Key facts
- Brand
- Vaisala
- Model
- HMP240
- Industry
- Industrial
- Documents
- 2
- Languages
- EN
- Last added
- 2012-04-12
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Vaisala HMP240 User Manual
The HMP240 is a microprocessor‑based transmitter for measuring dewpoint temperature, especially in high humidity or rapidly changing conditions. It can be equipped with one or two sensor heads and offers analogue outputs, serial interfaces and optional display/keypad covers. The manual describes the product features, options such as additional temperature probes, filters, and cable lengths.
The guide covers installation, wiring, commissioning, command sets, calibration procedures for humidity and temperature, maintenance, technical data, and several appendices including serial command reference, wiring diagrams and re‑gaining procedures.
Vaisala HMP240 specifications
| Dewpoint temperature measurement range | -40 to +100 °C |
|---|---|
| Optional temperature sensor range | -40 to +180 °C |
| Response time (90% at +20 °C) | 15 s |
| Analog output options | 0.20 mA, 4.20 mA, 0.1 V, 0‑5 V, 0.10 V |
| Serial output | RS‑232C |
| Relative humidity range | 0 %‑100 %RH |
| Power supply | 24 VDC/VAC (20‑28 V), 200 mA max. |
| Probe cable lengths | 2 m, 5 m, 10 m |
Source: Vaisala HMP240 Series Dewpoint Transmitter User Manual
All Vaisala HMP240 documents by type
Day-to-day operation, settings and troubleshooting. Start here if the product is already set up.
Questions answered in these manuals
What is the response time of the HMP240 series dewpoint measurement?
The 90 % response time at +20 °C in still air is 15 seconds.
From: Vaisala HMP240 Series Dewpoint Transmitter User Manual
What optional sensor is available for the HMP240 series?
An additional temperature sensor head can be added to measure ambient temperature, enabling calculation of relative humidity, absolute humidity, wet‑bulb temperature and dewpoint difference.
From: Vaisala HMP240 Series Dewpoint Transmitter User Manual
What is the dewpoint measurement range of the HMP240?
The HMP240 can measure dewpoint from –40 °C up to +100 °C.
How can the analogue temperature output be scaled?
It can be scaled from –20 °C to 460 °C to produce a 0 V‑10 V signal.