MIL-STD-810 TEST METHOD 511.5 EXPLOSIVE ATMOSPHERE

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Jim Shaw, EVP of Engineering at Crystal Group, discusses MIL-STD-810 Method 511.5 Testing.

MIL-STD-810 Test Method 511.5 Explosive Atmosphere

Hi, Jim Shaw here from Crystal Group, just wanted to take a moment to talk a little bit more in-depth about our investigation into MIL-STD-810 and today we’re talking about method 511. And 511 is talking about explosive atmosphere. What does that mean? Well there’s essentially 2 procedures in 810 511 that have a little bit different purposes. The first procedure is can you create a product that will operate in an explosive atmosphere and not ignite the vapors? And so that’s generally in aircraft, or confined spaces where there’s not a lot of ventilation. But you have the potential for having fuel and fuel air mixture into that volume.

And so the purpose of the test is to make sure that you don’t have an ignition source in that environment. And so that is one of the tests that we look at. And the way that they do this test is they’ll actually put it in to a chamber, they’ll put your unit into the chamber and then they’ll put a hexane and an air fuel mixture together and they’ll elevate the temperature a little bit and then they’ll ask you to operate the equipment to see if it actually ignites the fuel air mixture. And so you may have to activate some switches, turn things on, turn things off. These are usually done remotely so that you don’t have to get inside the chamber obviously.

But the intent is to fully operate the equipment so that it has the opportunity to see if there’s any sparks or ignition sources that would create an explosion. You’ll see this primarily in military applications for this particular spec. Keep in mind the oil and gas industry has a completely different spec that is ATEX is one of them A-T-E-X.

Those are a similar type of a thing but they actually go down into zones and classifications where you can and can’t operate and what the level of hermeticity is required for your unit. So a little bit different specification, we can go into that some other time but this is MIL-STD-810 Method 511. Getting on to procedure 2, procedure 2 is if there is fuel inside the unit and there’s an ignition source, will it come apart? That’s really essentially procedure 2.

And so that doesn’t necessarily apply to the type of equipment we make at Crystal Group but it’s just something to recognize that there’s two different procedures for the testing. So that is a brief explanation about what MIL-STD-810 Method 511 is all about. It’s generally fairly easy to pass that with the right kind of conformal coatings and sealing and the technologies that you use. An example is no relays or anything like that that is contact-based. So that’s an explanation, thanks for listening, have a great day.

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