Abstract: A module containing a reverse osmosis membrane for a water purification system is provided. A membrane assembly is mounted in the center of a pressure vessel with a seal surrounding the membrane assembly between the outside of the assembly and the inner wall of the pressure vessel. An inlet port passes through the pressure vessel and enters the vessel between the seal and one end of the pressure vessel in close prximity to the seal. An outlet port passes through the pressure vessel at a point between the seal and the other end of the pressure vessel, also in close proximity to the seal. The water pressure differential between the two ports maintains the integrity of the seal and their location insures a turbulent water flow throughout the module.

Abstract: The cuvette rotor assembly is adapted for use in a multistation photometric analyzer of the type wherein several chemical reactions are sequentially monitored over a predetermined time span. Such an assembly includes a ring shaped cuvette rotor having an outer circular periphery, an inner circular periphery, a first side, a second side and cuvette forming slots extending between the sides and into the rotor from the inner periphery toward the outer periphery. A mixture of reagent and sample is urged by centrifugal force into the cuvette forming slots as the rotor is rotated. A fixed beam of light is directed at one side of the rotor as the rotor is rotating and the light that passes through each cuvette as a reaction is taking place therein is sensed and measured.

Abstract: An improved drive is provided for a syringe having a barrel and a plunger. The drive utilizes an electric motor which has an axial shaft that moves back and forth axially when the shaft is prevented from rotating. A syringe barrel holder is fixed relative to the electric motor housing and a plunger holder is rigidly fixed to the shaft. When the electric motor is energized, the plunger holder will move back and forth relative to the syringe barrel holder. A plurality of switches for controlling the electric motor are positioned in fixed locations relative to the motor housing. The plunger holder is operative to actuate and deactuate the switches during axial travel of the shaft.