GB883438A - Improvements in or relating to tank contents indicators - Google Patents

Abstract

883,438. Control of two motors. PARKINSON COWAN Ltd. June 12, 1959 [June 20, 1958], No. 19782/58. Class 38 (3). [Also in Group XIX] An arrangement for indicating the quantity of liquid in a tank comprises a counter operated additively by liquid flow into the tank and subtractively by liquid flow out of the tank, and a detector actuated by the liquid surface when it reaches a predetermined level to reset the counter to a value corresponding to the predetermined level. To supply fluid to the tank, an " open " button is depressed to energize a relay RA which holds over its contact RA2 and whose contact RA1 closes to open a valve " in " in the tank supply line. A contact RA3 opens to inhibit operation of the outgoing valve, and a contact RA4 closes to enable an impulsing contact " TIN " operated by a meter in the liquid supply line, to supply pulses to a relay RB, the periodic closure of whose contact RB1 drives an impulse motor 15, Figs. 2 and 3. The motor 15 is adapted to drive a numeral wheel counter, Fig. 2, additively via gearing 14, 13. A similar arrangement is provided for registering fluid flow out of the tank, a motor 16 driving the counter subtractively. Resetting.-To obviate cumulative errors due to inaccuracies in the meters, means are provided to reset the counter automatically to a predetermined reading whenever the liquid surface reaches a predetermined level. A level detector on actuation, closes a contact TEK1 to energize a relay RE thereby energizing a relay RF over a contact RE1. Contacts RF1, RF2 then open to prevent impulses from the meters from reaching the motors 15, 16 during resetting and a contact RF3 closes to allow pulses from a motor-driven contact M1 to be supplied to the motor 15 or 16 depending on the state of contacts 23-26 which are operated by cams on the numeral wheels 10-12, Fig. 2. The contact 23 controlled by the units wheel 10 is normally closed but is opened when the units digit of the predetermined setting is showing. The contact 24 is similarly controlled by the tens wheel 11. Contacts 25, 26 are controlled by the hundreds wheel 12, the contact 25 being closed only when digits lower than the predetermined hundreds digit are showing and the contact 26 being closed only when the required digit or higher digits are showing. Thus, assuming that the error is less than 100, the counter is driven forwardly or reversely to the required setting, when the opening of both contacts 23, 24, Fig. 3, cuts-off the driving impulses. The time relay RE de-energizes after the maximum resetting time is passed.