Cold water is very essential for drinking in the summer season. For domestic use the water is cooled by adding ice in it or by keeping the water bottles in a refrigerator. But for offices, hospitals and commerical establishments where the consumption of cold water is more the water is cooled by water coolers. The method of cooling water by adding ice in it, is not a hygenic way of cooling water because the ice may not be made from pure drinking water. But in a water cooler a pure drinking water through a water filter is allowed to enter in the cooling tank of the water cooler. This water can be cooled according to the required temperature. From medical point of view one should drink water not less than 60 F to 70 F. Therefore we use a water cooler.
After studying this lesson, you will be able to
. explain the working of a water cooler
. mention the main parts of a water cooler
. describe the types of water coolers
. understand the systematic wiring diagram of a water cooler
WORKING OF A WATER COOLER:
The principle of operation of all refrigerating machines is similar. The only difference is the construction of the cooling coil. The cooling coil of a water cooler is soldered to a steel tank in which drinking water is filled. Water tapes are attached to this tank for taking cold water When the compressor is switched on it starts working. It sucks vapours from the cooling coil and compresses them into high pressure and high temperature gas which is discharged into the condensor through the discharge line. In the condenser the gas is cooled by circulating air through the condenser and the gas becomes liquid. This liquid refrigerant is filtered with the help of a liquid line filter and then liquid enters in the cooling coil through the capillary tube. This capillary tube controls the flow of liquid refrigerent and permits a calculated quantity of liquid to enter in the cooling coil through the capillay tube. This capillary tube controls the flow of liquid refrigerant and permits a calculated quantity of liquid to enter in the cooling coil in the form of fine spray. Due to this the pressure of the liquid refrigerent drops and the liquid starts evaporating in the cooling coil by absorbing heat from the water filled in the water tank. This process is repeated and after some time the water in the tank becomes cold. the temperature of this water is controlled with the help of a thermostatic switch which is adjusted between 60 to 70° F. When the water reaches at this temperature the compressor stops and when the temperature of water starts rising the compressor starts automatically. Thus, the water in the water cooler is cooled.
Main Parts of a Water Cooler:
The main parts of a water cooler are divided into following two parts. (a) Mechanical parts b) Electrical parts
(a) Mechanical Parts
1. Body 2. Water tank attached with a cooling coil 3. Condenser 4. Compressor 5. Condenser fan motor 6. Float valve 7. Water tapes
(b) 1. Relay 2. Overload Protector 3. Thermostat 4. Running capicitor
Working of each part of a Water Cooler:
1. Body :
The body of a water cooler is made of mild steel sheet (M.S Sheet). The complete body rests on four metalic legs. At the top a water tank which is surrounded by cooling coil, is placed. This tank is made of stainless steel. It is fully insulated from all sides with the help of glass, wool or thermocole. There is a provision of water inlet from the top of the tank and outlet from the bottom of the rank. At the lower part of the body compressor, condenser and fan motor is fitted
3. Condenser : compressc incrcases to stop an compressor It is used to cool the gas with the help of air and the gas turns into 4 Startin quid form. Generally fin and tube type condenser is used with all water cooler motor
4. Compresser: It is called the heart of the machine. It is used to suck low pressure and low temperature vapours from the cooling coil and to compress and discharge them into the condenser in the form of high pressure high temperature gas Thus, it also maintains a pressure difference in the system and it helps the gas to circulate in the system. 5. Condenser Fan Motor t the circuit: in series w S. Runnir It is an elec motor and electromoti It is used to keep the condenser tubes cool by blowing air through the condenser fins It uses a fractional horse power motor usually between 1/35 to 1/16 H.P. A fan blade is fitted on the motor shaft. This motor is fixed very close to the condenser
6. Float Value : which the s current tha constant sp uned. It there are t It is used to maintain the level of water in the water cooler tank It is fitted at the top of the water tank and the drinking water pipes is connected to this foat valve. When the water level in the tank is reduced the valve is open and water enters in the tank. When the tank is filled the plastic ball, attached to the float valve moves up and closes the valve and the water stops entering in the tank. Thus, this float valve helps in maintaining the water level in the water cooler tank automatically.
7. Water Taps : (a) Instant It 15 a sma storing cold water is les b) Storage It is used for taking cold drinking water from the water cooler. It is fitted at the lower part of the cold water tank. It is made up of brass and are usually crome plated A bigger sia a storage t the quantit of water.
(B) Electrical parts
1. Relay :
It is used to start a sealed compresser motor and when the compressor starts it disconnects the starting winding or the starting capacitor.
2. Overload Protector : In short it is called O.L.P. It is used to protect the compressor m a sealed compressor motor draws miore current than the rated am it disconnects the electric supply to the compressor. l connected in series with the compressor motor.
3. Thermostat : It is also known as temperature control switch. It is used to control the temperature. If the water becomes cool in the water tank of the water cooler it cuts off the electric supply to the compressor motor and the compressor stops. After some time when the temperature of water increases it starts the compressor motor. Thus, it makes the compressor to stop and start automatically. It is always connected in series with compressor motor.
4. Starting Capacitor : It is an electrical device used to give an extra torque to the compressor motor at the time of start. When the compressor motor picks up speed it is disconnected with the help of a voltage type relay. If it remains in the circuit for a longer period it burst due to over charge. It is connected in series with the starting winding.
5. Running Capacitor : It is an electrical device, It is used to give extra torque to the compressor motor and when the motor starts it eliminates the back E.M.F. (bachk electromotive force) from the circuit. This back E.M.F is produced in the motor which opposes the direction of rotation of the motor due to which the speed of the motor is reduced and the motor draws more current than the rated amperes. To run the compressor motor a constant speed and to draw the rated amperes the running capacitor is used. It is connected in series with the starting winding.
Types of Water Cooler
There are two types of water coolers
(a) Instant Type b) Storage Type
a) Instant Type or Instantaneous Type
It is a snall capacity water cooler in which there is no provision for storing cold water in it. It is used where the consuimption of cold drinking water is less.
b) Storage Type: A bigger size of water cooler in which cold water can be stored is called storage type water cooler the quantity of water it can cool in one hour, for esmaple if the sapacity of water cooler is 150 litre per hour it means it can cool 150 litre water.