Explosion-Proof Pressure Transmitter for Zone 1/2 Hazardous Areas
1. Why You Need It
In oil refineries, chemical plants and gas processing, a single spark can trigger a catastrophic explosion. Standard transmitters are unsafe in these atmospheres. This flameproof transmitter encloses its electronics in an Ex d IIC T6 housing that contains any internal ignition and prevents flame from propagating to the surrounding gas. Certified to ATEX, IECEx and NEPSI for Zone 1 and Zone 2, with an optional SIL 2/3 rating, it provides safe, reliable pressure measurement where the consequences of failure are severe.
2. Working Principle
The sensor converts process pressure into a 4-20 mA signal with HART digital communication. The electronics are sealed inside a flameproof (Ex d) enclosure, engineered so that if an internal spark ignites gas, the explosion is contained and the escaping gases are cooled below the ignition temperature of the surrounding atmosphere. This 'flameproof' principle prevents the internal ignition from becoming an external fire, allowing the transmitter to operate safely in flammable atmospheres.
3. Key Advantages
- Ex d IIC T6 flameproof enclosure
- ATEX / IECEx / NEPSI certified
- Zone 1 and Zone 2 rated
- 4-20 mA with HART communication
- IP65 / IP68 protection
- SIL 2/3 option for safety loops
- Range 0-1 kPa to 10 MPa
- Accuracy ±0.25% / ±0.5% FS
- -40 to 85 °C operating range
- Suitable for gas and liquid media
Common Pain Points & Solutions
| Problem | Conventional Issue | Our Solution | Result |
|---|
| Ignition risk in hazardous areas | Standard transmitters are unsafe | Ex d IIC T6 flameproof housing | Safe operation in Zone 1/2 |
| Certification required by site | Non-certified units rejected | ATEX / IECEx / NEPSI certified | Passes site safety approval |
| Wide pressure span needed | Limited-range units unusable | 0-1 kPa to 10 MPa range | One instrument, many duties |
| DCS integration and diagnostics | Analog-only limits visibility | 4-20 mA + HART | Remote configuration and status |
Application Cases
Industry: Oil & Gas
Application: Refinery separator vessel pressure
Medium: Crude oil / hydrocarbon gas
Pressure Range: 0-2.5 MPa
Operating Temperature: -20 to 80 °C
Installation Environment: Zone 1 hazardous area
Customer Challenge: Certified safe pressure measurement
Previous Problem: Uncertified transmitter risk
Solution: Ex d IIC T6 transmitter, HART
Installation Location: Separator vessel
Result: Certified safe, remote monitoring
Industry: Chemical
Application: Reactor vessel pressure control
Medium: Process chemical / solvent
Pressure Range: 0-4.0 MPa
Operating Temperature: 10-120 °C
Installation Environment: Zone 1 process area
Customer Challenge: Stable pressure for batch control
Previous Problem: Standard sensor unsuitable
Solution: Flameproof transmitter, HART output
Installation Location: Reactor top
Result: Safe, accurate process control
Industry: Gas Processing
Application: Pipeline pressure monitoring
Medium: Natural gas
Pressure Range: 0-6.0 MPa
Operating Temperature: -40 to 60 °C
Installation Environment: Outdoor Zone 2 area
Customer Challenge: Reliable measurement in extremes
Previous Problem: Weather and hazard exposure
Solution: IP68 flameproof transmitter
Installation Location: Pipeline station
Result: Reliable in extreme conditions
Industry: Storage
Application: LPG tank pressure monitoring
Medium: LPG / propane
Pressure Range: 0-1.6 MPa
Operating Temperature: -20 to 40 °C
Installation Environment: Tank farm (Zone 1)
Customer Challenge: Safety-loop pressure measurement
Previous Problem: No SIL-rated option
Solution: SIL 2 transmitter for SIS
Installation Location: LPG tank
Result: Meets functional safety requirement
Technical Specifications
| Specification | Value |
|---|
| Certification | Ex d IIC T6, ATEX/IECEx/NEPSI |
| Area Rating | Zone 1 / Zone 2 |
| Measurement Range | 0-1 kPa to 10 MPa |
| Accuracy | ±0.25% / ±0.5% FS |
| Output | 4-20 mA + HART |
| Power Supply | 24 V DC |
| Protection | IP65 / IP68 |
| Operating Temperature | -40 to 85 °C |
FAQ
Q: What does Ex d IIC T6 mean?
Ex d is the flameproof protection method, meaning the enclosure contains any internal explosion. IIC is the gas group covering the most dangerous gases including hydrogen and acetylene. T6 is the temperature class, limiting the surface temperature to 85°C. Together these markings define the transmitter's suitability for the most demanding hazardous locations, where even a small ignition source could be catastrophic.
Q: Is it certified for hazardous areas?
Yes, the transmitter carries ATEX, IECEx and NEPSI certifications for use in Zone 1 and Zone 2 hazardous areas. ATEX covers the European Union, IECEx is the international scheme, and NEPSI covers China. This means the transmitter can be installed directly in flammable atmospheres in oil refineries, chemical plants and gas processing facilities, subject to the area classification.
Q: What output and protocol does it use?
It provides a 4-20 mA analog signal with HART digital communication. The 4-20 mA loop carries the primary measurement to the control system, while HART allows remote configuration, calibration and diagnostics without opening the enclosure in the field. This is important in hazardous areas, where opening a flameproof enclosure requires a work permit and de-energization.
Q: What is the measurement range?
The measurement range spans 0-1 kPa to 10 MPa, covering low-pressure to high-pressure hazardous-area applications. The span is configured to the specific process, from low differential pressures in gas lines to high pressures in reactor and pipeline service. This wide range allows a single platform to serve many duties across a plant.
Q: What protection grade does the housing offer?
The housing is rated IP65 and IP68. IP65 protects against dust and low-pressure water jets, while IP68 protects against the effects of continuous immersion in water. These ratings ensure reliable operation in outdoor installations, washdown areas and locations exposed to weather, dust and moisture in hazardous environments.
Q: Does it support safety instrumented systems?
Yes, a SIL 2/3 option is available. SIL (Safety Integrity Level) indicates the reliability of the device in a safety instrumented function. The SIL-rated version can be used in safety loops for overpressure protection, emergency shutdown and other protective functions, where the transmitter must respond reliably to a demand and fail in a safe manner.
Q: What media can it measure?
The transmitter measures gas and liquid media compatible with the wetted materials. It is used on process gases, hydrocarbons, chemicals and steam in hazardous areas. The diaphragm material is selected for the specific media to ensure corrosion resistance and long service life. For highly aggressive media, a remote seal or alternative diaphragm material may be specified.
Q: How is it installed in a hazardous area?
The transmitter is installed by a qualified technician following the site's hazardous-area procedures. The flameproof enclosure is connected to the process via a threaded or flanged fitting, and the cable enters through a certified flameproof gland. The installation must comply with the area classification and the certification requirements, including correct earthing and sealing of the cable entry.
Q: Why is flameproof (Ex d) chosen over other methods?
Flameproof Ex d is chosen because it is robust, widely accepted and suitable for Zone 1 use with high power electronics. Unlike intrinsic safety (Ex ia), which limits energy, Ex d allows normal power levels inside a strong enclosure that contains any explosion. This makes it practical for transmitters with HART electronics and local displays in demanding hazardous areas.
Q: Where are explosion-proof pressure transmitters used?
They are used in oil refineries, gas processing plants, chemical facilities, storage terminals and any location classified as Zone 1 or Zone 2. They measure process, pipeline, reactor and storage tank pressure where flammable gases or vapors may be present, providing safe, certified measurement that meets site and regulatory safety requirements.
