Abstract: Method and apparatus are disclosed for controlling dialysis and ultrafiltration. Precision control over the operation of an artificial kidney (dialyzer), particularly the removal of waste water by ultrafiltration, is achieved by the use of two pumps in the respective paths to and from the artificial kidney. One of the pumps may be operated at constant speed and the other at a variable speed under control from a level sensor at the storage tank, whereby a prescribed rate of ultrafiltration is maintained by a third pump. If desired, the pumps may be operated at complementary speeds so that as the speed of one is increased, the speed of the other is decreased, maintaining a prescribed rate of ultrafiltration by a third pump, under the control of the level sensors at the tank. A further feature provides automatic switching back and forth between two storage tanks of blood cleansing fluid (dialysate) in conjunction with the two pumps in the respective paths to and from the artificial kidney.

Abstract: A remote monitoring terminal is disclosed for connection with a utility meter to encode and store the meter readings in digital form. The terminal can be interrogated to obtain the stored reading in serial form suitable for encoding and transmission over a communication line. Means are provided to prevent the stored meter reading from being lost in the event of a line-power interruption. A communication system is disclosed including a central office and a plurality of such remote monitoring terminals for addressing each of such terminals to retrieve the stored information therein to the central office.

Abstract: Apparatus for indicating when a change has taken place in a desired operating condition of a device using retriggerable multivibrators which are adjusted to represent particular periods with respect to the desired operating rate of the device. In the case of a motor, the multivibrators indicate when the motor is operating at, below or above a desired operating speed.