PRIVATE WATER SYSTEMS - Installation - Control Units - Water-Supply

Water-Supply

Pressure switches are for use with elastic pressure cells or pressure tanks (see storage). With either gravity tanks or reservoirs, a float switch or drawdown control switch should be used.

Pressure Switches (2)

Pressure Switches Pressure switches are by far the most common water control switch since they control pumps which develop the necessary pressure for water distribution. The several different designs all have the same basic operating principle: A rubber diaphragm in the pressure switch is exposed to pressure on the delivery side of the pump. As the pump builds up pressure, pressure increases on the diaphragm. The diaphragm moves up and gradually compresses a large range spring. This action moves the lever that operates the cam wheel. As it is forced over the top of the operating cam lever, the electrical contacts are opened and the pump motor is stopped.

When tank pressure decreases, the diaphragm is forced down by the range spring. The cam that operates the switch mechanism rides over the top of the operating cam lever and closes the circuit. The motor starts.

Most pressure switches are set by the factory to operate on a 20 to 40 pound pressure range, but pressure switches can be set higher or lower.

Float Switches (2)

Float Switches A float switch is used to control the pump motor in systems using gravity tanks or reservoirs. The switch mechanism is similar to that of the pressure switch, but instead of being activated by water pressure, it is controlled by the float that follows the water level up and down in the tank or reservoir.

When the water level in the tank lowers, the float automatically trips the switch and starts the pump. When the water level rises, the float moves with it and turns off the pump motor when the desired level is reached.

Drawdown Control Switches (2)

Drawdown Control Switches The drawdown control switch can also be used in gravity tanks and reservoirs. It consists of electric sensors which can be adjusted to the desired positions in a water storage so as to start the pump motor when the water level gets low, and stop it when the water reaches the desired height.

These switches may also be used when there is limited yield from a well. The two sensors are lowered into the well. One sensor is placed at the lowest drawdown level desired, while the other is placed at the static water level. As the well is pumped the water level drops. When the level reaches the height of the lower sensor, the pump is turned off. The pump motor will not start up again until the water level has risen to the level of the upper sensor.

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