2 channel humidity & temperature transmitter

HygroFlex8 - HF8

effective dryer control
2 channels
data logging capability
extra analogue input

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The HygroFlex HF8 relative humidity and temperature measurement transmitter provides great flexibility, with all the features of the HF5, and more.

Two inputs, compatible with any of the HC2 series probes, are available.  This makes the HF8 suitable for many applications where monitoring two locations is required to perform good process control, for example:

    • process and ambient conditions
    • dryer input and dryer output conditions
    • comparing humidity in controlled vs uncontrolled areas
    • multiple rooms, areas or ducts

Drying processes consume large amounts of power, and improving energy efficiency by monitoring and controlling humidity (H2O) in the outlet or re-circulation air can be very cost effective.  For further information about humidity measurement and hygrometry issues, please visit our Masterclass section.

During trials or investigations into humidity and temperature, the data logging capability of the HF8 allows all data to be stored for later analysis, without the need for an additional data logger.  10,000 measured values offers sufficient capacity for lengthy logging periods between downloads.

The HF8 is suitable for connection to DCS, SCADA or building management systems, with up to 4 analogue (current or voltage) outputs.  A Breeze display can also be connected to the output for remote indication of humidity or temperature values.  Where control systems are not available, the HF8 can control a process directly with its 4 volt-free relays.  Beacon or audible alarms can also be connected to alert operators when the process is outside acceptable limits.

For extra flexibility, the HF8 can be used to monitor an external sensor that produces either a current or voltage signal; this could include a pressure or flow measurement.



Humidity and temperature

Number of probes

2 (any HC2 probe) digital or analogue probes

Analogue probe input

Supply voltage to probe: 5VDC Max.

Signal from probe: 0 to 3.3 V with configurable measuring range and units


Compatible with all HC2 probes

Measurement range

-100 to 200 °C and 0 to 100 %RH (probe dependent)

Accuracy at 23 °C

Probe dependent

Calculated parameters

All psychometric parameters

Max. cable length

5 m or 100 m with AC3003 signal amplifier

Display (optional)

LCD, 1 or 2 decimals resolution, backlight, trend and alarm indications

Start-up time

1.9 sec. (typical)

Data refresh rate

1 sec. (typical)

Firmware upgrade

Via HW4 software


CE / EMC compatibility

EMC directive 2004 / 108 / EC, EN 61000-6-1:2001, EN61000-6-2:2005, EN61000-6-3:2005, EN61000-6-4:2001+A1

Solder type

Lead free (RoHS directive)

Fire protection class

Corresponds to UL94-HB

FDA / GMP conformity



Housing material /protection



up to 540 grams depending on model


192W x 102H x 52D dependent on version

IP rating

IP65 (models with USB or ethernet interface, IP40)

Probe material

Probe dependent

Probe connection/interface

E2 (threaded coupling) / UART


HF8 operational range (with LCD)

-10 to +60 °C , 0 to 100 %rh

HF8 operational range (without LCD)

-25 to +60 °C, 0 to 100 %rh

Storage and transit (with LCD)

-20 to +70 °C, 0 to 100 %rh non-condensing

Storage and transit (without LCD)

-50 to +70 °C, 0 to 100 %rh non condensing

Temperature limit on probe

probe dependent


Power supply HF83x

15 to 40 VDC or 12 to 28 VAC, 50 to 60 Hz

Power supply HF84x

9 to 36 VDC, with galvanic isolation

Power supply HF86x

85 to 265 VAC, 5 Watts, 50 to 60 Hz

Analogue outputs

up to 4 output signals, scalable by user:

0 to 20 mA, 4 to 20 mA, 0 to 1 V, 0 to 5 V or 0 to 10 V

Parameter options

Analogue outputs user configurable to all psychrometric scale via HW4 software


Up to 4 relays, SPDT, Max. switching Voltage 250 VAC at 6 A(resistive load)

Interface and digital output

RS-485 and analogue output Ethernet (wired)

RS485 and analogue output Ethernet with PoE

All specifications subject to change