Fluid sensing systems

A fluid flow sensing system, said system comprising:

• a flowmeter having an output lead and a first device for producing a train of pulses thereon of a pulse repetition frequency directly proportional to the volume rate of flow of a fluid through said flowmeter;
• a densitometer having an output lead and a second device for producing a signal thereon directly proportional to the specific gravity of said fluid;
• a first switch connected from said flowmeter output, said first switch having a switch position control lead;
• a first digital pulse counter connected from said first switch;
• and a gate generator connected from said densitometer output lead to said first switch, said gate generator producing an output pulse having a time width which is a predetermined percent of the period thereof, said predetermined percent being the percent of one of at least two different parts of said fluid, said first switch having first and second positions, said gate generator being adapted to hold said first switch in said first position during the generation of each output pulse of said gate generator and to hold said first switch in said second position thereof at all other times during normal operation, said first switch connecting said flowmeter output lead to the input of said first counter when said first switch is in one of said first and second positions and to disconnect said flowmeter output lead from said first counter all the normal operating time that said first switch is in the other of said first and second positions, said gate generator including a comparator having a first input lead connected from said densitometer output lead, said comparator having an output lead connected to the control lead of said first switch, a first source of potential having first and second output leads, said first source being adapted to produce a constant potential +E on said first lead thereof and a constant potential -E on said second lead thereof, an integrator, cycle means to sample the said potentials +E and -E alternately, said cycle means being connected from said first source leads to the input of said integrator to impress a rectangular wave thereon having a high level of +E and a low level of -E, said cycle means including a second switch connected from said first source leads to said integrator input, said second switch having a switch position control lead, a flip-flop having a set 1 input, a set 0 input and a 0 input, said 0 output being connected to said second switch control lead, said switch being actuable by said flip-flop to connect said first source first lead to said integrator when the integrator output first falls below the low limit of said low limit detector and to connect said first source second lead to said integrator input when the integrator output first rises above the high limit of said high limit detector, said high limit detector being connected from said integrator output and being constructed to set said flip-flop to the 1 state when said integrator output first has a magnitude greater than said high limit, said low limit detector being connected from said integrator output and being constructed to set said flip-flop to the 0 state when said integrator output first has a magnitude less than said low limit, said comparator having a second input lead connected from said integrator output, said comparator producing an output pulse on said output lead of a pulse width which is the time that the output signal magnitude of said integrator exceeds the magnitude of the signal on said comparator first input lead.