SU1733936A1 - Device for testing articles for tightness - Google Patents

Abstract

The invention relates to the monitoring of the tightness of closed products by manometric methods and allows for increasing the reliability by compensating for the change in pressure in the test chamber. The device comprises a measuring chamber 2 connected through valve 3 to the prechamber 4 and through valve 5 to main pressure. The measuring chamber 2 is also connected to a threshold element 6 for detecting a coarse leak and an analog amplifier 7 for a small leak. The output signal of the Pig amplifier 7 controls, by means of the valve 8 and the comparison element 9, the conductivity of the resistance R, as a result of which the parameters of the RC-chain and the frequency f of the generator 10, including the three-tuned element 11 and the capacitance 12, change. Pt (through the inverter 13) is supplied to the active resistance 14, which includes normal-closed and normally-open contacts, respectively, 15 and 16 and the dosing volume 17 placed between them. Active resistance 14 is included in the line between the output channel of the force ate 7 and the measuring chamber 2. 1 z.p.f BACKGROUND yl 1. and

Description

The invention can be used in the engineering, petrochemical, gas and other industries.

Pressure gauge leak testing devices 1 are known, containing a threshold device for monitoring coarse and minor leaks, valves and control devices for automating the inspection process.

The disadvantage of these devices is the low reliability of the hontrol results due to the lack of compensation for changes in test pressure in the presence of a leak.

It is also known to have a pressure gauge leakage tester 2, in which compensation has been introduced in the form of feedback in an analog amplifier of a small leak connected to an analog-digital converter and a secondary device.

However, this device, although possessing higher reliability of measurements compared to its analogue, does not suit this parameter due to the presence of compensation only by the internal measurement circuit, which is an analog amplifier.

The overall task of increasing the reliability of measurements is to compensate for the leakage within the external circuit of the installation, including the measuring chamber with the product placed in it. Building such a closed co

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with

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The leakage compensation system was associated with the lack of technical equipment with adjustable linear conductivity of the resistance, the capacity of which would be sufficient to maintain a small change in test pressure in a stochastic process such as leakage through leaks that can occur under different conditions: molecular, intermediate, in viscosity, etc.

The purpose of the present invention is to increase the reliability of the tightness control by compensating for the change in pressure in the measuring chamber.

To achieve this goal, a device for monitoring leaktightness of products, containing a measuring chamber, a source of test pressure connected to it, a coarse leak sensor and a small leak sensor, and a secondary recording device connected to the coarse leak sensor directly, an inverter is introduced, which is normally pneumatic. open and with normally closed contacts, with an air cavity placed between them and connected to the contacts with the first control input located with the side Normally open contact is given, and the second is from the side of a normally closed contact, with a control signal generator, the control input of which is connected to the low-leakage sensor output, the output is connected to the second input of the recording device and the first active resistance control input through the inverter, the active resistance input is connected to the low leakage sensor output, and the output is connected to the cavity of the measuring chamber, and the second active resistance control input is connected to the output of the control signal generator and the air cavity is adjustable in volume.

The drawing shows a diagram, explaining the principle of operation of the proposed device.

The product 1 is placed in the measuring chamber 2 connected through valve 3 with the bladder 4 and through valve 5 with the main pressure. On the other hand, the measuring chamber 2 is connected to a threshold element 6 for detecting a coarse leak and an analog amplifier 7 for a small leak. The output signal Pbyh of the amplifier 7 controls, by means of the valve 8 and the comparison element 9, the conductivity of the resistance R, as a result of which the parameters of the RC-chain and the frequency f of the generator 10 are changed,

including a three-membrane element 11 and a capacitor 12. The output signals of the generator 10 Pt and Pt (through the inverter 13) are fed to the active resistance 14, which includes

normally closed and normally open contacts 15 and 16 and a dispensed volume 17 placed between them. Active resistance is included in the line between the output channel of amplifier 7 and

measuring chamber 2. The output signals of coarse and small leaks are recorded by the secondary device 18. The operation modes are controlled through valves 3,5,8 and 19 programmable controller

(not shown) using the commands

to, t1, t2, T.Z.

The device works as follows.

Switching valves 3,5,8,19 using the commands to, ti, t2 and tz establishes a control mode of operation, at which at the initial moment of time the pressure in the measuring chamber is equal to Pu. In the case of a small leak output pressure PW

the analog amplifier drops, resulting in a change in the resistance R of the reference element 9. The generator 10 outputs the signals Pt and Pt with a frequency f proportional to the output pressure P out. Pt and Pt signals,

sequentially connecting the metered volume 17 with the line Pout and measuring chamber 2, results in an increase in the pressure Pu to the initial value. When the process is established during the time control flow

Q v t (Rvyh-Ri).

where V is the dosed volume 17.

The frequency f displayed on the secondary device 18 unambiguously determines the value of the leakage flow Q at constant V AND (Pout-R).

The economic effect of the introduction

The proposed device consists in increasing the reliability of leakage control by increasing the relative measurement error of 0.5.

Claims (2)

1. A device for monitoring the tightness of products, comprising a measuring chamber, a test pressure source connected to it, a coarse leak sensor and a small sensor and a secondary recording device connected directly to the coarse leak sensor, characterized in that. in order to increase reliability by compensating for the pressure change in the chamber, it is equipped with an inverter, active pneumatic resistance, made with normally open and normally closed contacts, with an air cavity placed between them and connected to the contacts, with the first control input, located on the side of a normally open contact, and on the second side - on the side of a normally closed contact, and a generator of control signals, the control input of which is connected to the output of a low-leakage sensor, the output is by the entrance 0 the recording device directly and with the first control input of the active resistance through the inverter, the input of the active resistance is connected to the output of the low leakage sensor, and the output is connected to the cavity of the measuring chamber, and the second control input of the active resistance is connected to the output of the control signal generator 2. The device according to claim 1, of which is that the air cavity is made adjustable in volume.  /////////// /