HOW AIRFLOW HELPS (AND HURTS) CONDENSATION CONTROL EFFORTS
This week’s guest blog entry comes to us from FABTECH Exhibitor Big Ass Solutions (Booth S4179). You can hear more from Mike Robinson of Big Ass Solutions at FABTECH in Session F94: NEW! Improving Environmental Working Conditions in the Job Shop Wednesday, November 11, 2015: 1:30 PM – 3:30 PM. Mike’s presentation will focus on Condensation Abatement Through Elevated Air Speeds. Learn more here.
Spring and fall bring great weather, but they also bring a problem all too familiar to facility managers: condensation. It’s more than an annoyance – it creates dangerous conditions and ruins products, costing businesses billions of dollars each year.
As a direct-sales manufacturer, Big Ass Fans worked directly with customers to understand the problem, and members of the company’s staff of more than 75 degreed engineers visited numerous facilities in researching and developing Dewtect, a one-of-a-kind, completely automated condensation solution.
There are several ways airflow can help prevent or reduce condensation – and there are ways airflow can make the problem worse, which is why a control system capable of monitoring and predicting the possibility of condensation is needed. To understand how airflow mitigates condensation, you must learn how and why condensation forms.
HOW CONDENSATION OCCURS
Condensation forms when warm, moisture-laden air contacts a colder surface – think of a cold can of soda “sweating” on a hot summer day. That occurs because air cools next to the can, and cooler air holds less moisture. Water is deposited on the cold surface when the air cools to the point it can no longer hold moisture – commonly known as the dew point.
The same thing happens with a concrete floor or a giant coil of sheet metal or cardboard boxes. But unlike a soda can, wet floors and products can be costly.
Spring is most problematic because large, dense objects are slow to react to air temperature changes. A roll of sheet metal might hold its winter temperature for days or weeks after the weather warms up. And it can take a month or more of warm weather for the core temperature of a concrete slab to rise above the dew point.
In fall, it’s common for the dew point to surpass the surface temperature of floors, products and equipment. When warmer air moves in during the day, with it comes a rise in dew point and humidity, causing a slick layer of condensation form over colder objects. And in fall and winter, it’s common for condensation to form on product that has been moved from a cold truck into a heated warehouse.
Wet floors cause people to slip and fall, and prevent forklifts from slowing down. Slip-and-fall accidents cost $70 billion in workers’ compensation claims and associated medical costs every year, at an average of $20,000 in claims per accident.[1] Condensation also causes rust, mold and mildew, which costs businesses billions. Rust alone costs the production and manufacturing sectors $17.6 billion each year, and can be damaging to both products, facilities and equipment.[2]
HOW AIRFLOW HELPS
There are numerous factors that cause condensation, including weather patterns, heat, humidity and dew point. There are numerous ways to combat it, too, such as the use of dehumidifiers, air conditioners and undertaking massive, costly projects to seal and insulate facilities. However, one of the most cost-effective ways of combating condensation involves the use of energy-efficient equipment many facilities already own: fans. Airflow from overhead fans reduces condensation in several ways, including:
Spring and fall bring great weather, but they also bring a problem all too familiar to facility managers: condensation. It’s more than an annoyance – it creates dangerous conditions and ruins products, costing businesses billions of dollars each year.
- Reduction of stagnant, cool air: Air molecules don’t have to touch a cold surface directly to fall below the dew point and deposit moisture. Cold surfaces have a boundary layer of cool air around them. It’s in this boundary layer of air that temperatures fall below the dew point and condensation forms. Air movement generated by overhead fans can disperse this layer of stagnant air and reduce the real estate in which condensation forms.
- Raising surface temperature: Cold surfaces in warm rooms will eventually warm up due to natural convection – the transfer of heat energy from the air into the cold surface. Fans speed up the process by exposing the cold surface to warm air quickly and in greater volumes. In order to prevent condensation, the air being blown over the surface must be warmer than the dew point prior to the arrival of a warm, moist weather front. Heaters may be used to achieve this, but even the heat from equipment, lights and people, which naturally rises to the ceiling in a tall building, can be “recycled” and used to prevent condensation.
- Reducing and stabilizing humidity: Many factors affect indoor humidity levels, including perspiring occupants, evaporation from sinks and mop buckets, and steam-generating processes. Throughout the course of the day, the air in a facility can become more humid than the air outside. In that case, fans in conjunction with natural or mechanical ventilation can replace humid air with drier air from outside.
- Drying moisture: When a condensation event can’t be prevented, elevated airflow can quickly dry the water that forms on surfaces and raising surface temperature faster than would naturally occur.
