useful service life

基本解释

This nm-class hydrophilic aluminum foil heat exchanger can prolong its useful service life for 5-10 years, although it costs 3 times more than the conventional aluminum foil heat exchanger.
虽然纳米亲水铝箔换热器的制作成本高于一般用铝箔换热器，但它却能使换热器的使用寿命延长5-10年。
Living examples in repair of air hammer parts by manual bead welding of electrical are have been introduced, which are useful for lengthening service life of air hammer parts and saving cost.
介绍了用手工电弧堆焊的方法将一些空气锤零件修复的实例，对延长空气锤零件的使用寿命、约生产成本有一定的参考价值。
Living examples in repair of air hammer parts by manual bead welding of electrical are have been introduced, which are useful for lengthening service life of air hammer parts and saving cost.
介绍了用手工电弧堆焊的方法将一些空气锤零件修复的实例，对延空气锤零件的使用寿命、节约生产成本有一定的考价值。

In practice, however, it is a formula for condemning America's armed forces to operating obsolete equipment long after its useful service life is ended -- and inviting others to perceive and perhaps to act upon exploitable weaknesses on the part of the United States.
CENTERFORSECURITYPOLICY: Center For Security Policy
Anyone who has taken a life-saving medication or paid for a useful service, for example, has left behind a profit for the provider and is thankful for the benefits received.
FORBES: Success and Social Value