Self-dispensing spaced electronic markers
AssigneeMinnesota Mining and Manufacturing Company
InventorsArmond D. Cosman, Joe T. Minarovic, David C. Worboys
Life of this patent
Estimating the term…
Abstract
A marked conduit allowing electronic location of the conduit after burial, having a plurality of electronic markers spaced thereon at predetermined intervals. The distance between the markers encodes information about the buried conduit. The markers are preferably passive circuits tuned to a specific frequency. The markers may be oriented in a predetermined pattern to encode additional information, and may be attached to the outer or inner surface of the conduit, or imbedded in the wall of the conduit.
Claims15
An article for supplying an underground utility which may be electronically detected from above ground, comprising:
- a plurality of passive electronic markers, each having a coil of wire connected in parallel with a capacitor, forming a resonant circuit;
- and
- a hollow conduit member having a wall, an outer surface, and an inner surface, said markers being attached to said conduit member at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
An article for supplying natural gas underground, which may be electronically detected from above ground, comprising:
- a plurality of passive electronic markers;
- and
- a tubular pipe formed of polyethylene, having a wall, an outer surface, and an inner surface, said markers being imbedded in said wall at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
A method of manufacturing an article for supplying an underground utility, the article being electronically locatable from above ground, comprising the steps of:
- obtaining a plurality of electronic markers;
- constructing a hollow conduit, having a wall, an inner surface, and an outer surface;
- and
- attaching said electronic markers to said inner surface of said conduit at predetermined intervals, said predetermined intervals forming a pattern which encodes information about the underground utility.
Dependencies are inferred from the claim text.