Report Open Access
A study was carried out on the risks involved in not replacing a domestic pressure regulator as part of the conversion from natural gas to hydrogen. The potential risks were inventoried and, in consultation with the guidance group and sparring group, the risks requiring further investigation were identified. A test programme has been determined based on the findings, also in consultation with the guidance/sparring group.
The distribution network operators have been removing pressure regulators from their networks, some due to complaints and some without complaints being received. 40 of these regulators were tested with hydrogen. Based on the findings, 10 regulators were selected and subsequently also tested with natural gas.
The general conclusion based on the studies is that there are no safety risks when the existing domestic pressure regulators are used in converting the pipeline network from natural gas to hydrogen. Nevertheless, there is a chance of more failures occurring due to the more sensitive (earlier) intervention of the UPSO (under-pressure shut-off) valve. The valve shut-off pressures will also increase by a few millibars when hydrogen is used.
This does not give an urgent reason to replace all pressure regulators, seeing as all hydrogen appliances will be equipped with a flame protection device that mitigates the safety risk. If a network operator chooses to replace the pressure regulators in homes as part of the conversion to hydrogen, there is no need to replace them immediately. New pressure regulators can be installed at a later stage and are not necessarily needed at the time of conversion.
The following is recommended to distribution network operators:
When converting to hydrogen, a choice should be made based on one's own considerations as to whether or not to replace the existing pressure regulators, with or without a UPSO valve that is or is not equipped with a bypass. This choice can be made using the decision tree in figure 6, based on the arguments for and against the various options given in table 11.