The Vaisala HM40 is a compact handheld humidity and temperature instrument with dual model options, multi‑language display, and interchangeable sensor probes.
The HM40 is a portable handheld instrument designed for field measurements of relative humidity and temperature. It offers a large graphical LCD, ten language options, and interchangeable HMP113 probes that can be calibrated on site or at a Vaisala service center.
The device operates on two AA batteries (optional USB‑rechargeable NiMH pack), provides IP54 protection, and includes accessories such as a wrist strap, handle, and various probe options. Detailed performance specifications cover humidity and temperature ranges, accuracies, response times, and mechanical characteristics. This manual is written in Chinese.
| Humidity measurement range | 0 %RH … 100 %RH |
|---|---|
| Humidity accuracy (0‑40 °C) | ±1.5 %RH (0‑90 %RH) |
| Humidity accuracy (90‑100 %RH) | ±2.5 %RH (90‑100 %RH) |
| Temperature measurement range | -10 °C … +60 °C |
| Temperature accuracy (0‑40 °C) | ±0.2 °C |
| Temperature accuracy (-10‑0 °C, 40‑60 °C) | ±0.4 °C |
| Power supply | 2 × AA batteries (1.5 V) or optional USB‑rechargeable NiMH pack |
| Display resolution | 140 × 160 pixels LCD |
| Weight (with batteries) | 230 g |
| Ingress protection rating | IP54 |
| Battery life (no backlight) | 100 hours |
The HM40 is powered by two AA batteries and can also use an optional USB‑connected rechargeable NiMH battery pack.
Calibration can be performed by returning the instrument to a Vaisala service centre, by inserting a calibrated interchangeable HMP113 probe, or by using a Vaisala humidity calibrator such as the HMK15 on site.
The HM40 supports ten languages, including English, German, French, Japanese, Chinese, Portuguese, Spanish, Russian, Finnish and Swedish.
The instrument has an IP54 protection rating.