A fluid meter is described having certain elastically displaceable wall portions arranged to be elastically displaced in response to a pressure variation propagating into the measurement volume. The computer 10 makes a request to the identified target device TD for attachment of the logical device LDEV that stores the snapshot files for which access is requested. A communication channel in the receptacle assembly extends from the controlled pressure zone to an area of ambient pressure. A report of the error is automatically generated. The outlet of the gas supply line is provided at an upstream side of gas flow in the reaction furnace. In other embodiments, such components have an average spatial density at least partially sufficient for selective particle interaction andor separation.