Leak testing

HELLING GmbH

Since 1863

Leak testing

Leak testing or leak detection is a non-destructive testing method for the detection and localisation of leaks in pressure and vacuum systems.

"Leakage" means liquid or gas passing through a leak regardless of its physical size. A leak can be, for example, a crack, a breach, a notch or a hole, the gas (e.g. air) or liquid (e.g. water).

Leakages can significantly endanger the operational safety of vacuum or pressure systems (e.g. pressure vessels). Dangerous gases or liquids may escape. The leak test is also carried out for pyrotechnic devices, electronic parts, air conditioning systems, food packaging, etc..



Detection of vessel decompression with fluorescent concentrate H 849



The following table illustrates the relationship between the leak rate, the size of the leak and the resulting Leakage:

Leakage rate
[m³ Pa/s]
Diameter
of the leak
Leakage through the leak
at Δp = 1 bar
     
10¹ 1.0 mm Water is leaking out
10-1 0.1 mm Water is dripping
10-3 0.03 mm Waterproof but gas permeable
10-5 ≈ 3 µm 1 air bubble ( ≈1 mm³) in 10 seconds
10-7 ≈ 0.1 µm approx. 1 cm³ gas loss in 12 days
10-9 -- approx. 3 cm³ gas loss in 1 year
10-11 -- approx. 1 cm³ gas loss in 300 years

Bubble test

More information

Bubble test method using the Proof Check leak detection spray



The bubble test method is a frequently used visual leak test method, i.e. the test surface must be visible.

After establishing a pressure difference at the test part, the test liquid, a foam-forming indicator, is applied to the underpressure side of the test part. A uniformly thin, well-wetting layer is required to detect small leaks. At the site of the leakage, bubbles are formed due to gas leakage.

The pressure difference can also be generated with a vacuum pump and special vacuum goggles.

This method is mainly used to find continuous leaks, e.g. in the case of

  • Welded joints
  • Joints or walls of systems under atmospheric pressure
  • Systems that can not be squeezed off

The method can also be used to improve the sensitivity of the colour contrast penetrant testing: The area to be tested (e.g. on a weld seam) is sprayed with the leak detection spray. The transparent vacuum goggle is then put on. The space under the vacuum goggles is evacuated. Any leaks then show up as more or less large foam fungi.

Application areas

Leak testing of pressure vessels, hydraulic or gas systems.

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Proof Check leak testing foam indicator

Wetting agent for leak testing of

  • Containers
  • Pipelines
  • Valves, taps
  • technical installations with gases (also flammable)
  • Liquid gas systems

Can also be used for testing oxygen systems if precautions are taken.

Technical data

Test pressure 1.5 bar - 2 bar
Test sensitivity 1.3 10-7m3 Pa/s
Temperature 5 °C to 40 °C
Leakage rate > 10-4 m³ Pa/s approx. 10-7 m³ Pa/s
Reaction time 2 s -3 s approx. 15 min

Packaging:

Aerosol can - 400 mL
Item number :616.000.001
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Safety Data Sheet Spray

Proof Check PLUS leak testing foam indicator

Wetting agent with high detection sensitivity for leak testing (leak detection) of e.g.

  • Containers such as gas cylinders
  • Pipelines
  • Soldered, flanged and welded connections
  • Fittings
  • Valves and armatures

The emulsion consists of wetting, film-forming and moisture-binding agents

  • Non-flammable
  • Low surface tension
  • Good foaming ability and slip resistance

Technical data

Leakage rate > 10-4 m³ Pa/s approx. 10-7 m³ Pa/s
Reaction time 2 s - 3 s approx. 15 min
Test sensitivity 1.3 10-7m3 Pa/s
Temperature -15 °C to +50 °C

Packaging:

Aerosol can - 400 mL
Canister - 10 L
Item number :616.000.010
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Safety Data Sheet Spray
Safety Data Sheet Container

Vacuum leak detector EV 20

The vacuum leak detector EV 20 is suitable for leak detection on

  • Tubes
  • Containers
  • Sheet metal structures

Butt welds, fillet welds, corner welds and weld-on nozzles can be tested. This method has proved particularly successful in pipeline construction.

To increase operational safety, the pump is protected by water separator, float valve as well as check valve and filter.

Technical data

Max. Volume flow 6m3/h
Max. rel. Vacuum -900 mbar
Mains connection 230 V / 50 Hz
Motor power 120 W
Rotational speed 2,800 rpm
Connection cable 2 m
Dimensions 280 mm x 290 mm x 225 mm
Weight 9.7 kg
Tube length pump - frame 3 m
Protection class IP54

Delivery only with transport box!

Version:

EV 20
Transport box
Item number :611.010.001
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Vacuum goggles for circumferential seams

  • Clear Makrolon pane
  • Foam rubber seal guarantees 100% contact of the goggles on the surface of the test object under vacuum

OPTIONAL

  • with vacuum gauge

Version:

DN 50
DN 50 with vacuum gauge
DN 60
DN 60 with vacuum gauge
DN 70
DN 70 with vacuum gauge
DN 80
DN 80 with vacuum gauge
DN 100
DN 100 with vacuum gauge
DN 110
DN 110 with vacuum gauge
DN 125
DN 125 with vacuum gauge
DN 140
DN 140 with vacuum gauge
DN 150
DN 150 with vacuum gauge
DN 200
DN 200 with vacuum gauge
DN 250
DN 250 with vacuum gauge
DN 300
DN 300 with vacuum gauge
DN 350
DN 350 with vacuum gauge
DN 400
DN 400 with vacuum gauge
DN 450
DN 450 with vacuum gauge
DN 500
DN 500 with vacuum gauge
DN 550
DN 550 with vacuum gauge
DN 600
DN 600 with vacuum gauge
DN 650
DN 650 with vacuum gauge
DN 700
DN 700 with vacuum gauge
DN 750
DN 750 with vacuum gauge
DN 800
DN 800 with vacuum gauge
DN 850
DN 850 with vacuum gauge
DN 900
DN 900 with vacuum gauge
DN 950
DN 950 with vacuum gauge
DN 1000
DN 1000 with vacuum gauge
DN 1100
DN 1100 with vacuum gauge
DN 1200
DN 1200 with vacuum gauge
Item number :611.001.002
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Vacuum frame for corner welds

Side length 300 mm

OPTIONAL

  • With vacuum gauge

Version:

Vacuum goggle for corner seams
with vacuum gauge
Item number :611.001.033
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Vacuum frame for fillet welds

Dimensions 600 mm x 100 mm

OPTIONAL

  • With vacuum gauge

Version:

Vacuum goggle for fillet welds
with vacuum gauge
Item number :611.001.030
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Vacuum frame for butt welds

Dimensions 600 mm x 100 mm

OPTIONAL

  • With vacuum gauge

Version:

Vacuum goggle for butt welds
with vacuum gauge
Item number :611.001.031
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Acoustic leak test methods

More information

The acoustic emission leak testing method is used to find leaks in pressure or vacuum systems, e.g. for testing

  • Pipelines
  • Pressure vessels
  • Boilers
  • Manifolds

The gas or liquid flowing through the leak generates ultrasonic vibrations due to turbulence eddies, which can be localised. For this purpose, ultrasonic detectors are used to determine the vibrations oscillating in air or in the test object. Signal converters convert inaudible high-frequency sound into low-frequency sound within the range of human hearing or into electrical signals.

.

Remote listening of sound signals for gas or liquid leaks often has many practical advantages over other leak detection methods. Especially when direct access to the test surface and visual inspection of the leak indications is not possible.

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SONAPHONE Pocket

Simple and compact ultrasonic flaw detector SONAPHONE Pocket for maintenance, and for quick and easy inspection of small leaks.

  • Compact mobile handheld device
  • Easy handling
  • Cost-effective
  • Extensive accessories for a wide range of applications

Applications

  • Leak detection on compressed air lines as well as steam, gas and vacuum systems
  • Wear control on rotating machines
  • Detection of partial electrical discharges on insulation damages
  • Functional check of steam traps and valves
  • Leak test of pressureless system

Technical data

Operational frequency 40 kHz; bandwidth +/- 2 kHz
Functionality Detection and conversion of ultrasonic signals

  • Ultrasound audibility
  • Indication of the sound level on the display
  • Auto powe-off function
Display Illuminated LC display
Connections For various ultrasound probes;
Jack socket stereo
Power supply 2 AA batteries or rechargeable batteries
Operating time approx. 24 hours with battery operation
Dimensions 85 mm x 130 mm x 30 mm
Weight approx. 280 g
Operating temperature -10 °C to +60 °C
Storage temperature -20 °C to +60 °C
Protection class Device: IP54; Probe: IP20

Scope of delivery (basic package)

Ultrasonic test device SONAPHONE Pocket with

  • LC display with background lighting
  • Stereo headphones with coiled cable (with high sound damping)
  • Large carrying case
  • Lanyard
  • Airborne sound probe L50
  • Shotgun microphone with top
  • Acoustic horn
  • 25 pieces leak tags
  • 2 AA batteries non-rechargeable
  • Instruction manual

OPTIONAL probe overview

  • L51 - Structure-borne sound probes
    Application: Inspection of valves, gate valves, safety valves.
  • L52 - Structure-borne sound probes
    Application: Capacitor conductor testing
  • L53 - Flexible probe
    Application: Leak detection in angled areas
  • L54 - Parabolic mirror SONOSPOT
    Application:Precise location of leaks and partial discharges over long distances.
Item number :613.100.015
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Pressure test

More information

Application of the push-off method with coloured fluorescent indicator liquid



Leak testing using a coloured indicator liquid is a leak detection method similar to penetrant testing for finding material defects which are open to the surface.

In leak testing, the penetrant is applied to one side of the object wall to be tested (weld, joint). Visual inspection is performed after the specified exposure time on the other side of the wall.

The test part can also be filled with the test liquid.



Leak test on a motor vehicle engine with the fluorescent concentrate H 800



In the push-off method using an oil- or water-based fluorescent concentrate, this is added to the test liquid. The concentrates are composed of luminophores, wetting agents and rust inhibitors. After that, the system is depressurised. After a certain pressure holding time, a visual inspection of the test part surface takes place under UV irradiation. Any leaks produce brilliant fluorescent indications.

This test method is mainly used for leak testing of hydraulic systems, engines, tanks and boilers. The sensitivity of the method is about 10-5m3 Pa/s.

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Fluo H 800 oil-based concentrate

  • Oil-suspendable
  • Fluorescent

Technical data

Consumption 0.5 mL/L - 2 mL/L
Optimal wavelength for excitation 365 nm
Colour under UV irradiation Yellow

Packaging:

Aerosol can - 500 mL
Canister - 1 L
Canister - 10 L
Canister - 20 L
Item number :616.000.033
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Fluo H 849 water-based concentrate

  • Water suspendable
  • Fluorescent
  • With emulsifier additive and corrosion protection

Technical data

Consumption 2 mL/L - 5 mL/L
Optimal wavelength for excitation 365 nm
Colour under UV irradiation Green

Packaging:

Canister - 1 L
Canister - 10 L
Item number :616.100.102
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NORD-TEST Penetrant FP 93 TU

Fluorescent penetrant

Under UV irradiation yellow-green fluorescent penetrant for leak testing

Technical data

Optimal wavelength for excitation 365 nm
Colour under UV irradiation yellow-green
Density 0.790 g/cm³
Dynamic viscosity 1,716
Fluorescence brightness in relation to FP-4PE 76%

Do not remove with water!

Packaging:

Canister - 1 L
Canister - 10 L
Barrel - 200 L
Item number :122.500.102
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NORD-TEST Penetrant FP 93 A(M) TU

Fluorescent penetrant

Under UV irradiation yellow-green fluorescent penetrant for leak testing

Technical data

Optimal wavelength for excitation 365 nm
Colour under UV irradiation yellow-green
Density 0.791 g/cm³
Dynamic viscosity 1,957
Fluorescence brightness in relation to FP-4PE 90%

Do not remove with water!

Packaging:

Canister - 1 L
Canister - 10 L
Barrel - 200 L
Item number :122.102.302
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Safety Data Sheet Container

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