Water detector

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A Water detector is a small electronic device that is designed to detect the presence of water and alert humans in time to allow the prevention of water damage. A common design is a small device that lays flat on a floor and relies on the electrical conductivity of water to decrease the resistance across two contacts. A 9 volt battery then sounds an audible alarm in the presence of enough water to bridge the contacts. These are useful in a normally occupied area near any appliance that has the potential to leak water, such as a washing machine, refrigerator with icemaker, dehumidifier, air conditioner, or water heater.

[edit] Water leak detection

Water Leak Detection is an expression more commonly used for larger, integrated systems installed in "high-tech" buildings or those containing valuable artefacts, materials or other assets where early notification of a potentially damaging leak would be beneficial.

The Water Leak Detection industry is small and specialised with only a few manufacturers operating world-wide. The original application was in the void created by "computer room" floors in the days of large main-frame computer systems. These use a modular, raised floor based around a structural "floor tile" usually 600mm square and supported at the corners by pedestals. The void created gave easy access and routing for the mass of power, networking and other interconnecting cables associated with larger computer systems - processors, drives, routers etc. mainframe computers also generated large amounts of heat so a void under the floor could also used as a plenum to distribute and diffuse chilled air around the computer room. The void therefore was like to have chilled water pipes running through it along with the drains for condensates associated with refrigeration plant. In addition designers also found the floor void a very convenient place to route other wet services feeding bathrooms, radiators and other facilities.

Al leak occurring within a floor void would therefore go unnoticed until the hydrostatic head of pressure meant that the water found its way through to floors below where its dripping through the ceiling would be noted or, and more disconcerting, the water would penetrate the joints and connectors of the power or network cabling and cause system failure from short circuit.

[edit] Integrated Multi-Zone Systems

The computer room therefore became the early application for systems which would alert the operator to a leaking pipe in sufficient time for remedial action to be taken to prevent a disaster.

As computer rooms could be quite large simple "point of use" detectors were not really appropriate although Point Sensors do have value where simple, single point detection is required in, say, basements and sumps. Most modern leak detection systems developed around the use of a water sensitive cable which can be laid in long lengths and complex patterns around the base of the floor; around the perimeter of rooms; as a "barrier" over which water has to flow; following, tracing or attached directly to lines of water pipes.

[edit] General Application

The mainframe computer room has largely disappeared but the application has remained with almost universal use of "computer-room" style raised floors in nearly all new commercial and office construction. To warrant the installation of leak detection the operator has to perceive the risk in addition to the circumstances but most Mechanical and Electrical Design Engineers will take a view of the risk of damage from a leak in terms of affect on the client's own operations, services and assets and, often as important, those of their adjoining neighbours and the those on floors below.

The installation of leak detection systems is therefore becoming more commonplace in most new commercial office construction schemes along with the more obvious targets of museums, galleries and archives.

Leak detection systems must be unobtrusive, effective and robust enough to withstand getting dirty and the moderate physical abuse of other works being carried out under the same floor.

Zoned systems have a reputation for being safe, reliable and not prone to the same types of false alarms which those systems which use cumulative resistance techniques.

The leak detection industry is very small and it can be expected that manufacturers will also offer an installation and after sales service.