Britain’s Meggitt Plc has agreed to acquire Danaher Corp.‘s [DHR] Pacific Scientific Aerospace business for $685 million, boosting its presence in key commercial aerospace programs and on defense programs.

Pacific Scientific Aerospace had $378 million in sales last year and contributed 7 cents earnings per share to Danaher’s bottom line. Sales are roughly split between defense and commercial customers. Commercial customers include Boeing [BA] and Airbus.

The business unit designs, develops, manufactures and markets smoke detection and fire suppression systems, energetic material systems, electronic security systems, linear actuators, electrical power generation systems and submarine periscopes and related sensors.

The deal is expected to close in the second quarter of 2011. Danaher is a diversified engineering and manufacturing firm with $11.2 billion in annual sales.