What Gasket Materials are Commonly Used for Freezers and Coolrooms?07 November 2018
When seeking low-temperature gaskets, coolroom designers use their engineering skills to select suitable materials. A conventional sealing material, although compressible and surface conformable, isn’t necessarily good enough here, not if it becomes brittle when the temperature drops below zero degrees Celsius. Clearly, then, as well as all of the normal, highly desirable material compressibility features, freezer gaskets require a little something extra.
Studying Seal Fracturing Events
If a freezer seal does harden and become inelastic, then the slightest amount of material expansion will be enough to cause a sealant crack. All it takes is one tiny crack. Such fractures grow, they propagate until they compromise energy-efficient freezers and coolrooms. It’s impossible to stop a material from expanding then contracting, and it’s impossible to eliminate compressibility stress. It’s also plainly impossible to eliminate door seal strain, as caused by a forcefully closed coolroom entryway. Spring-loaded door closers help, but the mechanical stress still works its way into the portal gasket. As for the other system seals, there’s just no avoiding the material-deforming forces that are pushing down on their stiffening forms.
Equipped With Freeze-Resisting Resilience
To be brutally honest, those gaskets must endure, even when the enclosure temperature dips far below freezing point. Logically, then, if the cold is unavoidable, what can be done to fix matters? There are heating elements of course, which are designed to protect door gasket elasticity. Better yet, though, system designers opt for gasket materials that feature low-temperature performance. In profile, the door gaskets mentioned earlier tend to be manufactured out of extruded silicone. Double or triple layered, the strip geometry conserves energy. As a heavily reinforced door closes, the folded silicone uses an air cushion to protect the compressible rubber so that it squashes evenly all around the door frame. Expect this material to function when the enclosure temperature drops as low as -60°C. Of course, few freezers and no coolrooms require this degree of ultra-low elastomeric performance.
Silicone and PTFE gasketing materials retain their squashable features, even when they’re used in cryogenic applications. For more conventional applications, however, soft PVC, nitrile, and other synthetics are acceptable. Other desirable features, ones that play a role in the decision-making process here, include pressure handling capabilities, tensile strength, and even an aptitude for accepting magnetically charged additives. Easy to clean, not impacted by popular cleaning chemicals, and unaffected by sudden temperature spikes, the chosen gasketing elastomer should also be die-cut congenial and extrusion tool friendly. Incidentally, since coolrooms and freezers contain oil-laden foodstuffs, the selected rubber should be as oil-resistant as it is low-temperature capable.
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