------------------------ From: "WOODS, RICHARD" <[email protected]> Subject: Water Damage to Chambers Date: Tue, 1 Sep 1998 13:38:22 -0400 To: 'emc-pstc' <[email protected]>
> As part of our hurricane preparedness, we have to consider what would happen > to our EMC chambers if they get wet. > > 1) Can anyone provide some real life guidance on the ability of the > laminated walls (steel and wood) to withstand a good soaking? It depends on the quality of the panel construction. (We are assuming a modular romm construction, with the typical 3/4" plywood, 48" by 96" panels with a 26 gauge galvanized steel sheet laminated on each face.) If you get a flood, or persistent rain, you will get water into the wood edge. If the panels are made of marine-grade plywood (not likely), you will fare better than if the plywood is AC grade. The wood will swell, possibly cracking some bolts along the clamping rails. Replacement of bolts or blind nuts is a pain! After the wood is dryed out (and this may take days), you will definitely have to retorque the clamping bolts (thousands of 'em). You will also have corrosion problems; mild to horrible. Even if you start the drying process immediately, small nicks in the rails will start to rust. You may have to remove some of the clamping rails and send them out for re-plating. You will have problems with contamination of the underlayment; ie, the 1/8" fiberboard and the sheet plastic (Visquene) used to isolate the room off of the parent room floor. This may take a long time to dry, fungus growth might start, isolation might be permanently impaired. You will have problems inside, too. Your vinyl floor tile may come loose. Depending on the height of the flood, you may have to clean out wiring conduits and boxes. And your foam absorber material might be destroyed, or at least, be a messy and long task to dry out. This is beyond the scope of your question, but I once had a Lindgren copper foil room and a Universal bronze screen room seriously damaged by a 1/2" deep flood. I came in one morning to find a slurry of green goo all over the concrete floor. It seems that my industrial neighbor ran a NiCad battery operation, and the concentrate KOH used in their process corroded its way through the concrete block wall between us. When I took the rooms apart, I found that the chemical had removed all of the copper from the floor panels; all I had was gooey plywood! > > 2) Also, what is the most advisable fire protection method for inside of > chambers: water, CO2, other? Halon is nice, but is no longer environmentally correct, as it is a fluorinated hydrocarbon. After all I have said above, you may get the idea that water sloshing into your room is almost as bad as a fire. CO2 is good, but you need tankage and plumbing for room-size protection. At least CO2 is cheap. Watch out for safety people worried about sudden overpressure, chilling and breather hoods for providing personnel escape time. They may also want your room door to have a "panic-bar" internal release mechanism. Consider trying to make the case that the chamber is inherently safe. Not normally occupied, very low fuel within room, equipment under test consumes little power and generates little heat, all power removed at night, external power disconnects, always monitored during use. Parent room is already fire protected. BTW, I have always added an extra air exhaust port (sometimes called a "speaking panel" to the shielded room wall very near to the test technician's station. This allows internal air to gently blow out toward my technicians, giving them a rapid alert to toasting insulation. > > > Richard Woods > Sensormatic Electronics > [email protected] -------------------------- Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: [email protected] Date: 09/01/1998 Time: 12:10:10 -------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators).
