Abstract: A temperature differential detection device for detecting the temperature differential between predetermined portions of a container wall is disclosed as comprising a Wheatstone bridge circuit for detecting resistance imbalance with a first circuit branch having a first elongated wire element mounted in thermal contact with a predetermined portion of the container wall, a second circuit branch having a second elongated wire element mounted in thermal contact with a second predetermined portion of a container wall with the wire elements having a predetermined temperature-resistant coefficient, an indicator interconnected between the first and second branches remote from the container wall for detecting and indicating resistance imbalance between the first and second wire elements, and connector leads for electrically connecting the wire elements to the remote indicator in order to maintain the respective resistance value relationship between the first and second wire elements.

Abstract: Changes in the flow-rates of each one of a plurality of fluid streams which pass from respective conduits (13) to a common conduit (12) are monitored by taking a representative sample of fluid from a sampling point (16) of the common conduit, determining the change in composition of at least key components of the sample relative to a preceding sample obtained in the same manner, and computing from the change in composition the composition of the fluid stream whose flow-rate has changed, so that the fluid stream can be identified by reference to a library or database of fluid stream compositions. When the fluid streams are gases (e.g. gases to be flared at an oil refinery or chemical process plant), each sample may be analyzed by a gas chromatograph (18) at predetermined intervals and the fluid stream whose flow-rate has changed may be identified automatically by comparison with a database or library (22) of fluid streams. The thus identified fluid stream may be recorded and/displayed (19).