OK you engineering and fluid dynamics types...

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Patriot

Isabella is Lazarus
Joined
Dec 2, 2008
Messages
4,677
Reaction score
92
Location
Metairie, LA suburb of Ole Nawlins'
I'm wondering ???

My dogs water bowl has a 5 gallon jug that sits in a hole and feeds the bowl just like the jug of water Kentwood delivers for your water dispenser at home

I pull that empty jug out, place it in the sink, and pull out the flexible hose nozzle from the faucet (one of them fancy delta faucets)

I'm too lazy to stand there for 5-7 minutes holding the nozzle over the hole in the spout of the bottle and wait for it to fill with 5 gallons of water (OK what's the average flow of a air rated nozzle outta the sink?)

So today, I rubber banded with figure eights the nozzle to the spout to hold it while it fills and putter around the kitchen doing other things like dishes while it fills. All was well, but as I watched it, I wondered if it's OK to time it once and on later fills, set the alarm for appropriate time and buzz notice, and go into another room and not watch it at all because what I'm doing is safe and secure.

So question of the day ???

does the force to remove the nozzle from the spout and pressure against the rubber bands INCREASE with time as the jug fills.

at first I said no, but then see that the distance from the opening of the faucet to the surface of the water in the jug DECREASES with time and wonder if force on the faucet pushing it off the mouth of the spot is increasing with time. I'm guessing yes and the most dangerous time for calmanity is at the end of the fill and maybe I shouldn't leave it unattended after all since there's no guarantee the rubber band thingys working OK at the beginning of the fill, will continue to work under increased force/pressure toward the end of the fill.

any comments or analyis for this curious layman...?

 
Assuming you don't have an air tight seal at the nozzle to jug union, the pressure doesn't change. As water fills the jug, air is constantly being pushed out and with an equal flow of water, there will be an equal pressure the entire time.

There is no increased pressure at the end. Now just go outside and use the garden hose, it will only take a minute that way.

:dribble:

 
Assuming you don't have an air tight seal at the nozzle to jug union, the pressure doesn't change. As water fills the jug, air is constantly being pushed out and with an equal flow of water, there will be an equal pressure the entire time.
There is no increased pressure at the end. Now just go outside and use the garden hose, it will only take a minute that way.

:dribble:
Correct. No change.

Try the tub instead of hauling all 40+ pounds around, faster than the sink

 
So the short answer is, yes the water pressure against the nozzel insreases as the jug fills. The air pressure felt by the nozzell remains almost constant.

Detail:

The one thing you need to watch out for is Mr. Newton (2nd law specifically). As the water level rises, OCfjr is correct that the air will still be coming out at the same rate (the rate of the water pouring in has not changed, therefore the rate of the air coming out will not either.) However, as the water level in the jug gets closer to the nozzel, it will put a greater force on the nozzel itself and that is what will cause the nozzel to dislodge from the mouth of the jug and giving you the opportunity to see how dry you can stay while trying to get to the faucet to turn it off. :assassin:

 
Detail:The one thing you need to watch out for is Mr. Newton (2nd law specifically). <snip>, as the water level in the jug gets closer to the nozzel, it will put a greater force on the nozzel itself and that is what will cause the nozzel to dislodge from the mouth of the jug and giving you the opportunity to see how dry you can stay while trying to get to the faucet to turn it off. :assassin:
I would agree with that, except for the fact that the pressure generated by an aerated sink spray nozzle is pretty minimal. It's for rinsing off dishes, not blasting paint. ;) The 'backpressure' ,if you will, against the nozzle will increase, but not a significant amount, in this case.

 
To give you a solution that works:

5 gallon water bottle? Sounds like a big dog. A dog big enough to drink from a small sink or the like mounted to the floor. You could then use a float valve from a toilet to fill the sink (or plastic tub, etc) automatically as the water is drunk, evaporates, or spills out everywhere. Then you never have to change a bottle again. I suggested the sink so you could turn off the supply, drain, and clean it occasionally.

 
Holy cow.

We have the same pet watering water dealio here. Two dogs, (and 3 cats) drain that 5 gallons in less than a week.

No, the fill rate will not change during the fill.

Why?

Because the back-pressure cause by the displaced air is insignificant as compared to the water pressure out of the spout.

But here's a wicked simple tip for you: Forget about it.

What happens if you are too late returning to the filling jug?

The jug over-fills in the sink and the excess water goes down the drain! :eek:

Oh the horror!!!

 
Last edited by a moderator:
Top