The 7ETO-100 operates on the electrochemical detection principle, leveraging a three-electrode cell immersed in an electrolyte solution:

1. Gas Diffusion: Ethylene oxide gas in the environment diffuses through a porous membrane (gas-permeable membrane) into the sensor’s internal electrolyte.
2. Electrochemical Reaction: At the working electrode (cathode), ETO undergoes oxidation, producing electrons, protons (H⁺), and harmless byproducts (e.g., CO₂, H₂O).
3. Current Generation: The electrons generated by the oxidation reaction flow through an external circuit to the counter electrode (anode), creating a measurable electrical current. The magnitude of this current is linearly proportional to the concentration of ETO in the sample gas (per Faraday’s Law of Electrolysis).
4. Stability Maintenance: The reference electrode provides a stable voltage reference, preventing drift in the working electrode’s potential and ensuring long-term measurement accuracy.

4. Typical Applications

The 7ETO-100 is engineered for scenarios requiring ETO monitoring, with core use cases including:

4.1 Medical Sterilization Industry

Ethylene oxide is widely used to sterilize heat-sensitive medical devices (e.g., surgical instruments, syringes, implants). The 7ETO-100 is integrated into:

• Sterilization Chamber Monitors: Real-time tracking of ETO concentration during the sterilization cycle to ensure effective microbial inactivation.
• Post-Sterilization Ventilation Systems: Detection of residual ETO in sterilized equipment or exhaust air, ensuring levels meet safety standards (e.g., ≤ 1 ppm for personnel exposure) before devices are used or air is released.

4.2 Chemical & Pharmaceutical Manufacturing

In facilities producing ETO or using ETO as a raw material (e.g., for ethylene glycol synthesis, detergent production):

• Fixed-Point Leak Detectors: Installation near pipelines, valves, or reaction vessels to trigger alarms if ETO leaks occur (preventing toxic exposure or fire risks).
• Process Control Systems: Monitoring ETO concentration in reaction streams to optimize production efficiency and ensure product quality.

4.3 Environmental & Occupational Safety

• Portable Gas Detectors: Used by maintenance workers, laboratory staff, or emergency responders to monitor personal exposure to ETO in confined spaces (e.g., sterilization rooms, chemical storage areas) or during leak investigations.
• Indoor Air Quality (IAQ) Monitors: In facilities where ETO may accumulate (e.g., hospitals, pharmaceutical plants), the sensor ensures indoor ETO levels comply with occupational health regulations (e.g., OSHA’s permissible exposure limit (PEL) for ETO: 1 ppm over an 8-hour workday).

4.4 Food Processing (Optional)

In some food sterilization applications (e.g., low-temperature sterilization of packaged foods), the 7ETO-100 monitors residual ETO to ensure food safety and compliance with global food standards.

5. Installation & Operation Guidelines

5.1 Installation Notes

• Location: Mount the sensor in areas where ETO is likely to accumulate (e.g., near sterilization chambers, ETO storage tanks) or where personnel frequent. Avoid direct sunlight, extreme temperatures, or high-humidity (condensing) environments.
• Gas Inlet: For diffusion-type sensors, ensure unobstructed air flow around the sensor (minimum 5 cm clearance from walls/obstacles). For pump-type sensors, connect the gas inlet tube to the sampling point (tube length ≤ 2 meters to avoid response delay).
• Wiring: Follow the sensor’s pinout diagram (provided in the datasheet) for power and signal connections. Use shielded cables for analog signals to reduce electromagnetic interference (EMI).

5.2 Calibration

• Initial Calibration: Perform a two-point calibration (zero calibration with clean air, span calibration with a known ETO concentration gas) before first use.
• Routine Calibration: Recalibrate every 3–6 months (or as required by local regulations) to maintain accuracy. Calibration gas should be certified (NIST-traceable or equivalent) with a concentration close to the sensor’s full scale (e.g., 80 ppm for a 0–100 ppm sensor).

5.3 Maintenance

• Cleaning: Periodically wipe the sensor’s exterior with a dry, lint-free cloth. Do not use solvents or water on the gas inlet membrane.
• Replacement: Replace the sensor if: (1) response time exceeds 60 seconds, (2) accuracy deviates by >10% of FS after calibration, or (3) the sensor reaches its rated lifespan.

6. Safety Precautions

• Toxic Gas Risk: Ethylene oxide is toxic and carcinogenic—always wear appropriate PPE (e.g., gas mask, gloves) when handling ETO or performing sensor maintenance in potentially contaminated areas.
• Flammability: ETO is flammable (explosion limit: 3%–100% by volume in air)—avoid installing the sensor near open flames, sparks, or high-temperature surfaces.
• Sensor Handling: Do not disassemble the sensor (risk of electrolyte leakage, which may cause skin irritation). Dispose of old sensors in accordance with local hazardous waste regulations.