Atmospheric pressure dew point meter and detector - SKA/WSD-LDY

Atmospheric pressure dew point meter detector

Dew Point Transmitter

First: The SKA/WSD-LDY type dew point transmitter uses a polymer high-molecular sensitive capacitor, with fast response, stable and reliable performance, measuring range of -80°C to 20°C Td, and accuracy of ±2°C Td across the full range. This product has automatic zero calibration function and automatically heats to clean chemical substances attached to the sensor surface, ensuring extremely stable long-term use. This polymer dew point capacitor is the result of over twenty years of arduous research. Typically, polymer capacitors struggle to measure dew points below -40°C Td due to the extremely low rate of change, making the signal difficult to distinguish in the circuit. We conducted extensive fundamental research and finally mastered the technology to improve low-humidity sensitivity. Currently, when changing from -70°C Td to -50°C Td, the base capacitance changes from 300pF to 305pF, surpassing all polymer dew point capacitors on the market.

Atmospheric pressure dew point meter detector

2: Output signal:

Analog: 4-20mA two-wire system (most common in industry, loop powered)

Digital: RS485 Modbus-RTU, can simultaneously output dew point and temperature, some models can output PPMV moisture concentration.

Common thread interfaces: G1/2, NPT1/4, directly screwed onto the pipeline; the probe comes with a sintered filter to protect the sensor and block dust particles.

3. Typical application scenarios

Compressed air systems: online monitoring at the outlet of refrigerated dryers and adsorption dryers to determine if the dryer has failed, meeting ISO8573 compressed air quality standards.

Industrial gases: nitrogen, argon, hydrogen, SF6 insulating gas, high-purity gases, glove boxes.

Plastics industry: Monitoring hopper drying gas to prevent product bubbles and silver streak defects.

Pharmaceutical, lithium battery, semiconductor: Clean gases, freeze-drying equipment, inert protective gases.

Power: GIS, transformer insulation SF6 gas trace moisture monitoring.

Atmospheric pressure dew point meter detector

4. Key selection parameters

Dew point range

Refrigerated dryers: generally 0 to -20°C Td

Adsorption dryers: -40 to -70°C Td

Ultra-dry high-purity gases: -80 to -100°C Td

Try to keep the actual operating dew point in the middle of the range; do not use at the range limits for extended periods.

Accuracy: general industrial ±2°C Td; high precision within ±1°C Td. Low dew point (below -60°C) accuracy will degrade.

Pressure resistance: confirm the pipeline working pressure; compressed air is generally 0.7-1.0MPa, choose high-pressure type for high-pressure conditions.

Medium operating conditions: Check whether the gas contains oil mist, dust, or solvent vapor; for heavy oil vapor conditions, install a pre-filter for sampling.

Output method: two-wire 4-20mA or RS485; power supply DC12-24V.

Calibration cycle: generally requires laboratory calibration every 1-2 years, as the sensor will drift slowly.

Atmospheric pressure dew point meter detector

5. Installation and usage points

Install downstream of the dryer and upstream of the point of use, avoiding elbows, dead corners, and water accumulation areas; install the probe vertically or facing downward.

The dew point transmitter measures pressure dew point; when atmospheric dew point is needed, pressure conversion is required.

Liquid water must not directly hit the sensor, as it can cause damage; if there is condensation risk, choose an anti-condensation sensor.

Gas flow rate should not be too high; for high-pressure and high-flow conditions, a sampling pressure-reducing circuit is recommended.

Oil vapor can contaminate aluminum oxide sensors; oil removal filters must be installed.