Abstract: To provide a protective coat on a refrigerated sample collector for a corrosive environment a unitary frame includes a support unit with condenser and evaporator coils mounted to the support unit and an orifice connecting the condenser and evaporator coils. The evaporator coils, condenser coils and a restrictor are powder coated after being connected, whereby an effective seal is provided for the restrictor, condenser coils and evaporator coils after they are assembled to the support. The unitary frame can be easily removed or connected as a unit to the sample collector. The bottle rack for the sample collector is made by injection molding two halves of the rack each of which has a matching surface and a bottle positioning surface. The matching surfaces are fastened together by placing the matching surfaces together back to back whereby locating members are spaced apart a sufficient distance.

Abstract: To provide a protective coat on a refrigerated sample collector for a corrosive environment a unitary frame includes a support unit with condenser and evaporator coils mounted to the support unit and an orifice connecting the condenser and evaporator coils. The evaporator coils, condenser coils and restrictor are powder coated after being connected, whereby an effective seal is provided for the restrictor, condenser coils and evaporator coils after they are assembled to the support. The unitary frame can be easily removed or connected as a unit to the sample collector. A peristaltic pump may be used for drawing at least one sample into the refrigerated sample collector and depositing said sample into at least one sample bottle. The peristaltic pump may include contoured tube guides to reduce movement of the peristaltic pump as a roller paddle rotates.

Abstract: To provide a protective coat on a refrigerated sample collector for a corrosive environment a unitary frame includes a support unit with condenser and evaporator coils mounted to the support unit and an orifice connecting the condenser and evaporator coils. The evaporator coils, condenser coils and restrictor are powder coated after being connected, whereby an effective seal is provided for the restrictor, condenser coils and evaporator coils after they are assembled to the support. The unitary frame can be easily removed or connected as a unit to the sample collector. A peristaltic pump may be used for drawing at least one sample into the refrigerated sample collector and depositing said sample into at least one sample bottle. The peristaltic pump may include contoured tube guides to reduce movement of the peristaltic pump as a roller paddle rotates.

Abstract: To provide a protective coat on a refrigerated sample collector for a corrosive environment a unitary frame includes a support unit with condenser and evaporator coils mounted to the support unit and an orifice connecting the condenser and evaporator coils. The evaporator coils, condenser coils and a restrictor are powder coated after being connected, whereby an effective seal is provided for the restrictor, condenser coils and evaporator coils after they are assembled.

Abstract: The bottle rack for the sample collector is made by injection molding two halves of the rack each of which has a matching surface and a bottle positioning surface. The matching surfaces are fastened together by placing the matching surfaces together back to back whereby locating members are spaced apart a sufficient distance. To warm a compressor to a starting temperature during cold weather, the ambient temperature is measured and when the ambient temperature is lower than a preset temperature and the compressor is not running, current is applied to the motor windings to warm the compressor.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: Pumping for chromatograph applications calls for constant flow at high pressures and for accurate control of liquid composition. A two-cylinder pump, and associated controls provide an accurate, fixed flow rate. During the initial portion of the pumping stroke of a first piston, while its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Once the pressure inside the first piston's cylinder has reached that of the discharge and its discharge check valve opens, the control system switches to a constant-pressure control mode, to maintain a fixed flow rate. Constant-pressure control is switched off when the second piston's discharge check valve closes, and pump control returns to fixed rotational speed. Determining the angular displacement at which to effect these control-mode switches is carried out by monitoring changes in the discharge pressure.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the pressure inside the first piston's cylinder has reached that of the discharge and its discharge check valve opens, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off when the second piston's discharge check valve closes, and pump control returns to fixed rotational speed.

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.