Level Control - Madison
Level control is essential for many industrial and commercial applications, ranging from simple water tanks to complex chemical processing systems. Industrial applications often require control to maintain safe and...
Float switches are one of the simplest and most dependable ways to sense liquid level. A buoyant float rises and falls with the liquid and opens or closes a switch at a set point to start a pump, stop a fill or trigger a high or low level alarm.
Float Switch Types
- Tethered cable floats – wide switching range for sumps and wastewater
- Vertical stem floats – compact, precise point level in tanks
- Side-mount floats – install through the tank wall
- Multi-point float switches – several level points on one stem
- Sanitary and chemical-resistant floats – stainless, PVDF and polypropylene
Choosing a Float Switch
Consider the liquid's specific gravity, temperature and chemical makeup, along with the tank's size and mounting options. Check the switch rating against the load. Many pumps need a relay or motor control panel. Avoid using floats in turbulent or heavily coated liquids unless they're designed for it.
Centro offers float switches for water, wastewater, chemical and process tanks, and can help you match material and mounting to your application.
Related categories: Liquid Level | Level Transmitters | Float Switch | Radar | Differential Pressure Control
Liquid level switches detect when a liquid reaches a set point in tanks, sumps and vessels. They control pumps and valves and trigger high and low alarms.
Level Switch Types
- Float switches – simple, reliable switching
- Vibrating fork switches – unaffected by foam or turbulence
- Conductivity switches – conductive liquids
- Optical switches – compact point detection
- Capacitive switches – liquids and slurries
Choosing a Switch
Consider liquid type, temperature, pressure, buildup and mounting. Use an independent high-level switch for overfill protection.
Centro supplies liquid level switches for tanks and sumps.
Related categories: Liquid Level | Level Sensors | Differential Pressure Control | Water Gauges | Radar
Panel meters and displays turn signals from transmitters, sensors and electrical circuits into clear readings on a control panel. Operators can see flow, temperature, pressure, level, speed or current at a glance, and many models also provide alarms and retransmitted outputs.
Display Options
- Process meters – read 4-20 mA and 0-10 V signals in engineering units
- Electrical meters – AC/DC voltage, current and power
- Temperature displays – direct thermocouple and RTD inputs
- Rate and totalizer meters – flow rate, totals and counts from pulse inputs
- Large-digit displays – visible across the plant floor
Choosing a Meter
Match the input type and range, then decide whether you need relay alarms, analog retransmission or serial communication. Check the panel cutout size (1/8 DIN is common), power supply and front-panel rating for washdown areas. Loop-powered meters are useful where no separate power is available.
Centro carries panel meters and displays from leading instrumentation brands and can help you match one to your signal.
Related categories: Controllers | PID
Liquid level sensors detect or measure liquid in tanks and containers. They support pump control, inventory tracking and overfill protection.
Sensor Types
- Ultrasonic sensors – non-contact continuous level
- Capacitive sensors – point and continuous level
- Optical sensors – compact point detection
- Submersible pressure sensors – hydrostatic level
- Float sensors – simple, dependable
Choosing a Sensor
Consider liquid type, tank size, mounting and the output you need. Foam, vapor and buildup affect some technologies.
Centro supplies liquid level sensors.
Related categories: Liquid Level | Water Gauges | Level Switches | Differential Pressure Control | Radar
Flow switches monitor liquid or air flow and trigger alarms or shutdowns when flow is too low or too high. They protect pumps, heat exchangers, chillers and cooling systems.
Flow Switch Types
- Paddle flow switches – simple, rugged
- Thermal flow switches – no moving parts
- Piston and magnetic flow switches – precise set points
- Air flow switches – ducts and HVAC
Choosing a Switch
Select by media, flow range, pipe size, pressure and temperature. Adjustable set points add flexibility.
Centro supplies flow switches.
Related categories: Flow Control | Flow Transmitters | Flow Meters | Flow Sensors | Flow Control Accessories
Configure product to see pricing
Configure product to see pricing
.webp)
$517.33$649.00
$656.03$823.00
$710.23$891.00
$167.40$210.00
Subject to factory lead times
$334.79$420.00
Subject to factory lead times
$148.27$186.00
$38.27$48.00
$361.10$453.00
$167.40$210.00
Subject to factory lead times
$598.64$751.00
$271.82$341.00
Subject to factory lead times
$271.82$341.00
Subject to factory lead times
$543.64$682.00
Subject to factory lead times
$403.35$506.00
$94.86$119.00
Subject to factory lead times
$94.86$119.00
Subject to factory lead times
$189.72$238.00
Subject to factory lead times
$121.96$153.00
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
$0.00$273.00
Configure product to see pricing
Configure product to see pricing
$517.33$649.00
$656.03$823.00
$710.23$891.00
$167.40$210.00
Subject to factory lead times
$334.79$420.00
Subject to factory lead times
$148.27$186.00
$38.27$48.00
$361.10$453.00
$167.40$210.00
Subject to factory lead times
$598.64$751.00
$271.82$341.00
Subject to factory lead times
$271.82$341.00
Subject to factory lead times
$543.64$682.00
Subject to factory lead times
$403.35$506.00
$94.86$119.00
Subject to factory lead times
$94.86$119.00
Subject to factory lead times
$189.72$238.00
Subject to factory lead times
$121.96$153.00
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
Subject to factory lead times
$0.00$273.00
- Monitoring and controlling liquid level in a tank requires a level sensor or transmitter paired with a controller, PLC, or alarm system. The first decision is whether you need point level detection (knowing when the level hits a specific high or low threshold — for alarms or pump control) or continuous level measurement (knowing the actual level height at all times — for inventory tracking or closed-loop control). For point level, float switches are the simplest and most cost-effective option — a buoyant float actuates a switch when the liquid reaches a set point. Vibrating fork switches are a good alternative when the liquid is viscous or foaming. For continuous measurement, ultrasonic transmitters work well in open atmospheric tanks with clean liquids, radar transmitters handle pressurized vessels, vapors, and foam, and differential pressure transmitters are the traditional choice for high-pressure or high-temperature vessels. The level signal is sent to a PLC or controller that operates inlet/outlet valves or pump starts/stops to keep the level within the desired range.
- Level measurement technologies fall into two categories: point level (detecting when the level reaches a specific threshold — high, low, or intermediate) and continuous level (measuring the actual level height across the full range). Common point level technologies include float switches (a buoyant float actuates a switch at a set level — simple, reliable, and low-cost), vibrating fork switches (a tuning fork vibrates at its natural frequency in air and dampens when immersed in liquid), and capacitance point switches. Common continuous level technologies include ultrasonic (measures distance to the liquid surface using sound waves — non-contact, works well for open tanks), radar and guided wave radar (uses microwave pulses — handles high temperatures, pressures, and vapors), differential pressure transmitters (infer level from hydrostatic pressure — the traditional workhorse for pressurized vessels), magnetostrictive float-based systems, and capacitance/admittance transmitters. The right choice depends on the media (clean liquid, slurry, foam, solids), vessel conditions (temperature, pressure, agitation), accuracy requirements, and budget.
- A float switch uses a buoyant float attached to or enclosing a mechanical or magnetic switch mechanism. As the liquid level rises, the float rises with it; when it reaches the switch actuation point, the switch changes state (opens or closes a circuit), sending a discrete signal to the control system. Float switches are the simplest and most widely used point-level devices — they are reliable, inexpensive, require no power supply for mechanical types, and work in a wide range of liquids. Common applications include high-level and low-level alarms on storage tanks, sump pump control (turning the pump on when level rises and off when it falls), coolant reservoir monitoring, and condensate tank level switching. Limitations include susceptibility to fouling in viscous or coating liquids, and they are not suitable for applications with heavy turbulence or foam. For these challenging conditions, vibrating fork or capacitance-based switches are more appropriate.
- Both ultrasonic and radar are non-contact continuous level measurement technologies, but they perform differently in various conditions. Ultrasonic level transmitters are cost-effective and work well in atmospheric tanks with clean liquids and moderate temperatures — they are the standard choice for water and wastewater tanks, chemical storage, and open vessels. However, ultrasonic performance degrades in heavy vapor, dust, foam, and extreme temperatures because sound waves are affected by the medium they travel through. Radar (non-contact and guided wave) uses electromagnetic waves that are unaffected by temperature, pressure, vapor, or dust — making radar the better choice for pressurized vessels, high-temperature processes, tanks with heavy vapor blankets, and media that produce foam or surface turbulence. Guided wave radar (a probe that contacts the media) provides excellent accuracy and reliability in narrow vessels, still wells, and applications with low dielectric liquids. Radar instruments are typically more expensive than ultrasonic, so ultrasonic remains the preferred choice where conditions allow.
- Differential pressure (DP) level measurement uses a DP transmitter to infer the liquid level in a tank based on the hydrostatic pressure exerted by the liquid column. The transmitter measures the pressure difference between the bottom of the tank (where the liquid column creates pressure proportional to its height) and the top of the tank (the reference or vapor space pressure). Since pressure increases linearly with liquid height (P = ρ × g × h), the DP reading is directly proportional to level. DP level measurement is the traditional workhorse for pressurized and vacuum vessels where non-contact technologies may not perform well, and it remains widely used in oil and gas, chemical, pharmaceutical, and power generation applications. It is well-suited for high-temperature, high-pressure vessels and can handle a wide range of media. Limitations include the need for impulse piping (or remote diaphragm seals for corrosive or viscous media), and it requires the specific gravity of the liquid to remain relatively constant for accurate measurement.