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Humidity / Temperature / Dew Point / Carbon

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Humidity / Temperature / Dew Point / Carbon HUMIDITY / TEMPERATURE / DEW POINT / CARBON DIOXIDE / MOISTURE IN OIL / DISSOLVED GAS ANALYSIS IN TRANSFORMER OIL / PRESSURE / WEATHER / SERVICE OFFERING Humidity and Temperature / TECHNOLOGY DESCRIPTION Vaisala HUMICAP® Sensor for Measuring Relative Humidity ® In 1973, Vaisala introduced HUMICAP , the world’s first thin- HUMICAP in Brief film capacitive humidity sensor. Since then, Vaisala has Box headline here ▪ A capacitive thin-film polymer become the market leader in relative humidity measurements, sensor and thin-film capacitive humidity sensors have developed from ▪ Full measurement range one company’s innovation into a global industry standard. 0...100 %RH ▪ Accurate to ±1 %RH Vaisala HUMICAP sensors guarantee the dielectric properties of the ▪ Traceable humidity quality and reliability, with their polymer film change, and so does measurement reputation for accuracy, excellent the capacitance of the sensor. The ▪ Nearly 40 years on the market long-term stability, and negligible instrument’s electronics measure hysteresis. the capacitance of the sensor and convert it into a humidity reading. HUMICAP’s Unique Benefits How It Works ▪ Excellent long-term stability HUMICAP is a capacitive thin-film Typical Applications for Insensitive to dust and most polymer sensor consisting of a Humidity Measurement ▪ chemicals substrate on which a thin film of Vaisala’s humidity instruments with polymer is deposited between two HUMICAP sensors are suitable for ▪ Chemical purge option for stable measurements conductive electrodes. The sensing a wide range of applications. From in environments with high surface is coated with a porous power and steel to life sciences and concentrations of chemicals metal electrode to protect it from building automation, many industries contamination and exposure to need to measure humidity – here are ▪ Sensor heating for measurements even in condensation. The substrate is just a few: condensing environments typically glass or ceramic. Humidity must be measured and Full recovery from The thin-film polymer either absorbs controlled in many drying processes, ▪ condensation or releases water vapor as the such as those in construction relative humidity of the ambient material and paper manufacturing, air rises or falls. The dielectric and fluid bed dryers. The humidity Cleanrooms and other critical properties of the polymer film of the process air is a good indicator environments also require high- depend on the amount of absorbed of the progression of the drying performance environmental water. As the relative humidity process. measurements in order to operate around the sensor changes, consistently and within 4 In building automation, optimizing Vaisala INTERCAP® Sensor both the temperature and relative humidity of the indoor environment ▪ Same measurement principle enables a greater level of comfort as in the HUMICAP® sensor for occupants than optimizing Factory pre-calibrated - no ▪ Humidity temperature alone. Careful humidity additional calibration or control is a must in museums, adjustment needed archives, warehouses, and other ▪ Fully interchangeable environments where humidity- Used in humidity instruments sensitive materials are stored. ▪ with ±3 %RH accuracy Vaisala HUMICAP Humidity Products Family of HUMICAP sensors. Vaisala has everything you need for measuring humidity, with a Upper electrode specifications. In addition, glove boxes wide range of humidity instruments Thin-film polymer and isolators – used for handling covering applications from HVAC Lower electrode moisture or gas-sensitive materials to the most demanding industrial Glass substrate – benefit from accurate and reliable applications, both indoors and humidity measurements. Measuring out. Vaisala’s humidity instrument humidity in a critical environment can offering includes transmitters, be especially challenging. modules for volume applications, In the food industry the dryers and portable and handheld humidity ovens used in bread baking and meters, and humidity calibrators. cereal manufacture require a carefully The full range of humidity controlled humidity level to maintain products can be found at consistent quality and high yield, and www.vaisala.com/humidity Structure of the HUMICAP sensor. to give distinctive characteristics to the finished product. HUMICAP® – The Story of Innovation Until the early 1970s, hair the sensor had no moving parts, museums. The need for reliable hygrometers were commonly and due to the advanced use humidity measurement was used in radiosondes. At that time, of semiconductor and thin-film common to all, and instruments reliable humidity measurement technologies, it was amazingly that could do this accurately were was an unresolved challenge small. The sensor had a fast few and far between. and to solve this, Vaisala began response time, good linearity, low By 1980, a variety of products developing a new type of humidity hysteresis, and small temperature based on HUMICAP technology sensor using semiconductors coefficiency. – from hand-held meters to and thin-film materials. The Despite the fact that the innovation industrial transmitters, calibrators, revolutionary HUMICAP humidity was designed for a new type of a and other accessories – were sensor was introduced two years radiosonde, the greatest interest being sold in over 60 countries. later, in 1973, at CIMO VI congress. came from elsewhere: people Since its birth, HUMICAP has been HUMICAP was a radical working in environments as part of Vaisala’s core business, innovation that changed humidity diverse as greenhouses, bakeries, propelling the company to industry measurements for good. The new warehouses, construction sites, leadership in the field of humidity technology was groundbreaking: brick and timber kilns, and measurement. For more information, visit Ref. B210781EN-C ©Vaisala www.vaisala.com or contact This material is subject to copyright protection, with all copyrights retained by Vaisala and its individual partners. All rights reserved. us at [email protected] 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. 5 How to Choose the Right Instrument for Measuring Humidity and Dew Point What is Humidity? An Introduction to Humidity Parameters Partial Pressure of Water Vapor Humidity is simply water in its gaseous phase, properly called water vapor. Because water vapor is a gas, most of the common gas laws apply to it, including Dalton's law of partial pressures. Dalton's law says that the total pressure of a gas is equal to the sum of the partial pressures of each of the component gases: Ptotal = P1 + P2 + P3… Learn the basics and get the best out of your humidity measurements. If we consider air, the equation means that the total atmospheric pressure of 1.013 bar (14.7psia) is the sum of Humidity measurement and control is called for in a wide variety the partial pressures of nitrogen, of industrial applications. Each application has a different set of oxygen, water vapor, argon, carbon requirements for humidity instruments, such as required measurement dioxide, and various other gases in trace amounts. range, tolerance to extreme temperature and pressure conditions, ability to recover from condensation, ability to operate in hazardous Definition of Water Vapor environments, and options for installation and calibration. There is Pressure no single device that is suitable for all needs. In fact, the range of Water vapor pressure (Pw) is the available equipment is quite large, varying both in cost and quality. pressure exerted by the water vapor present in air or a gas. Temperature dictates the maximum partial pressure of water vapor. This This paper discusses the following • Sensor properties that influence maximum pressure is known as topics in order to help in selecting the choice of humidity instrument saturation vapor pressure (Pws). the right humidity instrument: • Practical guidelines for selecting a The higher the temperature, the • Different humidity parameters humidity instrument higher the saturation vapor pressure and the more water vapor the air • Environmental conditions that can hold. Thus, warm air has a influence the choice of humidity greater capacity for water vapor instrument than cold air. 6 If saturation vapor pressure is reached in air or in a gas mixture, the introduction of additional water vapor requires that an equal amount condenses out of the gas as a liquid Humidity or a solid. A psychrometric chart shows graphically the relation between saturation vapor pressure and temperature. In addition, vapor pressure tables can be used to see Some humidity measurement instruments allow an individual humidity parameter the saturation vapor pressure at to be chosen which can then be followed on a graphical display. This picture shows any temperature, and there are different views of the Vaisala HUMICAP Hand-Held Humidity and Temperature Meter also a number of computer-based HM70 display. calculation programs available. Effect of Pressure Relative Humidity Dew point directly correlates with saturation vapor pressure (P ). on Humidity When thinking conceptually of water ws The partial pressure of water vapor Dalton's law states that a change in vapor as a gas, it's easy to define associated with any dew point can the total pressure
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