Leakage Monitoring & Detection

What is leakage monitoring & detection?

Operating principles of leak detection

Leak detection systems detect unwanted escaping liquids before larger quantities leak out or safety-relevant components are reached. Depending on the physical properties of the medium, different measurement principles are used. Selecting the right leak sensor depends largely on whether the liquid is electrically conductive or not.

Conductive leak probe (rod electrode)

With conductive sensors (such as rod electrodes), the electrical conductivity of a liquid is used for detection. When two or more electrodes come into contact with a conductive medium such as water or coolant, a measurable current flow is created. This is captured by an evaluation unit and forwarded as a switching signal.

Typical properties and benefits:

• Suitable for conductive liquids such as water, saline solutions, condensates
• No moving parts, therefore low-maintenance and mechanically robust
• Flexible installation length: electrodes can be positioned close to the bottom of the drip tray
• Simple signal processing via conductive relay modules or PLC inputs

Such leak probes are often used in drip trays, raised floors or technical rooms. They are ideal when a reliable and fast response to conductive liquids is required. This is the case, for example, with condensate or leaks from water-bearing systems.

Float switch (straight mini design)

Float switches work according to a mechanical principle: as the liquid level rises, the float lifts and actuates a magnetic contact (reed contact) inside. This technology is suitable for both conductive and many non-conductive media.

Compact mini float switches, such as those offered by Reed, are particularly space-saving and are predestined for use in drip trays or confined areas under machines.
They offer:

• Mechanically reliable leak detection without electronic evaluation
• Easy integration via threaded connection or mounting bracket
• Flexible mounting positions, e.g. vertical or horizontal
• Individually adjustable switching points, depending on the desired level or warning threshold

This makes mini float switches a practical solution when simple and robust leak detectors are required

Other sensor technologies (brief overview)

In addition to conductive and mechanical principles, there are other technologies for leak detection, such as optical or capacitive sensors. These are particularly suitable for media that are neither conductive nor reliably detectable via float switches (for example oils, chemicals or demineralized water).

Such systems detect changes in light refraction, capacitance or reflection as soon as a liquid touches the sensor area, and generate an electrical signal from this.

Combining these technologies with Reed sensors can be useful if different media occur in a system or if a redundant safety concept is desired. This can significantly increase the reliability of leakage monitoring and ensure continuous detection in all operating conditions.

Media & locations of use

The requirements for reliable leakage monitoring vary depending on the type of liquid and the environment. While in water-bearing systems the early detection of small quantities is crucial, for oils or chemicals material resistance and the detection principle are the focus. The key factor is always that the sensor matches the medium and the installation situation.

Water-bearing media (drip tray, raised floor, technical rooms)

In technical systems, server rooms or HVAC systems, even a small leak can cause significant consequential damage (short circuits, corrosion, etc.).
Here, conductive leak probes or mini float switches are generally used. Both variants react quickly to rising liquid levels in drip trays or raised floors.

Typical applications:

• Condensate monitoring in cooling systems and air conditioning systems
• Water leak detection under pipelines or tanks
• Leakage warning in raised floors of server rooms
• Collection trays under pumps or hydraulic units

The combination of compact design and simple signal forwarding allows direct integration into leak detectors or building management systems.

Non-conductive media (oil/diesel)

With non-conductive liquids such as heating oil, diesel or lubricating oil, conductive measurement principles fail because no electric current flow is created. In such cases, mechanical float switches or, in sensitive areas, optical sensors are used.

Both systems respond independently of conductivity, but must be made of corrosion-resistant materials (e.g. stainless steel, PTFE) in order to withstand chemical exposure.
Especially with oil-containing media, regular functional testing is recommended, as viscosity and film residues can affect the float’s mobility.

Leakage monitoring on the oil tank (note)

For heating oil or diesel tanks, a special form of leakage monitoring applies:
For double-walled tanks, the interspace (the so-called monitoring space) is continuously checked for negative pressure. If the pressure drops, the leak detector signals a leak. This principle is known as interstitial leak monitoring.

Such systems differ fundamentally from point leak sensors in drip trays, as they cover the entire tank space.
In practice, both concepts can be combined: a permanent pressure monitor for the tank itself and an additional leak detector for a drip tray.

Finding the right leak sensor

Optimal leak detection depends on several factors: the medium, the spatial conditions, and the requirements for signal processing or automation. To avoid false alarms and ensure reliable detection, the selection of the leak sensor should follow clear criteria.

Checklist for product selection

For a practical selection, the following approach is recommended:

1. Identify the medium: Check conductivity, consult the manufacturer’s datasheet if necessary.
2. Define the installation location: e.g. drip tray, raised floor, tank room.
3. Set the alarm level: At what liquid height should the system trigger?
4. Clarify signal output: Relay output, PLC input, or external leak detector.
5. Check material requirements: Corrosion resistance, temperature range.
6. Plan regular functional testing: e.g. manual testing or a test button.

With this structured approach, misapplications can be avoided and the sensor, leak detector and evaluation unit can be optimally matched.

Still unsure which sensor is the right one for your application?

Get in touch now!

System structure & signaling

A functioning leakage monitoring system usually consists of several components that together form a reliable alarm system. The sensor itself detects the liquid, the evaluation electronics process the signal, and the leak detector provides a visual or audible warning. Depending on the type of system, the alert can also be forwarded to a PLC or building management system.

Leak detector & alarming

As soon as a leak is detected, the sensor (such as a conductive rod electrode or a float switch) sends a switching signal to an evaluation device or relay. This in turn activates the leak detector, which is available in different versions:

• Visual indication via LED or display
• Audible alarm with buzzer or signal tone
• Potential-free output for forwarding to control systems
• Voltage output for coupled warning systems or remote signaling devices

In sensitive applications, such as in cleanrooms, server rooms or under sensitive measurement technology, a combination of local alarming and central fault reporting is often provided. This allows personnel to react immediately while system monitoring logs in the background.

Line failure and fault monitoring

Another aspect of modern leak systems is the functional safety of the signal path.
Evaluation units for conductive leak probes therefore often include line monitoring: if the cable is interrupted or a short circuit is detected, the device signals a fault even without any liquid present.
This additional check prevents false triggering and ensures that a sensor defect does not go unnoticed.

In automated environments, the status can be forwarded to higher-level systems via digital outputs. This makes leakage monitoring an integral part of plant monitoring and actively contributes to operational safety.

Integration into plant systems & building automation

Modern leakage monitoring systems can be easily integrated into existing control, safety or building automation systems. This makes the detection of liquid leaks an integral part of system monitoring – from individual devices through to a central control room.

In industrial environments, the connection is usually implemented via potential-free relay contacts, which are forwarded directly to a PLC (programmable logic controller) or a control system.

These signals can be used to:

• Shut down pumps or valves automatically,
• Display warnings on operator panels or displays,
• Or activate remote reporting systems for maintenance and service teams.

In building management systems (BMS), leak detectors are often integrated via digital inputs. This enables central monitoring of laboratories, technical rooms, heating or air conditioning systems.
For systems with higher criticality (such as data centers or chemical production areas), multi-stage alarming may also be useful: locally via optical signals and in parallel centrally via a fault message in the automation system.

The simple signal structure of our float switches (e.g. switch contact or 4–20 mA output) makes integration into almost any system easier. In this way, leak detection can be implemented not only as a standalone solution, but as part of a comprehensive safety and monitoring concept.

Operation, testing & maintenance

A leak monitoring system only reliably fulfills its protective function if it is regularly tested and maintained. The focus is not only on the functionality of the sensors, but also on the electrical and mechanical integrity of the entire signal path: from the sensor and wiring through to the evaluation unit or PLC.

Recommendations for safe operation:

• Regular visual inspection of the sensor position and connecting cables to detect corrosion, deposits or damage at an early stage.
• Functional testing at defined intervals, for example by deliberately wetting the electrode or manually lifting the float.
• Signal test at the evaluation unit to ensure that alarm and fault messages are transmitted correctly.
• Documentation of tests in the maintenance plan, especially for systems with monitoring obligations (e.g. under AwSV).

In automated systems, regular simulation of the leak alarm is also recommended to verify the response times of connected systems (shutdown, alarming, logging).

These measures ensure that leak detection remains reliably functional over the long term, even under changing environmental conditions or when media change.
The robust design of our conductive rod electrodes and float switches helps keep maintenance effort low and ensures high system availability.

FAQs – Frequently asked questions about leak detection

How does a leak sensor work?

A leak sensor detects leaking liquid by responding to electrical conductivity (in the case of water) or mechanical movement (in the case of floats). The signal is transmitted to a leak detector or a controller, which triggers an alarm.

Where are leak sensors typically installed?

In drip trays, raised floors, technical rooms, under pipelines or tanks. Anywhere liquid leakage would not be immediately visible. The position should be chosen so that leaks collect there first.

How is it connected to a controller or alarm system?

Via potential-free contacts, voltage signals or an additional conductive relay, which can be connected directly to a PLC, building management system or a separate leak detector. This enables automatic alarming or shutdown.

How often should a leak warning system be tested?

At least once a year, and more often for safety-relevant systems. The sensor or sensors (e.g. a conductive probe and a float switch: for safety-relevant systems, redundancy should always be used) are deliberately activated to test the response behavior and signal transmission.