The toilet physic?
Asked by
mea05key (
1812
)
January 23rd, 2009
I am confused on how a toilet tap works.Probably because of insufficient sex these days. Kiddin’. You see when you open the tap bigger, you get larger flow rate. Correct. It directly means that the valve has bigger opening. Correct.
Try to see where i go wrong here.
When the valve opening is bigger, you get lesser pressure drop and provided that the flow rate is constant, the velocity of the water increase. OK but the fact is the flow rate is not constant ( water comes out more with larger valve opening), in fact it increases with the bigger valve opening. So is this due to compressible flow effect that for larger valve opening you get smaller pressure drop but higher flow velocity and flow rate. HELLO still with me? correct me. i knwo i am wrong somewhere.
Observing members:
0
Composing members:
0
30 Answers
Forgive me, but I must post how amused I am that the first question after the great “Fluther is down” trauma is on the topic of toilets.
Sorry to be off topic. Hope you don’t mind….
:)
Hahha no probs snoopy. I didnt realise and now that u tell me the situation , i find it amusing also LOL
I’m confused as to what a toilet tap is???? Now, flush, leak, wax ring, tank, bowl, handle, float, lid, hinge, valve I understand, but tap???? Lost me, need more info.
A faucet? Who or what supplies you with water? If it is a private well your pressure may very well fluctuate independent of the tap opening. If you are getting a pressure fluctuation it will affect the flow rate from the tap regardless of the opening size.
If you are on a city water supply, there should be no fluctuation in pressure, so a fluctuation in rate will only happen with more or less restriction of the flow (turning the handle on or off).
Am I getting close?
Im talking about city water supply.
Am i right to assume that the water flow rate does not change even when i adjust my sink tap?
Nope, when you adjust the handle, you restrict or open the supply route thereby increasing or decreasing the flow rate but only due to a larger or smaller opening, nothing to do with pressure fluctuations. The pressure with be the same with a small flow or large unless you have a limiting restriction after the adjusting handle and prior to the point where the water exits.
Okay. its logical to say that with bigger opening you get larger flow rate.
But what about the static pressure of the water at the valve and the differential pressure across the pipe? how to relate to the above?
Other factors that affects your water pressure is the size of the pipe from the water main to the house, and mineral build-up.
I absolutely hate toilets!
Stupidest invention in my book! Get a friggin outhouse for Christ’s sake! It clogs, it overflows, it costs money for tile replacement, money in the first place to install——gaah!
You should see my basement toilet….
umm..not my basement, but its a step down from my whole apt.
anyone please, can help me explain how does a sink tap work by including static pressure, differential pressure across the pipe, valve in the tap, flow rate.
That defines what I said :)
OK. I think your biggest problem here is that probably the majority of people reading this question think you are talking about a toilet (easy to see why based on your topic selection) when in fact you are asking about bathroom sinks
Please note that I am NOT trying to correct your word choice. I am just trying to clarify for people what you are asking so that you can get your question answered.
I’m lost as to why static pressure would play a part in a faucet?
Static pressure if I understand it, would only play a minuscule part, unless of course the portion of the tap that was downstream of the valve were several feet higher than the valve. Differential pressure is related to pipe size?? As you can surmise, not an engineer.
@mea05key For the life of me, if this isn’t a homework question, I cannot imagine why you care. (No offense!!!)
I took physics back in the day….but it is much too late and I am much too tired to try to fire up thoses synapses in my brain.
Hope you get your answer :)
@pekenoe
You know, there is an “Edit Response” option
[edited to save space]: vvv But in the guidelines, Spam is against the rules.
[edited to save even more space]: vvv I would not be sure of what he was talking about if I read it or not. I did. And I thought he was talking about toilets (hence the ONLY topic)
I am stopping this because it is off topic.
@90s_kid You didn’t even read the post to find out it was about a faucet before you jumped in with your toilet tirade.
@pekenoe, 90s kid knows more about toilets than anyone else in his high school. I suspect he’s somewhat traumatized by it. It may serve him well one day on a quiz show…
Thanks, alfredaprufrock! :D
@AlfredaPrufrock: Looks like a t paper expert as well, Charmin???
@90s kid: I’ll try not to Spam anyone here
Did anyone figure out what was the question really? I never knew a faucet could be so complicated.
“Toilet” was a misnomer. Faucet is more accurate—I believe the real question is “What physics principles are involved in creating water pressure when you turn on a faucet?”
@AlfredaPrufrock : exactly, good question :) I’m looking forward to an answer, even though I still may not understand it.
I do know, from watching the movie Cluny Brown (with Jennifer Jones) many years ago, that the pipe that goes up in the wall to the roof has something to do with creating proper water pressure with atmospheric pressure. In order to make water flow you have the pipes carrying water into the house, the faucet where the water comes out, and the air vent pipes that provides pressure. How the vent pipe works and how they figured it out is beyond me. you’re probably wondering what Cluny Brown and Jennifer Jones has to do with plumbing. The lead character was very adept at fixing plumbing, and had a passionate, recreational interest in it.
@AlfredaPrufrock : lost me at the air vent pipe, if there was a vent in a pressurized system it would leak? Vents are however, necessary in sewer pipes to prevent a vacuum that would hold dirty water in the pipe instead of flushing it down the tubes.
No, the vent pipe is vertical, and is open on the roof to provide pressure. Somewhere inside your walls is a pipe configuration that looks like an upside down T, with an open pipe going up to the roof. The air pressure keeps a certain amount of water from coming up the pipe, while pushing down. Laws of physics seem to affect plumbing a lot. However did the ancient Romans figure it out? Drain pipes aren’t level. When we added a separate shower in the bathroom, the plumber told me the drain pipe had to have a 15 degree slope on it’s way to the connection to the stack pipe.
Now I want a Dorling-Kindersley book on plumbing!
Answer this question 
This question is in the General Section. Responses must be helpful and on-topic.
Composing members:
0
