초록 ▼

A system for maintaining back-pressure in chemical laboratory testing apparatus includes a modified flow control valve governed by a special control system which includes an input/output controller. That controller includes a microprocessor and memory into which a program developed specifically for

A system for maintaining back-pressure in chemical laboratory testing apparatus includes a modified flow control valve governed by a special control system which includes an input/output controller. That controller includes a microprocessor and memory into which a program developed specifically for the modified valve has been placed. A pre-pressure valve is also used upstream of the instrument in which the pressure is to be maintained for effecting quicker control of the pressure. The input/output controller, in conjunction with the servo-amplifier, integrates out the error between the desired set-point pressure and actual pressure thereby enabling maintenance of pressure within one pound.

대표청구항 ▼

A system for maintaining back-pressure in a low flow, low volume chemical testing apparatus, said apparatus including a chamber having input and output ends and in which pressure is to be maintained, means for applying at least one gas to the input end of said chamber, transducer means for measuring

A system for maintaining back-pressure in a low flow, low volume chemical testing apparatus, said apparatus including a chamber having input and output ends and in which pressure is to be maintained, means for applying at least one gas to the input end of said chamber, transducer means for measuring the pressure of said gas at the output end of said chamber and producing a first signal corresponding thereto, means downstream of said transducer for adjusting the back pressure of said chamber, means for producing a second signal corresponding to the magnitude of a desired back Pressure within said chamber, a microprocessor-based control subassembly coupled to receive said second signal from said signal-producing means and to receive said first signal from said measuring means transducer, said subassembly producing a modified set-point signal in response to said two signals indicating the departure of the actual pressure as measured by said transducer from said desired back pressure, servo means for comparing said first signal and said modified set point signal for producing a difference error signal and supplying the latter to regulate said means for adjusting the back pressure thereby to cause the pressure within said chamber to approach closely the desired back pressure; said means for applying said gas including a first automatically-operated flow valve in parallel with a second fast-acting prepressure flow valve, said second flow valve enabling said chamber to be quickly filled to approach the desired pressure at start up of said system; and said control subassembly including means for producing a third signal which is applied to said second valve for opening said second valve when the actual pressure in said chamber as measured by said transducer deviates by more than a predetermined amount from the desired set-point pressure.