Interview: Reliable Moisture Content Measurement Results

“But fundamentally, measuring moisture content is about product quality. In plastics, the wrong moisture content can cause structural or cosmetic defects that lead to scrap or product failure. Food products with too much moisture will mold, or will have non-ideal texture or other properties; think potato chips that go “squish” instead of “crunch.”

source: https://www.azom.com/article.aspx?ArticleID=11394

Interview by Alexander Chilton

Insights from industry

GarrettROWE

Customer Service Manager

Arizona Instrument LLC

Garrett Rowe, Customer Service Manager at Arizona Instrument LLC, talks to AZoM about the importance of moisture content analysis in industry.

About Garrett Rowe

Garrett’s eight years at Arizona Instrument LLC have focused relentlessly on helping our customers achieve their application goals, first as the Application Lab Manager and now as the Customer Service Manager. Throughout that time, Garrett has solved the most difficult application challenges thrown his way and delivered accurate, repeatable results with a smile. A native of Dayton, Ohio, Garrett relocated to sunny Arizona for school and never looked back.

Could you please provide a brief introduction to the industries that Arizona Instrument LLC works within?

You’ll find Arizona Instrument’s Computrac® line of moisture analyzers in any industry where moisture is important to product quality, performance, or longevity. Some of our biggest customers are major pharmaceutical companies, plastic manufacturers and molders, leading food companies, oil and lubrication companies, and manufacturers of gypsum, paper, paints and coatings, and chemicals of all sorts. And there are a lot of one-off applications, as well. For example, some organizations that monitor forest health toss the Computrac® in a truck, drive into a forest, and run the analyzer off of a power inverter to do in-the-field analysis.

We also manufacture the Jerome® line of mercury vapor and hydrogen sulfide gas analyzers, which are used in a whole host of other industries.

How has Arizona Instrument LLC grown since it was founded in 1981?

What we have done consistently over the past thirty-plus years is to keep innovating. We developed the first rapid loss on drying instrument and we haven’t slowed down, always working on how to make our instruments the most accurate, most durable, and easiest to use in an evolving marketplace. And our customers have responded; we have probably learned as much from our customers as they have learned from us, and we can share that understanding of moisture analysis with our new customers. It really comes in handy when dealing with difficult applications.

Measuring moisture content is a key area Arizona Instrument works within – why is this important to your customers?

Really, there are as many reasons as there are customers. But fundamentally, measuring moisture content is about product quality. In plastics, the wrong moisture content can cause structural or cosmetic defects that lead to scrap or product failure. Food products with too much moisture will mold, or will have non-ideal texture or other properties; think potato chips that go “squish” instead of “crunch.” Many companies also check moisture content at materials receiving. A lot of contracts are specified by material weight, and you want to make sure you’re not paying for more water than you expect. This is especially important for hygroscopic materials like dry grains.

In short, companies test for moisture because they want to know that the material they are working with, whether they’re receiving it, processing it, or shipping it out, is at a level of quality they expect and are comfortable with.

How can checking the moisture content in their materials save customers money in the future?

Customers can certainly save money with moisture analysis by reducing scrap and rework, and by ensuring they’re getting what they pay for in deliveries from vendors. But there are a lot of other ways that companies can save money that they might not have thought of.

Reducing energy use is one. Many industries depend on materials being at or below a certain moisture content before processing, and so they use dryers. But dryers, like microwaves, can vary in their effectiveness for a number of reasons. If the production team uses a moisture analyzer, they can stop the drying process when the target moisture content is reached, saving energy and preventing damage to the material which could result from over-drying.

Process control is another dimension of the quality issue where companies can save money: if you have a target for moisture content for your product, you can quickly test the product and adjust your process to ensure you’re hitting your desired standards.

Computrac® also saves our customers money compared to other analysis methods because Computrac® moisture analyzers do not require expensive or toxic chemical reagents, like some other moisture analysis methods do.

Could you explain to our readers the main ways in which moisture content can be measured?

There are two broad categories for moisture analysis: loss on drying and moisture specific. Loss on drying moisture analysis measures the change in mass of a sample as water is evaporated off, but because chemicals other than water can also evaporate off, you need to set parameters correctly to get an accurate result.

Moisture specific methods are those which detect only moisture. One of the most prevalent methods is the Karl Fischer method, a “wet chemical” method discovered in the 30s. The Karl Fischer method is useful, but requires technical skill on behalf of the operator and uses toxic chemical reagents. Arizona Instrument developed the Computrac® Vapor Pro® to address these issues. The Vapor Pro® is moisture-specific like the Karl Fischer method, but is far simpler to use and requires no toxic chemical reagents.

How does the process of loss on drying moisture analysis work?

Loss on drying methods are good for many applications, but slow. For example, AOAC method 925.09 for flour takes more than 5 hours, while ASTM E871 for particulate wood fuels takes more than 16. Basically, you weigh your material, put it into an oven for several hours to evaporate the moisture, and then weigh it again. It’s simple enough, but it requires manual steps which may introduce error into the analysis.

Rapid loss on drying is an improvement on the loss on drying methods. For rapid loss on drying, a specialized instrument like our Computrac® MAX® 4000XL combines a balance with a heating chamber and continuously monitors the mass of the sample during the drying process. This enables the Computrac® to end the test immediately after all water has been evolved off, resulting in tests that run in less than 1/10th the time of traditional methods without sacrificing accuracy.

Still, as advanced as rapid loss on drying instruments have become, some applications just are not a good fit for it. Materials with very low moisture content like polypropylene or PET, or materials that have high volatile content or a high price tag are generally a better fit for the Vapor Pro®, which excels at analyzing the moisture content of very low moisture materials.

You mentioned the Computrac® Vapor Pro® can be used to obtain reliable measurements when the moisture levels of the sample are very low – what are the main features and advantages of this piece of equipment?

Well, first of all the Vapor Pro® is very, very precise. It counts micrograms of water, with a resolution of a 10th of a microgram. And because it can reliably operate in the 50 microgram range for water content, you can get a reliable reading even with a small sample—often a gram or less. Loss on drying methods have a hard time getting repeatable results in this situation. Even if you were to use a 10 gram sample at 0.001% moisture content, you will not get a difference in weight of more than 0.1 milligrams. That’s in the noise range for most balances.

Another really big advantage of the Vapor Pro® over the Karl Fischer is the lack of chemical reagents. In addition to being cheaper to run and easier to use, the lack of chemical reagents makes the Vapor Pro® a much better choice for environments where chemical contamination can cause a big problem, like clean room facilities.

When looking to purchase a moisture analyzer, what considerations should a customer make?

Anyone looking at moisture analyzers should take a long, hard look at what level of service and application support they will receive after they’ve handed over their money. You want to be able to talk to an expert immediately if you have questions about your process. We do that really well; you can always reach a human being in customer service, any time, day or night. And we have an internal laboratory dedicated to developing methods and parameters for our customers. You never know when an application which seems routine might present some unique challenges, and in that situation you want to know that you don’t have to do it on your own.

Next, look at your particular application. Where will the instrument be used? On the production line? In a lab? A clean room? In the back of a truck? Durability is a strong consideration for most environments where glass or other breakable parts might cause a problem. Who will be using the analyzer, a Ph. D. or a regular guy? Are you looking for moisture only, or for total volatile content? Do you need temperatures up to 600°C, or is 275°C enough? There are a lot of variables that go into finding the right solution for your application, and you shouldn’t have to go through the process alone.

What are the main advantages of choosing a moisture analysis product from Arizona Instrument?

The single biggest advantage is the service, support and knowhow that comes with the instrument. We have more experience with rapid loss on drying applications than any company in the industry, and we know how to apply that knowledge to suit your unique application. So, in addition to an extraordinarily accurate, reliable moisture analyzer, you get the peace of mind that comes with having over 30 years of moisture analysis experience at your disposal.

Are there any recent case studies that you are particularly proud of?

We often get requests from potential customers who have had a difficult time getting good results from other moisture analyzers, so they send us a sample. Every situation is unique, but they follow the same general pattern: a customer has a difficult application and they’re having trouble getting repeatable results. They speak with an applications consultant or send us a sample, and we figure out a process to get them the right result quickly and easily. Here are a couple of our more recent challenges.

A customer had a gluten free dough where the dough would “pop” off the pan during a measurement. And when I say pop, I mean pop like popcorn. The pieces of dough would actually eject themselves off of the pan. And because loss on drying instruments work by measuring the change in mass of a sample, the fact that some of the dough had been flung off the pan had a huge impact on the results. They sent us a sample, and our laboratory was able to develop a process that solved the problem of the popping dough and delivered repeatable results.

A customer was working to develop a manufacturing process for medicated bandages, for which moisture control was critical. Our laboratory worked closely with them to develop the moisture testing procedures, and in so doing determined that the bandage had a higher moisture content in the middle than at the edges; if we hadn’t helped them catch that issue, they could have been looking at high product reject rates, a big, expensive recall, or worse.