The photo above depicts an autoclave with its computer control panel situated just above the opening. This particular customer uses their autoclave to process fish in a very controlled manner so they do not damage the meat while processing. The problem is that the controls for such equipment become overheated due to the simple process of the machinery to which they are attached. There are also critical times during the processing when the door is opened and heat as well as steam in this case waft out and up into the control box above, thus heating the components inside to a level that can cause intermittent or permanent failure.
Autoclaves are pressure chambers used within industrial processes needing higher temperatures and pressures than ambient air. They are only one example of machinery that associates the use of electronics on or near the heated portion of the “machine”. Other such examples are ovens, furnaces, steam turbines, metal casting machines, injection molding machines, extrusion lines and web processing lines.
The thing that makes these kinds of applications sometimes difficult is the original decisions taken by the designer to locate the control panel in what they feel is the most appropriate and convenient place on the machine for the operators. However, as the photo above demonstrates, the heat generated by the process is sometimes the last consideration when trying to package everything in a nice, tidy package as well as to keep the machine foot-print of an already large item to be as small as possible. I’m working with the mindset that having a remote mounted control cabinet to keep the sensitive electronics away from the heat source would be the ideal situation. But as we all know, ideal isn’t always and most likely will not be what you are left to deal with.
So, when confronted with a similar situation, what is a controls engineer to do? That’s where EXAIR Cabinet Cooler systemcomes into play. EXAIR makes Cabinet Coolers to keep the temperature of those sensitive electronics down at a reasonable operating level for issues such as high process heat load as given above, or perhaps it is just a really hot summer and you are in a facility without air conditioning. We manufacture Cabinet Cooler Systems in NEMA 12, 4 and 4X configurations to cover a wide variety of application variables.
In the application above, we have recommended our Model 4825SS (NEMA 4X Cabinet Cooler System, 1700 Btu/hr., with thermostat control). The customer’s calculated heat load was approximately 600 Btu/hr. according to the data they provided. When I made the recommendation, I did take into account the periods where the heat will be billowing out of the autoclave as well, thus the reason for the recommendation of a unit one size larger than I would normally recommend. Not to worry though. The included thermostat control will maintain the cabinet temperature at 95°F (35°C) at all times without wasting precious compressed air.