Vaisala HUMICAP MMT310 Guide de l'utilisateur télécharger pdf (Page 11)

Chapter 2 __________________________________________________________ Product Overview

VAISALA ________________________________________________________________________ 9

CHAPTER 2

PRODUCT OVERVIEW

This chapter introduces the features, advantages, and the product

nomenclature.

Introduction to MMT318 and MMT317

Vaisala HUMICAP

moisture in oil transmitter MMT318 and

MMT317 are designed for industrial applications. The MMT318 and

MMT317 transmitter measure water in oil in terms of water activity

(aw) which can be determined as follows: water activity indicates the

amount of oil in the scale of 0 - 1 aw. In this scale, 0 aw is an

indication of completely water free oil and 1 aw an indication of oil

fully saturated with water. Water is present in free form. The water

activity is used for alarming at the point of > 0.9 aw where the risk for

free water is obvious.

The most advanced feature which distinguishes the measurement of

water activity (aw) from the traditional measurement of absolute water

content (in ppm) is that the in the water activity measurement

saturation point remains stable regardless of the oil type, aging of oil

or additives used. As water activity of the oil exceeds 0.9 aw, there is

a risk for segregation (especially if the temperature decreases).

The MMT318 and MMT317 transmitters can be used for continuous

on-line measurements and it can be calibrated against salt solutions,

no reference oils are needed.

Appendix presents application information when using the MMT318

and MMT317 with transformer oil (output unit= ppm). General

information on paper machine use is also included in the Appendix.

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Vaisala HUMICAP MMT310 Guide de l'utilisateur Page 11