Has the PID Sensor Passed Intrinsic Safety Explosion-Proof Certification? Complete Analysis and Selection Guide

In industrial scenarios such as petrochemical, chemical, pharmaceutical, and hazardous chemical storage facilities where explosive gas atmospheres exist, VOCs (Volatile Organic Compounds) monitoring equipment must meet strict explosion-proof requirements. Users often ask: “Has the PID sensor passed intrinsic safety explosion-proof certification?”

The answer is: a PID sensor itself does not independently “pass” or “fail” intrinsic safety explosion-proof certification. Whether it can be safely used in hazardous areas depends on whether the complete detector instrument incorporating the sensor has passed explosion-proof certification by an authorized body.

Nexisense industrial-grade PID solutions are optimized for explosion-proof requirements. Some of our PID detector models have passed dual intrinsic safety and flameproof certifications and are suitable for Zone 0, Zone 1, and Zone 2 environments. Below, we provide a clear reference for system integrators and engineering project owners from technical principles and certification logic to practical selection.

Why Is Certification Applied to the Complete Instrument Rather Than a Single Sensor?

Intrinsic safety explosion protection (Ex ia / Ex ib) is a system-level safety certification. It evaluates whether the maximum ignition energy (spark energy and surface temperature) generated by the entire circuit under fault conditions is lower than the minimum ignition energy (MIE) of the explosive gas.

• Core components of PID sensors (UV lamp, ionization chamber, signal circuits) feature low power consumption, no open flame, and no high-temperature surfaces, making them inherently suitable for intrinsic safety design.

• However, the final certified object is the complete instrument, including power supply, circuit boards, display, enclosure, and interfaces.

• Standalone PID sensor modules (such as OEM bare boards) are generally not certified independently, as they cannot operate alone and must be integrated into a complete instrument tested by the manufacturer.

Therefore, there is no such statement in the market as “the PID sensor has passed intrinsic safety certification.” The correct expression is “a specific PID detector model has passed Ex ia IIC T4 Ga certification.”

Why Is PID Technology Particularly Suitable for Intrinsic Safety Explosion-Proof Design?

From the core requirements of intrinsic safety, PID technology has natural advantages:

• Extremely low power consumption: UV lamp operating voltage and current can be controlled within safe limits (usually only a few watts or less).

• No high-temperature surfaces: During normal operation, lamp and ionization chamber temperatures are far below T4 (135°C) or even T6 (85°C) limits.

• No spark risk: No mechanical contacts or large inductive/capacitive energy storage components; circuits can easily limit energy through current limiting, voltage limiting, and isolation.

• Low energy output: Ion currents are extremely weak (nA to μA level), making them easy to protect with safety barriers or intrinsic safety power supplies.

These characteristics make PID instruments easier to obtain ia-level (highest intrinsic safety level) certification compared with catalytic combustion (requires heating elements) or infrared methods (often requiring higher-power light sources), allowing use in Zone 0 environments where explosive gases are continuously present.

How to Determine Whether a PID Detector Has Intrinsic Safety Explosion-Proof Certification?

The following key information must be verified during selection (all are essential):

1. Integrity of Explosion-Proof Marking

Typical intrinsic safety PID explosion-proof marking example:

Ex ia IIC T4 Ga or Ex ia ⅡC T4 Ga

• Ex: Explosion-proof marking

• ia: Intrinsic safety level ia (highest level, allows live maintenance)

• IIC / ⅡC: Gas group, covering the most dangerous gases such as hydrogen and acetylene

• T4: Temperature class, maximum surface temperature ≤135°C

• Ga: Equipment Protection Level (EPL), suitable for Zone 0

  

2. Certification Body and Certificate Number

Common authoritative certification bodies include:

• China: NEPSI (National Supervision and Inspection Center for Explosion Protection and Safety of Instrumentation), CQST

• International: ATEX (EU), IECEx (IEC system), UL/cUL (North America)

Certificate numbers are usually printed on the nameplate and can be verified on the official websites of the certification bodies.

3. Applicable Zones and Gas Groups

• Zone 0: Requires Ex ia Ga

• Zone 1: Ex ia / ib Gb

• Zone 2: Ex nC / ec Gc (non-intrinsic safety may also be acceptable)

4. Other Supporting Requirements

• Must be powered by an intrinsic safety power supply or safety barrier

• Cables and junction boxes must comply with explosion-proof standards

Features of Nexisense Explosion-Proof PID Detectors

Nexisense has launched multiple PID monitoring devices certified for intrinsic safety explosion protection for high-risk scenarios such as hazardous chemicals, petrochemicals, and pharmaceuticals. Key features include:

• Explosion-proof rating: Ex ia IIC T4 Ga (some models support higher requirements)

• Detection principle: 10.6 eV / 11.7 eV UV lamps, supporting ppb-level TVOC detection

• Output interfaces: 4–20 mA + RS485 Modbus RTU (intrinsic safety outputs)

• Built-in humidity compensation and response factor correction algorithms

• Ingress protection: IP65/IP67, suitable for outdoor and humid environments

• Supports both fixed online installation and portable inspection

These models have passed NEPSI certification and are supplied with complete explosion-proof certificates and user manuals, enabling system integrators to directly apply them in explosion-proof projects.

Selection and Usage Considerations

• Prioritize complete instruments clearly marked with “Ex ia IIC T4 Ga” or higher.

• Confirm certificate validity period (explosion-proof certificates are usually valid for 5 years).

• Strictly follow explosion-proof wiring requirements and use intrinsic safety junction boxes and safety barriers.

• Maintenance should be performed in safe areas or after power-off; lamp replacement must be carried out by qualified personnel.

• For Zone 0 projects, ia-level certified products are mandatory.

Frequently Asked Questions (FAQ)

1. Can a bare PID sensor module be used in hazardous areas? No. Without complete instrument certification, safety cannot be guaranteed.

2. Which is more suitable for PID, intrinsic safety or flameproof certification? Intrinsic safety (Ex ia/ib) is more suitable due to low power and low temperature; flameproof (Ex d) is also feasible but larger and more costly.

3. How to verify explosion-proof certificates? Enter the certificate number on NEPSI, IECEx, or ATEX official websites.

4. Can explosion-proof PID instruments be used in hydrogen environments? Yes, but IIC group certification (e.g., Ex ia IIC) is required.

5. Does an explosion-proof PID require a special power supply? Yes, an intrinsic safety power supply or certified safety barrier is required.

6. Can lamp replacement be performed in hazardous areas? No. Replacement must be done in a safe area or by certified personnel following procedures.

7. Does explosion-proof design affect PID response time? Basically no; response time remains fast at 2–5 seconds.

8. What is the warranty period for Nexisense explosion-proof PID? Standard 2 years, with corresponding support for explosion-proof components.

9. What explosion-proof rating is required for Zone 0? Ex ia Ga or higher; Nexisense offers suitable models.

10. How can I obtain Nexisense explosion-proof PID certification documents? Contact the technical team for certificate copies, test reports, and selection guides.

Conclusion

PID sensing technology itself is highly compatible with intrinsic safety explosion-proof requirements. There are already many PID detectors on the market certified to high levels such as Ex ia IIC T4 Ga, which can be safely used in hazardous environments such as Zone 0 and Zone 1. The key lies in complete instrument certification rather than the sensor alone.

During selection, it is essential to verify explosion-proof markings, certificate numbers, and applicable zones to avoid assumptions. Nexisense provides rigorously certified explosion-proof PID solutions, helping chemical, petrochemical, and pharmaceutical industries achieve safe and reliable VOCs monitoring. For certificate verification, model recommendations, or project support, feel free to contact our technical team. We are committed to delivering trusted sensing solutions for high-risk environments.