Abstract: A heat exchanger used in a screw air compressor has a low temperature chamber through which low temperature fluid flows and a high temperature chamber through which high temperature fluid flows. The low temperature chamber and the high temperature chamber are separated by a partition plate. The high temperature chambers and the low temperature chambers are alternately arranged in layers, so that the low temperature chambers are disposed at both ends in a layered direction. Additionally, the flowing direction of the low temperature fluid in the low temperature chambers and the flowing direction of the high temperature fluid in the high temperature chambers are substantially orthogonal to each other.

Abstract: In a system for monitoring each of compressors distant from each other through at least one of internet communication, optical communication line, electric communication line and wireless communication, a server computer obtains actual condition data of the each of the compressors through the at least one of internet communication, optical communication line, electric communication line and wireless communication, and stores therein the obtained actual condition data and predetermined database to be compared with the obtained actual condition data to find a remarkable technical point in the compressor, and a service center computer outputs the remarkable technical point to at least one of a service person and the compressor so that the at least one of the service person, the compressor and the user of the compressor can handle appropriately the remarkable technical point in the compressor.

Abstract: In a charging member having a support and one or more cover layer(s), the ten-point average surface roughness of the surface of the charging member, the height of a hill of the surface of the charging member, the area at the part of the hill, and the area of a region surrounded by hills each having the height H (?m) and other hills each having a height of not less than the height H (?m), and not including any hills having a height of more than 0.5H (?m) satisfy a specific relationship. Also, a surface layer of the charging member contains high-molecular compound particles whose average particle diameter is between 2 and 50 ?m and whose range of particle size distribution of average particle diameter is above 0?m and not greater than 7 ?m.

Abstract: In a conductive member having a support and provided thereon at least one cover layer, the cover layer has a surface layer, and the surface layer contains fine particles. In the surface layer, fine particles present at the surface-layer lower part corresponding to a range within 30% of the total layer thickness from the lowermost plane have an average particle diameter which is larger than the average particle diameter of fine particles present at the surface-layer upper part corresponding to a range within 30% of the total layer thickness from the uppermost plane. A process cartridge and an electrophotographic apparatus have such a conductive member.

Abstract: A heat exchanger used in a screw air compressor has a low temperature chamber through which low temperature fluid flows and a high temperature chamber through which high temperature fluid flows. The low temperature chamber and the high temperature chamber are separated by a partition plate. The high temperature chambers and the low temperature chambers are alternately arranged in layers, so that the low temperature chambers are disposed at both ends in a layered direction. Additionally, the flowing direction of the low temperature fluid in the low temperature chambers and the flowing direction of the high temperature fluid in the high temperature chambers are substantially orthogonal to each other.

Abstract: In a charging member having a support and provided thereon one or more cover layer(s), where the ten-point average surface roughness of the surface of the charging member is represented by Rz (&mgr;m), the height of a hill of the surface of the charging member is represented by H (&mgr;m), the area at the part of the hill is represented by Sa (&mgr;m2), and the area of a region surrounded by hills each having the height H (&mgr;m) and other hills each having a height of not less than the height H (&mgr;m), and not including any hills having a height of more than 0.5H (&mgr;m) is represented by Sb (&mgr;m2), these Ra, H, Sa and Sb satisfy a specific relationship.

Abstract: A package-type screw compressor includes a low-pressure stage state compressor and a high-pressure stage compressor. Motive power is transmitted from an electric motor to the two compressors via a speed increaser. The discharge gas, compressed and heated to a high temperature by the low-pressure stage compressor, is cooled by an intercooler. The discharge gas, compressed and heated to a high temperature by the high-pressure stage compressor, is cooled by an aftercooler. A casing of the intercooler and that of the aftercooler are formed integrally with a speed increaser casing, reducing the number of component parts. A cooler portion, formed by the intercooler and the aftercooler, is spaced from the speed increaser casing, thereby preventing heat, produced by the compressed air, from being transmitted to the speed increaser casing.

Abstract: In a conductive member having a support and provided thereon at least one cover layer, the cover layer has a surface layer, and the surface layer contains fine particles. In the surface layer, fine particles present at the surface layer lower part corresponding to a range within 30% of the total layer thickness from the lowermost plane have an average particle diameter which is larger than the average particle diameter of fine particles present at the surface layer upper part corresponding to a range within 30% of the total layer thickness from the uppermost plane. A process cartridge and an electrophotographic apparatus have such a conductive member.

Abstract: A screw compressor system comprises a plurality of screw compressors the capacity of each of which is controlled by repeating load operation and no-load operation. Using a timer output corresponding to compressed gas consumption in a demander including gas consumption equipments, a parent controller determines the number of compressors to be operated among the plurality of compressors. Among the compressors determined to be operated, all compressors other than one are put in load operation. In accordance with a load factor of the excepted one screw compressor, the parent controller controls discharge pressure of each compressor. At this time, the control is made so that discharge pressure of the screw compressor system measured by a pressure gauge be lower than that upon the maximum gas consumption.

Abstract: A package-type screw compressor includes a low-pressure stage state compressor and a high-pressure stage compressor. Motive power is transmitted from an electric motor to the two compressors via a speed increaser. The discharge gas, compressed and heated to a high temperature by the low-pressure stage compressor, is cooled by an intercooler. The discharge gas, compressed and heated to a high temperature by the high-pressure stage compressor, is cooled by an aftercooler. A casing of the intercooler and that of the aftercooler are formed integrally with a speed increaser casing, reducing the number of component parts. A cooler portion, formed by the intercooler and the aftercooler, is spaced from the speed increaser casing, thereby preventing heat, produced by the compressed air, from being transmitted to the speed increaser casing.

Abstract: In a system for monitoring each of compressors distant from each other through at least one of internet communication, optical communication line, electric communication line and wireless communication, a server computer obtains actual condition data of the each of the compressors through the at least one of internet communication, optical communication line, electric communication line and wireless communication, and stores therein the obtained actual condition data and predetermined database to be compared with the obtained actual condition data to find a remarkable technical point in the compressor, and a service center computer outputs the remarkable technical point to at least one of a service person and the compressor so that the at least one of the service person, the compressor and the user of the compressor can handle appropriately the remarkable technical point in the compressor.

Abstract: An air compressor comprises a compressor main body, and a capacity adjusting apparatus connected to an intake side of the compressor main body for adjusting the intake air flow into the compressor main body. The capacity adjusting apparatus is provided in an intake pipe. The intake pipe is adjacent to a discharge pipe of the compressor. A communicating passage is formed in the adjacent portion so as to introduce the compressed air discharged from the discharge pipe into the intake pipe system. The intake pipe is provided with an opening port for limiting the intake air flow into the compressor main body. The capacity adjusting apparatus opens and closes the communicating passage and the opening by means of an intake port switch valve and a discharge ventilating port switch valve which are provided in an end portion of the capacity adjusting apparatus.

Abstract: A package-type screw compressor includes a low-pressure stage state compressor and a high-pressure stage compressor. Motive power is transmitted from an electric motor to the two compressors via a speed increaser. The discharge gas, compressed and heated to a high temperature by the low-pressure stage compressor, is cooled by an intercooler. The discharge gas, compressed and heated to a high temperature by the high-pressure stage compressor, is cooled by an aftercooler. A casing of the intercooler and that of the aftercooler are formed integrally with a speed increaser casing, reducing the number of component parts. A cooler portion, formed by the intercooler and the aftercooler, is spaced from the speed increaser casing, thereby preventing heat, produced by the compressed air, from being transmitted to the speed increaser casing.

Abstract: A screw compressor system comprises a plurality of screw compressors the capacity of each of which is controlled by repeating load operation and no-load operation. Using a timer output corresponding to compressed gas consumption in a demander including gas consumption equipments, a parent controller determines the number of compressors to be operated among the plurality of compressors. Among the compressors determined to be operated, all compressors other than one are put in load operation. In accordance with a load factor of the excepted one screw compressor, the parent controller controls discharge pressure of each compressor. At this time, the control is made so that discharge pressure of the screw compressor system measured by a pressure gauge be lower than that upon the maximum gas consumption.

Abstract: A heat exchanger used in a screw air compressor has a low temperature chamber through which low temperature fluid flows and a high temperature chamber through which high temperature fluid flows. The low temperature chamber and the high temperature chamber are separated by a partition plate. The high temperature chambers and the low temperature chambers are alternately arranged in layers, so that the low temperature chambers are disposed at both ends in a layered direction. Additionally, the flowing direction of the low temperature fluid in the low temperature chambers and the flowing direction of the high temperature fluid in the high temperature chambers are substantially orthogonal to each other.

Abstract: An air compressor comprises a compressor main body, and a capacity adjusting apparatus connected to an intake side of the compressor main body for adjusting the intake air flow into the compressor main body. The capacity adjusting apparatus is provided in an intake pipe. The intake pipe is adjacent to a discharge pipe of the compressor. A communicating passage is formed in the adjacent portion so as to introduce the compressed air discharged from the discharge pipe into the intake pipe system. The intake pipe is provided with an opening port for limiting the intake air flow into the compressor main body. The capacity adjusting apparatus opens and closes the communicating passage and the opening by means of an intake port switch valve and a discharge ventilating port switch valve which are provided in an end portion of the capacity adjusting apparatus.

Abstract: A package-type screw compressor includes a low-pressure stage state compressor and a high-pressure stage compressor. Motive power is transmitted from an electric motor to the two compressors via a speed increaser. The discharge gas, compressed and heated to a high temperature by the low-pressure stage compressor, is cooled by an intercooler. The discharge gas, compressed and heated to a high temperature by the high-pressure stage compressor, is cooled by an aftercooler. A casing of the intercooler and that of the aftercooler are formed integrally with a speed increaser casing, reducing the number of component parts. A cooler portion, formed by the intercooler and the aftercooler, is spaced from the speed increaser casing, thereby preventing heat, produced by the compressed air, from being transmitted to the speed increaser casing.

Abstract: Compressor bodies, an accelerator and a main motor are disposed on a base, while an innercooler, an aftercooler an oil cooler and a coolant cooler are disposed perpendicular to the axial direction of the motor so that the directions, in which the tube nests of the gas coolers are drawn out, are made to be the same. A control panel having a maintenance display is mounted on a front panel composed of panel portions which are mounted pivotally around respective remote or opposite side ends. Portions to be inspected daily are disposed near the front panel and one side panel adjacent thereto.

Abstract: Compressor bodies, an accelerator and a main motor are disposed on a base, while an intercooler, an aftercooler, an oil cooler and a coolant cooler are disposed perpendicular to the axial direction of the motor so that the directions, in which the tube nests of the gas coolers are drawn out, are made to be the same. A control panel having a maintenance display is mounted on a front panel composed of panel portions which are mounted pivotally around respective remote or opposite side ends. Portions to be inspected daily are disposed near the front panel and one side panel adjacent thereto. The compressor bodies including rotors that have been coated with a melted and solidified substantially homogeneous and continuous layer of a tetrafluoroethylene-perfluoroalkylvinylether copolymer that is substantially devoid of pinholes.

Abstract: A two-stage vacuum pump apparatus has a first stage of vacuum pump constituted by a screw-type vacuum pump and a second stage vacuum pump constituted by an oil-sealed rotary vacuum pump operative to maintain the back pressure of the first stage vacuum pump at a level ranging from 1 to 100 Torr., whereby a high level of vacuum can be attained in a system to be evacuated without any risk of contamination of the evacuated system by oil. Also disclosed is a method of operating the two-stage vacuum pump apparatus.