Impact and water ingress tend to be the two biggest threats to any industrial electronic enclosure. But don’t underestimate the threat that chemicals can pose. It’s easy to assume that a big, tough box with a high IP rating will safeguard your PCBs from most threats. And indeed they will…but they’re not invulnerable.
For every ‘Superman’ enclosure there’s at least one ‘kryptonite’ vulnerability. Beware – even the most robust diecast aluminum enclosures can be affected by certain chemicals in the right (or rather wrong) concentrations…
Diecast aluminum enclosures are completely resistant to all concentrations of brake fluid, butanol, calcium chloride, fuel oil, hydraulic oil, potassium chloride, engine oil, mineral oil and zinc sulphate. So far so good…
But they have little or no resistance to petrol, acetone and chemicals such as chlorine benzole, methylene chloride and xylene. And only limited resistance to caustic potash solution, potassium hydroxide, sodium hydroxide, nitric acid and toluol.
So what’s the solution? Glass reinforced polyester (GRP) enclosures.
GRP enclosures offer complete resistance to a long list of chemicals. They offer superior protection when compared with other plastics such as polyamide (PA), polycarbonate (PC) and ABS.
ROLEC offers three models of GRP enclosures, each with their own technical features and benefits:
For more information, read our guide to specifying GRP enclosures.
But even GRP can fall victim to some chemicals such as acetone, ammonia, caustic potash solution, methanol and sodium hydroxide. The solution is to select different enclosure materials such as aluminum, polyamide or ABS:
Gaskets can be the Achilles heel of your enclosures when it comes to chemicals. There’s no point specifying a GRP enclosure that’s resistant to butanol…and then fitting a silicon gasket that isn’t.
Silicon offers excellent temperature resistance (-50°C to +140°C) but does not respond well to a whole host of chemicals. Get it wrong and your seal will fail, leaving your PCBs exposed to water and/or dust ingress.Chloroprene (CR) gaskets are one answer. They’re resistant to a wide range of chemicals – but even they are no panacea. They can fail when exposed to benzol, formaldehyde or xylene.
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