Figured It Out!
There was this awful noise that I’d sometimes hear in my room at school. It sounded like a machine in the walls suddenly turning on. Sometimes for a half a second, sometimes for a minute. On and off, on and off! It’d come on a bit more around 11am or so so I thought it might be related to kids going to the nearby bathroom. When it was happening and I had the opportunity, I’d run around the building looking for the source. It wasn’t the air conditioning, wasn’t the bathrooms, wasn’t the heaters, wasn’t the neighboring classrooms playing with power tools. I talked to the school custodian, to the neighboring teachers. But they all thought I was mad. I wasn’t mad! I wasn’t! I swear it!
Then, a few days ago, more than a YEAR after first noticing the sound, I found it! A water hammer in the sink of the classroom two doors down. So simple! When the kids were cleaning up from morning work, they’d turn on the water. Curiously, it was quieter in the room with the offending sink than in mine.
I got the most joy when Ms. S. the teacher one door down told me how for the last DECADE she was explaining-away that horrible sound to her students. We were both beaming!
I went to the custodian and explained what was going on. We wrote up a work order for the plumber together. And 3 days later, with one gentle turn of a wrench, the problem dissolved into the mists!
There’s a really interesting style of pump that uses the water hammer effect to move water uphill to holding ponds usually. It’s called a hydraulic ram, and it uses the water hammer to lift a check valve.
Wikipedia has some pretty neat diagrams of the system.