Vaisala INTERCAP HMDW80 SERIES Especificaciones descargar pdf (Pagina 113)

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For more information, visit

www.vaisala.com or contact

us at sales@vaisala.com

Ref. B211231EN-A ©Vaisala 2012

This material is subject to copyright protection, with all copyrights

Any logos and/or product names are trademarks of Vaisala or

its individual partners. The reproduction, transfer, distribution or

storage of information contained in this brochure in any form

without the prior written consent of Vaisala is strictly prohibited.

All specifications — technical included — are subject to change

without notice.

Water activity measurement indicates

directly whether there is a risk of free

water formation. With a relative scale

from 0 (no water present) to 1 (the

oil is saturated with water) it gives a

reliable indication of how close the

saturation point of water is.

In contrast to traditional

measurement techniques, water

activity measurement is independent

of oil type. Regardless of the

saturation point of the fluid, water

activity measurement always

provides a true indication for the risk

of free water formation, even when

the saturation point is increasing or

decreasing. In its simplicity, water

activity value is understandable

at a glance. Trends can be quickly

identified.

Vaisala HUMICAP® for

Measuring Water Activity

The Vaisala transmitters used

for measuring moisture in oil

feature the HUMICAP

sensor, a

capacitive thin-film polymer sensor

especially developed for demanding

moisture measurements in liquid

hydrocarbons.

The HUMICAP sensor consists of four

functional layers: glass substrate,

lower electrode, water-active polymer

layer, and porous upper electrode.

The thin-film polymer either

absorbs or releases water as the

surrounding moisture level changes.

Water molecules move to/from the

polymer layer until there is moisture

equilibrium between the polymer and

the oil. The dielectric properties of

the polymer depend on the moisture

level. As the moisture level changes,

the dielectric properties of the

polymer film change, and so does

the capacitance of the sensor. The

instrument’s electronics measure

the capacitance of the sensor and

convert it into water activity.

Oil molecules or additives do not

penetrate the electrode. Thus the

sensor output is independent of the

oil type.

On-line Measurement

On-line water activity measurement

ensures reliable performance

of equipment at all times. Time-

consuming sampling and laboratory

analysis are no longer needed. This

not only reduces the risk of human

induced error but also provides cost

savings in equipment and chemicals.

Typical Applications

for Moisture in Oil

Measurement

Moisture is an important factor

determining the condition of both

lubricating and transformer oils.

With on-line information on the

quality of the oil, preventive actions

can be taken and the maintenance

costs cut substantially.

Upper electrode

Lower electrode

Thin-ﬁlm polymer

Glass substrate

Structure of the HUMICAP sensor.

HUMICAP in Brief

▪

A capacitive thin-film polymer

sensor

▪

Water activity (a

)

measurement within range 0…1

▪

Accurate to +/- 0.02 (a

)

▪

15 years of experience in

measuring moisture in oil

Moisture in Oil

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