How Do Float Switches Work (Diagram & Working Principle)

Float Switch Working Principle

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How Old Float Switches Work

How Do Float Switches Work Diagram

Older Float Switches work by opening and closing circuits (dry contacts) as water levels rise and fall. Typical float switches are normally resting in the closed position, meaning the circuit is incomplete and no electricity is passing through the wires yet.

Old Float Switch Working Principle

Once the water level drops below a predetermined point, the circuit completes itself and sends electricity through the completed circuit to trigger an alarm.

How does the electricity pass through the circuit? The electricity passes through, what are called, magnetic reed switches. Once the water does drop low enough, the reed switches come in contact with each other and complete the circuit, allowing electricity to be passed through them and turn on the alarm. Once the water gets high enough again, the switches break apart and disconnect the circuit.

The Magnetic Reeds Open & Close To Control Water Levels

The magnetic reeds are sealed in a stainless steel or plastic stem. The magnetized reed switches move and down as the water level increases and decreases and are set to come together and break apart at different heights that you specify during installation.

The problem with the way these old float switches work is that they can deteriorate due to poor water quality and electricity passing through them. That’s why Water Level Controls created their own float switch replacement that uses sensing probes to gauge water levels instead of floats.

Float Valves

Other cooling tower operators typically used float valves instead of sensor rods for automatic control of water levels. Float valves use a floating mechanism and arm to gauge water levels and turn on and off pumps. These types of float switches could only do 1 or 2 operations unlike new float switches that can be programmed to handle many automatic operations.

How New Float Switches Work

Float Switch Diagram - How Do Float Switches Work

Water Level Control’s float switches work by using probes instead of float switches.

The sensor probes actually act as their own sensors and do not pass electricity through the probes which keeps them from fouling, degrading and deteriorating. Also, all of the electronics are built into the head so you can connect directly to your control panel. Once the water level is detected by one of the sensors, this causes one of six alarms to be triggered (High Alarm, Low Alarm, Fill Start, Fill Stop, etc). Depending on the type of float switch you have, there can be single point alarm or a multi point alarm that is triggered.How Do Float Switches Work

Single Point & Multi Point Float Switches

Single point and multipoint float switches allow you more control of your storage tank filling mechanisms and will last 5 times longer than traditional float switches.

How Single Point Float Switches Work

Single Point Float Switch Working Principle

Single point float switches work with 3 sensor rods (Reference, Start & Stop) that work in conjunction to turn on and off your water pump automatically. This helps keep water levels at a consistent level.

How Multi Point Float Switches Work

Multi Point Float Switches Working Principle

In Multi-point float switches, there are 4-6 sensor rods (High alarm, fill 1 stop, fill 1 start, fill 1/fill 2 stop, fill 2 start, low alarm, reference). These rods can programmed to do multiple tasks such as stop water levels once they reach a predetermined point and start filling water once its drops below a certain level.

The most basic way to explain this is; the sensor probes stick down in the water to detect water levels at different heights, depending on the height of the water, the probes all have different tasks they perform. If the water level is too low, it sets off the low water alarm, if the water is too high, it sets off the high level alarm etc.

Buy Cooling Tower Float Valves

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Cooling Tower Vibration Analysis | Vibration Cut-off Switch

cooling tower vibration analysis Vibration Cut-off Switch

Vibration is a common problem in cooling towers and other types of mechanical or industrial equipment.

Cooling tower vibration limits?

Machines that require moving parts are built to withstand a specific limit of vibration without losing their reliability or performance. Issues occur when vibration exceed manufacturer limits, usually caused by abnormal situations.

Cooling towers use fans, drive-shafts, and motors which operate 24 hours a day, every day of the year. Vibration in cooling towers must be addressed quickly to avoid long shut down times, and avoid severely damaging major components in the cooling tower (due to the fact that the fans and cylinders are so close together).

There are many sources of cooling tower vibration:

  • Unbalanced cooling tower fan blade
  • Uneven pitch of fan blade
  • Worn shaft, couplings, or drive-shaft inserts
  • Worn mechanical equipment bearings (fan-shaft bearings, motor, gear reducer)
  • Gear tolerances inadequate in gear boxes
  • Gearbox is damaged
  • Structural deterioration of mechanical equipment
  • Worn belts in belt driven equipment
  • Misalignment of mechanical equipment, pulleys/sheaves or drive-shafts
  • Fasteners loose in mechanical equipment and its supporting structure

Can vibration damage your cooling towers?

Sustained period of vibration in cooling towers can cause severe damage, including damaging mechanical equipment (For example – fan cylinder being hit by fan blade tips, damaging both fan blades and cylinder) and impacting surrounding installations. In less common situations, vibrations in cooling towers can cause discomfort to people in the vicinity and the surrounding structures.

The best way to avoid abnormal vibration and mechanical failure is to install a vibration cut-off switch.

What is a vibration cut-off switch?

The cooling tower part/accessory will shut down the evaporative cooling equipment of cooling tower when vibration levels exceed manufacturer specification limits.

It is wise to test your vibration switches periodically to make sure they are operating properly. Another great practice is to install data loggers for your vibration switch, the data logger will help monitor the vibration and help you implement better preventative actions as needed.