SEDL / STP / STP1395-EB / STP12487S

Investigations about Oxygen Fires in Electronic Circuits of Medical Devices

Kohl, H-J
Dr. and engineers, Design and Development Intensive Care Systems, Dräger Medizintechnik GmbH, Lübeck,

Morbach, A
Dr. and engineers, Design and Development Intensive Care Systems, Dräger Medizintechnik GmbH, Lübeck,

Degenhart, R
Dr. and engineers, Design and Development Intensive Care Systems, Dräger Medizintechnik GmbH, Lübeck,

Pages: 13    Published: Jan 2000

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Abstract

For the purpose of designing safe medical devices in the presence of oxygen we investigated two aspects of circuits. First, we examined the ignition of adjacent material by sparks, generated by opening contacts of solder tin in pure oxygen at ambient pressure under different electrical loading conditions. Second, the burning of electronic circuits in an oxygen chamber at 300 or 500 kPa absolute pressure and 21% or 25% oxygen concentration after ignition with a tantal capacitor was studied. Safe values of power for resistors and energy for capacitors and inductances are concluded for circuits with a supply voltage less than 30V. Measures to avoid burning in an oxygen chamber were defined.