SU1089442A2 - Device for detecting gas leakage from articles - Google Patents

Abstract

DEVICE FOR DETECTION OF GAS LEAKAGE FROM PRODUCTS on aut.St. . 954832, characterized in that, in order to increase the sensitivity and. noise immunity; it is equipped with a comparison circuit, the input of which is connected to the amplifier output, and the output is connected to the third control input of the memory block, and a time delay unit connected to the control one. mu input pre-alarm unit. (/}

Description

The invention relates to a test technique, is intended to detect the location of a leak of combustible gas (hydrocarbons) and can be used to search for leaks in fittings and appliances for gas supply systems. On the main auth; sv. No. 954832, a device for detecting gas leakage from products is known, comprising a gas sensor, an amplifier, a memory unit whose output is connected to the input of the amplifier, a threshold circuit connected to the amplifier output, an integrator connected to the amplifier, a time relay, unit pre-alarm, light signaling unit clock generator and additional threshold circuit with a high response level, the output of which is connected to the input of the light signaling unit; the input is connected to the amplifier output and the threshold circuit input; The operator is connected to the input of the pre-alarm unit, the control input of the clock generator, the output of which is connected to the first control input of the memory unit, and a time relay whose output is connected to the second control input of the memory unit l. The disadvantages of the known device are a decrease in sensitivity when the signal from the sensor deviates from the equilibrium state, due to various internal or external destabilization, to the inoperative area of the device, as well as low noise immunity, resulting in the occurrence of false alarms during short-term fluctuations (INPUT signal due to the fact that the integrator accumulates smoothed fast fluctuations of the input signal with a tracking period shorter than the integrator recovery time, and this is This leads to triggering a threshold circuit and creating a false signal at the output of the pre-alarm unit. The purpose of the invention is to increase the sensitivity and noise immunity of the device. This goal is achieved by having a device for detecting gas leaks from products containing a gas sensor, amplifier, unit a memory whose output is connected to the amplifier input, a threshold circuit, an integrator connected to the amplifiers, a time relay, a pre-alarm unit, a light signaling unit, a clock generator, up to Complementary threshold circuit with a trigger level, the output of which is connected to the input of the light signaling unit, and the input is connected to the output of the amplifier and the input of the threshold circuit, the output of which is connected to the input of the preliminary alarm unit, the control input of the clock generator, the output of which is connected to the first control input of the unit memory, and the time relay input, the output of which is connected to the second control input of the memory unit, is equipped with a comparison circuit, the input of which is connected to the output of the amplifier, and the output to the third control the memory block stroke and the time delay block connected to the control to the main input of the pre-alarm unit. The drawing shows the block diagram of the device. The device contains a gas sensor 1 connected to the input of amplifier 2, the output of which is connected to the input of memory block 3, the output of the latter is connected to the input of amplifier 2, threshold circuit 4-, integrator 5 connected to amplifier 2, time relay b, block 7 pre-alarm, light-signaling unit 8, clock generator 9, additional threshold circuit 10 with a high response level, the output of which is connected to the input of the light-signaling unit 8, and the input to the output of amplifier 2 and input of the threshold circuit 4, whose output is connected to input b pre-alarm lock 7, a control input of a clock generator 9, the output of which is connected to the first control input of the memory unit 3, and an input of the time relay 6, the output of which is connected to the second control input of the memory unit 3. The device also contains a comparison circuit 11, the input of which is connected to the output of amplifier 2, and the output is connected to the third control input of memory block 3, and the time delay unit 12, which is connected to the control input of pre-alarm unit 7. The device works as follows. When moving the gas sensor 1 along the monitored surface (not shown), the input of the amplifier .2 receives a signal consisting of both fluctuations and reactions of the sensitive element of the sensor 1 to a combustible gas. Output voltage of amplifier 2,. smoothed by integrator 5, is memorized in memory block 3 when there is a pulse on the first control input of block 3 Memorization that comes from the clock generator 9. From the output of memory block 3, the voltage goes to the input of amplifier 2 and the input signal is compensated. During the next pulse The comparison coming from the clock generator 9, is amplified

the difference between the current and memorized signal in the memory block 3, while the input of the memory block 3 is disconnected from the output of the amplifier 2. Pulse duration Memorization is much less than the pulse duration Comparison,

If during the pulse operation Comparison of the output signal of amplifier 2 is shifted to the inactive region relative to the memorized one, which is equivalent to an increase in the response voltage of the threshold circuits 4 and 10 and leads to a decrease in the sensitivity of the device, the comparison circuit 11 generates a signal through the third control input memory unit 3 connects the input of memory unit 3 to the output of amplifier 2, and the signal is compressed.

When the voltage from the amplifier 2 output reaches the threshold value of the threshold circuit 4, the clock generator 9 stops the generation of impulses Remembering and the time relay 6 switches on, the dwell time of which is associated with the rise time of the signal from sensor 1 when exposed to a specified minimum concentration gas and also through time

determined by time delay unit 12 / performing additional time selection of the input signal and eliminating the possibility of false alarms in the presence of fast periodic fluctuations, the preliminary alarm unit 7 is activated.

If during the time of action of the relay 6 of time the threshold circuit 0 10 triggers with a high response level, which determines the sensitivity of the gas leak detection device, the light alarm unit 8 is turned on and the leak is detected at the end of the LED indicator (not shown).

At the end of the time delay, the & time, a signal is compensated, and a device for detecting

0 gas leak comes to its original state.

The proposed device allows to increase the sensitivity and noise immunity during the work related

5 with possible mechanical impacts of the SWIRAM on the gas sensor, allows the use of gas sensors with lower requirements for their internal debalance.

Claims (1)

DEVICE FOR DETECTING GAS LEAKAGE FROM PRODUCTS by ed. . No. 954832, characterized in that, in order to increase sensitivity and. noise immunity, it is equipped with a comparison circuit, the input of which is connected to the amplifier output, and the output - with the third control input of the memory unit, and a time delay unit connected to the control -. mu input of the pre-alarm unit. □ About With 4 ^ 4 ^ GF>