correct input format to record a time

Looking for content template input tag required just for time, that outputs in format hours:minutes:seconds e.g. 12:32:55

This is for recording the time taken to complete an event so 'time' must not change with locale or go 12 or 24 hour format!

My template tag below does not work - suggestions please for correct format

<perch:content id="ttrecord_time" type="time" label="Time" format="h:i:s" />

There may be a number of records and would need to be able to sort low to high

Many thanks for any help. TGIF!