Abstract: A system and method for balancing flows of renal replacement fluid is disclosed. The method uses pressure controls and pressure sensing devices to more precisely meter and balance the flow of fresh dialysate and spent dialysate. The balancing system may use one or two balancing devices, such as a balance tube, a tortuous path, or a balance chamber.

Abstract: A method and apparatus for locating the edge of a headlamp and for centering a headlight aiming device with respect to a particular location on the headlamp includes an elongated hollow tube having first and second ends, the first end of which has an entrance opening designed to have light from the headlamp incident thereon. The entrance opening of the tube and the length of the tube provide an appropriate field of view such that the light incident upon the entrance opening of the tube travels down the tube and is incident upon a light detection device located at the far end of the tube. The light detection device is connected to signal amplifying circuitry which provides a digitally coded output signal indicative of the intensity of the light from the headlamp. The tube is moved vertically and horizontally from positions outside of the headlamp beam pattern to locations within the headlamp beam pattern and across the plane of the headlamp edge.

Abstract: A water treatment apparatus has a tank that contains a resin bed through which water flows. The apparatus is controlled by occasionally measuring the conductivity of the resin bed at two spaced apart locations to produce first and second conductivity measurements. The ratio of the two conductivity measurements is calculated periodically. The present ratio value, along with the minimum and maximum ratio values that occurred since a previous regeneration of the resin bed, are used to determine the movement of an exhaustion front through the resin bed. A probability of exhaustion also is determined and when that probability exceeds a given value, regeneration of the resin bed is initiated. The conductivity measurements are used to determine if the resin bed has lost efficiency and in which event a warning signal is sent to the user.

Abstract: An ultrasonic flowmeter which measures gas velocity including a pair of ultrasonic transducers oppositely located around a conduit at a predetermined angle to the flow direction. Each transducer alternates between acting as a transmitter and a detector of ultrasonic frequencies, thus as one transducer transmits, the other receives. A measurement is made of the time of flight of the ultrasonic signal between the transmitter transducer and the receiver transducer and a microcomputer calculates the velocity of the gas by a known mathematical relationship utilizing the difference between the time of flight of the ultrasonic signals traveling upstream and those traveling downstream. The time of flight is determined by the phase shift or difference in phase angle between the signal at the transmitter transducer and the signal detected by the receiver transducer. To prevent ambiguity arising when the phase angle difference exceeds 360.degree.

Abstract: A membrane and the method of making the same is disclosed for use with glucose analyzers to detect the level of glucose in liquid mediums such as whole blood. The membrane comprises a thin base wafer of a hydrophobic fluorocarbon material such as polytetrafluoroethylene (TEFLON). The wafer is initially etched by removing surface fluorides to produce a hydrophilic surface and is then contacted with a mixed reagent formed by combining in a volume ratio of about 1:1:1 about 4% paraformaldehyde in water, about 5% bovine serum albumin in water and about 10% glucose oxidase in water. The resultant membrane contains glucose oxidase covalently bonded to the surface of the base wafer.