A small valve positioned in the pipe of a steam boiler or cylinder of a steam engine for drainage or testing.
- ‘They were fitted with a dial gauge, a vent port in the form of a petcock or counterweight, and a safety fuse.’
- ‘Steam for ten minutes, then shut off the steam by either closing the petcock or dropping the weight gauge into place.’
- ‘This time I put a piece of tape over the petcock opening instead of using the screw on block off plate I had made to use on the first steps.’
We take a look at several popular, though confusing, punctuation marks.