The Health & Safety Laboratory and Kiwa have tested hydrogen blends (up to 20%) on a range of common household gas appliances. This has shown that hydrogen at this level does not affect the safe day to day operation of appliances. As part of the laboratory testing programme, the impact of long term operation on hydrogen is being evaluated, and will form part of the definition of the hydrogen blend proposed.
The gas appliance safety checks that will be carried out on the Keele site and spot checks during the live trial will provide valuable additional information about the performance of appliances on a real network.
All appliances sold after 1996 must comply with a 1990 Gas Appliance Directive which demonstrates that they can operate on a wider range in gas quality than specified in the current regulations. This includes a gas composition of 23% hydrogen.