Liquid Level Indicators

A liquid level indicator is a device used to monitor the quantity of liquid inside tanks, reservoirs, or equipment. It provides a visual or digital indication of fluid height, ensuring processes operate safely and efficiently. From sight glass level indicators on hydraulic tanks to digital oil level indicators in industrial systems, these devices are critical across multiple industries.

How Do Liquid Level Indicators Work?

The basic principle of a level indicator is to provide a reliable, visible reference of the liquid inside a closed or open vessel.

Sight glass level gauges and fluid level gauges work by physically displaying the liquid through a transparent tube or window. The liquid inside the indicator matches the level of liquid inside the tank, allowing operators to see the current volume.
Float-type level indicators use a buoyant float connected to a pointer or sensor. As the liquid rises or falls, the float moves, displaying the level on a scale.
Digital oil level indicators use electronic sensors to measure fluid height and transmit real-time data to control systems.

This allows for accurate monitoring of fluids such as water, oil, fuel, and hydraulic fluid.

Applications Of Liquid Level Indicators

Hydraulic Power Units

Hydraulic level gauges and hydraulic sight glasses are fitted to hydraulic power units, enabling operators to confirm correct oil levels and avoid pump damage or system failure.

Industrial Machinery

Oil level gauges and oil level sight glasses are widely used in gearboxes, compressors, and lubrication systems, allowing quick inspection of lubricant condition and volume.

Liquid Storage Tanks

Water tank level indicators and tank water level indicators provide an effective way to monitor liquid reserves in tanks for municipal, agricultural, and industrial use.

Cooling Systems

Water level gauges are fitted to boilers, chillers, and cooling towers to ensure adequate liquid circulation and to prevent overheating or equipment failure.

Pressure Vessels

Sight glass level gauges are used in pressurised tanks and vessels to provide direct visibility of the liquid level, even under high-pressure conditions.

Fuel Tanks

Oil level indicators and fluid level gauges are used in diesel and petrol tanks for vehicles, generators, and stationary engines to track fuel reserves.

Processing Plants

In food, chemical, and pharmaceutical processing, liquid level gauges are used to maintain precise liquid volumes during mixing, batching, or reaction processes.

Liquid Level Indicator Types

By Function

Column Level Indicators: Transparent tubes or chambers mounted externally to show the liquid level directly.
Sight Glasses: Includes oil level sight glass, hydraulic sight glass, and sight glass level gauges, offering direct visibility into tanks or reservoirs.
Digital Level Indicators: Electronic sensors such as digital oil level indicators, providing remote monitoring and integration with control systems.

By Fluid Type

Water Level Indicators: Includes water level indicators and water level gauges for tanks, boilers, and cooling systems.
Oil Level Indicators: Includes oil level indicators, oil level sight glasses, and liquid level gauges designed for lubrication systems and fuel storage.

By Features

With Thermometer: Combines temperature and level measurement in a single device.
With Contrast Screen: A contrast screen or OLED display Improves visibility of fluid in low-light or dark-coloured liquids.
With Level Points: Provides visual markers for minimum, maximum, or setpoint levels.

By Connection

Threaded Connection: Allows easy installation into small tanks or machinery.
Flange Connection: Suited for larger tanks requiring secure, sealed fittings.
Weld-in: Provides permanent installation in pressure vessels or heavy-duty equipment.

How To Install Liquid Level Indicators

Determine the mounting location. Select a position where the indicator will clearly show the liquid level without obstruction.
Prepare the tank or vessel. Drill or cut holes for threaded, flange, or weld-in connections, ensuring proper alignment with the expected fluid level range.
Install the indicator. Secure the sight glass level indicator, oil level gauge, or water level indicator using the appropriate seals or gaskets to prevent leakage.
Check for leaks. Once installed, fill the vessel partially and inspect the fittings for any signs of leakage.
Calibrate if required. For digital oil level indicators or electronic gauges, carry out calibration so the sensor readings match the tank dimensions.

How To Choose The Right Liquid Level Indicators

When selecting a liquid level indicator, consider:

Fluid Type: Use oil level gauges for lubricants, water level indicators for water systems, and hydraulic level gauges for hydraulic oils.
Application: Select sight glass level gauges for simple visual inspection, or digital oil level indicators for automated monitoring.
Operating Pressure and Temperature: Ensure the indicator can withstand system conditions, especially for boilers, hydraulic units, or pressure vessels.
Connection method: Choose between threaded, flange, or weld-in connections based on tank design.
Visibility: For dark fluids, select indicators with contrast screens; for critical systems, use models with min/max markers.
Durability: For heavy-duty environments, select rugged materials such as borosilicate glass or reinforced housings.

By matching the indicator to the application, users ensure accurate and reliable liquid monitoring in industrial systems.

The Trusted Supplier Of Liquid Level Indicators In Australia

RS provides a comprehensive range of liquid level indicators in Australia, supporting industries that require reliable monitoring of fluids in tanks, machinery, and processing systems. Alongside level indicators, we also stock complementary products such as pressure gauges, thermistor sensors, and flow meters, sourced from established manufacturers including Elesa, Stauffand Parker.

For details on delivery schedules, Australia-wide coverage, or assistance with purchasing, please refer to our delivery page.