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Jim Shaw, EVP of Engineering at Crystal Group, discusses what processes are involved in MIL-STD-810 test for Method 500 Low Pressure.

Video Transcript: Episode 65 – “MIL-STD-810 Test Method 500 Low Pressure”

Hi, Jim Shaw here from Crystal Group.  Taking just a moment to do a little bit deeper dive into MIL-STD-810. There’s been some interest in going down a little bit deeper into 810 and talking about some of the methods and procedures that are more common in some of the testing that we in the industry are subjected to. I thought we’d talk today about Method 500 which is low pressure or altitude. This test method essentially has four procedures that you can test to. The purpose of the test is really looking at storing things at high altitude, or operating them at a high altitude or transporting them at a high altitude.

The testing that is done around these kinds of environments really intended to look for leaking gaskets, or deformation of containers or sealed containers bursting. You’re looking for problems specific to what happens at altitude when you’re taking your unit to and from someplace or you’re trying to operate it in that kind of environment. What kind of heights are we talking about here? And generally you’re in the 15,000 feet to 40,000 foot range in this test spec. Depending on what it is that you’re are trying to do whether transportation or operation.

There are four test procedures in this method. They are essentially storage, they are operations, they are rapid decompression, and then explosive decompression. We talked a little bit about what you are looking for, gaskets leaking, rupturing containers, things like that. In the electronics industry we are most concerned about overheating. That’s probably one of the bigger issues that we deal with.

And essentially it stands to reason as you go up in altitude, air density decreases so your mass flow rate is in effect reduced. Mass flow rate of air is how you get things cool therefore things get warmer much easier when you’re up in the altitude. That becomes the challenge. You’re also looking for things like arcing, components, anything that is high voltage. Air is a great dielectric so you don’t get spark gap types of situations.

There are four procedures. The storage procedure is essentially you know is can you store a box or a unit for a period of time at a higher altitude. There is a operational procedure that talks about can you operate a box in a mountainous environment or on an aircraft. There is a transportation procedure that talks about whether or not you can safely transport the box. Is there any damage when you fly it in an unpressurized cargo hold from the United States to anywhere of your choice.

And then the last one, which is a little more interesting is rapid decompression. And that is essentially where, take an extreme you’re flying at 40,000 feet in a pressurized container or cargo hold and there is an accident or the aircraft has a mishap and essentially there is a rapid decompression say it’s around a tenth of a millisecond from one altitude to the other, or one pressure to the other. In that case you’re looking for do you have any damage to the unit after its undergone that type of pressure, pressure change. These are all standard tests.

We see more of the operational tests and rapid decompression tests being the more common ones that we do here. You can also find similar types of testing requirements on spec like DO160, STANAG 4370. So there’s several of these types of test methods out there. There’s a European spec, an EN spec and an IEC spec. That’s just one of test methods that’s out here that we’re most familiar with and that’s MIL-STD-810 500. Thanks a lot.

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