The Technische Anleitung zur Reinhaltung der Luft, in short referred to as TA Luft, is a regulation/standard seeking to classify valve performance regarding fugitive emissions leakage to atmosphere.
It is a German national directive with the associated test procedure VDI 2440. This directive was established in 1964 and until 2006 it was the only acknowledged industry standard for valves used to classify fugitive emissions leakage to atmosphere.
TA-luft specifies how much a stem/gland is allowed to leak, but different to the ISO standard it does not stipulate under which conditions, or how many cycles the valve must undergo to pass a test.
This standard was introduced in 2006 to meet the increasing demand for sustainable valves – the lack of a harmonized standard to verify and classify the environmental impact of leakage to atmosphere from valves was the main motivator behind it. Different from the TA-luft all valves are tested in the same manner (three different classes to choose from) with clearly stated test terms and conditions.