What is a Moisture Analyzer?

Moisture Analysis: What is Moisture Analyzer?

Let’s start out by explaining why you may need a moisture analyzer.  One example (of many) is in the food industry.  As described in Food Quality and Safety  “International and national standards define the permitted thresholds for moisture content in commercially sold products.” 

After listing some of these standards, the article continues “….this translates into increased workload around quality assurance and the development of efficient and cost-effective solutions. According to the stated legal requirements, methods of analysis and procedures must be clearly described and tested.”

Moisture analyzers are widely used in meeting these standards.  They go far beyond the food industry – affecting such diverse products as pharmaceuticals, plastics, paint, wood, birdseed, soybeans, fertilizer, cement, detergent, shampoo…..etc.

So, What is Moisture?

Excellent Question.  For the subject of this post, moisture is anything that evaporates on heating.

In addition to water this may include fats, oils alcohol and solvents.

Please note that certain volatile substances may be given off during moisture analysis.  Procedures should be in place to take this into account.  Do not perform analysis on explosive or flammable materials or those that may become hazardous on heating.

What is a Moisture Analyzer?

A moisture analyzer, also called a moisture balance, is a programmable benchtop laboratory instruments used to measure the moisture content of small samples of products being manufactured or processed.  Moisture analysis can be performed prior to, during, or after processing just before product packaging.

They combine an analytical balance with a heater to drive off moisture from products being tested.

Unlike large oven dryers performing bulk drying on production lines, a moisture analyzer is used to confirm bulk dryers are doing the job correctly, or that adjustments must be made in processing lines. 

How does a Moisture Balance Operate?

Most moisture analyzers today operate on what is called the thermogravimetric principal – that is determining the lost of weight on drying (LOD).  The loss represents the amount of moisture given off during the drying process while the change in weight is recorded by the analytical balance. 

Testing procedures are programmed into to the moisture balance and the change in weight is continually calculated as it performs the drying operation. Because of small sample sizes the analysis can be accomplished very quickly.

Drying temperature is supplied by either infrared or halogen heaters with the latter technology being most prevalent because it can be used to determine the moisture content of virtually any substance.  It is also faster than infrared drying. 

Microwave drying is another technology but these instruments are somewhat larger and significantly more expensive than halogen-heated moisture analyzers.

A popular halogen moisture analyzer is the XM 60 available from Tovatech.  It serves as an example of the specifications to be considered in purchasing such units.  It operates at a temperature range of 30 –  230˚C in 1˚C increments. 

Researchers and QC personnel select soft (slow), standard and boost (high) heat rate drying profile management without requiring ramp programming. Report generating is simplified by pressing the Key- Select™ mode until the display shows the desired report, then releasing the key to send the report to a printer or via the RS232 output to the computer.

Moisture Analyzers for Specific Tasks

You can specify a moisture analyzer that is designed to simplify specific tasks.  The XM60 mentioned above, for example, is recommended for gauging moisture content in the food industry

DSC 71P Moisture Analyzer
DSC 71P Moisture Analyzer

Companies striving to deliver superior quality injected molded products are aware that the moisture content of their resins feeds is absolutely critical to product quality. The DSC 71P is an excellent moisture analyzer for testing low moisture plastics. To save you time it has a default program to test 75% of the most commonly used resins.

And as a final example, measuring moisture content in the wood, paper and pulp industries can be accomplished by several models including the portable IL 50.01 or the XM 60 moisture analyzer with a 20 program memory.

Moisture Analyzers are Easy to use, but…

With their large LED displays moisture analyzers are relatively easy to use.  But operators must be familiar with and follow the precise steps necessary to obtain accurate readings for the specific products being analyzed.  While their operations may differ based on specific models here’s a typical analysis sequence:

  1. Establish the procedures for the products being tested and program the balance accordingly.  Include each of these procedures in your company’s operations manual.
  2. Place the sample plate on the moisture balance sample plate holder then tare the balance
  3. Spread the recommended amount of product evenly on the sample plate and record the weight. 
  4. Close the cover of the moisture balance to start the sequence.
  5. The unit’s display panel continually updates the status of the process. The analysis automatically terminates when drying is complete and the dry weight is stable, or after a fixed time specified by the operator, or manually.

At the end of the moisture weighing all relevant data concerning initial mass, residual mass, test parameters and results can be printed out via an RS-232 interface.

When the moisture analyzer is connected to a PC the data acquisition software allows the operator to produce a graph plotting results against time, providing valuable information on speed of drying and confirmation of dry weight stability.

Results of individual tests can be stored in the computer memory for subsequent comparison. All  moisture analyzers offered by Tovaech meet GLP/ISO record keeping requirements.

Note that moisture analyzers must be recalibrated on a regular basis and every time they are moved from one location to another.  Recalibration procedures for both weight and temperature are spelled out in the user manual.  

Examples of where moisture analyzers find use and how they operate will be found on other Tovatech moisture analyzer blog posts.  And please call us for more information on selecting and operating precision moisture analyzers.

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world. Read More