Before delving into the different types of moisture analyzers, what they are, and how they work, one has to first understand the process of moisture analysis. Analyzing moisture content in any given item, whether it be high level or trace amounts of gases, solids, or liquids, covers a wide range of methods. Measurement of trace moisture is important in a variety of applications, such as in process quality assurance and marketing.
Trace moisture measurements in solids like pharmaceuticals, plastic, heat treatment processes and the like must be done to control moisture content and maintain quality. For liquid or gas products, moisture measurement applications for moisture are hydrocarbon processing, dry air, bulk pure gases, pure semiconductor gases, natural gas pipeline transport, and dielectric gases like what is found in transformers and in power plants.
Basic Moisture Analysis Methods
- Loss on Drying or LOD
LOD is a classic laboratory moisture analysis method used to measure high moisture level in semi-solid or solid materials. Using this method, a fraction of the material being measured is taken and weighed. It is then over-heated for a particular period of time, cooled in a dry place, and once cool, reweighing of the sample is undertaken. If the solid material contains mainly water, a fairly accurate measurement can be provided by the LOD method.
But this method is rather slow, especially by today’s standards. The development of automated moisture analyzers has significantly reduced the amount of time it takes to measure moisture found in a solid or semi-solid material.
- Karl Fischer Titration
Created German chemist Karl Fischer in 1935, this moisture content measuring technique is quite accurate in reading the amount of water in solid or semisolid samples. But unlike the LOD method, which spots unstable substances, the Karl Fischer titration only measures water content.
- Natural Gas Moisture Analysis Techniques
Compared to solids and most forms of liquids, natural gas is a slightly unique material that requires equally unique moisture measurement methods. Because natural gas can have solid and liquid contaminants in high levels and a variety of corrosive properties, moisture analysis methods employed on such material can also vary. The following are some of the more common moisture analysis techniques used on natural gas:
- Aluminum Oxide and Silicone Oxide
- Chilled Mirrors
- Color Indicator Tubes
- Piezoelectric Sorption or Quartz Crystal Microbalance
There are, of course, other techniques in moisture measurement available, but they are not commonly used for industrial purposes for a variety of reasons.
The Moisture Analyzer
So, what is a moisture analyzer in relation to all the basic moisture analysis methods that exists? Moisture analyzers are devices that are primarily used to measure moisture content in any substance or material. That much is clear. These devices are employed in a variety of applications in many different industries, from food processing to construction, to chemical preparation, and pharmaceuticals.
For most consumers, a little moisture here and there really has no significance. As a matter of fact, a little bit of moisture is often welcomed in a warm sunny day. But when it comes to laboratories and other controlled environments, such as food processing plants, natural gas plants, and even climate-controlled storage facilities, monitoring moisture content is absolutely crucial. Letting moisture levels get out of hand could have disastrous effects in such environments.
How Do These Moisture Analyzers Work?
Today’s moisture analyzers are relatively small instruments that look like your average kitchen appliance. They come in many different forms and sizes, designed for a variety of specific applications. But, even though there are many different types of analyzers made by a number of reputable companies, these instruments all have a few things in common. For one, most moisture analyzers in the market today are mainly designed for practicality, portability, and ease of use.
The basic features and design elements of most analyzers in the market tend to be quite similar, and they operate quite the same way as well. When using these devices, you will need to obtain a sample from the material you want tested. You place the sample into a small chamber and start the machine. A computer obtains readings from inside the chamber by constantly recording the weight of the sample as it gets heated.
As you can see, even though these analyzers are automated, they still use the same basic moisture analysis method, which is loss on drying or LOD. During the heating process, the machine will periodically check the weight of the sample until it remains constant, which usually means the evaporation process is completed. Once the process is done, the analyzer will make the necessary computations and give you a read out of the moisture content of the sample.
Although you may find different moisture analyzers with different names and models, they all pretty much work and perform the same way. What you need to look for when buying such a device is the application the analyzer is designed for. Make sure that it is specifically made to analyze the type of solids, liquids, or gas you intend to measure.