Keep cool! Portable air conditioners offer flexible solutions
Plant engineers can benefit from understanding the basics of how to choose and use portable cooling equipment for a range of applications.
As summer arrives, heat waves can wreak havoc with manufacturing processes while also causing miserable conditions for workers. Though plants with no air conditioning are particularly vulnerable, even climate-controlled facilities are subject to problems if an overworked HVAC system should fail or if supplemental cooling is needed to deal with excessive heat.
Portable air conditioners can often provide fast and effective solutions, and not just for hot weather emergencies. The applications for industrial plants are virtually unlimited but can be roughly divided into three categories:
- Improving manufacturing speed and/or quality through focused cooling of products or processes;
- Protecting the health and safety of production personnel; and
- Delivering cooling to non-manufacturing areas such as server rooms, equipment rooms, offices and conference rooms.
This article will investigate all three areas of application and will provide an overview of the different types of portable coolers to choose from and how to size and select this equipment properly.
Types of portable cooling equipment
There are three main categories of portable equipment in use today. Your HVAC contractor or portable cooling supplier can help you identify the best type for your application:
- Air-cooled portable air conditioners work by exhausting hot air out through duct work. Air-cooled portables are the most common system of choice because they can be installed almost anywhere, usually in minutes. One- to 5-ton units (one ton of cooling = 12,000 Btu/hr) are the most common, though in recent years the market has expanded to include 12-ton portables that are compact enough to fit through a standard door.
- Water-cooled portable air conditioners connect to an external water source. They are very efficient to operate but are best suited to use in facilities where it is possible to tap into a central cooling tower or chiller system, or in regions where the municipal water supply is plentiful and economical. Water-cooled systems need no exhaust ducts, so they are often specified when there is no convenient way to exhaust hot air out of the room.
- Evaporative coolers use an internal or external water source to lower temperatures and a fan to push the cooling vapor across the space. Though their performance is not comparable to portable air conditioners, when correctly set up in the right environment they can provide a simple, low-cost cooling option for large manufacturing areas, warehouses and loading docks -- especially in situations where budget or power supply is limited. One important caveat is that the units add cool moisture to the air and can potentially interfere with any humidity-sensitive processes within the plant. Evaporative coolers perform better in low- humidity environments since dry air is not at saturation and has a strong affinity for the cooling moisture.
Improving manufacturing speed and/or quality
Portable cooling is most frequently employed in plants to speed up production processes, to protect heat-sensitive equipment on the manufacturing floor, or to preserve raw materials or finished products from heat degradation. Following are examples of each.
A manufacturer of plastic magnifying glasses used on solar panels needed to find a way to improve output. By using a portable air conditioner to inject cool air into a specific location in the assembly machine, they were able to increase production line speed and ramp up output without having the expense of adding a second line.
Although the plant was equipped with central air conditioning, this focused “spot cooling” approach was still needed to achieve production goals. Portable cooling is used in this way in many areas of plastics manufacturing to cool parts faster and speed up production.
Similarly, gluing or bonding of parts can often be a temperature-sensitive task. Portable cooling directed at this assembly process helps ensure more precise temperature control and allows adhesives to cure at the desired speed. The resulting benefits can be increased product output, lower product rejection rates or both.
Sometimes product needs to be cooled prior to bagging or packaging operations. In the fertilizer industry, pellets of fertilizer are spot-cooled using portable air conditioning before they go into a feeder that dispenses measured amounts into bags. If not properly cooled in this manner, pellets can gel and cause the feeder to jam, resulting in line shut-downs and maintenance headaches.
There are many similar applications in food and chemical processing. If powders become too warm, they tend to gel and clog machinery or cause the manufactured end-product to clump together. Portable cooling directed at conveyors, hoppers or at other points where finished product is being transported and collected at the end of the manufacturing process can help guard against these problems. Targeted cooling of bakery items and candies coming off the line is also common, allowing product to be packaged more quickly in order to speed production throughput.
Powder coating is another process that benefits from spot cooling. A manufacturer of metal air conditioner components has used portable air conditioning for years in the area where metal parts are being powder-coated, for the dual purpose of cooling the process and assembly line personnel.
Protecting equipment and product
Sometimes the role of portable air conditioning is not to cool a process but rather to protect equipment, raw materials or finished products from heat damage. For example, laser-cutting machines often depend on heat-sensitive electronics to control the process. If electronic controls overheat, they can malfunction and cause the machine to shut down, resulting in costly downtime. Similarly, printing presses are subject to jamming in hot and humid environments. By reducing humidity as well as temperature levels, portable cooling is an effective solution.
In the packaging industry, the shrink sleeves used to wrap a variety of food and beverage products come in enormous rolls of plastic sheeting. A packaging converter found that hot and humid conditions in the non-air conditioned storage room would cause the sheeting to deteriorate, resulting in costly loss of material and production slow-downs. Several large portable coolers installed in the storage room now keep the area cool during summer months to avoid further problems. Warehouses that store finished products such as chocolates are also common locations for portable cooling, to prevent inventory from melting before it leaves the plant.
Keeping workers cool
In addition to the obvious comfort factor, portable cooling directly impacts safety by reducing heat-related fatigue, illness and accidents. It can also improve productivity and morale. Portable units can be moved around to different locations and easily installed to deliver spot cooling to the most demanding production areas.
At a steel pipe and tube plant, the use of a 5-ton portable cooler in a galvanizing area succeeded in bringing ambient temperatures down by as much as 30 degrees F. Instead of being limited to 30 minutes, crews can now work for two hours in the galvanizing area before needing relief for ergonomic (not heat) fatigue. There have been no heat-related illness problems in the plant since installing the cooler. That is compared to four to five incidents per year over the previous two seasons, and twice that number in prior years. As a result, the manufacturer plans to bring in more portable coolers to handle additional processes in the galvanizing shop this summer.
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After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.
The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.