leak detection techniques helium leak testing techniques ... · september 2009 helium leak testing...
TRANSCRIPT
September 2009
Helium Leak Testing Techniques for Industry.
Leak detection techniques
September 2009
If a system is leaking.......
....... you are in trouble!
Leak detection techniques
September 2009
Finding a leak......
.......can also cause problems!
Leak detection techniques
September 2009
Environmental
Safety ISO 9000
Product life
Reliability
Product specifications
Marketing advantage
Reasons for Leak Testing:
Leak detection techniques
September 2009
Leak detection techniques
Application list
Analytical Mass spectrometer systemsElectron beam microscopes
AutomotiveACBrake tubingHeat exchnangerFuel tanksCompressorsEvaporatorsValves Thermostat
Medicine technologyPacemakerElectron microscopeX-ray tubesAmpulla
Power engineeringPower turbine Power condensorHigh voltage components
R&DHe bath cooler3He coolerIon beam acceleratorsUHV ^/XHV systemsHe transfer lines
ITTransfer chambersLoad looksTubing
Vaccum equipmentWhole vacuum programPump housings
Process industryFurnacesSoldering ovensHigh pressure vales
September 2009
Automotive
BMW
Mercedes/DC
Audi
VW
Ford
Volvo
Peugeot
etc.
Cars Application Sub-systems
Pressure / Vac
Air conditionHe and refrig.
Pre-
tes t
with
He-
LD in
tegr
ated
in a
re
frig
eran
t fill
ing
unit
for A
C
Fuel tanks Walbro etc
tubes, hoses Contitech / Eaton
Valves Buerkert
Heat exchangers Behr
air bags Temic / Dyn.Nobel
high pressure Witzenmanbellows
injection pumps Bosch
Supplier
Leak detection techniques
September 2009
Types of Leaks
Leaks at connectionsflanges, welding, soldering, grindings ( glass fittings)
Permeation leaksgas transport through materials e.g. elastomeric seals, glass
Porosity leaks castings
Virtual leaksgaps, small volumes in castings, evaporation of liquids, sintered metal, plastic parts
Hot /cold leakscracks open or close due to thermal tensions
Leak detection techniques
September 2009
Volume of 1 liter
time /s
rise
pres
sure
mba
r
Definition of mbarl/s
Leak detection techniques
September 2009
Water tap 1 drip per second 1,7x10-1 mbarl/s
Hair between O-ring and flange 1x10-3 - 5x10-2 mbarl/s
Bicycle tube in water 1x10-2 mbarl/s ( bubble test, 1 bubble/sec )
Car wheel loses air 4x10-5 mbarl/s 1,8 1,6 bar in 6 month
Leak detection techniques
Examples of well known leaks
September 2009
Leak detection techniques
understanding particel size remarks for Helium
mbarl/s for air at 20°C
kg/h
water tight 10-2 10-5 drip
vapour tight 10-3 10-6 sweat
bacteria tight 10-4 10-7 d~10-6 m
fuel and oil tight 10-5 10-8
virus tight 10-6 10-9 d~0,3x10-6 m
gas tight 10-7 10-10
"absolut tight" 10-10 10-11 technical
leak rate range
Understanding of tightness
September 2009
Procedure medium limit of leak ratembarl/s pressure range quantifiable
rise pressure air & others 10-4 vacuum limited
pressure drop air & others 10-4 overpressure limited
foaming agent air & others 10-5 overpressure no
bubble test air & others 10-4 overpressure limited
supersonic air & others 10-2 overpressure / low pressure no
thermal conductivity air & others 10-5 overpressure / low pressure no
mass spectrometerquadrupole refrigerents;gases 10-7 overpressure yes
mass spectrometermagnet. Sector field
HeliumHydrogen < 10-7 overpressure yes
mass spectrometermagnet. Sector field
HeliumHydrogen < 5x10-12 vacuum yes
Methods of Leak Tests
Leak detection techniques
September 2009
a) Leak
b) Desorbtion
c) Leak + Desorbtion
Pressure rise effects in a chamber
Leak detection techniques
September 2009
Why is Helium a good Test Gas?
Low concentration in air , only 5 ppm, so low natural background
Inert gas, non toxic, non- explosive, environmentally friendly
Good separation in a mass spectrometer ( no cross sensitivity to other gases and no mass fragments
Lighter than air
Very small gas molecule, can easily pass through small holes/gaps
Leak detection techniques
September 2009
Vacuum methodglobal detection ( He outside )
global detection ( He inside )
Local detection
Overpressure method
Local detection ( sniffing )
Principle Methods of Leak Detection
Leak detection techniques
September 2009
Helium
3
Test unit( under vacuum)
1 Pressure chamber w Helium
2 Test vessel
3 Leak detector
4 Helium
5 Auxiliary Pump System
1
2
Lowest detectable leak rate < 5x10-12 mbarl/sGlobal Detection
Vacuum Method
Leak detection techniques
September 2009
Vacuum Method
1 Vacuum chamber
2 Test body
3 Leak detector
4 Helium
5 Auxiliary Pump System for huge vessels
Global Detection
3
Lowest detectable leak rate < 5x10-12 mbarl/s
Leak detection techniques
September 2009
Vacuum Method
Local Detection
1 Spray gun
2 Test body
3 Leak detector
4 Helium
5 Auxiliary Pump System
(for large vessels)
3
Lowest detectable leak rate < 5x10-12 mbarl/s
Leak detection techniques
September 2009
y
Overpressure Method
Local Detection (sniffing) Lowest detectable leak rate < 1x10-7 mbarl/s!!!
1 Sniffer probe
2 Test vessel
3 Leak detector
4 Helium
3
Leak detection techniques
September 2009
Worked sample
How long does it takes to rise the pressure in a volume of 1 l from 1 to 2 mbar if a leak of 1x10-6 mbarl/s is present?
1x10-6mbarl/s
q L = V /t ∗ Δp
V = 1 l
Δp = 1mbar
q L = 1x10-6mbarl/s
t = V / qL ∗ Δp
= 1l / 1x10-6mbarl/s ∗
1 mbar
= 100 000s
= 277,7h
= 11,5d
Leak detection techniques
September 2009
Pressure rise method with vacuum ( no Helium )
Example:
Test volume: V = 1m³
Δp: p = 1 · 10-3 mbar until 8 · 10-3 mbar
Time : t = 5 min
QL = ??
Q =
=
=
V t
· Δ
p [mbar · l · s-1]
1000 l 300 s · 7 · 10-3 mbar
2,33 · 10-2 mbar · l · s-1
Δ
p = p2 – p1 = 8 · 10-3 – 1 · 10-3 = 7 · 10-3 mbar
Air leak rate
Leak detection techniques
September 2009
Partial Flow System
Leak detection techniques
September 2009
Partial Flow Principle
Chamber
PhoeniXL300
SLD = 2,5 l / s
SP = 60 m³ / h = 16,66 l / s
QHe = 3 · 10-5 mbar · l / s
Auxiliary pump
Test leak
The Helium flow will be splitted into 2 directions
2,5 2,5 + 16,66Flow to LD QL : 3 · 10-5 · = 3,9 · 10-6 mbar · l / s
16,66 2,5 + 16,66Flow to auxiliary pump QP : 3 · 10-5 · = 2,6 · 10-5 mbar · l / s
Total = 3 · 10-5 mbar · l / s
display LD leak rate Test leakFlow ratio γ
=
p QHe =Ssum . p
QL =SLD . p
QL =QHe . SLD /Sp +SLD
p = QHe /Ssum
Ssum = SLD + SP
Leak detection techniques
September 2009
Partial Flow SystemLeak detection techniques
September 2009
1↓ = ... → mbar · l/s kg·h–1 kg·h–1 cm3/h cm3/s Torr · l/s g/a g/a m · cfm lusec Pa · l/s slpm (20 °C) (0 °C) (NTP) (NTP) (F12. 20 °C) (F12. 25°C)
mbar · l/s 1 4.28 · 10–3 4.59 · 10–3 3554 0.987 0.75 1.56 · 105 1.54 · 105 1593 7.52 · 102 100 59.2 · 10–3
kg · h–1 (20 °C) 234 1 1.073 8.31 · 105 231 175 – – 37.2 · 104 1.75 · 105 23.4 · 103 13.86
kg · h–1 (0 °C) 218 0.932 1 7.74 · 105 215 163 – – 34.6 · 104 1.63 · 105 21.8 · 103 12.91
cm3/h (NTP) 2.81 · 10–4 1.20 · 10–6 1.29 · 10–6 1 2.78 · 10–4 2.11 · 10–4 44 – 44.7 · 10–2 2.11 · 10–1 2.81 · 10–2 1.66 · 10–5
cm3/s (NTP) 1.013 4.33 · 10–3 4.65 · 10–3 3600 1 0.760 1.58 · 105 – 1611 760 101 6 · 10–2
Torr · l/s 1.33 5.70 · 10–3 6.12 · 10–3 4727 1.32 1 2.08 · 105 2.05 · 105 2119 1 · 103 133 78.8 · 10–3
g/a (F12. 20 °C) 6.39 · 10–6 – – 2.27 · 10–2 6.31 · 10–6 4.80 · 10–6 1 – 10.2 · 10–3 4.8 · 10–3 6.39 · 10–4 37.9 · 10–8
g/a (F12. 25 °C) 6.50 · 10–6 – – – – 4.88 · 10–6 – 1 10.4 · 10–3 4.89 · 10–3 6.5 · 10–4 38.5 · 10–8
m · cfm 6.28 · 10–4 2.69 · 10–6 2.89 · 10–6 2.24 6.21 · 10–4 4.72 · 10–4 98.16 96.58 1 0.472 6.28 · 10–2 37.2 · 10–6
lusec 1.33 · 10–3 5.70 · 10–6 6.12 · 10–6 4.737 1.32 · 10–3 1 · 10–3 208 205 2.12 1 13.3 · 10–2 78.8 · 10–6
Pa · l/s 1 · 10–2 4.28 · 10–5 4.59 · 10–5 35.54 9.87 · 10–3 7.5 · 10–3 1.56 · 103 1.54 · 103 15.93 7.50 1 59.2 · 10–5
slpm 16.88 72.15 · 10–3 77.45 · 10–3 60.08 · 103 16.67 12.69 2.64 · 106 2.60 · 106 26.9 · 103 12.7 · 103 16.9 · 102 1
Conversion of mass flowes-(Leak Rates)
1 cm3 (NTP) = 1 cm3 under normal condition (T = 273.15 K; p = 1013.25 mbar)NTP = normal temperature and pressure (1 atm; 0 °C) R = 83.14 mbar · l · mol–1 · K–11 cm3 (NTP) · h–1 = 1 atm · cm3 · h–1 = 1 Ncm3 · h–1 = 1 std cch1 sccm = 10–3 slpm = 10–3 N · l · min–1 = 60 sccsSI-System kohärent: 1 Pa · m3 · s–1 = 10 mbar · l · s–1; R = 8.314 Pa · m3 · mol–1 · K–1; M in kg / mol1 cm3 (NTP) · s–1 = 1 sccs = 60 cm3 (NTP) · min–1 60 sccm = 60 std ccm = 60 Ncm3 · min–1
1 lusec = 1 l · μ · s–1 1 · μ = 1 micron = 10–3 Torr 1 lusec = 10–3 Torr · l · s–1
Freon F 12 (CCl2F2) M = 120.92 g · mol–1; Luft M = 28.96 g · mol–1
Achtung: Anglo-amerikanische Einheiten werden uneinheitlich abgekürzt! Beispiel: Standard cubic centimeter per minute → sccm = sccpm = std ccm = std ccpm
Leak detection techniques
September 2009
Technical DataPhoeniXL300 PhoeniXL300 Dry PhoeniXL300Modul
Lowest detectable He leak rate ( vacuum mode ) mbarl/s <5x10-12 <3x10-11 <5x10-12 / <8x10 -12
Lowest detectable leak rate ( sniffer mode ) mbarl/s <1x10-7 <1x10-7 <1x10-8
Max. detectable He leak rate ( vacuum mode ) mbarl/s > 0,1 > 0,1 > 0,1
Max. permissable inlet pressure mbar 15 15 15
Max. permeissable inlet pressure w partial flow set mbar 1000 - -
Pumping speed during pump down m3 2,5 ( 50 Hz )3 ( 60 Hz )
1,6 ( 50 Hz )1,8 ( 60 Hz )
16/20 ( 50 / 60 Hz ) D16B25/30 ( 50 / 60 Hz )D25B30/36 ( 50 / 60 Hz )Scroll
Pumping speed for Helium l/s > 2,5 > 2,5 > 2,5
Pumping speed with partial flow set and D16B l/s 16 ( 50Hz)
Pumping speed with partial flow set and D25B l/s 25 ( 50 Hz )
Time constant for leak rate signal s < 1 <1 <1
Time until ready for operation min < 2 < 2 < 2
Mass spectrometer
Detectable masses 4He; 3 He ; H2 amu 4; 3 ; 2 4; 3 ; 2 4; 3 ; 2
Relay outputs 4 4 4
SPS inputs 6 6 6
Test port connection
Length of hand unit cable ( option ) m 4 ( max. 32 ) 4 ( max. 32 ) 4 ( max. 32 )
Power consumption 420 VA 350 VA 350 VA
Dimensions ( L x H x D ) mm 495 x 456 x 314 495 x 456 x 314 495 x 456 x 314
Weight kg 40 37,5 29
180° magn. Sector field
DN 25 KF
PhoeniXL300Modul pump connection flange size DN25KF
Leak detection techniques
September 2009
PhoeniXL340
LD work station for serial production of small parts
Customised test stations(Customized by OLV)
Leak detection techniques
September 2009
September 2009