The Moisture Hunters

Rigorous moisture testing is a crucially important step deployed at various stages throughout the manufacturing process to ensure high product quality. Tobacco Asia looks at some of the latest moisture metering models available – both for offline and online use.

By Thomas Schmid

Germany’s Brabender GmbH & Co. KG has for decades enjoyed an excellent reputation in the tobacco industry for its variety of analyzing equipment. About 100 distributors represent the company and its products in about 130 countries around the globe, although greater Asia and the MENA region currently are its most important markets. “In Asia, we work closely together with our agent Melchers Techexport GmbH and its local offices and partners in China, Cambodia, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, Sri Lanka, and Vietnam. Furthermore, Brabender is represented by local agents in Japan, South Korea, India, Pakistan, Thailand, Taiwan, as well as in the Middle East,” says Alexandra Petz, the company’s sales manager for Europe and Southeast Asia.

One Model, One Application

In terms of moisture metering equipment Brabender offers its moisture tester MT-CA, which, although actually being its only model, is very widespread in the industry. “MT-CA and its predecessor models MT-C and MT-E [or HAV] are renowned among nearly all tobacco producers in the world. And we also rely on our broad and sustainable network of agents to maintain that renown,” claims Petz. MT-CA was, of course, developed exclusively for offline use; in a lab setting, that is. “Just as our [other] instruments, our moisture tester is likewise intended for laboratory use. We have not considered a moisture measuring system to be applied on the line so far,” Petz explains, adding that “we never got any inquiry from customers to provide such a device, but are always open to consider developing one should sufficient demand occur.”

A Reliable Reference Method

MT-CA uses the time-tested and extremely reliable drying oven (a.k.a. drying chamber) method to analyze moisture content, which has several advantages over other analyzing methods like, for example, NIR (near-infrared reflectance) metering. For one, the drying chamber method is a globally recognized reference method; in other words, no special calibration for different sample types is necessary. Secondly, the gentle and uniform drying process ensures precise results, determining the moisture content of any sample with an accuracy of +/- 0.1%. The analyzer also saves time as it can handle up to 10 samples simultaneously. User or environmental influences (which can potentially falsify test results) are minimal as the sample feeding chamber is part of a closed system. Explains Petz: “Since MT-CA operates independent from surrounding influences, the system provides high-accuracy results with an error margin of than 0.1% in readings, which is negligible, especially when compared to the [manual] drying oven method where test results always depend on the prevailing environmental conditions in the lab, like air temperature and humidity. Flaws like improper sample handling between oven, desiccator and finally the measuring scale also are not relevant for MT-CA since it is a closed, integrated measuring system.”

Is it Water or Something Else?

But Petz does concede that even the MT-CA unit is unable to determine whether the evaporated substance mass is indeed only water moisture or perhaps also some other volatile substance. “Such distinction cannot be 100% achieved based on the analyzing method, of course. But since for tobacco we use a very low drying temperature of 110°C in accordance with European Commission regulation (EC)2182/2005], the influence of other evaporating substances is very low compared to water moisture, thus negligible in this case.”

Not Mobile but Remotely Accessible

The unit is not intended for mobile use, but strictly stationary. “It is placed in the lab and operated there by lab staff,” says Petz. However, Brabender’s terrific-looking proprietary MetaBridge software, which can be integrated into the customer’s company network, nevertheless permits a certain degree of mobile deployment. “The software is web-based and allows tracking of the results independently on different devices like mobile phones, tablets or PCs from any location anywhere in the world and anytime through a simple browser log-in,” Petz elaborates. “Several users can simultaneously retrieve measurement results in that way and the software also enables cross-platform monitoring. Our customers see this as a big advantage because they can access test results wherever they are needed, for instance in the raw material reception area in a warehouse at a remote location.”

Stylish Design for Decentralized Working

The software’s interface boasts a contemporary, attractive tile design, with individual tiles giving access to a multitude of operator-friendly applications and possible network options, including responsive web design. “The intelligent software automatically adapts to each monitor resolution or screen size, meaning that it is also ideal for mobile end devices,” says Petz. Independent devices at their respective laboratory workstations can thus be linked to devices at decentralized workstations, for example in home offices. “This multi-access feature saves time thanks to the continuous exchange of information between team members involved, but also when it comes to decision making on the part of those responsible for quality management,” asserts Petz. “And of course a company’s entire measurement results can be saved and managed centrally so that every user can access data and documentation for any defined equipment environment.” Last but not least, MT-CA also allows the generation of in-house standards for tobacco moisture measurement. “These standards can be stored in the MetaBridge software in order to draw comparisons with production processes,” concludes Petz.

Meanwhile, yet another long-standing Germany company, TEWS Elektronik GmbH & Co. KG, offers an entire phalanx of moisture-measuring instruments under its MW range. All models within the product range deploy the microwave method, whereby the material to be tested is subjected to resonant wave frequencies. A change in amplitude and frequency shift is monitored and from that the moisture level can be calculated.

A Veritable Range for Any Need

The smallest model in the range is the portable and light-weight, hand-held, single-application MW1100, which permits for quick and accurate monitoring of moisture on the line, at goods receiving stations or in quality control departments. However, the microwave penetration depth is only about 5cm.

More sophisticated are the models MW1150 and MW4300/4310, which besides testing finished product also can be used for moisture readings of raw tobacco such as leaves, lamina or stems if they are fitted with an appropriate sensor head. Next in the line-up would be MW4420, a unique filter and cigarette/cigarillo test station for finished product. The range is rounded out with MW4430, specifically designed to measure moisture in cigars. “However,” says the company’s global key account manager Jürgen Kröger, “apart from moisture content the TEWS MW technology simultaneously also determines product density at the same time.

That is why we can also calculate the tobacco weight in a cigarette, determine NTRM in a tobacco rod on a maker machine, can see capsule positions in filter rods and so on.” TEWS even can provide a solution for measuring moisture and density of incoming bales and outgoing C48 in GLT with its microwave transmission system MW-T (see side box) and all the way through primary processing via its MW4260 sensors that are installed at different stages in the production process.”

Lightning Fast, Hazard Free Metering

“It is very fast. It takes seconds instead of minutes or even hours required for oven methods. There are no complex regulations to follow like with nucleonic systems, for example, and the method is hazard-free, thus safe,” Kröger extols the advantages of the microwave method over other measuring methods. Moreover, when compared to the NIR method, both surface and core moisture can be determined independently of product color, surface structure or ambient stray light. Unlike with a measuring rod that has to be inserted into the product, the microwave sensors can be deployed for direct measurement during product flow and even under high-speed conditions. Easy operation, no wear and tear (thus low maintenance) and no need for sample preparation are further advantages, according to Kröger. While calibration of the units still is needed, it is straightforward and detailed in the accompanying manual. “The intuitive user interface is guiding operators through the entire process, so even a basic user can perform measurement with very little training,” Kröger assert. “But of course we do provide extensive training and additional technical information for advanced users as well as service technicians through our distribution or servicing partners.”

One of the largest of these official TEWS distributors and servicing partners is U.K.-based Cerulean, carrying the whole MW portfolio. But the company also offers its very own moisture metering instruments in the form of its C2, Quantum and QTM range, all of which are used on final product including cigarettes, cigarillos, and filter rods. And just like the TEWS models, they are utilizing the microwave method.

Banking on NIR Technology

Sensortech’s prime and latest moisture metering instrument is the NIR-6800, which was launched only in 2014. “Our engineering philosophy is firmly rooted in our commitment to the process of continuous improvement of our instruments. This guarantees that our customers are receiving the latest developments in NIR technology currently available,” McCallion says. And compared to its now obsolete predecessor, NIR6800 can indeed offer a long list of improvements including reduced influence of ambient noise, greater intensity of measurement, reduced height sensitivity, better durability and reliability due to its new modular construction. The unit also is very simple to set up and operate.

Suitable for GLT and Primary

Unlike many of the other moisture metering instruments we have so far introduced in this article, the NIR6800 is not primarily deployed on the production line, at the cigarette maker or in the lab, but instead is mostly used in GLT and primary processing for determining the moisture content of, for example, whole leaf, strips, re-dried cut lamina, final tobacco blend, rolled stems and water-treated stems, as well as expanded tobacco, just to mention a few.

Designed strictly for online applications, the NIR-6800 is designed for online applications and deploys near-infrared reflectance (NIR) technology to measure moisture. While metering accuracy very much depends on the location where the unit is installed, it “generally ranges from +/-0.10% to +/-0.50%,” according to McCallion.

To the Core of Business

While most of the moisture metering units introduced in the main article are used either on the line or final product, the TEWS-supplied transmission measuring instrument MW-T goes to the core of business, literally. Core moisture is of particular interest in the case of C48 boxes and tobacco bales. The MW-T allows for non-contact measuring of core moisture irrespective of product density. It has connectors for two antennae which mount on either side of the product to be tested. The sending antenna will emit microwaves penetrating through the product to be picked up by the receiving antenna on the other side. The MT’s electronic control then analyzes the signal and uses it to calculate moisture and density. Readings are stored digitally or can be printed out to labels. The transmission technique itself has been patented by TEWS.