pressure-vacuum valve

21 LETTERS · STARTS WITH P

pressure-vacuum valve is a valid 21-letter word worth 34 points in Scrabble and 44 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

P3R1E1S1S1U1R1E1-0V4A1C3U1U1M3V4A1L1V4E1

3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 0 + 4 + 1 + 3 + 1 + 1 + 3 + 0 + 4 + 1 + 1 + 4 + 1 =34 PTS

DOUBLE WORD → 68TRIPLE WORD → 102

MEANING

What does pressure-vacuum valve mean?