Technology

John Taylor High School Engineering.

The 2000-2001 Project

Following the normal selection procedure of written application and interview, this year's team members are; Jennifer Hill, Russell Kelly, Ben Mayer and Jonathan Williamson.

The task given to the 2000-2001 team is concerned with mains water leak detection in commercial buildings.

The title is; Water Leak Detection

The Brief - Design and make a remote alarm system for an office block type building that will detect a major water leak, especially outside of working hours.

Project Design Criteria

The targets set by TXU for the team are: -

•  The system must protect the whole building

•  The system has to be capable of being installed in premises other than the Drakelow Business Centre.

•  A working prototype must be produced.

•  A specification and manufacturing drawings to allow commercial manufacture are required.

Background...

Following a complete refurbishment of the Business Centre at Drakelow Power Station the staff arrived on day one and met by water cascading under the front door. It was later discovered that a joint in the plumbing system had not been fully tightened and with the increase of mains water pressure overnight (due to low demand) the loose joint had failed to retain the water pressure. A tide mark on the wall indicated that the water had been up to eighteen inches deep. Although the Business Centre in unoccupied outside of normal working hours the main gatehouse is manned by security staff twenty four hours every day. Some form of alarm system would have alerted security who could then have responded to this incident.

Initial contact with insurance companies revealed that millions of pounds are paid out each year on claims for similar events.

Research

Initially the task was divided into two main areas;

•  Leak detection.

•  Alarm systems.

Extensive research was carried out on methods of detecting leaks including Moisture sensors, Chemical sensors, flow sensors and pressure sensors.

From analysis on the above detectors we found:-

Moisture/Chemical Cheap and easy to install but difficult to bring a signal to a central point.

Flow Monitors water at all times and is not affected by changes in water pressure.

Pressure Monitors water at all times but constant pressure is not maintained.

From our analysis it was decided that flow measurement was the most viable option.

Alarm systems that we investigated included Sirens, flashing lights, radio waves, micro waves and telephone voice diallers.

After analysis of these systems we concluded that:-

Sirens and flashing lights would alert people inside the building and would be seen/heard within a certain distance from the building.

Radio/micro waves would alert people away from the building but the signals may be subject to electrical interference.

Telephone voice diallers would alert people external to the building, would not be affected by electrical interference but are quite expensive.

The solution.

We considered that under normal circumstances, once the building became unoccupied there should not be any flow of water and therefore the installation of a flow switch would detect abnormal flow which would then activate a solenoid valve, shutting off the main water supply. This however was not quite the case as we realised that the central heating system may require topping up during the night and also there was frequent flushing throughout the night in the toilet system. Close monitoring of these existing systems over several days allowed us to determine the maximum time that these systems were operative, resulting in the introduction of a timer into our system.

The flow of water is detected by the flow switch which then initiates the timer. If the normal flow time for the existing systems is exceeded the solenoid valve is then activated shutting off the water supply. A reset switch is included to reactivate the system once the problem is resolved. Connections to external warning lights, audible devices and telephone diallers are also included.

Commercial Potential.

Our system, called H 2 OLD (Water Leak Detector), has the potential to be marketed for use in any commercial or domestic premises, single or multi storey. It can be quickly and easily installed by a competent plumber. Current costs are estimated to be in the region of £330 per unit for a 15mm pipe system. This cost could be significantly reduced if units were made in quantity.

The team would like to thank TXU Energy for their continuing support, Drakelow Business Centre for their help and hospitality throughout the duration of the project, Mr John Kilkie station engineer, John Ashworth instrumentation dept, Mr Evans and Mr Baker at JTHS.