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Portable Dew Point Meter (Handheld)
A battery-powered handheld meter that reads air temperature, relative humidity, dew point, and wet-bulb temperature from one external probe. Built for fast spot checks in HVAC, surface and coating preparation, storage, and the lab, with a 32,000-record data logger and USB output.
- Measures: air temperature, RH, dew point, wet bulb
- Dew point range: −60 to +60°C (−76 to +140°F)
- Accuracy: temperature ±0.1°C; humidity ±1.5 %RH
- Probe: RHT35, 316L stainless steel, IP66
- Power / logging: 9 V battery ~300 h; 32,000 records, USB
Overview
A portable dew point meter is a handheld instrument for taking a moisture reading on the spot, then moving on. This model reads four values from one external probe: air temperature, relative humidity, dew point, and wet-bulb temperature. It is the tool you carry to a job rather than wire into a line, with a backlit LCD, a 32,000-record logger, and USB download so a walk-around becomes a record.
It is sized for ambient and surface-condition work, not for high-pressure trace moisture. The dew point is derived from a capacitive humidity and temperature measurement, which is the right method for HVAC, storage rooms, greenhouses, and coating preparation. For the pressure dew point of compressed air down to an ISO 8573-1 Class 1 or 2 limit, use an in-line transmitter instead; see the selection note below.
Features
Air temperature, humidity, dew point, and wet bulb together.
Stainless steel RHT35 probe shrugs off dust, splash, and mild chemicals.
Log a survey and download it over USB for a report.
A single 9 V cell runs about 300 hours; external 9 V DC for long jobs.
Read in the dark, freeze a value, and switch °C / °F.
About 200 g and 215 mm long; auto-off after 20 minutes idle.
Working principle
The probe carries a capacitive humidity sensor and a temperature sensor. The humidity sensor holds a thin film whose capacitance changes as it takes up water vapor, which gives relative humidity; the temperature sensor gives air temperature at the same point. From those two values the meter computes the dew point, the temperature at which the air would reach saturation, and the wet-bulb temperature, the reading a wetted thermometer would show under evaporative cooling. Because the dew point is derived from humidity and temperature rather than from a chilled mirror, the instrument is fast and rugged, which is what a walk-around survey needs.
Technical specifications
| Parameter | Specification |
|---|---|
| Measured values | Air temperature, relative humidity, dew point, wet-bulb temperature |
| Probe | RHT35, external, 316L stainless steel shell, IP66 |
| Temperature | −30 to +80°C; accuracy ±0.1°C @ 25°C; resolution 0.01°C |
| Relative humidity | 0 to 100 %RH; accuracy ±1.5 %RH (0–80 %RH); resolution 0.1 %RH |
| Dew point | −60 to +60°C (−76 to +140°F) |
| Wet bulb | −20 to +60°C (−4 to +140°F) |
| Response time | < 10 s (90% at 25°C, 1 m/s air); sampling 1/s |
| Logging | 99-group key storage; 32,000-record logger; USB; data hold; min/max |
| Power | 9 V battery (6LR61 / 6F22), ~300 h; external 9 V DC option; auto-off 20 min |
| Operating / storage | Operate 0 to 40°C, <80 %RH; store −10 to 60°C, <80 %RH; both non-condensing |
| Size / weight / cert | 215 × 58 × 33 mm; ~200 g with battery; CE |
Representative specifications; confirm the exact probe range and options per datasheet for your order.
Portable vs inline: which dew point meter
The two jobs are different. A portable meter answers “what is it right now, here,” and an in-line transmitter answers “is it staying in spec, all the time.” Match the tool to the question, and to whether the moisture is ambient or a low pressure dew point in compressed gas.
| Your need | Use |
|---|---|
| Spot check ambient or surface conditions (HVAC, storage, coating prep, lab) | This portable meter |
| Continuous pressure dew point in a compressed air line, alarmed to a PLC/DCS | In-line dew point meter / transmitter |
| Very low dew point trace moisture in compressed gas (ISO 8573-1 Class 1/2) | In-line transmitter or a trace-moisture hygrometer, not an ambient handheld |
Applications
It is used wherever someone needs a humidity or dew point number quickly and on the move: HVAC commissioning and fault-finding, surface and coating preparation, dry storage and warehousing, greenhouses and agriculture, food and chemical handling, laboratories, and museum or archive conservation. The wet-bulb reading makes it useful for evaporative cooling and psychrometric checks as well.
Application example
Protective coating, surface preparation. Before a crew sprays a structural steel surface, the coating standard ISO 8502-4 calls for the steel to be at least 3°C above the dew point, or condensation forms on the blasted metal and the coating fails early. An inspector uses the handheld to read air temperature, humidity, and dew point at the work face, then compares that dew point against the measured surface temperature to confirm the 3°C margin before painting starts, and logs the readings as the environmental record for the job. The dew point and the air readings come straight from this meter; the surface temperature is taken with a separate surface thermometer.
Related products
Online Dew Point MeterIn-line 602/608 transmitter for continuous pressure dew point on 4-20 mA and RS485.
Compressed Air Flow MeterThermal mass meter for compressed air consumption and leak baselines.
More gas analysis instruments in this series are available. Ask our application engineers for the right tool for your gas and conditions.
FAQ
What is a portable dew point meter?
It is a handheld instrument that reads air temperature, relative humidity, dew point, and wet-bulb temperature from one external probe, for quick spot checks rather than continuous monitoring. This model logs up to 32,000 records and downloads over USB.
How does a handheld dew point meter work?
A capacitive humidity sensor and a temperature sensor in the probe give relative humidity and temperature; the meter then computes the dew point and wet-bulb temperature from those two values. It is faster and more rugged than a chilled-mirror instrument, which makes it suited to walk-around surveys.
Can a portable dew point meter measure compressed air?
This ambient handheld is built for room and surface conditions, not for the low pressure dew point of dried compressed air. For a pressure dew point down to an ISO 8573-1 Class 1 or 2 limit, use an in-line dew point transmitter or a trace-moisture hygrometer instead.
What is the dew point range of this meter?
The dew point reads from −60 to +60°C (−76 to +140°F), derived from the humidity and temperature measurement. Temperature accuracy is ±0.1°C and humidity accuracy is ±1.5 %RH over 0 to 80 %RH.
About this product page
Specifications drawn from the portable dew point meter (RHT35 probe) datasheet and reviewed by the Instranova engineering team — last reviewed 2026-06-30. The ISO 8502-4 surface-condensation rule is per the published standard. Questions? Reach our application engineers.
Request a quote
Tell us where you will use it and what you need to read, and we will confirm the right handheld or in-line option for the conditions, not a shelf part.