GB1442753A - Control systems - Google Patents

Abstract

1442753 Delivering measured quantities BEAVEN & SONS Ltd 7 Sept 1973 [7 June 1972] 26441/72 Heading B8N [Also in Division A5] A control system for controlling the delivery of measured quantities of fluid to and from a utilisation or storage unit, e.g. a human body in peritoneal or renal dialysis, comprises a first measurement device E in which the amount of fluid to be fed to the unit is measured, a first sensor G B responsive to a zero level of fluid in the device E, a second sensor GA responsive to a settable level of fluid in the device E, means responsive to operation of the sensors GB, GA whereby a controlled amount of fluid may be fed to the device E and the feed means, e.g. a pump C, then deactuated, and means whereby opening of an outlet valve J associated with the device E is enabled when feeding of the controlled amount has been sensed whereby that amount can be withdrawn from the device E for passage to the consumption or storage unit. The system also includes a second measurement device 11 to which fluid passes after having remained in the unit for a controlled period, sensor means G1 for sensing when a predetermined quantity of fluid has passed into the device 11 and therupon transmitting a signal to close a valve N in a line between the unit and the device U, means co-ordinating operation of the sensor means of the measurement devices E and U to ensure that a set cycle of operations is effected in a predetermined sequence, and first, second and third timers which respectively produce signals a predetermined time after initiation of withdrawal of fluid from the device E, after the fluid has been in the unit/patient for a predetermined time period, and a predetermined time after the commencement of passage of fluid to the device U. As described the sensors GA, GB, G1 and G2 are photo-electric devices which sense the liquid level in branch pipes of float chambers F, F2 connected to the measuring devices E and U respectively. As described the valve J is closed and fluid is supplied from reservoirs A to device E by a pump C. When sensor GA detects that the device E is filled to the desired level pump C is stopped and subsequently valve J is opened to allow fluid to flow under gravity via a heater M to the consumption or storage unit. The valve J is closed when sensor GB detects that device E is empty. After a dwell time valve N is opened and fluid flows from the unit to device U until sensor G1 is actuated to close valve N and open a discharge valve P. When device 11 is empty as detected by sensor G2 valve P is closed. Timing devices control the start of the cycle and the dwell time. The system is controlled by an electric or electronic circuit, both of which are described in detail, and this includes alarm devices which operate when the cycle is not followed or is interrupted. Means may be included to count the number of operations of the valves J and N.