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Basics of Helium Leak Detection with Pfeiffer …

1 HAG_0303 Basics of Helium Leak Detection with Pfeiffer Vacuum2 HAG_0303 What are the reasons for Leak Detection ? Environmental protection and their constraints or legal standards Industrial norms and partially detailed specifications of the customers Optimization of the process Quality Management3 HAG_0303 The denseness requirements are in general quantizised by the maximum allowable leak rate. Types:zPressure increase in a vacuum - reservoirzPressure decrease in a pressure - tankLeak ratePo> PiPo< PiPiPoV4 HAG_0303 DefinitionThe leak rate value is 1 mbar l/sif in a vacuum - reservoir with a volume of 1 Litrethe pressure rises in 1 Secondabout 1 mbaror in a pressure - reservoir it drops about 1 mbar. Unitz[mbar l/s]zSI Units:[Pa m3/s]zFluid Technology:[sccm; sccs]zClimate Technology:[g/a; oz/y]Leak rate5 HAG_0303 Example: leak rate in mbar l/s The wheel of a bicycle allows in 175 days a maximum pressure drop of 1000 mbar without pumping up!

2 HAG_0303 What are the reasons for Leak Detection? ¾Environmental protection and their constraints or legal standards ¾Industrial norms and partially detailed specifications of …

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Transcription of Basics of Helium Leak Detection with Pfeiffer …

1 1 HAG_0303 Basics of Helium Leak Detection with Pfeiffer Vacuum2 HAG_0303 What are the reasons for Leak Detection ? Environmental protection and their constraints or legal standards Industrial norms and partially detailed specifications of the customers Optimization of the process Quality Management3 HAG_0303 The denseness requirements are in general quantizised by the maximum allowable leak rate. Types:zPressure increase in a vacuum - reservoirzPressure decrease in a pressure - tankLeak ratePo> PiPo< PiPiPoV4 HAG_0303 DefinitionThe leak rate value is 1 mbar l/sif in a vacuum - reservoir with a volume of 1 Litrethe pressure rises in 1 Secondabout 1 mbaror in a pressure - reservoir it drops about 1 mbar. Unitz[mbar l/s]zSI Units:[Pa m3/s]zFluid Technology:[sccm; sccs]zClimate Technology:[g/a; oz/y]Leak rate5 HAG_0303 Example: leak rate in mbar l/s The wheel of a bicycle allows in 175 days a maximum pressure drop of 1000 mbar without pumping up!

2 Volume= Liter 175 days=approximately x 107 Seconds What is the maximum acceptable Leak rate?6 HAG_0303 Example: leak rate in mbar l/s Result:zUnit: mbar l s-1zqL=[V * (p2-p1)] / t [qL] = mbar l s-1 Leak rate [V] = l - Volume Test object (piece?) [p1] = mbar pressure at the start of the measurement [p2] = mbar - pressure at the end of the measurementslmbarslmbarQL/100,1105,15,11 00047 = = = 7 HAG_0303 Example: leak rate in mbar l/s Testing of Car tires Testing method: manual underwater sight check (Bubble test) Test conditions: testing pressure and temperature constant Volume:approximately 40 Litres Ascension of several air bubbles oft air - bubbles: 2,26 mmBubbles /1 Bubble / Minute1 Bubble / Secondtime - periodLeak rate6,0 x 10-03cm /min 0,3636 cm /min1,0 x 10-04mbar l/s 6,0 x 10-02mbar l/s 8 HAG_0303 of a Bubble per minute = 2,26 mm qL= V / t with p = const.

3 QL= 6,06 mm /min or 6,0 x 10-03cm /min Because 60 cm /min is nearly similar to 1 mbar l/s it follows, that qL= 1,0 x 10-04mbar l/sExample: leak rate in mbar l/s 06,63) 13,1(4 34mmmmrV= = = 9 HAG_0303 Equivalent leak ratesDefinitionkg air/hmbar l/sWater tight10-0510-02 Vapour tight (sweat)10-06 10-03 Bacteria tight10-07 10-04 Fuel and Oil tight10-08 10-05 Virus tight10-09 10-06 Gas tight10-10 10-07 Technically tight10-13 10-10 Conversion: 1 mbar l/s = 4,3 x 10-03kg/h air at 20 C and the same test pressure10 HAG_0303 Conversion table of leak ratesmbar l/skg/h(air, 20 C)kg/h(air, 0 C)cm3/h(NTP) cm3/s(NTP) Torr l/sg/a(R12, 20 C)Pa m3/smbar l/s14,28 * 10-34,59 * 10-335540,9870,751,56 * 1051,00 * 105kg/h(air, 20 C)23411,0738,31 * 10523117523,4 * 106kg/h(air, 0 C)2180,93217,74 * 10 21516321,8 * 106cm3/h(NTP) 2,81 * 10-41,20 * 10-61,29 * 10 -612,78 * 10-42,11 * 10-44428,10cm3/s(NTP) 1,0134,33 * 10-34,65 * 10-3360010,7601,58 * 1051,01* 105 Torr l/s1,335,70 * 10-36,12 * 10-347371,3212,08 * 1051,33* 105g/a(R12, 20 C)

4 6,39 * 10-62,27 * 10-26,31 * 10-64,80 * 10-616,41 * 10-1Pa m3/s104,28 * 10-24,59 * 10-235,54 * 1039,87 7,50 1,56 1 NTP = 1 cm under normal conditions (T = 273,15 K, p = 1013,25 mbar)11 HAG_0303 Testing methodsMethodsdetectable Leak rateprinciplePressure drop 10-02mbar l/sOverpressurePressure rise 10-04mbar l/sVacuumBubble Test10-04mbar l/snumber of Bubbles with defined He Sniffing10-06mbar l/schange of Helium concentrationHe Integral10-10mbar l/schange of integralLeak rate Other Methods12 HAG_0303mbar l/sPressure drop Pressure riseUltrasonic - BubbletestHe sniffing leak detectionHe vacuum leak detectionBubbletest10 -1210 -1110 -1010 -910 -710 -810 -610 -510 -410 -310 -210 -110 010 1H2- sniffing leak detectionSF6 vacuum leak detectionSF6 sniffing leak Detection 13 HAG_0303 Why Helium ?

5 Low concentration in the normal atmosphere ( 5ppm) Small molecule - mass 4 Easy to detect with standard mass spectrometer Fast spreading in atmospheric and vacuum surrounding Does not undergo chemical reactions, does not stick to surfaces Not poisonous14 HAG_0303 Overpressure leak detectionTestgasIntegralLocalTestgas15 HAG_0303 Local leak detectionTestgasSample under vacuum16 HAG_0303 Leak Detection integralTestgasSample under pressureChamber under vacuumSample under vacuumChamber under testgasTestgas17 HAG_0303 Why testing in vacuum? Suppress of the Helium background in the atmosphere Faster spreading of the test gas Effect: fast and reproducible measurement results18 HAG_0303 HLT 26019 HAG_0303 LCD DisplaysIndustryAutomotiveIC sMedicineAviationSemiconductor technologyOne device for a lot of applications20 HAG_0303 Advantages of the HLT 26021 HAG_0303 Advantages of the HLT 260 Simple, user - friendly operationzOnly Start/Stop and Zero are required for standard operation Vacuum modezSmallest detectable leak rate: 5 10-12mbar l/szLeak testing is possible at 18 mbar inlet pressure short Test cycleszHelium pumping speed at the inlet 2,1 l/s very fast recovery time Sniffer modezSmallest detectable leak rate.

6 5 10-08mbar l/sz5 m3/h rotary vane pump for roughing faster Leak testzCompletely oil free leak test with a diaphragm pump possible22 HAG_0303 Advantages of the HLT 260 ISO 9001 compatiblezProduct identification via Barcode reader Product documentationzPrintout protocol Integrated total-pressure measurements Metal housing23 HAG_0303 Advantages of the HLT 260 Helpful AccessorieszDifferent sniffer probeszFlexible Sniffer tipszCartzCalibrated sniffer test leakszBarcode Reader, Signal Lam


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