valve to release pressure has the advantage of returning the system to the currently set pressure immediately when the system is restarted. After all pressure has been released, the clamping bolts retaining the extractor chamber lid can be loosened and the chamber opened safely.
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Further
Information
ASTM. 2000. D2325-68(2000) Standard Test Method for Capillary-Moisture Relationships for Coarse- and Medium-Textured Soils by Porous-Plate Apparatus. AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA.
ASTM. 2000. D3152-72(2000) Standard Test Method for Capillary-Moisture Relationships for Fine-Textured Soils by Pressure-Membrane Apparatus. AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA.
ASTM. 1998. D421-85(1998) Standard Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants. AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA.
ASTM. 1998. D2217-85(1998) Standard Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants. AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA.
Klute, A. 1986. Water retention: laboratory methods. in Klute, A. (ed), Methods of Soil Analysis: Part 1 - Physical and Mineralogical Methods, American Society of Agronomy/Soil Science Society of America: Madison, Wisconsin, USA.
Richards, L.A. 1941. A pressure-membrane extraction apparatus for soil solution. Soil Science, 51(5):377-386.
Richards, L.A. and L.R. Weaver. 1944. Moisture retention by some irrigated soils as related to soil-moisture tension. Journal of Agricultural Research, 69(6):215-235.
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Earth Systems Solutions Santa Barbara, CA 93111 USA Phone:1+805-967-2726 |
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