A tank type toilet flushes by dumping the water from the tank into the bowl. When the tank is empty, the flush is over. But what makes a valve type of toilet stop flushing?
We have two adjacent stalls at work - one toilet flushes for about five seconds, sometimes barely enough to get everything down on the first flush. The toilet in the stall right next to it will flush for a minute or more. I can flush, leave the stall, wash and dry my hands, and be walking out the door and the toilet will still be flushing. Why such a big difference?
tank toilets have a flapper valve that closes with gravity when the tank is empty and is held closed by the pressure of the water. if the valve does not open far enough it may have a short flush.
I’ve seen other kinds of valves that simply have some kind of internal timer. Sort of like the flush-handles on urinals, or water faucets where you press for the water to flow, and, after a bit, it stops again. Some kind of pressure-vs-friction arrangement.
The Wiki article on flushometer (which, to be fair, is not a word one would know to Google for) has a quote from the original patent (#977,562) on how it works. Basically, the mechanism consists of a small pressure chamber that controls a main valve. When you hit the lever, you empty the water out of the pressure chamber, which moves a diaphragm that releases the main valve, and allows water to flow into the toilet. The pressure chamber then refills through a small opening, and once the chamber is repressurized, it closes the main valve again.
The amount of time that the main valve stays open is therefore determined by how quickly the water flows through the small opening mentioned above. If it’s gotten clogged up with mineral deposits over the years, it would take longer for the pressure chamber to refill, and therefore leave the main valve open for longer.
Sometimes a bit of sand or something will get in the works, the usual service is to disassemble, clean, and put back together. Sometimes just turning the water on and off when it’s running can dislodge the sand (the fitting right before the flush valve is usually a 90 with a stop, remove the cap to reveal a screwdriver slot that opens and closes the isolation valve.)
At the top of the valve is a diaphragm with a pin size hole in it. City water pressure is introduced into the valve under the diaphgram. The diaphgram has a valve disk in the center of it. The city water enters the valve body as water enters the body it also goes through the pin hole to the top of the diaphgram. The water pressure builds on the top and pushes the diaphgram and valve disk down shutting off the water flow.
When the flush handle is pushed a lever is push in the valve body. This lever hits the “relief valve” relieving the pressure on the top of the diaphgram and the pressure under the diaphgram pushes everything up opening the valve.
Sorrr about the right up but I am doing three things at once.