UTILITIES - MECHANICAL

Air Conditioning

The process of treating air so as to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the requirements of the conditioned space.

Temperature

The hotness & coolness of a body.

Humidity

The amount of moisture in the air.

Compressor

Transports the refrigerant at the required pressure through the air conditioning system. It increases the refrigerant pressure and also its temperature so it becomes a high pressure gas.

Condenser

Works in the opposite way to the Evaporator. The refrigerant gives up its heat generated by the Compressor by passing cold air across its fins and tubes by ram air or by an extra fan.

Filter Drier

Depending on the type of air conditioning system fitted, this item can be called a Receiver Drier or an Accumulator.

Accumulator

Fitted on the low pressure gas line of an air conditioning system between the Compressor and the Evaporator and is used in conjunction with an orifice tube.

Receiver Drier

Fitted on the high pressure liquid line of an air conditioning system between the Condenser and Expansion Device. It has two parts to it, the receiver and the drier.

Receiver Section

Holds the right amount of refrigerant required by the system to ensure correct operation and to supply a steady flow of liquid refrigerant to the Expansion Device.

Drier Section

Responsible for removing moisture from the air conditioning system by means of a bag of desiccant which absorbs small quantities of moisture.

Expansion Device

Comes in many forms. It can be a brass internally or externally equalized valve, a block type valve or an orifice tube. It has an inlet and an outlet which separates the high side of the system from the low side.

Evaporator

As soon as the liquid pressure drops, the refrigerant begins to boil. As it continues to boil the Evaporator absorbs the heat passing over its tubes and fins and as a result the air is cooled.

Unitary Aircon System

A self-contained aircon unit cabinet commonly known as window type air conditioner or “through the wall” air conditioner.

Split - Type Aircon System

An aircon system consisting of two separate equipment: the Aircon Condensing Unit (ACU or ACCU) and the Fan Coil Unit (FCU).

Aircon Condensing Unit

Contains the compressor and is placed outdoors for heat rejection.

Fan Coil Unit

Contains the evaporator and is found indoors as part of the cooling and air handling assembly.

Centralized Aircon System

An aircon system that usually has an Air Handling Unit (AHU), an Air Distribution System, a method of cooling, and control equipment.

Air Handling Unit

Equipped with filters, humidifier and cooling coils; this is the air conditioner component of the system.

Air Distribution System

Consisting of fans and ducts that bring the conditioned air to the rooms and back to the air conditioner for recooling.

Direct Expansion Type

A system where the air used for cooling space is directly chilled by the refrigerant in the cooling coil of the air handling unit.

Chilled Water Type

Plants installed where whole large buildings comprising of several floors are to be air conditioned, where the refrigerant first chills the water, which in turn chills the room air.

Elevator

A hoisting and lowering mechanism equipped with a car or platform which moves in guides in a vertical direction, and which serves two or more floors of a building or structure.

Governor

Stops car and (if required) counterweight in case of emergency by actuating the Safety.

Safety

A device incorporated in the bottom beam of the car frame and counterweight which exerts retarding force in case of overspeed, by gripping the guide rails.

Limit Switches

Automatic devices which stop the car within the overtravel, independently of the operating device.

Counterweight

Balances the weight of the car, and usually equals weight of car plus 40% of car capacity.

Buffer

A device that absorbs the impact of car or counterweight at the lower limits of travel.

Dumbwaiters

Small lifts installed in kitchens for transferring cooked hot food, dirty utensils, raw materials, etc. to various pantries at all floors in multistoried hotels, large households, marriage halls, restaurants, etc.

Escalator

A moving staircase in which the steps move as a unit upward or downward at an incline of about 30 degrees.

Moving Walks

Continuous moving passenger conveyors or belts that operate at speeds of either 27 meters or 36 meters per minute, most useful in buildings where large groups of people must move long distances horizontally.

Traction

Use geared AC or DC motors with worm gears for mid-rise buildings (up to about 1000 feet) high-speed gearless have drive shafts attached directly to the motor; use more expensive induction motors.

Hydraulic

First developed by Dover (now Thyssen Krupp) economical for 2-7 floors uses piston (plunger) to push elevator up some soil contamination risk due to use of oil in piston shaft.