User manual VAISALA HMM212

[. . . ] USER'S GUIDE Vaisala HUMICAP Humidity and Temperature Module HMM212 ® U338EN-1. 2 PUBLISHED BY Vaisala Oyj P. O. Box 26 FI-00421 Helsinki Finland Phone (int. ): +358 9 8949 1 Fax: +358 9 8949 2227 Visit our Internet pages at http://www. vaisala. com/ © Vaisala 2009 No part of this manual may be reproduced in any form or by any means, electronic or mechanical (including photocopying), nor may its contents be communicated to a third party without prior written permission of the copyright holder. Please observe that this manual does not create any legally binding obligations for Vaisala towards the customer or end user. All legally binding commitments and agreements are included exclusively in the applicable supply contract or Conditions of Sale. ________________________________________________________________________________ Table of Contents CHAPTER 1 GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Vaisala's liability shall under no cir-cumstances exceed the invoice price of any Product for which a warranty claim is made, nor shall Vaisala in any circumstances be liable for lost profits or other consequential loss whether direct or indirect or for special damages. 12 ____________________________________________________________________ U338EN-1. 2 Chapter 2 __________________________________________________________ Product Overview CHAPTER 2 PRODUCT OVERVIEW This chapter introduces the features and advantages of the Vaisala HUMICAP® Humidity and Temperature Module HMM212. Introduction to HMM212 The HMM212 modules are designed especially for relative humidity measurements in environmental chamber applications with high temperature and humidity levels. The HMM212 module is a microprocessor-based instrument with temperature compensation in RH measurements. Furthermore, the customer can also order the module with: - a suitable cable length (0. 65 m, 1. 50 m or 3. 0 m) - a temperature loop current scaled for that particular application (0 . . . +180 °C) The HMM212 modules are connected to process control systems with screw terminals. These versatile modules incorporate the HUMICAP®180R humidity sensor, which uses an operating principle based on changes in the capacitance of a thin polymer film as it absorbs water molecules. The HMM212 modules measure temperature with the reliable Pt 1000 sensor. VAISALA _______________________________________________________________________ 13 USER'S GUIDE____________________________________________________________________ This page intentionally left blank. 14 ____________________________________________________________________ U338EN-1. 2 Chapter 3 ________________________________________ To Be Noted When Measuring Humidity CHAPTER 3 TO BE NOTED WHEN MEASURING HUMIDITY This chapter describes issues that need to be noted in the measurement of humidity. In the measurement of relative humidity and especially in calibration, it is essential that the temperature equilibrium is reached. Even a slight difference in the temperature between the measured object and the sensor causes an error. For example, at +20 °C (+ 68 °F) and 50 %RH, a temperature difference of ±1 °C between the measured object and the sensor causes an error of ±3 %RH. A graph of the measurement error at 100 %RH when the temperature difference between ambient air and the sensor is 1 °C is presented in Figure 1 on page 16. The error is at its greatest when the temperature of the sensor differs from that of the surroundings and the humidity is high. A difference of a few degrees in temperature may cause water to condense on the sensor surface. Efficient ventilation accelerates the evaporation of the condensed water whereas in an unventilated space, it may take hours. The HUMICAP®180R sensor returns to its normal functioning as soon as water has evaporated. Contaminated water condensing on the sensor may shorten its life span and alter the calibration. VAISALA _______________________________________________________________________ 15 USER'S GUIDE____________________________________________________________________ 9 8 7 dRH (%RH) 6 5 4 3 2 1 0 -40 -20 0 20 40 60 80 100 Temperature (°C) Figure 1 Measurement Error at 100 %RH when the Temperature Difference between the Ambient Air and the Sensor is 1 °C 16 ____________________________________________________________________ U338EN-1. 2 Chapter 4 _______________________________________________________________ Installation CHAPTER 4 INSTALLATION This chapter provides you with information that is intended to help you install this product. Selecting Location Finding a suitable site for HMM212 is important for getting representative ambient measurements. Select a place that gives a true picture of the environment or process and is as clean as possible. Install the sensor head to a sufficient distance from the duct or chamber walls. Make sure to insert enough cable to the same space with the probe in order to prevent heat conduction. VAISALA _______________________________________________________________________ 17 USER'S GUIDE____________________________________________________________________ Dimensions Figure 2 Dimensions in mm (inches) Electrical Connections Connect wires according to Figure 3 on page 19. 18 ____________________________________________________________________ U338EN-1. 2 Chapter 4 _______________________________________________________________ Installation 2 3 1 Figure 3 Electrical Connections of HMM212 Module The following numbers refer to Figure 3 above: 1 = During normal use, leave the jumper as indicated here (factory setting). 2 = Calibration connector for the HMI41 3 = Calibration jumper when not in use VAISALA _______________________________________________________________________ 19 USER'S GUIDE____________________________________________________________________ This page intentionally left blank. 20 ____________________________________________________________________ U338EN-1. 2 Chapter 5 _______________________________________________________________ Calibration CHAPTER 5 CALIBRATION This chapter contains information that is needed to calibrate this product. Vaisala recommends a recalibration of the HMM212 module after six months of use. After the first recalibration, the recommended calibration interval is approximately 12 months. However, please note that these intervals depend on the operating conditions and the required accuracy. [. . . ] This is a very demanding procedure and requires both expertise and extremely accurate references. Furthermore, it is important to allow enough time for the stabilization during calibration. If for some reason, it is necessary to perform the temperature calibration, follow attentively the instructions given below. Temperature Calibration of an RH and T Module - Allow enough time for the instruments to stabilize to the temperature in which calibration is performed. Adjust the reading with UP and DOWN switches (see Figure 5 on page 24). [. . . ]