tower with two 96 in. fans driven by 25 h.p. motors; three 60 h.p. chilled water pumps (one standby); three 60 h.p. condensing water pumps (one standby); a separate 50 h.p. reciprocat- ing system, using the same cooling tower, to serve the 20th floor pent- house; and an electrode boiler for heating chilled water under extremely cold conditions during reverse cycle.
Due to the limited floor space of the plant room, the refrigeration equip- ment is split up into two levels. The two centrifugal machines, the chilled water pumps and the motor control centres are placed on the 22nd floor while the rest of the equipment is located on the 21st. floor.
Pneumatic controls are used throughout the building to operate the cooling and heating valves on the air handling units and the sequencing valves on the fan coils. Reverse cycle change-over is also done by a series of pneumatic valves.
All motor starters for the refrigera- tion plant are packed into two motor control centres one for high tension centrifugal compressors and the other for low tension machineries. From these two motor control centres, start- ing of all the refrigeration equipment in its proper sequence can be done automatically.
The whole air conditioning plant and all other mechanical services are supervised from an air-conditioned control room on the 21st floor. A master control console is provided and is divided into six panels: main equip ment panel; load indication meters;
Plant room at 23rd floor level
intercom system; air handling units; ventilation units; and alarm points.
Also provided in this main control room is a multi-point temperature recorder which records 24 hours a day 15 different temperatures of the air- conditioning equipment.
Electrical installation
The main power supply is 11 kv from the HK Electric Co. grid to HT switchgear and 11kv/350v transformers owned and installed by the power company within the property. From the power company's equipment 350v is supplied to the owner's LT switch- gear and 11kv to the owner's HT gear.
In the owner's LT switchgear pro- vision has been made for a separate supply to the lifts and the emergency lighting. This separate submain is pro- tected by an emergency diesel generator which will cut in as soon as the mains supply fails.
The LT switchgear is so arranged that it is fed by two feeders from two different HK Electric transformers with interlocking couplers to switch over power to supply the essential loads in the event of a transformer failure. Either miniature circuit breakers or cartridge fuses are used in the electrical installation and there are no rewirable fuses.
Three separate risers, off another separate transformer from HK Electric, are provided for the tenants, each serving about seven floors. Owners' supply risers, which are off the owners' LT switchboard and are metered at bulk combined demand rate, have tee-
off cut-out provisions on every floor.
Lighting and power on each floor are controlled from a distribution board located in the meter room on each floor. All the exterior floodlights and car park lights are remotely con- trolled in the watchman's room situated at the Hau Tak Lane lower ground 4th floor entrance.
Under the electrical contract, a system of heat detectors and manual alarm fire stations, in addition to hosereels, have been provided through- out the building. The complex is divided into 30 detection zones, in- cluding one for each typical floor, and a comprehensive indicative fire panel is installed in the watchman's room.
The HT switchroom and the HT transformer room are protected by automatic CO2 system with rate of rise pneumatic detectors. Car parking areas and the garage are protected by an automatic sprinkler system which is also incorporated into the fire in- dicating panel.
For AIA's own offices a four- cabinet Siemens ESK 400 E semi- electronic PABX system has been in- stalled to provide 20 exchange lines, 150 extensions and 15 internal links. It can be expanded to 40 exchange lines and 400 extensions by the addition of further cabinets.
Contractors
The general contractor for the pro- ject was Paul Y. Construction Co. Ltd.
Main sub-contractors were:
Air conditioning International En- gineering Ltd.
Electrical
-
The China Engineers Ltd. Plumbing - Dodwell & Co. Ltd. Lifts Otis Elevator Co. Suppliers included:
Refrigeration machinery and air handling
units
Carrier Air Conditioning Co., USA LT and HT motor control centres and LT main switchboard - Siemens Schuckert, Australia
Air conditioning water pumps - Deming Division, Crane Co., USA
Cooling tower The Marley Co., USA Air conditioning controls and control panel components and fire panel Honey- well Inc., USA
HT distribution board
Co., UK
Transformers
Ltd., UK
-
M
A. Reyrolle &
The English Electric Co.
Typical floor light fittings - The China
Engineers Ltd.
Aluminium windows
—
Crittal-Hope Ltd.
Glass Olivier & Co. (HK) Ltd.
Vinyl tiles - American Engineering Corp. Acoustic ceiling tiles Getz Bros. & Co. Inc.
Ltd.
Rolling shutters - Shewan Tomes (Equip.)
Gorbin hardware - China Engineers Ltd. Marble Marblecraft Inc., Manila
—
Mineralite
Ltd.
Harrisons & Crosfield (HK)
Tube wells - Dreyer & Co. Ltd.
24
Far East BUILDER, February 1969