COMET D3121P – Thermo-Hygrometer with Data Logger & External Temperature and Humidity Probe for Compressed Air up to 25 bar

COMET D3121P – Digital Thermo-Hygrometer with Data Logger & External T+RH Probe for Compressed Air up to 25 bar, −30 to +105 °C (±0.4 °C) / 0–100 %RH (±2.5 %), Dew Point 

The COMET D3121P is a professional digital thermo-hygrometer with integrated data logger and external temperature and humidity probe (sensor Ø 18 mm, length 135 mm). It is the ideal solution for long-term measurement and documentation of temperature, relative humidity, and dew point in compressed air systems up to 25 bar. Perfect for compressors, adsorption dryers, refrigeration dryers, pneumatic systems, blow molding, paint booths, food and pharmaceutical production, or anywhere humidity in compressed air is critical and must be recorded. With memory for 16,000 measured values (non-cyclic or cyclic), freely adjustable logging interval (10 s to 24 h), and a traceable calibration certificate, it is optimal for quality management, audits, and ISO 8573 compliance.

The external combined probe measures temperature from −30 to +105 °C (±0.4 °C) and humidity from 0 to 100 %RH (±2.5 %RH from 5 to 95 % at 23 °C). The dew point is calculated automatically (−50 to +80 °C, ±1.5 °C at T<25 °C and RH>30 %). The audible and visual alarm immediately warns when adjustable limits are exceeded. Min/Max memory displays extreme values, while the Hold function allows manual storage of current readings for later viewing. The backlit LCD display is easy to read; measurement rate (0.7 to 5 s) and display update time are adjustable. The robust housing (IP20) and battery power supply (9 V block or 12 V adapter with NiMH battery) make it portable and independent of mains power – battery life approx. 6 months.

The free PC software enables easy data transfer via USB cable (for download only, no measurement operation during connection). Data can be displayed graphically, exported, and analyzed. The device is maintenance-free, long-term stable, and comes with a 3‑year warranty. The included traceable calibration certificate ensures the highest measurement accuracy from the factory. Intuitive operation via push buttons and a clear menu. Whether used as a portable logger for service, a stationary monitor on compressors, or as a reference instrument in production – the D3121P impresses with precision, flexibility, and ease of operation. The external probe allows measurements directly in the compressed air flow.

Why the COMET D3121P is the best thermo-hygrometer for compressed air with data logger:

• Specially designed for compressed air up to 25 bar – external probe for direct integration
• 16,000‑value memory – cyclic or non‑cyclic recording
• Logging interval freely adjustable – 10 s to 24 h
• High accuracy – Temp. ±0.4 °C | Humidity ±2.5 %RH
• Dew point calculation – essential for compressed air quality
• Audible and visual alarm – immediate warning when thresholds are exceeded
• Min/Max memory & Hold function – extreme values and manual saving of readings
• Backlit LCD display – clearly readable even in low light conditions
• Traceable calibration certificate included – maximum measurement reliability
• Mobile battery operation – approx. 6 months runtime (9 V block or NiMH rechargeable battery)
• 3‑year warranty – COMET quality guaranteed

Technical data D3121P:

• Temperature (external): −30 to +105 °C (±0.4 °C)
• Humidity (external): 0 to 100 %RH (±2.5 %RH from 5 to 95 % at 23 °C)
• Dew point: −50 to +80 °C (±1.5 °C at T<25 °C and RH>30 %)
• Resolution: 0.1 °C / 0.1 %RH / 0.1 °C dew point
• Alarm: audible + visual (adjustable limits)
• Memory: 16,000 values (non‑cyclic or cyclic)
• Logging interval: 10 s to 24 h (adjustable)
• Measurement interval / display update: 0.7 to 5 s
• Display: backlit LCD
• Power supply: 9 V battery or 12 V DC adapter with NiMH 9 V battery
• Battery life: approx. 6 months
• Operating temperature: electronics −10 to +60 °C, external probe −30 to +105 °C
• Protection class: IP20
• Dimensions (without connector): 191 × 71 × 27 mm
• Weight (incl. battery): approx. 155 g
• Warranty: 3 years

Perfectly suited for:

• Compressed air systems and compressors
• Adsorption and refrigeration dryers
• Pneumatic and blow molding systems
• Paint booths and spray systems
• Food and pharmaceutical production
• Quality control according to ISO 8573
• Long-term monitoring and documentation
• Mobile testing and service applications

Installation and operation – ready for immediate use

Insert or connect the external probe into the compressed air line, insert the battery or connect the power supply – done! Set the limit values, start recording – later transfer data to the PC via USB. The backlit display and audible alarm ensure safe and convenient use. Calibration certificate included – ideal for audits and quality management.

Available versions:

• Cable length 1 meter
• Cable length 2 meters
• Cable length 4 meters

Summary:

• Thermometer and hygrometer for measurement and data logging of temperature and relative humidity in compressed air up to 25 bar
• Data stored internally in non‑volatile memory via cable connection
• Free PC software enables transfer, visualization, and analysis of recorded data
• Backlit LCD display
• The data logger connects to a PC via USB cable only for data transfer
• No measurement or recording during active PC connection
• Simultaneous measurement of temperature and relative humidity, dew point measurement optional
• External temperature and humidity probe
• Probe diameter: 18 mm, probe length: 135 mm

Scope of delivery:

• D3121P – depending on selected cable length
• User manual
• Traceable calibration certificate
• 9 V battery
• Mini‑USB cable
• Plastic transport case
• Self‑adhesive dual lock mounting system for easy installation
• Free full version of COMET Vision analysis software