Pressure Dew Point in Compressed Air: What Is It and How to Measure It
July 17, 2018
Compressed air is often used during the manufacturing process for a variety of purposes, including cooling, heating, powering tools, cleaning, and nitrogen production. Yet in the processes of compressing air, the air is generally cooled to a point that creates a film of condensation on the equipment. Some dew point condensation is common in manufacturing, but an excessive amount can damage nitrogen systems and compromise the quality of the products.
In order to create quality products, there is a standardized level of dew point allowed on compressed air machinery. The machinery must be consistently monitored to ensure the dew point temperature is at a normal level — and the condensation is within a normal range.
What Is Compressed Air Dew Point?
Dew point is the temperature at which water vapor is condensing at the same rate liquid water is evaporating. At dew point temperature, air is saturated with water vapor.
In compressed air manufacturing, dew point levels must be checked consistently to ensure the condensation doesn’t damage equipment or contaminate the compressed air with water particles.
What Is Dew Point Temperature of Compressed Air?
Just like any dew point, the dew point temperature of compressed air ranges from 50 degrees Fahrenheit to -94 degrees Fahrenheit. Dew point temperature is defined as the temperature at which dew point will form and create condensation. If not monitored correctly, this can affect the machinery in a manufacturing plant in a variety of negative ways.
Why Does Instrument Air Dew Point Matter for Industrial Settings?
According to CS Instruments, “meeting a certain moisture degree or dew point/pressure dew point is the basis for a permanent failure-free plants operation.”
The dew that settles on machinery in a manufacturing plant not only gets into the compressed air and contaminates it, but it can also corrode machinery and metal pipes. This can cause breakdowns in the manufacturing process or delay the process altogether.
The various types of dew point instruments include chilled mirrors and capacitive sensors. Capacitive sensors include aluminum oxide, silicon oxide, and thin film polymer. Depending on the temperature, dew point, and humidity, a different sensor should be used to detect and measure the air dew point.
Standards for Compressed Air
The ISO 8573.1 is the international standard for compressed air. This standard is recognized in the United States, the United Kingdom, Germany, and India. This standardization was put in place to ensure that manufacturing companies, testing facilities, and labs are all on the same page and adhere to the same standards.
The International Standards Organization (ISO) requires that the compressed air is tested in three categories for contaminants. These categories include maximum particulate size, maximum dew point temperature, and maximum oil content.
This testing will determine if the compressed air is safe for continued use. If it is not, the products may be contaminated and the machinery could be compromised.
How to Measure Dew Point of Compressed Air
The dew point of compressed air is measured by a dew point sensor. There are several types of dew point sensors that are specifically designed to measure different levels of dew points. It’s important to use all of the sensors, as a particular sensor may not detect the levels of dew point they were not designed to detect.
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