(T)FG800 pages

Galltec Mess- und Regeltechnik GmbHt

D-71145 Bondorf . Germany t
Tel. +49 (0)7457-9453-0 . Fax +49 (0)7457-3758 t
E-Mail: sensoren@galltec.de . Internet:www.galltec-mela.det

MELA Sensortechnik GmbH

D-07987 Mohlsdorf-Teichwolframsdorf . Germany
Tel. +49(0)3661-62704-0 . Fax +49(0)3661-62704-20
E-mail:mela@melasensor.de . Internet: www.galltec-mela.de

Humidity sensors - FG80...
and combined

Humidity-temperature sensors - TFG80...

with Polyga® humidity measuring element for the measurement of relative air humidity and temperature
- for rooms and air channels.
Model overview
passive sensors
t
FG80Ht
tt
t
TFG80Ht
tt
active sensors

Humidity Sensor
with resistance output up to 10k ohms
Humidity-temperature Sensor
with resistance output up to 10k ohms

t
FG80Jt
tt
t
TFG80Jt
tt
tFG80ACt
tt
t
TFG80ACt
tt

Humidity Sensor
0(4)...20mA or 0...10V DC for U=15...30V DC
Humidity-temperature Sensor
each 0(4)...20mA or 0...10V DC for U=15...30V DC
Humidity Sensor
each 0(4)...20mA or 0...10V DC for U=24V AC
Humidity-temperature Sensor
each 0(4)...20mA or 0...10V DC for U=24V AC

Description of the sensor :
The Polyga® humidity measuring element consists of several synthetic fabric bands each with 90 individual fibres with a diameter
of 3 µm each. In their untreated state, the synthetic fibres are
not hygroscopic - their hygroscopic properties are acquired by
means of a special process which allows the synthetic fibres to
absorb moisture. The molecular structure of the individual fibres
is arranged lengthways. When water is absorbed, the molecular
chains alter, the outward result being a change in length. A loss of
water has a converse effect on the fibre. If the fibre is in equilibrium
with the air humidity, there is neither absorption nor a loss of water.
The length at this point serves as a gauge for the relative humidity.
If the measuring element is exposed to an air humidity of 100%rh,
a film of water forms on the surface of the element (dew point).
The physical effect is one as if the measuring element had been
immersed in water. The measuring element is saturated. An ideal
fixed point is thus attained for adjusting or controlling the sensors.
The measuring element is waterresistant. Once administered to
the Galltec measuring element, the hygroscopic properties remain
stable, the sensitivity remaining until it becomes destroyed by
extraneous influences. Regeneration as with fine-measuring elements is not necessary, but does not cause any harm.

Design of the sensor
The expanding action (predominantly lengthways) of the fibres
is picked up by means of an electronic sensing system and converted by integrated signal preprocessing into standardised signals
0..20mA or 4..20mA or 0...10V.

FG80...
TFG80...

The fan-shaped measuring element, which faces outward from the housing, is protected by a perforated
sensor tube. The sensors are designed for pressureless systems. The unit should be installed in a location
where condensation cannot enter into the housing. A
preferred position would be ”sensor vertically down”
or ”sensor horizontal”. In these positions, a cover
plate with a 0.8 mm diameter hole will prevent water
from entering.
The TFG80 range of sensors have built-in temperature
sensors (mainly Pt100) for simultaneous measurement of temperature. Temperature readings are converted likewise into standardised signals 0..20mA or
4..20mA or 0..10V.

This information is based on current knowledge and is intended to provide details of our products and their possible applications. It does not, therefore, act as a guarantee of specific
properties of the products described or of their suitability for a particular application. It is our experience that the equipment may be used across a broad spectrum of applications under
the most varied conditions and loads. We cannot appraise every individual case. Purchasers and/or users are responsible for checking the equipment for suitability for any particular
application. Any existing industrial rights of protection must be observed. The perfect quality of our products is guaranteed under our General Conditions of Sale. Issue : September
2014 FG80_E. Subject to modifi