Photo-electric gas micro bubble flowmeter
Technical field
The present invention relates to a kind of photo-electric gas micro bubble flowmeter, especially be applied to the test of the inner little quantity of gas leakage of Subzero valve and device systems.
Background technology
At present have the equipment quantity of gas leakage of sealing requirements to detect and adopt gas meter to realize usually at valve and inner, under the normal temperature than atmospheric leakage rate (>10ml/min) and the ultramicron quantity of gas leakage (<1 * 10
-3Pam
3/ s) means of testing of comparative maturity arranged all; Like thermal gas flowmeter; Helium mass analyzer etc., but test does not have better means for the cryogenic gas leakage rate in above both testing range scopes, and also above-mentioned separate unit flowmeter can only be tested to the pure gas kind.
Summary of the invention
The objective of the invention is to provide a kind of flowmeter, can test variety classes gas tiny leakage amount, also can realize the leakage rate test of gas under worst cold case simultaneously.
For realizing above-mentioned purpose, technical scheme of the present invention is: a kind of photo-electric gas micro bubble flowmeter is characterized in that this flowmeter mainly comprises the gas access device, alcohol bubble generator, light quantity decay detecting device, event counter and computing machine; The interface of said gas access device is connected with the gas Leak Detection pipeline output interface of tested valve; Tested gas leakage gets into the alcohol bubble generator through pipe system; Output bubble signal after light quantity decay detecting device detects the optical attenuation value and the setting threshold in the light quantity decay detecting device is compared; Event counter is transferred to computing machine with the serial communication mode with instantaneous number of bubbles and accumulative total number of bubbles after receiving light quantity decay detecting device input signal; Computing machine is according to the test gas kind, and temperature, pressure parameter setting value be the actual quantity of gas leakage that records of output finally.
Said gas access device comprises temperature sensor, pressure transducer, gas circuit switching solenoid valve and pipeline fast interface, realizes the protection to flowmeter.
Said alcohol bubble generator adopts the clear glass Work container, and it is made up of gas access port and test chamber two parts of becoming the Y type, realizes that the side direction bubble takes place, and has prevented that gas is jammed, and has guaranteed that simultaneously bubble is big
Little, the consistance of direction and the homogeneity of blebbing speed.
Said light quantity decay detecting device is by laser generator, and light quantity detects and inner comparator circuit is formed, and realizes detection and judgement to sending the laser pick-off amount, through receiving the variation of light quantity, realizes leaking the counting of tolerance.Light quantity decay detecting device causes the decay that receive luminous flux to carry out with setting threshold judge to laser refraction through detecting flow of bubble when alcohol is inner; And with the mode of electric signal to outside output bubble signal; Signal finally transfers to computing machine through the communication interface mode of RS232, RS485 or USB by event counter; Finally export the gas flow that records, and can inform the tester with the mode of real-time curve by calculate the back by computing machine.
Beneficial effect of the present invention and distinctive feature are; The hardware change can be need not to carry out according to the data of computer-internal database storing and variety classes gas can be tested; Adopt photoelectric sensor to be implemented in the detection under the gas low temperature state, the gas flow measurement scope has remedied the blind area of current conventional flow measurement examination.
Description of drawings
Fig. 1 is a structural representation of the present invention;
Fig. 2 is an alcohol bubble generator structural representation;
Fig. 3 is a fundamental diagram of the present invention;
Fig. 4 is an application example cryogenic valve of the present invention worst cold case internal leakage test principle figure.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail, but present embodiment is not limited to the present invention, every employing and analog structure of the present invention and similar variation thereof all should be listed protection scope of the present invention in.
By shown in Figure 1, a kind of photo-electric gas micro bubble flowmeter is characterized in that this flowmeter mainly comprises gas access device 1, alcohol bubble generator 2, light quantity decay detecting device 3, event counter 4 and computing machine 5; The interface of said gas access device 1 is connected with the gas Leak Detection pipeline output interface of tested valve; Tested gas leakage gets into alcohol bubble generator 2 through pipe system; Output bubble signal after light quantity decay detecting device 3 detects the optical attenuation value and the setting threshold in the light quantity decay detecting device 3 is compared; Event counter 4 is transferred to computing machine 5 with the serial communication mode with instantaneous number of bubbles and accumulative total number of bubbles after receiving light quantity decay detecting device 3 input signals; Computing machine 5 is according to the test gas kind, and temperature, pressure parameter setting value be the actual quantity of gas leakage that records of output finally.Gas access device system comprises temperature sensor 6, pressure transducer 7, gas circuit switching solenoid valve 8 and pipeline fast interface.
By shown in Figure 2, alcohol bubble generator 2 adopts the clear glass Work container, guarantees that laser has stable damping capacity when penetrating, and the clear glass Work container is made up of the gas access port that becomes the Y type 12 and test chamber 13 two parts, realizes that the side direction bubble takes place.Realize that side direction bubble occurring mode guarantees that the bubble that produces in the bubble generator meets the requirement of test.Test chamber 13 both sides of alcohol bubble generator 2 are equipped with Laser emission end 10 and laser pick-off end 9 respectively.
Light quantity decay detecting device is by laser generator; Light quantity detects and inner comparator circuit is formed, and is connected with Laser emission end 10, laser pick-off end 9 through optical fiber 11, realizes detection and judgement to sending the laser pick-off amount; Through receiving the variation of light quantity; Realization can be set and revise in light quantity decay detecting device simultaneously leaking the counting of tolerance the light quantity threshold value of multiple gases, adopts alcohol to guarantee and can under-50 ℃ of worst cold cases, test as the medium of flow of bubble warp.
Computing machine can be with multiple kind gas through the nominal data storehouse; The unit volume bubble converts under different temperatures, the pressure; Convert quantity of gas leakage under the standard state to, test process shows in real time that with curve mode gas flow also can be through the historical query record.
Workflow of the present invention is: by shown in Figure 3; Turn-on flow rate meter power supply after gas access device 1 and equipment to be tested connect; The keying of gas circuit switching solenoid valve is judged by system according to flowmeter temperature inlet pressure; Gas feeds alcohol bubble generator 2 in the time of in inlet pressure is in normal range, and generation is big or small in alcohol bubble generator 2, direction is consistent, the uniform bubble of speed; The laser-transmitting that light quantity decay this moment detecting device 3 sends is crossed alcohol bubble generator 2; The light quantity that the other end receives when bubble process laser beam decays, the light quantity damping capacity that flowmeter is taken place when before work, at first confirming bubble through liquid alcohol, and in light quantity decay detecting device 3, set.As bubble light quantity decay detecting device 3 when the laser beam signal is sent to event counter then at every turn; Event counter 4 transfers to computing machine 5 with the momentary signal that receives and the accumulated signal mode through serial communication; Through calibrating parameters in the computer testing system internal database the most at last bubble number conversion of signals become the gas stream value to show to the user with the mode of real-time curve; With being stored in the historical record data storehouse, in order to consulting.In order to protect flowmeter not to be damaged, system detects flowmeter temperature in pressure in real time in the test process, and when surpassing normal range of operation, gas access device 1 will switch the air inlet solenoid valve, in system, also corresponding prompting is reported to the police.
Application example of the present invention:
By shown in Figure 4 be cryogenic valve worst cold case internal leakage test principle figure; By shown in Figure 4; The test fluid flow helium gets into test macro through filtrator 14 backs; Through current indicated pressure in the tensimeter 16 monitoring test macro pipelines; To needed test operating mode, safety valve 17 assurance system testing pressure are no more than top pressure are set, and promptly open the decompression protection system automatically in case system's internal pressure surpasses set pressure safety valve 17 by tested cryogenic valve 17 admission pressures of gaseous tension variable valve 15 adjustment.Place the tested cryogenic valve 19 of low temperature liquid nitrogen test trough 18 to close in the test process; Photo-electric gas micro bubble flowmeter 20 of the present invention is installed on tested cryogenic valve 19 endpiece; Be used to detect worst cold case internal gas leakage rate when test pressure lower valve closed condition; The number of bubbles that mode gas meter collection through opto-electronic conversion is produced through tested cryogenic valve 19 gas leakages also transfers to computing machine with the mode of serial communication; The gas leakage temperature of obtaining according to photo-electric gas micro bubble flowmeter 20, the flow that the pressure parameter secondary calculating goes out the test for leaks gas of wanting; Cause quantity of gas leakage to surpass 20 ability testing ranges of photo-electric gas micro bubble flowmeter or the gas leakage temperature is lower than the testing setup value in the test process as along with tested cryogenic valve 19 intake pressures raise; Apparatus of the present invention can be opened automatically and discharge after the internal bypass valve makes tested cryogenic valve 19 gas that leaks through the internal valves bypass; Protective device is not damaged, and in testing software, makes corresponding alarm.