ELECTRIC RADIANT PANEL TESTING: HARDWARE MAINTENANCE PARAMETERS KHANG D. TRAN, Ph.D. THE MEXMIL COMPANY SANTA ANA, CALIFORNIA, USA INTERNATIONAL AIRCRAFT MATERIALS FIRE TEST WORKING GROUP MEETING, 06/2003, HAMBURG, GERMANY

MEXMIL RADIANT PANEL TESTING SYSTEM Control panel Water supply Radiant panel Exhaust Burner

RADIANT PANEL TESTING RESULTS EQUIPMENT SETUP PARAMETERS OPERATIONAL PARAMETERS MATERIALS/SPECIMEN PARAMETERS HARDWARE MAINTENANCE PARAMETERS PARAMETERS THAT COULD AFFECT RADIANT PANEL TEST RESULTS This presentation describes how the hard-ware maintenance parameters affect results of a radiant panel test

POWER CONTROLLER CIRCUIT BREAKER FAILURE ELECTRIC RADIANT PANEL CORROSION RESISTANCE OF HEATING ELEMENTS BURNER TIP CLOGGING

A Watlow electric radiant panel including 6 stainless steel radiant emitter strips are used in the system. Maximum operating temperature: 1300 ºF Strip resistance: 11.2  /16 Amp each phase OBSERVATION: TEMPERATURE AND HEAT FLUX READINGS LEVEL OFF BEFORE REACHING SETPOINTS VERIFICATION:  Temperature of heating strips is not equal.  Strips are not uniformly red hot.

1. Check the fuses (using an Ohm-meter or a Continuity Checker) 2. Check the strip resistance (using an Ohm-meter) Each strip should read 11.2  (Watlow strips) 3. Detect any corrosion signs: High temperature corrosion occurs due to the interaction at high temperatures of gases, or solids with materials. 4. Check the current intensity for each phase using a clamp-on ammeter (qualified electrician is required) R UNPLUG THE POWER CORD TO PERFORM MEASUREMENTS A typical clamp-on ammeter The electronic circuit of the strips

BURNER TIP MAINTENANCE Flue way/Air inlets clogged Flame turns yellow, gets weaker, Burner orifice dirty and curves up. Gases are burning off The inner blue cone becomes blurred SPECIMEN THE BURNER TIP SHOULD BE CLEANED USING ULTRA-SONIC BATCH CLEANING

A clean burner tip produces blue flame with bright inner cone

A BLUE FLAME MEANS A complete combustion A higher flame temperature A higher heat transfer rate WHEREAS A YELLOW FLAME EXHIBITS An incomplete combustion A lower flame temperature A lower heat transfer rate TEST RESULTS ARE UNPREDICTABLE Surface burning occurs instead of flame penetration into supporting layers. This could make the process of flame propagation (on the surface of the specimen) unpredictable.