Abstract:
To collect analyte from a supercritical fluid extractor, the collector lifts vials into place by a biasing means that guides the file up to the restrictor where it is sealed. The vial can be moved back down from the collecting mechanism even if frost forms on the vial while the restrictor means remains stationary. This vial is held in place by a guide that contains the seal for sealing the vial when it is raised in place.
Abstract:
An aluminum or aluminum alloy surface which during use is exposed to sliding friction has a chemical conversion coating of mostly tin with 0.2-10.0 wt. % cobalt and 0.1 to 12 wt. % bismuth. For example, a swashplate of a swashplate type compressor may be conversion coated on at least part thereof, that is the part that during use contact the shoes. Preferably, the coating is between 0.8 to 2.5 microns thick. 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:
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 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:
In a piston pump for pumping liquid carbon dioxide at a temperature below 30 degrees Fahrenheit and pressures at least as high as 7500 psi at an outlet flow rate in excess of 10 milliliters per minute, the inlet to the pump and the pumphead are each cooled by thermoelectric heat exchangers that are air cooled. The pump is a cam-driven, single-plunger pump with a cam profile that enables the pumping system to avoid distructive reverse torque on the cam, gear train and drive motor after the cam passes top dead center. The volume leaving the pump is determined by measuring only pressure or other parameter related to flow and movement of the plunger. The piston of the pump is supported on both sides of the seal and the support for the piston within the pumphead are machined consentrically and colinearly to the seal gland.
Abstract:
To pump supercritical carbon dioxide into a supercritical extractor without overpressure in the reservoir and to record the volume being delivered, the pumping speed is controlled and the volume pumped is determined from a pressure-related signal used in a feedback circuit. The feedback controls the velocity of pumping in conjunction with programmed values to avoid destructive reverse torque. A cam in the pump controls piston stroke, has a depressurization portion with an initial slope equal to but in the opposite direction of the final slope, rounded transition slopes, increasing linear velocity to the refill portion and constant velocity in the refill portion.
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.
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 extractments, an automatic sample changer and an automatic carteidge transfer mechanism which provide completely automated extractions.
Abstract:
A swash plate type compressor is provided with a surface coating layer on the surface of a swash plate. The surface coating layer acts to prevent the frictional resistance which leads to seizure conventionally occurring by the direct contact of the shoes and the swash plate body. The swash plate body is produced from aluminum or aluminum alloy and the surface coating layer is made of tin and at least one metal selected from the group consisting of copper, nickel, zinc, lead and indium.
Abstract:
There are disclosed a shoe which is interposed between a swash plate and a piston of a swash plate type compressor and which converts rotary movement of the swash plate into reciprocal movement of the piston, and a method for manufacturing the same. The shoe has a hemispherical part which is in slidable contact with the surface of a piston defining a hemispherical recess, and a flat end face which is in slidable contact with a bottom end face of the swash plate. According to the method of the invention, a columnar element is compressed in the axial direction for plastic deformation in such a manner that one end of the columnar element is deformed along the inner surface of a hemispherical recess of a die while the other end is urged against the flat end surface of another die. A shoe can be easily manufactured with this method, which has a flank between the hemispherical part which is in slidable contact with the surface of the piston defining the hemispherical recess and the bottom end face of the swash plate which is in slidable contact with the swash plate. According to this method, a hole of a predetermined size may alternatively be formed at the end face of a columnar part of the element, and the end face of the columnar part is cut into a conical shape while reducing the diameter of the hole toward the opening side thereof. Still alternatively, the periphery of the end face of the columnar part may be cut into a conical shape and then pressed to form a hemispherical part. A great flow of the material and local exertion of a high load on the element are prevented.
Abstract:
There are disclosed a shoe which is interposed between a swash plate and a piston of a swash plate type compressor and which converts rotary movement of the swash plate into reciprocal movement of the piston, and a method for manufacturing the same. According to the method of the invention, a columnar element is compressed in the axial direction for plastic deformation in such a manner that one end of the columnar element is deformed along the inner surface of a hemispherical recess of a die while the other end is urged against the flat end surface of another die. A shoe can be easily manufactured with this method, which has a flank between the hemispherical part which is in slidable contact with the surface of the piston defining the hemispherical recess and the bottom end face of the swash plate which is in slidable contact with the swash plate. According to this method, a hole of a predetermined size may alternatively be formed at the end face of a columnar part of the element, and the end face of the columnar part is cut into a conical shape while reducing the diameter of the hole toward the opening side thereof. Still alternatively, the periphery of the end face of the columnar part may be cut into a conical shape and then pressed to form a hemispherical part. A great flow of the material and local exertion of a high load on the element are prevented.