PI 8-8-13 The business end of the PMT-330 — the knob and ring form the antenna.  The antenna projects an electric field into the material that the PMT-330 uses to detect the level of water present.

Plugged In

Seeing into walls and cookies: SensorTech Systems Inc. of Moorpark solves moisture issues

By Karl Geiger 08/08/2013

What do gypsum board, cookies, clothing and wheat have in common?

Water.  More specifically, levels of water, that is, the product’s moisture content.

Readers may recall reports about toxic houses in Florida and other southern U.S. states.  The walls of these houses began to mold, and their wiring and plumbing began to rot.  One of the underlying reasons was, the imported gypsum board (wall covering) contained too much water, which promoted fungal growth in humid climates.

Gypsum board is made to exact specifications. It is formed and then kiln-dried to make it hard, durable and stiff. Too dry and a board becomes brittle and unsuitable as a building material.  Too wet and the board sags or it can mold, leading to “toxic house” syndrome.

Likewise for cookies. Nice, chewy cookies (or conversely, crispy-crunchy cookies) have exact specifications for moisture.  Too wet is too gooey and the cookies fall apart; too dry and they shatter into crumbs and dust in the package.  Similar problems occur for fabrics in their manufacture, or wheat in storage and processing.

SensorTech Systems Inc. of Moorpark has an answer.


Portable Moisture Tester model 330 is a hand-held tester.

SensorTech (www.sensortech.com) makes devices that scan materials during their manufacture or handling to detect how much water they contain. The company’s sensors use either the company’s patented dielectric effect or near-infrared (NIR) methods. SensorTech’s technologies are noninvasive and work at high speeds. In the case of gypsum board, an array of SensorTech sensors thoroughly check the full width and length of each panel on the production line as it whizzes by at several meters per second.

The dielectric method relies on tuned radio circuit. The sensor circuit sets up an electric field inside the material to be tested.  The electric field spreads out and penetrates beneath the material’s surface for several centimeters.  The amount of water in the material affects the electric field’s strength, and the radio circuit reads the field change by shifting frequency — it changes tune.  Calculations based on the field change determine the moisture level.

The sensors themselves are made of solid metal and plastic so they are very robust and durable. For gypsum board sensors, they are mounted in arrays that can withstand the harsh manufacturing environment, which includes workers walking across them or accidentally dropping things on them. The sensors have no moving parts to wear or fail, and they can detect moisture in uneven or bulky materials. They can even test materials that are passing though pipelines. SensorTech’s high-temperature and ultrahigh-temperature sensors are capable of operating in temperatures up to 500°C (932°F), and sanitary sensors may withstand total immersion.

SensorTech Systems supplies detectors to many industries where moisture specification is critical: wood products such as plywood, veneer and particle board; coal and asphalt; roofing tiles and shingles; food, candy, food powders and animal feeds; and the textile industry, both for bulk fiber and woven and finished fabrics.

The company has been in business for 25 years. It has offices throughout the U.S. and Canada and regional offices in Europe, Australia and the Far East. Manufacturing and service takes place in Moorpark, and many parts are sources from local electronics suppliers in Ventura County.

In addition to its industrial products, the company also makes a portable, hand-held device that can be used anywhere by anyone. Contractors or building and health inspectors can use it to “see” the moisture content inside walls to determine if materials are defective or if a health hazard is present. The unit is sealed and has a simple readout that makes it easy to understand.

SensorTech Systems moisture sensors are found in nearly every gypsum board plant worldwide.  The company is continuing its research and development in Moorpark to expand its line of business products in new industries and with new applications. The company offers full design and development services so it can satisfy its customers’ demands rapidly.

The next time you work on your house, build something with plywood or just eat a cookie, remember SensorTech in Moorpark.

Plugged In is a monthly column focused on new technology in and around Ventura County and it will be featured the second week of every month. Plugged In authors Bridge Carney and Karl Geiger are chairman and past chairman, respectively, for the Ventura Section of the Institute of Electrical and Electronics Engineers [IEEE], the world’s largest professional organization, with more than 800 local members in Ventura County. Please find them at www.ieee-bv.org.


DIGG | del.icio.us | REDDIT

Other Stories by Karl Geiger

Related Articles


nice. thanks for keeping us informed of local business. i would also have liked to know how many people they employ locally and companies they interact with locally. but thanks.

posted by Packer on 8/14/13 @ 09:04 p.m.

Packer - the company employs about 20 engineers, service, and support staff locally, and four sales people across North America.

The company president, IEEE member Colin Hansen, did not specify who does his printed circuit board design. Ventura County has a number of PCB makers. See http://www.yellowpages.com/ventura-ca/ci...

-- Karl

posted by karl@ieee-bv.org on 8/16/13 @ 11:31 a.m.
Post A Comment

Requires free registration.

(Forgotten your password?")