Building an Under Car Washer--Water Pressure Question

[ski2]

Wandering around the plumbing department at Lowes today figured out how I could build an under car washer out of PVC pipe for about $15.

Basically a 3/4" pipe (with angle adapters) attached to the hose (with a female hose bib attachment) with 3-4' to go under the car.

At the end of the 3/4" pipe a "T" adapter so the actual washing portion (2-3' PVC with multiple small holes) would run 90 degrees to the handle.

So here's the question: Would the water pressure coming out of the holes in the 2-3' PVC used for the washing portion be higher if this portion of the pipe was 1/2" or would the pressure be higher if this portion was 3/4" like the water delivery portion of the device??

Basically like this device The Underwasher :: Hose accessory that lets you clean under your car, RV, boat or ATV! but with the actual washing portion running 90 degrees to the longer pieces--I think it would be easier to handle this way.

[FUNX650]

So here's the question: Would the water pressure coming out of the holes in the 2-3' PVC used for the washing portion be higher if this portion of the pipe was 1/2" or would the pressure be higher if this portion was 3/4" like the water delivery portion of the device??

Fluid Dynamics, specifically Bernoulli's Principle, is where you'll find the definitive answer to your question regarding any possible pressure differential between the 1/2" and 3/4" PVC-piping.

Then there's the frictional loss, that also needs to be taken into account.


Bob

[ski2]

Bob--Somehow I knew you'd help me out here, but you're going to make me work for it -- So as the speed of a fluid increases, the pressure within the fluid decreases and conversely. So am I correct in assuming as water flows down the 3/4" pipe to the 1/2" pipe the speed will decrease so the pressure would increase??? But how does volume enter into this??? More water in the 3/4" pipe, less in the 1/2" pipe and the 1/2" would have holes in it to create the spray. So would it be better to stay with 3/4" pipe (where the spray holes will be) because there would be more volume??? Think I'm getting a headache.

[KBsToy]

Wandering around the plumbing department at Lowes today figured out how I could build an under car washer out of PVC pipe for about $15.

Basically a 3/4" pipe (with angle adapters) attached to the hose (with a female hose bib attachment) with 3-4' to go under the car.

At the end of the 3/4" pipe a "T" adapter so the actual washing portion (2-3' PVC with multiple small holes) would run 90 degrees to the handle.

So here's the question: Would the water pressure coming out of the holes in the 2-3' PVC used for the washing portion be higher if this portion of the pipe was 1/2" or would the pressure be higher if this portion was 3/4" like the water delivery portion of the device??

Basically like this device The Underwasher :: Hose accessory that lets you clean under your car, RV, boat or ATV! but with the actual washing portion running 90 degrees to the longer pieces--I think it would be easier to handle this way.

I bought this washer and the T end would help out the washer. I was thinking of the same idea and moding this.

[ski2]

I bought this washer and the T end would help out the washer. I was thinking of the same idea and moding this.

Is it made from 1/2" or 3/4" PVC? What size would you estimate the spray holes are??

[KBsToy]

Is it made from 1/2" or 3/4" PVC? What size would you estimate the spray holes are??

1/2 " PVC 3/32 holes Its not bad but you bettter wear your rain gear when using this Where it connects the fittings have o rings so no leaks. Not a bad built but some fine tunning is needed. $25.00 price delivered. I got an email today from the ChickenRock one and price went up to $349.00

It needs something flat on it so it does not turn when ur moving it around.

I live off 376, Center Exit, PM if you want to see it and look it over.

[ski2]

Thanks for the info!! I think ChickenRock is going to have a hard time at $349. Figure I can put one together for $15-20. At this point planning to use 3/4" PVC with a "T" at the end of the long piece that goes under the car which should make it more stable with the holes in the T. If I can find the right brass nozzles may give that a try too. I'm down in Washington.

[KBsToy]

Thanks for the info!! I think ChickenRock is going to have a hard time at $349. Figure I can put one together for $15-20. At this point planning to use 3/4" PVC with a "T" at the end of the long piece that goes under the car which should make it more stable with the holes in the T. If I can find the right brass nozzles may give that a try too. I'm down in Washington.

Please keep me updated on your project. I am always interested in new ways to keep my car clean and shining.

THANKS

KB

[rwisejr]

For how cheap the Underwasher is I picked one up !!

[KBsToy]

For how cheap the Underwasher is I picked one up !!

It works good just be ready to get damp. I learned to have it under the car when I turn it on. I lke where it connects that it has O rings to prevent leaking. My wife just shakes here head at me out there cleaning underneath ...

Just needs alittle fine tuning to steady it a little. Thats why I like it here on AG somebodys always has a better idea...