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MIL-STD 883 Barometric Pressure Testing

MIL-883 barometric pressure testing simulates the low atmospheric pressure in the nonpressurized portions of vehicles in high-altitude flight. This test helps determine the ability of component parts to avoid voltage breakdown failures. These may result from the reduced dielectric strength of air and other insulating materials at reduced pressures. Even when low pressures do not cause electrical breakdown, corona and its undesirable effects, including losses and ionization are intensified.

MIL-STD-883 altitude, simulates the high-altitude conditions of vehicles in flight. This test can be used to investigate the influence on components’ operating characteristics. Other effects of reduced pressure include changes in dielectric constants of materials. It may also cause decreased ability of thinner air to transfer heat away from heat-producing components.

Keystone Compliance is a barometric pressure laboratory with significant MIL-STD 883 altitude testing experience. Our test engineers understand the requirements of MIL-883 altitude and barometric pressure testing. The following information is extremely technical in nature. It provides a summary of Method 1001 barometric pressure testing as drawn from MIL-STD-883K.

What Equipment is Needed in a Barometric Pressure Testing Lab?

All testing should be performed in a fully equipped barometric pressure laboratory. Altitude certification testing requires a fully equipped altitude testing lab, with altitude test chambers. The equipment needed for these labs is described below.

The test chamber for this test has a vacuum pump and a suitably sealed chamber. It should also have a means for visual observation of the specimen under test when necessary. The chamber must also have a suitable pressure indicator to measure the simulated altitude in feet in the sealed chamber. It should also have  a microammeter or oscilloscope capable of detecting current over the range from dc to 30 megahertz.

What Procedure is Used for the Best Barometric Pressure Testing?

For the best altitude testing materials are mounted in the test chamber of the altitude laboratory as specified. The pressure is reduced to the value indicated in one of the following test conditions. While the materials are maintained at the specified pressure, they are subjected to the specified tests.

During this test and for a period of 20 minutes before, the test temperature shall be 25°C ±10°C. The device shall have the specified voltage applied. It is monitored for malfunctions over the range from atmospheric pressure to the specified minimum pressure and return. If it exhibits arc-overs, harmful coronas, or other defects which may interfere with operation of it is considered a failure.

The device is connected for measurement and has the specified voltages applied during the entire pump-down cycle. The maximum voltage terminals are monitored with a microammeter or oscilloscope for corona currents from dc to 30 megahertz. Provision should be made for calibrating the current flow in the circuit minus the device, under the applicable test condition. This ensures that test readings are characteristic of the device under test.

Test Condition 

Pressure- Maximum

Altitude

Inches of mercuryMillimeters of mercuryFeetMeters
A17.3439.0015,0004,572
B8.88226.0030,0009,144
C3.4487.0050,00015,240
D1.1333.0070,00021, 336
E0.3158.00100,00030, 480
F0.0431.09150,00045, 720
G9.4362.4 x 10^(-6)656,000200,000

What are the Effects of a Low Pressure Environment?

The following describes some chemical, physical, and electrical problems that may arise when materials are exposed to low pressure environments. Sealed containers may become deformed, or they may rupture or explode. Hermetic and gasket seals may fail, allowing the league of gas and fluids. Lubricants of materials and component parts may evaporate.

As a result of the reduced heat transfer mentioned above, materials may overheat. Low density materials may experience a change in physical or chemical properties. Materials may operate or malfunction erratically from arcing or corona, this includes erratic starting and operation of engines. Altitude compliance testing helps determine the ability of material to withstand the potential effects of this environment.

Where is the Best Barometric Pressure Lab?

Keystone Compliance is a laboratory facility fully equipped to provide the barometric and altitude pressure testing. We have one of the best altitude labs in the country. Our certified test engineers understand the requirements of altitude and barometric pressure compliance testing.

Are you looking to receive a barometric pressure certification for your product? Keystone Compliance is able to provide a variety of compliance certifications for commercial, military, and aerospace products. Contact us to learn why so many manufacturers rely on Keystone Compliance’s testing services for all their compliance testing needs.

MIL-STD-883 testing contains several test methods. For more information about these test methods, please click on one of the links below.