Detection of step charges of pressure in vessels and apparatus therefor

Claim 2

A detector for monitoring step changes of pressure in a vessel which comprises means outside the vessel for detecting a change in the dimensions of the vessel, said means being mounted on a jubilee clip for clamping around the vessel and said means being surrounded by a potting compound to protect it from moisture and impact; and a filter adapted to pass from the said means substantially only signals characteristic of dimensional changes resulting from a fall in pressure of the vessel occurring at a minimum rate of 0.005 bars per second which is not followed by a rise in pressure at that minimum rate within 0.05 seconds.

Claim 3

A detector as claimed in claim 1 in which the filter passes only signals in the range 0.1 to 4 Hertz.

Claim 4

A detector as claimed in claim 2 which comprises four or more strain gauges positioned diametrically opposite one another.

Claim 5

A detector as claimed in claim 2 which comprises strain gauges surrounded by an electrostatic shield.

Claim 6

A detector as claimed in claim 1 in which the means outside the vessel for detecting a change in the dimensions of the vessel comprises one or more strain gauges adapted to sense changes in the circumference of the vessel.

Claim 7

Vessels comprising detectors for leaks as claimed in claim 1.

Claim 8

Apparatus for detecting leaks in pipelines which comprises two or more detectors each including means outside the pipeline for detecting a change in the dimensions of the pipeline and a filter adapted to pass from said means substantially only signals characteristic of dimensional changes resulting from a fall in pressure in the pipeline occurring at a minimum rate of 0.005 bars per second which is not followed by a rise in pressure at that minimum rate within 0.05 seconds, said detectors being situated at successive stations along the pipeline; and means for processing signals from both detectors and for producing a signal indicating the position of a leak in response to the time relationship between the detected signals.

Claim 9

Apparatus for detecting leaks in pipelines which comprises two or more detectors each including means outside the pipeline for detecting a change in the dimensions of the pipeline and a filter adapted to pass from said means substantially only signals characteristic of dimensional changes resulting from a fall in pressure in the pipeline occurring at a minimum rate of 0.005 bars per second which is not followed by a rise in pressure at that minimum rate within 0.05 seconds, said detectors being situated at successive stations along the pipeline; and means for processing signals from both detectors and for producing a signal indicating the position of a leak in response to the time relationship between the detected signals.