Find out about the differences between IR and hot-air dryers and discover which features might be most useful to your operation.
Capacity of air-heating system It is important to have enough heating power installed to keep the dryer temperature constant, especially as the load of garments through the dryer increases. When the dryer is idle, it takes relatively little heating power to keep the temperature constant, but when we start to load the dryer with printed garments, the garments extract heat from the dryer as they are heated up to 330°F. When the hot garments leave the dryer, they will carry heat out of the dryer as they exit. The installed heating elements or gas burner must therefore have enough capacity to compensate for this sudden heat loss without fluctuations in the drying temperature.
Insulation Heat insulation is important for the cost of operation and also for the operator’s well being in the printing environment. Dryers that are poorly insulated lose a large amount of heat through their walls and into the printing room, which can cause the water-based inks in the nearby presses to dry into the screens. Therefore, 3- to 4-in.-thick insulation is recommended in addition to specially designed heat brakes—manufactured slots—that minimize the heat transfer from the hot-air duct inside the dryer to the outside of the dryer.
Exhaust hoods Although the exhaust fan removes fumes and vapors, which are then are ducted out of the dryer, it is recommended—especially for wide large dryers—to have separate exhaust hoods at the entrance and exit of the dryer to capture any fumes and vapors that can leak out through the relatively large inlets and outlets.
Access for cleaning With the time dust and lint from the garment will accumulate inside the dryer. It is important that the interior of the dryer can be accessed for routinely cleaning to avoid any fire hazard as well as maintain a clear opening of all the air nozzles to ensure high air velocity. It is an preferable that the dryer be designed with special lint filter drawers for easy maintenance (Figure 1).
Conveyor drive The conveyor drive system should be powerful and accurate enough to run at constant set speed whether the dryer is idle or operating under a full load of garments. The conveyor speed is directly proportional to the retention time, and any variation results in a change of this important drying parameter.
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