Moisture is a broad term, encompassing a number of constituent properties derived by the presence of simple water to complex plastics in process control industrial applications. The advent of near infrared (NIR) technologies has opened wide vistas of moisture sensing and measurement enabling precise control within fractional percentage points of relative moisture content.
In some cases, simple analogue measurement by traditional means – for example, wet/dry bulb hygrostat or psychrostat devices for humidity control – is sufficient for routine air-washing or dehumidification. In the case of precision electronic assembly, pyrotechnics or explosives manufacture, or ambient humidity test and measurement for the tobacco or wood-curing industries; moisture tolerances are critical for controlling product production processes.
In general, moisture content is detectable in three constituent groups: Hydroxides (HO), Amides (HN), and polymers (HC). Humidity and dampness is usually associated with water-bearing air. The presence of nitrogen and hydrogen is a significant constituent of fertilizers, explosives, and ammonia processes. Hydrocarbon moisture monitoring is important in the manufacture of plastics, fuels, fats and other food processing. NIR uses various wavelengths to distinguish, qualify and quantify moisture content levels from near 0% to approximately 95% saturation and potentially beyond to super-saturation.
There are three basic criteria for moisture control in industrial environments. The first is detection, which detects the presence or absence of moisture. The next level of moisture processing is measurement, used to determine relative levels of moisture content. The last is performing actions based on various sensory inputs to control a device.
To effect a proper solution for moisture control, it is necessary to perform moisture analysis. This can range from extremely simple measurements involving temperature, pressure and volume with basic formulae to determine an appropriate solution. It can be extremely complex, requiring frequent sampling, checking the presence of multiple chemical compounds from any or all of the three major moisture sources; with sophisticated frequency and spectrum analysis used to identify, target, range and calibrate appropriate moisture control mechanisms.
Unattended operations need either automated timers, psychrostats or computer-controlled and monitored sensors. Moisture analysis associated software should be intuitive, flexible, platform independent and trouble-free. Backup systems in the event of a catastrophic monitoring failure or equipment dysfunction should be installed for critical processes. Human-readable interfaces in the form of analogue gauges, digital readouts, or monitor screens enable operators to determine any or all test and measuring devices, moisture sensors, moisture detectors and similar moisture determination technologies.