Testing of explosion-proof containers. Swedish regulations for flammable substances recommend that explosion-proof containers are used in work areas for storage of flammable liquids. Such containers must be approved by the competent authority, which is the National Testing Institute (Statens Provningsanstalt). As a basis for such an approval, a programme for type testing of the containers is proposed. It includes tests for mechanical strength to ensure the integrity of the container during transport and handling, as well as tests for resistance to fire and flames. Two criteria are assumed applicable for the classification as explosion-proof: 1) An external flame must not propagate into the container. 2) The container must be constructed in such manner that it will not burst when involved in a fire. It must also not start leaking and thus contribute to the fire propagation during a reasonable amount of time. The tests proposed are as follows. Reference tests have been carried out to evaluate the relevance and feasibility of each test. 1) Leakproofness test, with a 20 kPa gauge air pressure. 2) Hydraulic pressure test, with a test pressure of 250 kPa. 3) Drop test, with a drop height of 1.2 m. 4) Flame protection test, utilizing a flow of a propane-air mixture. 5) Fire test, where the container, filled up with acetone to 25 % of its capacity, is observed during three minutes in a heptane fire. Containers which have passed the tests will be accordingly marked and subjected to a mandatory production control.