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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Dianne Keating
Date posted: Tue Aug 28 13:23:00 US/Eastern 2001
Subject: Operating Environment
I was wondering if anyone could tell me the conditions that must be met in order for a system to be considered as operating in a ground fixed, uncontrolled environment (GF, GU). Thanks in advance! Dianne


Subject: Operating Environment
Reply Posted by: Gary Sunada ( )
Organization: Reliability Analysis Center
Date Posted: Wed Sep 5 10:17:55 US/Eastern 2001
Ground Fixed (GF) conditions are defined in MIL-HDBK-217 as “moderately controlled environments such as installation in permanent racks with adequate cooling air and possible installation in unheated buildings. The conditions are: Temperature (deg.C): -40 to 50 Solar radiation (BTUs/sq.ft/hr.): 0 Shock – lo & hi(g): 0 Shock – period (msec): 0 Humidity – lo and hi (%): 5 to 95 Random Vibration – lo freq (Hz): 2 Random Vibration – hi freq (Hz): 60 Random Vibration – lo g: 0 Random Vibration – hi g: 5
Ground Uncontrolled (GU) takes GF to the next level in severity by exposing the unit to the external environmental elements, subjecting it to numerous outside influences, such as rain, salt/fog, hail, wind and direct sunlight (solar radiation). Conditions for this include temperatures from –45 to 60 deg. C, solar radiation at 360 BTUs/sq.ft/hr, shock at 1 to 10g, humidity at 0-100%, and random vibration levels at 1 to 10g.

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