Glenfield - Water Engineers to the World

By Sam Gilbert, Glenfield Valves Ltd.

This project is typical of how the Glenfield special discharge valves can play a part in today's dams and reservoir activities.

It involves early seed sowing with designers at feasibility stage, providing technical input on vaving aspects and then following through with support at all stages until project completion. This can take a number of years from inception until completion as in this case.

This project was principally to upgrade an older system where 2 x 900mm Glenfield free discharge valves, push button operated were being replaced by the more modern submerged discharge valves.

These provided a much quieter operation as well as superior control and permitted automation from the nearby Shatin Control Centre.

Raw Water is drawn from a variety of sources, including the large High Island Scheme into Lower Shing Mun Reservoir from where it is released to Shatin treatment works for onward transmission as potable water to distribution networks.

The residual inlet heads at the valve can range from 5 up to 60 m. The design requirement is that the valve must be capable of passing flows up to 8.3 cumecs under a nett head of 15 metres. Also 5.6 cumecs with 7.5 metres available head.

The fact that the submerged discharge valve can be fitted with specially contoured ports enables such system requirements to be matched.

For these operating conditions the optimum valve size is DN 1400/1200. That is 1400 mm inlet bore and a DN 1200 downpipe and valve element.

WDD, who is the responsible client and end user, released the design of the contract to Black and Veatch Hong Kong.

After detailed discussion with our Glenfield technical department, it was shown that the Glenfield submerged discharge embodied the features necessary to fulfil the energy dissipation and flow control aspects required by such a contract.

Gammon were appointed as main contractors.

Ultimately, the contract was secured by Advance Trading, the Glenfield agents in Hong Kong. The contract not only included valve design supply and manufacture, but also supervision of installation, training of all operating personnel and supporting final on site testing and commissioning.

This work was successfully completed in May 2007.

Glenfield are delighted to have been associated with WDD in this project as they have been in the past at High Island, Plover Cove, Tai Po Tau, Tai Mei Tak etc.