How Do Humidity and Temperature Transmitters Work?
In short, Humidity and temperature transmitters measure and send environmental data to control systems. They are widely used in HVAC, pharmaceuticals, food processing, and cleanrooms
Item Number: HG808-G series
The HG808-G is an industrial-grade dew point and temperature transmitter specifically engineered for corrosive or chemically aggressive environments. Built with a 316L stainless steel sintered probe and a sealed aluminum housing, it ensures stable and accurate measurement even in the presence of acidic gases, solvents, salt spray, or oil mist.
In addition to measuring and transmitting dew point and temperature, the HG808-G can calculate and output relative humidity and PPM values, providing a comprehensive view of ambient moisture conditions for process control and quality assurance.
Here’s a breakdown of the key features:
Corrosion-Resistant Design: 316L stainless steel probe with nano-coated anti-corrosion finish, suitable for acidic, alkaline, and solvent vapors.
High Accuracy: ±3 °C Td dew point accuracy across a range of –80 °C to +60 °
Wide Power & Pressure Range: Operates on DC 12 – 24 V, withstands up to 10 bar pressure.
Flexible Output Options:
RS485 (Modbus-RTU) digital output
4-20 mA analog output
Optional 0-5 V / 0-10 V analog outputs
Industrial Protection: IP65-rated enclosure, anti-condensation heating, and strong EMI resistance for reliable long-term use.
Integration-Ready: Easily connects to PLCs, DCS, or SCADA systems for automated dew point monitoring and process control.
▪Engineered for Harsh Chemical Environments
Built with 316L stainless steel and anti-corrosion coating to withstand acids, alkalis, solvents, and salt mist. Ideal for chemical, pharmaceutical, and lithium-battery industries.
▪High Accuracy Dew Point Monitoring
Provides ±3 °C Td accuracy over a wide range (–80 °C to +60 °C), ensuring precise control in ultra-dry or low-humidity processes.
▪Comprehensive Measurement Capability
Simultaneously measures and outputs dew point, temperature, humidity, and PPM values, giving a full picture of environmental moisture conditions.
▪Flexible Output Options
Supports RS485 (Modbus-RTU) digital communication, plus 4–20 mA, 0–5 V, and 0–10 V analog signals for easy integration with PLC, DCS, and SCADA systems.
▪Industrial-Grade Reliability
IP65 aluminum housing with anti-condensation function, resistant to oil, dust, and high humidity for stable long-term operation under 10 bar pressure.
▪Compact and Service-Friendly Design
Modular structure with replaceable sintered probe, simplifying installation and reducing maintenance time and cost.
▪Wide Power Supply Range
Operates on 12–24 V DC with reverse-polarity and surge protection for reliable use in demanding industrial environments.
Here’s a specification details for the HG808-G series Humidity Transmitter :
| Category | Specification |
|---|---|
| Measurement Parameters | Dew Point, Temperature, Humidity, PPM (for reference) |
| Dew Point Range | –60 °C ~ +20 °C |
| Dew Point Accuracy | ±3 °C Td (±5.4 °F) |
| Temperature Range | –20 °C ~ +60 °C |
| Temperature Accuracy | ±0.2 °C (@ 23 °C) |
| Temperature Long-Term Stability | ≤ 0.1 °C / year |
| Humidity Long-Term Stability | ≤ 1 % RH / year |
| Digital Output | RS485 (Modbus-RTU); outputs temperature, humidity, dew point, PPM (humidity & PPM for reference only) |
| Analog Outputs | Temperature + Dew Point – select one: 4-20 mA / 0-5 V / 0-10 V |
| Pressure Resistance | ≤ 16 bar |
| Baud Rate | 1200, 2400, 4800, 9600, 19200, 115200 bps (selectable; default 9600 bps) |
| Acquisition Frequency | Fastest response 1 second; adjustable via PLC |
| Working Environment | –20 °C ~ +60 °C; 0 % ~ 95 % RH (non-condensing) |
| Power Supply | DC 12 V ~ 24 V, reverse-polarity protected |
| Power Consumption | < 0.5 W |
| Output Protocol | Standard Modbus-RTU; compatible with PLC, DCS, and SCADA systems |
| Construction | Compact aluminum housing with industrial grade ESD & anti-reverse protection |
| Installation & Customization | Custom probe design available according to application needs (structure, shape, length, material, mounting method) |
| Protection Rating | IP65 – dustproof and moisture-resistant |
| Applicable Probe Options | Two probe types available: • Gas Sampling Unit • 316L Stainless Steel Sintered Protective Housing (A-Type, 0A# / 8A#) |
We offer 6 types of probes for the HG808 Humidity Transmitter, with each type available in both A and B versions, providing a total of 12 probes for various application options.
0A#
8A#
M20 Hexagonal thread stainless steel probe connector
G1/2 Hexagonal thread stainless steel probe connector
NTP1/2 Hexagonal thread stainless steel probe connector
M27 Hexagonal thread stainless steel probe connector
M20 Flange stainless steel probe connector
| Line Color | Definition | Specification |
|---|---|---|
| Power Cord | ||
| Red | Power supply positive | 10 ~ 30V DC |
| Black | Power supply negative | GND |
| Analog Output Lines | ||
| Brown | Temperature signal positive | 4-20mA output |
| Blue | Temperature signal negative | Connects to Black (GND) |
| Grey | Humidity signal positive | 4-20mA output |
| White | Humidity signal negative | Connects to Black (GND) |
| RS485 Wiring | ||
| Yellow | RS485A | Twisted pair cable |
| Green | RS485B | Twisted pair cable |
Additional Notes:
Important:
Precise dew point and humidity monitoring is critical to prevent moisture contamination of electrolyte solutions and ensure uniform electrode coating quality.
Typical conditions: Dew point ≤ –40 °C, temperature 20 – 30 °C, humidity < 1 % RH.
Control requirement: Continuous online dew point monitoring in glove boxes and drying chambers for ultra-low humidity environments.
During chemical synthesis or solvent recovery, excessive moisture can affect reaction yield, purity, and safety. The HG808-G provides stable measurements even in acidic, solvent, or oil-vapor atmospheres.
Typical conditions: Dew point –40 ~ 0 °C, temperature 25 – 60 °C, humidity 5 – 40 % RH.
Control requirement: Corrosion-resistant dew point monitoring under HF, HCl, NH₃, or VOC exposure to prevent condensation and corrosion.
Humidity and temperature stability are essential to maintain API potency and drying uniformity. The HG808-G ensures accurate dew point and temperature control in cleanrooms and drying ovens.
Typical conditions: Dew point –30 ~ +10 °C, temperature 40 – 80 °C, humidity 2 – 20 % RH.
Control requirement: Real-time humidity feedback to optimize drying cycles and ensure GMP-compliant environmental monitoring.
FGD processes involve high-temperature, corrosive gases with varying moisture content. The HG808-G’s 316L stainless-steel probe withstands SO₂/SO₃ and acid mist for long-term reliability.
Typical conditions: Temperature 60 – 120 °C, humidity 10 – 80 % RH, dew point 0 ~ 50 °C.
Control requirement: Dew point monitoring for condensation control and corrosion prevention in gas treatment systems.
Stable dew point monitoring is required to prevent pipeline condensation, corrosion, and particulate accumulation in emission control systems.
Typical conditions: Temperature 30 – 90 °C, dew point –20 ~ 40 °C, humidity 5 – 70 % RH.
Control requirement: Continuous dew point trend tracking to maintain safe moisture levels before gas filtration or catalytic processing.
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The HG808-G is engineered with an integrated corrosion-resistant structure, using 316L stainless steel and a sealed cast-aluminum housing (IP65). It resists acids, alkalis, electrolyte vapors, and chemical solvents, making it ideal for lithium battery, chemical, and pharmaceutical applications where standard sensors fail.
This transmitter has undergone strict testing for oil-gas mixtures, chemical corrosion, and dust impact. Its IP65-rated aluminum enclosure and pressure-resistant 316L probe can withstand up to 16 bar, ensuring long-term stability and reliability even in challenging process environments.
The HG808-G offers flexible signal outputs for easy system integration:
Digital: RS485 (Modbus-RTU) for dew point, temperature, humidity, and PPM values.
Analog: Dual-channel outputs of 4-20 mA, 0-5 V, or 0-10 V (user selectable).
This design allows seamless connectivity with PLC, DCS, or SCADA systems for automated dew point and temperature control.
Yes. The transmitter includes data-recording functionality and supports connection to backend analysis software. Users can generate reports and trend charts with one click, enabling efficient monitoring, traceability, and process optimization.
The HG808-G can output dew point temperature, process temperature, relative humidity, and PPM values at the same time—providing a complete picture of gas dryness and system conditions.
By integrating advanced sensor technology and optimized circuitry, the HG808-G matches the performance of imported brands at a significantly lower cost. It delivers high precision, strong corrosion resistance, and excellent long-term stability, helping customers reduce maintenance and procurement costs.
Yes. HENGKO offers customized probe designs (structure, length, material, and mounting method) to meet specific process requirements—ensuring accurate and stable dew point measurement under any industrial condition.
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In short, Humidity and temperature transmitters measure and send environmental data to control systems. They are widely used in HVAC, pharmaceuticals, food processing, and cleanrooms
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