CM42 pH/ORP Explosion-Proof Transmitter Overview
The CM42 series is an explosion-proof pH/ORP transmitter designed specifically for hazardous areas, widely used in chemical, petrochemical, pharmaceutical, and other process industries. Its core function is to convert pH or ORP electrode signals into standard industrial signals, and it features intrinsic safety or flameproof characteristics. Part 1 of this manual focuses on basic product information and safety specifications.
Download CM42 pH/ORP Chinese Manual.pdf
Explosion-Proof Certification and Safety Levels
The CM42 transmitter has passed multiple international explosion-proof certifications, ensuring safe operation in flammable and explosive environments. When selecting a model, the corresponding model must be chosen based on the on-site hazardous area classification.
Common Explosion-Proof Certification Types
- Ex ia IIC T6 Ga: Intrinsic safety type, suitable for Zone 0, Zone 1, and Zone 2.
- Ex d IIC T6 Gb: Flameproof type, suitable for Zone 1 and Zone 2.
- Ex tb IIIC T80°C Db: Enclosure protection type, suitable for combustible dust environments.
Safety Level Comparison
| Explosion-Proof Type | Applicable Zone | Temperature Class | Typical Application |
|---|---|---|---|
| Intrinsic Safety Ex ia | Zone 0, Zone 1, Zone 2 | T6 | High-risk chemical reactors |
| Flameproof Ex d | Zone 1, Zone 2 | T6 | Oil and gas transmission pipelines |
| Dust Explosion-Proof Ex tb | Zone 20, Zone 21, Zone 22 | T80°C | Pharmaceutical dust workshops |
Installation and Wiring Key Points
Correct installation is a prerequisite for ensuring explosion-proof performance and measurement accuracy. Please strictly follow the steps below and comply with local electrical codes.
Installation Steps
- Confirm that the on-site hazardous area classification matches the transmitter's explosion-proof marking.
- Fix the transmitter on a stable bracket, avoiding vibration and direct sunlight.
- Use shielded cables to connect the electrode and transmitter, with the shield grounded at one end.
- For intrinsic safety type, a safety barrier must be connected and the loop parameters must be confirmed to meet certification requirements.
- Tighten all cable entry sealing connectors to ensure the protection level reaches IP66/IP67.
Wiring Precautions
- It is strictly prohibited to open the cover while energized in hazardous areas.
- Intrinsically safe circuits must use blue-marked cables and be routed separately from non-intrinsically safe circuits.
- Flameproof transmitters must use flameproof sealing connectors, and the grounding resistance must be less than 4Ω.
Main Technical Parameters
The CM42 transmitter supports multiple measurement modes including pH, ORP, and temperature. Below is a quick reference table of key parameters.
| Parameter | Specification |
|---|---|
| Measurement Range | pH: 0~14; ORP: -1500~+1500 mV |
| Output Signal | 4~20 mA, HART/Profibus optional |
| Power Supply | 24 V DC (intrinsically safe circuits require a safety barrier) |
| Protection Level | IP66/IP67 |
| Ambient Temperature | -20~+60°C (explosion-proof type) |
Selection and Ordering Guide
Select the appropriate model based on the measurement medium, hazardous area, and communication requirements. It is recommended to confirm electrode compatibility and explosion-proof certificate numbers before procurement.
- Medium Compatibility: For strong acid and alkali environments, corrosion-resistant electrodes must be selected.
- Communication Protocol: Choose HART or Profibus PA when remote configuration is required.
- Explosion-Proof Certificate: Request the certificate from the China National Quality Supervision and Testing Center for Explosion Protected Electrical Products (CQST).
For more detailed installation dimensions and troubleshooting content, please refer to subsequent parts of the manual.