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Moisture Analyzers – A Selection Guide

Moisture analyzers are critical industrial instruments used to sense moisture content in a wide range of solids, liquids, and gases. Sensors help manufacturers control product quality, regulate heat treatment processes, and maintain a dry working environment. Choosing the right moisture analyzer for these applications promotes efficiency and prevents moisture from interfering with critical processes.

MAC Instruments has manufactured precise, heavy-duty instruments for over 30 years, including innovative moisture analyzers that ensure accurate readings in variable conditions.

 

What are Moisture Analyzers?

Many industrial processes rely on precise moisture measurements to fine-tune the efficiency of different processes or assess product quality. While traditional testing methods can take hours to return an accurate reading, industrial moisture analyzers assess samples in a matter of minutes so that facilities can consistently control process parameters.

Moisture analyzers rely on various measurement methods to determine water content in a sample. MAC Instruments’ popular 125 and 155 models use a proprietary solid-state humidity measurement process that requires absolutely no chemicals, compressed air, wet bulb techniques, optics, or mirrors. Instead, an absolute pressure sensor measures the total process atmospheric pressure, while a high-temperature sensor calculates the sample’s partial water pressure. The quotient of partial vapor pressure divided by total process pressure yields a highly accurate moisture measurement.

 

Selecting the Best Moisture Analyzer for Your Application

The ideal moisture analyzer for an application depends on a number of process-specific factors:

  • Impact of Moisture. The more important moisture content is to product quality, the more accurate your sensor must be. Halogen moisture analyzers, for instance, use gravimetric detection to offer accuracy of 0.01 % with a resolution of 0.01 g. This level of significance may be critical when manufacturing moisture-sensitive pharmaceuticals, but it is usually unnecessary for general industrial applications. 
  • Material Being Measured. Most moisture analyzers are medium-specific, meaning they only measure moisture content in a specific material. Thus, you must identify a moisture analyzer that accommodates your particular samples.
  • Process Compatibility. It’s important to choose a moisture analyzer that suits your application’s process requirements. For instance, if you need continuous measurements, you will likely need an in-process moisture sensor that uses microwave-based detection. Another consideration is whether your samples can be damaged. If so, you should opt for a non-destructive measurement method.

 

Moisture Measurement Principles

The above variables determine which moisture measurement paradigm is most suitable for a given application. Options include:

  • Capacitive Moisture Detection. This option uses a dielectric sensor probe to measure electrical capacitance through a substance. These devices convert capacitance to a measure of moisture based on the characteristics of the sample material.
  • Conductivity/Resistance-Based Moisture Detection. This method involves inserting two probes into a sample and generating an electric field. The electrical resistance between the probe contacts indicates the relative moisture content. Like capacitive moisture detection, this calculation is material-specific. 
  • Gravimetric Moisture Detection. This method is one of the most precise methods available, although it can also take longer. These devices measure the initial weight of a sample, then dry the sample and calculate the amount of moisture lost based on the final weight. 
  • Microwave-Based Moisture Detection. This option is the best choice for continuous process monitoring. The technique employs a microwave sensor and an alternating magnetic field to measure a sample’s dielectric properties and extrapolate moisture content from the readings.

Importantly, capacitive and microwave-based analyzers are non-destructive, while conductivity and gravimetric analyzers require destructive sampling. Gravimetric sampling is also the only option that is material-independent, meaning the same analyzer can process various sample types.

 

Industrial Applications of Moisture Analyzers

Moisture analysis is an important quality assurance process across diverse industries. They enable stack emission monitoring in oil and gas facilities, as well as humidity management in food and beverage baking processes. They are similarly useful for managing product moisture levels in drying products from paper to concrete.

Industries that especially benefit from moisture analysis include:

  • Power generation
  • Cement
  • Oil, gas, and refinery
  • Pulp and paper
  • Horticulture and agriculture
  • Food and beverage
  • Metal

Moisture Analyzer Options at MAC Instruments

At MAC Instruments, we specialize in high-performance moisture and humidity analysis. Our moisture analysis tools ensure consistent, accurate readings even in high-temperature or highly variable conditions.

The MAC125, 155, and 116 moisture analyzers rely on our patented technology to generate reliable, NIST-traceable direct moisture level measurement.

  • MAC125. The MAC125 is our latest and most advanced humidity meter, offering in-situ measurements at virtually any temperature. Using its proprietary solid-state measurement process, this analyzer is equipped to generate accurate readings in extreme operating environments. It is suitable for indoor or outdoor applications and mounts directly to stacks, ovens, dryers, and similar equipment.
  • MAC155. With its built-in two-point calibration, the MAC155 is ideal for processes that require daily in-situ calibration checks. Clients across the globe trust the MAC 155 for 24/7 stack emission monitoring, which improves process safety, efficiency, and regulatory compliance. The device is operational up to 1200° F (650° C), or up to 2400° F (1300° C) with the addition of high-temperature accessories, so it can easily endure challenging operating conditions.
  • MAC116. Optimized for food and beverage clients, the MAC116 helps manufacturers control steam flow into cooking atmospheres. With the MAC116, users can easily maintain moisture levels, maximize product yield, and minimize cooking time. Additionally, the device is designed to withstand clean-in-place operations, and its built-in purge process means it can stay in place during sanitization procedures. Common applications include drying and pasteurizing food products, as well as continuous cooking applications.

Our moisture analyzers are rugged, accurate, and specifically designed to combat common industrial pain points. The expert team at MAC Instruments would be happy to discuss our solutions further if you have questions about your specific application.

 

Contact Our Experts for High-Quality Moisture Monitoring Solutions

MAC Instruments has manufactured in-situ industrial moisture analyzers since 1990, developing innovative products that function without the typical chemicals, compressed air, wet bulbs, or optics. The resulting analyzers enable continuous, accurate humidity readings even in variable or extreme conditions. At the same time, our devices are engineered for maximum ease-of-use, offering hassle-free installation and intuitive interfaces to help employees save time.

To learn more about how our products protect process integrity and product quality, contact our team today.

Importance of Moisture Measurement in Industrial Applications

For years, MAC Instruments has been producing high-quality moisture analyzers that are easy to install and maintain and offer instant, accurate results with high sensitivity to moisture. This is critical in a wide range of industrial applications because excess humidity can pose a danger to sensitive industrial equipment and the products you produce, resulting in higher operational costs and repair costs along with reduced product quality. In critical applications, moisture levels can’t be left to chance: they must be carefully monitored and adjusted as necessary.

 

Basics of Moisture Measurement

Just like temperature, air pressure, and contaminants like dust and odors, moisture in your industrial environment needs to be controlled to ensure consistent, accurate production processes and results. As both a liquid and a gas, moisture levels that are too high or too low can damage equipment, alter the quality of your finished product, and increase your operating costs in the form of higher utility bills and/or higher maintenance and repair costs.

Unfortunately, moisture can be challenging to measure and control in an ever-changing environment. That’s why it’s essential to use reliable moisture measurement tools in your facility. 

 

Moisture Measurement in Industrial Applications

Because moisture can penetrate porous surfaces and hide in even the smallest cracks and crevices, it’s as dangerous as any other contaminant when it comes to the quality of your product and the efficiency of your equipment. Excess moisture, whether in liquid or gas form, can cause a variety of problems:

  • Inaccurate test results, particularly in gas and compressed air applications
  • Corrosion on pipes and other equipment
  • Inconsistent product quality
  • Ice formation in low-temperature environments
  • Freezing and thawing in changing temperature environments, adding wear and tear to equipment
  • Equipment failure or inefficient operation
  • Moisture may mix with chemicals or vapors to create reactions that alter your process or product

In industrial environments, there are two primary technologies for measuring dew point: capacitive sensor technology and optical sensor technology. Capacitive sensors are an economical choice that offer a quick response to small changes in water vapor. Optical sensors are more expensive, but they are more accurate and may be a worthwhile investment in situations where the slightest changes in moisture levels can pose a major risk to sensitive equipment or products. These devices measure the dew point by cooling a gas until it forms frost. The frost is then vaporized and the device recalibrates, so it can continue to test.  

Both technologies are used in a wide range of applications, including paper mills, product drying, metal processing, baking and food processing, stack emission monitoring, power generation, semiconductor manufacturing, and more. We’ve supplied moisture measurement tools to several companies with challenging humidity and moisture situations, and we’re proud to share their success stories.

Moisture Measurement at MAC Instruments

Our moisture analyzers, steam flow meters, and steam flow transmitters are trusted in a wide range of industries and applications. With a user-friendly interface, high moisture sensitivity, and high performance stability, moisture measurement tools from MAC Instruments are easy to use, reliable, and durable. To learn more about our products, contact us or request a quote today. We’d love to work with you to ensure you get the most accurate moisture measurements in your facility. 

 

Absolute Humidity vs Relative Humidity

Moisture analysis involves the process of measuring moisture and humidity in a particular environment. In general, humidity refers to the amount of moisture in the air; however, humidity can be measured in two ways: absolute and relative. Absolute humidity and relative humidity measurements are crucial in a wide range of applications from HVAC and drying processes to refining oil and creating sensitive pharmaceutical products. Understanding the differences between these two measurements will ensure that you are collecting the right moisture analysis data for your application.

What Is Absolute Humidity?

Absolute humidity refers to the measurement of water vapor within a given volume of air. 

To determine absolute humidity, the mass of water vapor is divided by the mass of dry air within a specific volume of air at a given temperature. This measurement is expressed in grams of water vapor per cubic meter of air (g/m3).

Absolute Humidity can also be expressed as the percent moisture by volume of air. 

What Is Relative Humidity?

Relative humidity is typically expressed as a percentage and refers to the amount of water vapor in the air, relative to the maximum amount of water vapor that could be present in the air at a given temperature. It indicates the actual moisture content compared to the potential moisture content of the air. 

For example, relative humidity of 50% indicates that the water vapor in the air is half of the amount that could potentially be present in the air at complete saturation. Temperature is essential to measuring relative humidity because the maximum water vapor content of an air mass increases or decreases with temperature. A warm air mass can be mixed with more water vapor than a cool air mass of the same size.

Absolute Humidity is independent of temperature while relative humidity is a function of temperature.


Rely on MAC Instruments for Moisture Analysis

Absolute humidity and relative humidity are different methods of measuring air moisture content. Since moisture analysis is crucial for a wide range of industries and applications, it is important to have reliable moisture analysis equipment to ensure precise and accurate measurements. At MAC Instruments, we have been delivering high-quality moisture analyzers since 1990. Our equipment is capable of measuring absolute humidity in even the most extreme temperature situations. Our available moisture analyzers include:

  • Mac 155 Moisture AnalyzerMAC 125. The MAC 125 comes in digital and analog models and uses no chemicals, wet bulb techniques, compressed air, optics, or mirrors. Instead, it uses a solid state humidity measurement process to ensure accurate measurements even in extreme operating environments.  
  • MAC 155. The MAC 155  is the ideal solution for monitoring stack emission moisture for EPA regulations.
  • MAC 116. The MAC 116 delivers steam analysis for food preparation environments. It has been used in meat and poultry processing conveyor ovens since 2011 and can be installed in most ovens with a standardized and easy to sanitize design.

The easy-to-use moisture analysis tools offered by MAC Instruments are waterproof and resists high temperatures up to 1200 °F. 

To get started on your moisture analysis solution, request a quote from our team of experts today.

What is Stack Emission Monitoring?

Stack emission monitoring is a process that enables facility managers, inspectors, and other key personnel to measure the level of industrial waste and/or pollutants a stack emits into the atmosphere. Monitoring emissions from stack facilities air quality monitoring and measures the efficacy of pollution control equipment. The data gathered may also be used to prove regulatory compliance and benchmark performance.

What is a Stack?

Stacks are essentially large industrial chimneys designed to emit and disperse hot air, particulate matter, and pollutants into the atmosphere at such a height that they do not constitute a danger to surrounding life on the ground. There are several types of stacks in use today, such as:

  • Boiler stacks
  • Flue gas stacks
  • DG set stacks
  • Furnace stacks
  • Chimneys

Why Choose Continuous Stack Emission Monitoring?

Continuous stack emission monitoring enables plant managers and other key executives to see current emission levels in real-time, 24 hours a day, 7 days a week. This is an important capability for power plants and other facilities, since strict air quality standards regulate the allowed concentration of emitted pollutants such as SOx, NOx, and many other particles and gases. If these amounts are exceeded, the offending company may be subject to fines.

While many facilities use periodic stack emission monitoring systems, a continuously operative framework will help ensure that emission levels remain within acceptable parameters. If for any reason the emission levels rise past a certain threshold, continuous monitoring will help managers to quickly remedy the situation.

How Does Stack Emission Monitoring Equipment Work?

At MAC Instruments, our MAC 155 Moisture Analyzer’s humidity probe and humidity transmitter measure humidity in exhaust gases that are heated up to 1,200° F (650° C). With the addition of special accessories, the temperature range of the humidity probe can be extended up to 2400° F (1300° C).

The MAC 155 system measures the percentage of moisture by volume using a high-temperature capacitive sensor that reacts under pressure from water vapor in the presence of other gases. Moreover, the analyzer makes two-point, in-situ calibration and system checks possible on a daily basis and facilitates adherence to EPA regulations and local emission statutes. This moisture analysis system has a proven track record of providing continuous, accurate emission measurements, as demonstrated in this case study.

Continuous Stack Emission Monitoring From MAC Instruments

There are many compelling reasons for an organization to invest in continuous stack emission monitoring equipment. The real-time data collected by these cutting-edge monitoring systems enables facility managers to keep emissions well within acceptable parameters.

At MAC Instruments, we take great care in designing, manufacturing, and delivering the highest quality stack emission monitoring systems on the market, such as our MAC 155 Moisture Analyzer. For more information about this system or any of our other products, please request a quote to speak with one of our experts.

What Is the Density of Air at STP?

At MAC Instruments, we are a leading manufacturer of industrial moisture analyzers. These critical components measure the amount of moisture mixed into the air to help our customers keep their facilities in compliance with industry and environmental standards.

Air density plays a significant role in this measurement process, as discussed in our moisture measurement handbook. A popular method of moisture measurement is based on water vapor density in the air at various standard conditions of temperature and pressure (STP). Knowing these standard measures can help customers use monitoring equipment more precisely.

Density of Air at Standard Temperature and Pressure

STP—standard temperature and pressure—represents conditions that people and systems use to calculate gaseous factors. Commonly accepted STP values are 32° F (0° C or 273 K) and 1 atm pressure. However, while STP is a relatively common term, it can mean different things based on the agency applying the standard. For example, the National Institute of Standards and Technology (NIST) sets its standard at 68° F and 101.325 kPa. On the other hand, the International Standard Metric Conditions are 59° F and 101.325 kPa for natural gas.

As different industries and applications use different STP values, the best practice is to describe the standard and list out the exact conditions for each measurement. Stating the temperature and pressure conditions for every readout, inspection, and process can keep records clear.

According to the International Standard Atmosphere (ISA) values—15° C at sea level—the density of dry air is at:

  • In Metric units: 1.225 kg/m^3
  • In Imperial units: 0.0765 lb/ft^3

Although pure water vapor cannot exist at STP, these density values for dry air can be used to calculate a theoretical value for water vapor density at STP. As the density of pure water vapor is 62.19% of the density of dry air, theoretically, 100% water vapor would have a density of 0.7618 kg/m^3 or 0.048 lb/ft^3 at STP.

Uses of STP in Moisture Analyzer Applications

Knowing these measurements can help facilitate a better understanding of moisture analyzers. At MAC, we offer several high-performance moisture analyzers, including:

  • MAC 116 Moisture Analyzer controls the flow of steam in food industry applications to maintain proper moisture levels for optimal production yield and cooking time.
  • MAC 125 Moisture Analyzer can measure absolute humidity and total pressure to calculate the area’s moisture level. This continuous monitoring helps keep facilities compliant with environmental and industrial regulatory standards.
  • MAC 155 Moisture Analyzer monitors emission stack gases. The equipment can help ensure that the stack gas’s moisture or humidity levels meet regulatory requirements.

Contact MAC Instruments for Quality Moisture Analyzers

Continuous monitoring is the first step to keeping your facility compliant and safe. By using our moisture analyzers, customers benefit from:

  • MACEasier installation and operation
  • Higher sensitivity to water vapor and moisture content
  • Faster and more accurate results
  • A more user-friendly interface
  • Greater performance stability

If you are interested in learning more about our moisture analyzers, contact us at 419-621-2322 or request a quote.

What Does a Moisture Analyzer Do?

Since 1990, MAC Instruments has built high-quality, heavy-duty industrial moisture analyzers. Our instruments help facility managers measure an environment’s absolute humidity in challenging high-temperature conditions.

MAC products use patented, proprietary sensors that consistently provide accurate readings even in highly variable conditions. Clients across the industrial spectrum rely on our moisture analyzers to help them fine tune the efficiency of their processes.

Our clients include those in the following industries:

  • Power generation
  • Cement mixing
  • Oil and gas refining
  • Pulp and paper processing
  • Food and beverage processing
  • Horticulture and agriculture
  • Metalworking

How Is Moisture Analyzed?

Water is certainly essential to life, however, too much of it can corrode or short circuit your equipment, and too little of it can negatively affect the quality of perishable items and dried product. Moisture analyzers operate by taking holistic measurements of the following physical or chemical properties:

  • water vapor pressure

The moisture analyzer uses data from these readings to calculate the climate’s absolute humidity, or the measure of water vapor in the air regardless of temperature or other conditions. Maintaining a consistent absolute humidity means that you can create an optimal internal environment for whatever process you are conducting, be it drying product, refining oil, or creating sensitive pharmaceutical products.

Moisture content analyzers can be used to take direct measurements of the air, but our products also include features that allow you to analyze fluctuations in absolute humidity over time.

The FDA and other governmental and regulatory bodies stipulate a wide range of humidity standards that facility owners must follow in order to optimize efficiency and maintain customer health. An inconsistently monitored or controlled relative humidity can result in moldy or stale food items as well as corroded equipment.

How Do our Moisture Analyzers Work?

A sampling pump within the analyzer draws a sample of the atmosphere being monitored through the analyzer. The sample first passes through a 10 micron filter to remove any particulates from the sample stream. The sample travels through the barrel of the instrument and past the sensor. The sensor and the barrel are electrically heated to prevent condensation of any moisture in the sample. There are two pressure sensors in the analyzer. An absolute pressure sensor measures the total pressure of the process atmosphere. The partial pressure of the water vapor is measured by a proprietary high temperature capacitive sensor that responds only to water vapor partial pressure. The signals from these sensors are used to compute the % moisture by volume of the sample.

% water vapor by volume = (water vapor pressure / total pressure) X 100

The total pressure varies with altitude above sea level, local barometric pressure, and process induced pressure. In some applications the humidity ratio is preferred instead of % moisture by volume. The humidity ratio is defined as the mass of water vapor per unit mass of dry air. A jumper in the MAC125 allows the user to select the desired moisture scale.Some industries that require the use of moisture analyzers include:

  • Stack emission monitoring
  • Product drying
  • Metal processing
  • Cooking and baking
  • General industrial applications

MAC Instruments offers a number of different moisture analyzers intended to perform specific functions within a variety of industries. Our products include:

  • MAC 155: This moisture/humidity analyzer operates via user-friendly components that measure humidity in exhaust gases at temperatures of up to 1,200°F (650°C). The MAC 155 helps you to augment your safety process and comply with EPA regulations.
  • MAC 125: This high-temperature absolute humidity sensor operates without the use of chemicals, compressed air, wet bulb techniques, optics, or mirrors. Its moisture sensor and humidity meter rely on a patented, proprietary solid-state process for measuring humidity, making this a straightforward system that experiences few breakdowns.
  • MAC 116: This analyzer monitors humidity differences in the flow of steam in a cooking atmosphere, which will enable you to cook products as effectively and quickly as possible. It can be used to monitor the drying and pasteurization of food products, and facility owners can install it on continuous conveyor belts used to cook meat and poultry.

Contact MAC Instruments

At MAC Instruments we have been building high-quality moisture analyzers out of our Sandusky, OH, plant since 1990. If you’re looking for an efficient way to monitor your facility’s absolute humidity, we’ve got you covered. Be sure to contact us today to learn more about our moisture analyzers or any other industrial products that we deliver.

What’s Wrong with Relative Humidity Above 100°C?

Water vapor above a temperature of 100°C at atmospheric pressure is in the super heated state. The characteristics of the relative humidity scale change drastically in the super heat area. It is somewhat like going through the sound barrier, the physics take on new characteristics in the super heat area just as they do in the super sonic area. This can be confusing if not prepared for the change.

Below 100°C it is possible to achieve 100% relative humidity at any temperature. Above 100°C (in the super heat area) the maximum possible relative humidity plunges rapidly as the temperature increases. Pure steam (100°C dew point) will register only 20% on the relative humidity scale at 150°C. At 175°C the maximum possible RH is only 10%. At 200°C, maximum RH is only 5.9% and at 370°C, maximum RH is a mere .48%.

An RH instrument with a published accuracy of +/-1% will only indicate true moisture level with an accuracy of +/-5% at 150°C (+/-1% out of 20%), +/-10% at 175°C, +/-17% at 200°C, and will be useless at 370°C, even if the sensor is not destroyed by the high temperature.

Most RH instruments have a reduced accuracy specification above some specific temperature. An instrument with a published accuracy of +/-1% may be +/-2% above 90°C. This is sometimes hard to find on the data sheet, but is usually there somewhere. If the RH accuracy drops to +/-2% at elevated temperatures the true moisture level will have an accuracy of +/-10% at 150°C, +/-20% at 175°C, and +/-34% at 200°C.

Even if we forget about the absolute accuracy of an RH instrument above 100°C, the RH scale itself has problems in the super heat area. An RH instrument that is totally accurate may indicate 10% RH at a temperature of 150°C. This point is equivalent to 50% moisture by volume, or a dew point of 82°C or a humidity ratio (lb water vapor/lb dry air) of .622. This same instrument will display 10% RH at 175°C at 100% moisture by volume, or a dew point of 100°C, or a humidity ratio of infinity.

The above shows that the relative humidity scale is essentially useless or even misleading at temperatures above 100°C.

Some relative humidity instruments can indicate dew point or another absolute humidity scale. This is done by measuring RH and temperature and then calculating absolute humidity. This method is not accurate above 100°C because of the limited maximum indication on the RH scale.

For more in depth information on this subject refer to pages 7 & 8 of the
MAC Humidity/Moisture Handbook.”

The Mac Humidity / Moisture handbook can be viewed online.

What’s Wrong with Relative Humidity Above 212°F?

Water vapor above a temperature of 212°F at atmospheric pressure is in the super heated state. The characteristics of the relative humidity scale change drastically in the super heat area. It is somewhat like going through the sound barrier, the physics take on new characteristics in the super heat area just as they do in the super sonic area. This can be confusing if not prepared for the change.

Below 212°F it is possible to achieve 100% relative humidity at any temperature. Above 212°F (in the super heat area) the maximum possible relative humidity plunges rapidly as the temperature increases. Pure steam (212°F dew point) will register only 20% on the relative humidity scale at 300°F. At 350°F the maximum possible RH is only 10%. At 400°F, maximum RH is only 5.9% and at 700° F, maximum RH is a mere .48%.

An RH instrument with a published accuracy of +/-1% will only indicate true moisture level with an accuracy of +/-5% at 300°F (+/-1% out of 20%), +/-10% at 350°F, +/-17% at 400°F, and will be useless at 700°F, even if the sensor is not destroyed by the high temperature.

Most RH instruments have a reduced accuracy specification above some specific temperature. An instrument with a published accuracy of +/-1% may be +/-2% above 200°F. This is sometimes hard to find on the data sheet, but is usually there somewhere. If the RH accuracy drops to +/-2% at elevated temperatures the true moisture level will have an accuracy of +/-10% at 300°F, +/-20% at 350°F, and +/-34% at 400°F.

Even if we forget about the absolute accuracy of an RH instrument above 212°F, the RH scale itself has problems in the super heat area. An RH instrument that is totally accurate may indicate 10% RH at a temperature of 300°F. This point is equivalent to 50% moisture by volume, or a dew point of 179°F or a humidity ratio (lb water vapor/lb dry air) of .622. This same instrument will display 10% RH at 350°F at 100% moisture by volume, or a dew point of 212°F, or a humidity ratio of infinity.

The above shows that the relative humidity scale is essentially useless or even misleading at temperatures above 212°F.

Some relative humidity instruments can indicate dew point or another absolute humidity scale. This is done by measuring RH and temperature and then calculating absolute humidity. This method is not accurate above 212°F because of the limited maximum indication on the RH scale.

For more in depth information on this subject refer to pages 7 & 8 of the
MAC Humidity/Moisture Handbook.”

The Mac Humidity / Moisture handbook can be viewed online.