Liquid level measurement in hazardous environments presents unique engineering challenges. In industries where flammable gases, vapours, hydrocarbons, or combustible dusts may be present, level sensors must do more than simply detect liquid presence. They must operate safely and reliably in accordance with strict regulations for hazardous areas. At the same time, they must support efficient process control and preventative maintenance strategies. This is why ATEX and IECEx-certified liquid level switches are essential in many modern industrial systems.
Hazardous areas exist in oil and gas facilities, chemical plants, pharmaceutical manufacturing, wastewater treatment systems, and heavy industry. In these environments, a small electrical spark or even a high surface temperature can ignite explosive atmospheres. To reduce risk, all electrical instruments in hazardous zones must be purpose-built and certified for safe use.
Why Liquid Level Monitoring Matters in Hazardous AreasÂ
Liquid level switches can be critical for engineers designing hazardous area systems. They monitor liquid levels in tanks, reservoirs, vessels, and pipelines, helping operators maintain safe conditions.
Applications with fuels, solvents, hydrocarbons, or volatile chemicals, require accurate level monitoring. This prevents overfilling, leaks, dry-running of pumps, and contamination. Reliable liquid-level sensing ensures process consistency and cuts costly downtime from sudden equipment failures.
The role of hazardous area liquid level switches typically includes:Â
- Preventing tank overfill and leakage incidents
- Supporting automated process control
- Providing early warning of abnormal operating conditions
- Protecting pumps and equipment from dry-run damage
- Assisting facilities with ATEX and IECEx compliance requirements
Understanding Hazardous Area ClassificationsÂ
When specifying instrumentation for hazardous locations, engineers must understand hazardous area classifications, equipment categories, protection methods, gas/dust groups and temperature classes. ATEX and IECEx regulations divide hazardous gas environments into zones based on the likelihood of explosive atmospheres.
Zone 0 are areas where explosive gases will be present continuously. Zone 1 is where explosive gases are likely and Zone 2 where hazardous atmospheres occur less frequently.
Sensors in all of these areas must be certified so they cannot become ignition sources during operation or following the occurrence of foreseeable faults.
Intrinsically Safe vs Flame-Proof ProtectionÂ
One widely used protection method for instrumentation is intrinsic safety. Intrinsically safe liquid level switches limit electrical and thermal energy to levels below those that can ignite hazardous atmospheres – effectively preventing ignition from occurring in the first place. In contrast ignition may well occur in flame-proof equipment but is prevented from propagating outside it.
Intrinsic safety offers several advantages for liquid level monitoring. Liquid level switches are low power and are therefore well suited to intrinsically safe designs. Their more compact designs and connectivity, ease installation and simplify maintenance within the hazard zone. This is in contrast with the heavy and bulky enclosures and conduits required with flame-proof equipment.
These solutions can also lower installation costs by removing the need for heavy conduits and flameproof enclosures.
SST Intrinsically Safe Optical Liquid Level SwitchesÂ
SST’s intrinsically safe optical liquid level switches operate in hazardous areas with flammable liquids, fuels, hydrocarbons, or explosive gases. Certified to ATEX/UKCA and IECEx standards, they deliver reliable, compliant level detection for tough industrial environments.
These optical sensors use infrared technology and total internal reflection to detect the presence or absence of liquid. They contain no moving parts, unlike traditional mechanical float switches. This reduces wear, eliminates sparking, and improves long-term reliability.
Key features of SST hazardous area liquid level switches include:Â
- ATEX, UKCA, and IECEx certification
- Intrinsically safe design for hazardous environments
- Fast response times with repeatability of ±1 mm
- Stainless steel housing for durability and chemical resistance
- Operating temperatures from -30°C to +80°C
- No calibration requirements
These sensors are used in petrochemical systems and leak detection equipment. Other applications include hydraulic reservoirs, hydrogen generators, and analyser protection systems. Reliable level monitoring is essential for both safety and operational continuity in these uses.
ConclusionÂ
As industrial safety standards evolve, engineers prioritise sensor technologies that balance compliance, reliability, and ease of integration. Selecting the right ATEX-approved liquid level switch is no longer just about regulation. It helps improve process safety, minimise downtime, and support long-term performance in hazardous environments.
Engineers in oil and gas, chemicals, pharmaceuticals, or water treatment can depend on certified level switches from SST for safe, accurate monitoring in hazardous areas.
For more information on our liquid level sensors or to discuss your application, please contact our highly trained engineers who will be happy to help.
Frequently Asked QuestionsÂ
What is an ATEX-approved sensor?Â
An ATEX-approved sensor is certified for safe operation in certain potentially explosive atmospheres, equipment types and temperatures, under the European ATEX Directive. These sensors are designed to minimise ignition risks in hazardous environments.
Are ATEX sensors suitable for hazardous environments?Â
Yes. ATEX-certified sensors are specifically designed for hazardous environments where flammable gases, vapours, or combustible dusts may be present.
What is the difference between intrinsically safe and flame-proof equipment?Â
Intrinsically safe equipment works by limiting energy to prevent ignition, while flame-proof equipment is designed to prevent ignition propagating out-with a protective enclosure.
Where are hazardous-area liquid-level switches commonly used?Â
They are widely used in oil and gas facilities, chemical plants, pharmaceutical manufacturing, wastewater treatment systems, fuel storage applications, and heavy industrial equipment.
How can engineers determine whether a sensor is ATEX-approved?Â
Engineers should check for recognised certifications and product marking such as ATEX or IECEx, along with the indication of relevant hazard zone, equipment category, protection method, gas/dust group, and temperature classification for the intended application.
