Abstract:
A piston for use in a compressor comprises a head portion and an engaging portion. The engaging portion includes a first shoe pocket and a second shoe pocket formed therein, and an interior surface of the first shoe pocket includes a hollow potion formed therein. Moreover, the interior surface of the first shoe pocket includes a lubrication layer formed thereon. For example, the lubricant layer may include a solid lubricant or a grease having a viscosity which is sufficient to adhere the grease to the interior surface of the first shoe pocket or the second shoe pocket, or both. In an embodiment, an interior surface of the second shoe pocket also may have the hollow portion formed therein. In another embodiment, the interior surface of the second shoe pocket may have a penetrating aperture formed therein.
Abstract:
To provide performance particularly in handling supercritical extraction systems, a specially designed pump includes a cam-driven, single-plunger with a cam having a profile that enables the pumping system to avoid destructive reverse torque on the cam, gear train and drive motor after the cam passes top dead center. The plunger includes a seal having one side in contact with the supercritical fluid and a mechanism for supporting and aligning the piston on the other side of the seal to maintain the piston in alignment. The piston drive has Hertzian contact with the piston. The fluid volume leaving the pump is determined by measuring only pressure or other parameters related to flow and movement of the plunger. Measurement of the fluid volume leaving the pump is useful for recording or indicating the flow rate while the pump is operating.
Abstract:
A variable-orifice fluid restrictor for use with a supercritical extractor or chromatograph includes an inlet line for fluid at a pressure above its critical pressure, an extended tubular probe having an inner and an outer surface and a proximal and a distal end. The proximal end of the probe is disposed toward the inlet line. The distal end of the probe includes an adjustable orifice means adapted for metering the fluid and having first and second orifice members and an adjusting stem having first and second ends. The adjustable orifice means is adjacent to the outer surface of the probe and the orifice means is adjustable with the adjusting stem. The end of the adjusting stem is located at the distal end of the probe and is adapted for moving the first orifice member with respect to the second orifice member to control the adjustable orifice for varying the restriction of fluid passing through the adjustable orifice. The distal end of the probe is inside the collector and the adjusting stem extends outside of the collector.
Abstract:
A swash plate type compressor that provides long lasting high lubricating performance to the sliding contact surfaces of a swash plate and shoes. The surface of the swash plate or the shoes on which the swash plate comes in sliding contact with the shoes is provided with an alloy plating layer, in which tin is the main component, as a surface treating layer. A coating layer, in which molybdenum disulfide is the main component, is formed as a solid lubricant layer on the foregoing plating layer. Preferably, the swash plate is made of aluminum or an aluminum alloy, and its surface is provided with the plating layer and the coating layer. More preferably, the coating layer contains graphite.
Abstract:
A scroll type compressor comprises a stationary scroll and a rotary scroll which is assembled with the stationary scroll so as to define a closed space, the outer surface of the rotary scroll 22 is formed thereon with a tin compound film containing a tin compound and having a thickness of 50 .mu.m. Such a coating film is never peeled off from a member even after long time operation, and is excellent in sealability and conformability, in the displacement type compressor.
Abstract:
A compressor has pistons slidably housed in cylinder bores. Respective shoes slide against each of the pistons and a swash plate or cam to convert rotation of the swash plate to reciprocation of the pistons. Each piston has a recess for slidably receiving the shoe. A friction reducing layer containing tin as a major component is formed between the shoe and the piston. Additionally, a tin-based layer may be formed between the shoe and the swash plate.
Abstract:
A swash plate type compressor having a cylinder block with cylinder bores disposed parallel to the axis of the cylinder block. A rotary shaft rotatably mounted within the cylinder block carries an aluminum swash plate. The swash plate is fixed in the rotary shaft and has two facial surfaces and an end surface. The swash plate has a coating preferably between 0.8 to 2.5 microns, of a tin/cobalt coating of at least 0.2 wt% cobalt and the balance being tin. A piston reciprocally fitted within the cylinder bore contains shoes which slideably intervene between the piston and the swash plate facial surfaces and reciprocate the piston and the swash plate facial surfaces and reciprocate the pistons by rotation of the swash plate. The coating on the swash plate permits the use of low silicon alloy aluminum without the need of metal plating or high finish polishing.
Abstract:
An apparatus for supercritical fluid extraction incorporates a removable extraction cartridge which in operation has insignificant pressure difference between its inside and outside walls. Because of the low pressure difference, the extraction cartridge need not have the strength to withstand significant pressure and can be made out of molded plastic for disposable use as well as stainless steel and/or machined plastic for reusability. The extraction cartridge can be removed and opened for sample access without the use of tools. The outside of the cartridge can be purged after it is installed in a heated high pressure vessel to remove contamination from its exterior. In one embodiment, the extractor includes a fraction collector for extractants, an automatic sample changer and an automatic cartridge transfer mechanism which provide completely automated extractions.
Abstract:
To collect analyte in a supercritical fluid extraction process, the extractant flows to a collection container under pressure. In one embodiment, the collection container contains collection solvent through which the extractant flows to partition analyte. The extractant adds to the liquid and when the collection solvent-extractant mixture rises to a heating zone, the extractant vaporizes selecively since its vapor pressure is higher than the vapor pressure of the collection solvent. When its pressure exceeds a preset valve pressure it is vented so that extractant continually leaves the collection container. After the extraction is complete, the analyte is concentrated in the collection solvent. In another embodiment, the collection vessel includes a solid material on which the analyte collects. It is removed under pressure by a solvent that is concentrated under pressure.
Abstract:
An apparatus for supercritical fluid extraction incorporates a removable extraction cartridge which in operation has insignificant pressure difference between its inside and outside walls. In one embodiment, the extractor includes a fraction collector for extractants, an automatic sample changer and an automatic cartridge transfer mechanism which provide completely automated extractions. To automatically perform extraction, valves for the fluids are automatically opened and closed in synchronism with the insertion and removal of the cartridges. These valves force a hard valve element into a softer valve seat with a valve stem that does not rotate significantly under the control of a rotary motor.