Hydrogen leak testing

Hydrogen leak testing is the normal way in which a hydrogen pressure vessel or installation is checked for leaks or flaws. There are various tests.

• The Hydrostatic test, The vessel is filled with a nearly incompressible liquid - usually water or oil - and examined for leaks or permanent changes in shape. The test pressure is always considerably more than the operating pressure to give a margin for safety, typically 150% of the operating pressure.

• The Burst test, The vessel is filled with a gas and tested for leaks. The test pressure is always considerably more than the operating pressure to give a margin for safety, typically 200% or more of the operating pressure.

• The Helium leak test, The leak detection method uses helium (the lightest inert gas) as a tracer gas and detects it in concentrations as small as one part in 10 million. The helium is selected primarily because it penetrates small leaks readily.
• Usually a vacuum inside the object is created with an external pump connected to the instrument.
• Alternatively helium can be injected inside the product while the product itself is enclosed in a vacuum chamber connected to the instrument. In this case Burst and leakage tests can be combined in one operation.

• The Hydrogen microsensor, The object is filled with a mixture of 5% hydrogen/ 95% nitrogen, (below 5.7% hydrogen is non-flammable (ISO-10156). This is called typically a sniffing test. The handprobe connected to the microelectronic hydrogen sensors is used to check the object. An audiosignal increases in proximity of a leak. Detection of leaks go down to 5x10-7 cubic centimeters per second [1]. Compared to the helium test: hydrogen is cheaper than helium, no need for a vacuum, the instrument could be cheaper.

Additional recommended knowledge

How to quickly check pipettes?

How to ensure accurate weighing results every day?

Don't let static charges disrupt your weighing accuracy

Uses

Room testing

Stationairy unit, Hydrogen gas is only 7% the density of air, and thus rises. The hydrogen gas detector should be installed at the highest draft-free location in the room or compartment where hydrogen gas would accumulate.

In-Line testing

A fixed stationary unit on the assembly line or installation. Chemochromic Sensors

Hand held testing

A light mobile point-contact sensor

Hydrogen Concentrations of 4% to 75% mixed with air (around 40,000 ppm) can be explosive.

See also

• Hydrogen analyzer
• Hydrogen piping
• Tubing (material)
• Hydrogen station