Abstract: A corrosion resistant check valve having plastic components in the fluid path is provided. The check valve broadly comprises an inlet housing, an outlet housing, a valve poppet, and a spring. The inlet housing has an inlet passageway and the outlet housing has an outlet passageway. The inlet housing and outlet housing are connected to define an internal chamber of the check valve. An inner portion of the inlet housing has a transverse wall which includes a valve seat surface and a central hole which defines a flow passageway between the inlet passageway and the internal chamber. The valve poppet is disposed within the internal chamber and has a disk-shaped body and a stem extending perpendicularly outward from a centerpoint of the body. The stem of the valve poppet is positioned in a central bore in a planar end surface of the spring. The planar end surface of the spring also includes fluid flow passages disposed about the central bore.

Abstract: An improved dual-stage pump system is provided for the accurate pumping and filtering of viscous fluids. Two hydraulically activated pumps are provided in series with a filter and reservoir disposed in-line between the two pumps. The reservoir acts as a source bottle for the second pump and allows the first pump to pump the viscous fluid through the filter at a rate independent of the dispensing rate of the second pump. By operating the first pump at a rate independent of the second pump, back pressure at the filter is avoided. Each hydraulically activated diaphragm pump is equipped with an improved diaphragm that is pre-formed to the geometries of the process fluid cavity thereby eliminating any inaccuracies in the operation of the pumps due to expansion of retraction of the diaphragm during pump operation.

Abstract: A liquid pumping and filtering system for use in dispensing materials such as photoresist used to make semiconductors. A positive displacement diaphragm pump is used to draw source liquid from a source bottle. A pump valve is activated to direct fluid from the pump to a main dispensing line which includes a filter. A suckback line bridges the dispense line. The suckback line and the dispense line are each connected to a final dispense line, and the flow of liquid is controlled by a filter valve, which alternative causes fluid to flow through the suckback line or the dispense line, depending upon the mode of operation of the system. The use of an independent suckback line allows the quick withdrawal of fluid away from the dispense nozzle in the final dispense line. As a result, liquid in the dispensing line on opposite sides of the filter is generally maintained at constant pressure.

Abstract: An improved dual-stage pump system is provided for the accurate pumping and filtering of viscous fluids. Two hydraulically activated pumps are provided in series with a filter and reservoir disposed in-line between the two pumps. The reservoir acts as a source bottle for the second pump and allows the first pump to pump the viscous fluid through the filter at a rate independent of the dispensing rate of the second pump. By operating the first pump at a rate independent of the second pump, back pressure at the filter is avoided. Each hydraulically activated diaphragm pump is equipped with an improved diaphragm that is pre-formed to the geometries of the process fluid cavity thereby eliminating any inaccuracies in the operation of the pumps due to expansion of retraction of the diaphragm during pump operation.

Abstract: A precision liquid dispenser embodying the present invention includes a displacement diaphragm pump and a hydraulic system for selectively deforming the diaphragm. The diaphragm pump includes a pump body, a pump cavity, a pump diaphragm, and an input/output port. A solenoid operated valve assembly selectively connects the port to a source of liquid to be dispensed. The hydraulic system for selectively deforming the diaphragm includes a body with a cavity, a piston, a sealing ring, and hydraulic fluid in the space between the piston and diaphragm. The position of the piston is controlled by a stepping motor, a mechanical threaded coupling, which converts rotary motion of the motor output shaft to linear motion of the piston. The volume of fluid dispensed is determined by the number of pulses applied to the stepping motor. The output flow rate as a function of time is controlled by the rate of pulses applied to motor as determined by the control logic.