Water cooler questions

So with the new torch on the way, hopefully here by next Wednesday (4 day weekend WOOHOO) I'm in serious thought mode for a cooler. Have a sink in the shop, so city water will work while doing the build.

Started looking at pumps, well, there's where it gets confusing. I look at Procon pumps and see things like 130psi, 6ft head, but things don't add up. If you look at the conversion of head height to PSI, http://www.engineeringtoolbox.com/pu...ure-d_663.html some things are funny.

Which leads me to wonder PSI vs GPH... if I hook up a pump, and it outputs 1qt/min which is what WeldCraft calls for on their WP20, then what difference does PSI make? (assuming of course max PSI isn't exceeded).

I'm just needing to be concerned with flow rate, correct?

I'm sure it's out there somewhere, but I came up with an idea based on an old Mr Wizard experiment. Fitting connected on a board to be used as a scale, set flow of the output to fill a 1qt jar, set it down flat and mark where the water hits the board, distance from the fitting. Turn up the flow till it fills the jar in 30 seconds, make another mark, and when running, as long as the water hits between the marks, I'm in the 1-2qt/min range.

My logic making sense or do I need more than 20 minutes a day sleep again ;)

Quote:

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Originally Posted by Trip59

So with the new torch on the way, hopefully here by next Wednesday (4 day weekend WOOHOO) I'm in serious thought mode for a cooler. Have a sink in the shop, so city water will work while doing the build.

Started looking at pumps, well, there's where it gets confusing. I look at Procon pumps and see things like 130psi, 6ft head, but things don't add up. If you look at the conversion of head height to PSI, http://www.engineeringtoolbox.com/pu...ure-d_663.html some things are funny.

Which leads me to wonder PSI vs GPH... if I hook up a pump, and it outputs 1qt/min which is what WeldCraft calls for on their WP20, then what difference does PSI make? (assuming of course max PSI isn't exceeded).

I'm just needing to be concerned with flow rate, correct?

I'm sure it's out there somewhere, but I came up with an idea based on an old Mr Wizard experiment. Fitting connected on a board to be used as a scale, set flow of the output to fill a 1qt jar, set it down flat and mark where the water hits the board, distance from the fitting. Turn up the flow till it fills the jar in 30 seconds, make another mark, and when running, as long as the water hits between the marks, I'm in the 1-2qt/min range.

My logic making sense or do I need more than 20 minutes a day sleep again ;)

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Flowrate, friction, and pressure are all tied together. You will need to test the flowrate with the actual torch and lines installed. The pump will have a flow curve, based on PSI or head pressure. As the pressure goes up the flow will go down. The torch and lines will act like a fixed orifice and there will only be one pressure for a given flowrate. Anytime you adjust pressure the flowrate will change. There will also be a change depending on the height of the torch above or below your pump. The best thing is to use a pump that exceeds what you need then limit it with a pressure relief valve. Many of the Procon pumps have this built in. That way you have extra capacity to handle variation in torch height, and coolant viscosity changes from different temperatures.

Quote:

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Originally Posted by Rambozo

Flowrate, friction, and pressure are all tied together. You will need to test the flowrate with the actual torch and lines installed. The pump will have a flow curve, based on PSI or head pressure. As the pressure goes up the flow will go down. The torch and lines will act like a fixed orifice and there will only be one pressure for a given flowrate. Anytime you adjust pressure the flowrate will change. There will also be a change depending on the height of the torch above or below your pump. The best thing is to use a pump that exceeds what you need then limit it with a pressure relief valve. Many of the Procon pumps have this built in. That way you have extra capacity to handle variation in torch height, and coolant viscosity changes from different temperatures.

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Right, I follow the interdependence, fluid dynamics is very similar to electrical and electronic design... I'm just trying to weed through the 'I saw it on the internet' BS that floods search engines and come to a conclusion.

The key to proper function is the actual flow rate out of the end of the torch return line, correct? 1-2qt/min is what it looks like from what I've seen. I realize that this will vary based on height, there's more to my plan to accommodate that. If getting that flow out of the return line sets it to where it needs to be, than PSI, head, etc. don't really matter if the flow is there.

Also thinking about city water... same deal, it's on enough if that flow is achieved, right?

The fun part of this is the size of the hose, size of internal passages, etc. will all change everything around. Getting 2 gallons through a 1/16 hole will take a much higher pressure than through a 1" hole if the transfer is to be made at the same flow rate and vice-versa.

Or is the goal to put 40PSI to the torch head and not worry about the flow rate? I guess that's where I'm going, is achieving the right flow going to work, or does it need the right pressure... what should be measured?

Quote:

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Originally Posted by Trip59

Right, I follow the interdependence, fluid dynamics is very similar to electrical and electronic design... I'm just trying to weed through the 'I saw it on the internet' BS that floods search engines and come to a conclusion.

The key to proper function is the actual flow rate out of the end of the torch return line, correct? 1-2qt/min is what it looks like from what I've seen. I realize that this will vary based on height, there's more to my plan to accommodate that. If getting that flow out of the return line sets it to where it needs to be, than PSI, head, etc. don't really matter if the flow is there.

Also thinking about city water... same deal, it's on enough if that flow is achieved, right?

The fun part of this is the size of the hose, size of internal passages, etc. will all change everything around. Getting 2 gallons through a 1/16 hole will take a much higher pressure than through a 1" hole if the transfer is to be made at the same flow rate and vice-versa.

Or is the goal to put 40PSI to the torch head and not worry about the flow rate? I guess that's where I'm going, is achieving the right flow going to work, or does it need the right pressure... what should be measured?

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Sounds like you got it. For an open cooling system like this, it's all about the flow. Measure the flowrate. As you said the pressure will fluctuate depending on several factors. But the thing you have control over is the pressure, so you will make adjustment to that to get the flow you are looking for. You would have to have a positive displacement pump to have control over the flowrate directly.

Cool, thanks! I have a handful of pumps accessible, from small submersibles to industrial, while I like overkill, a certain point becomes ridiculous, if you're bleeding off half the pressure or restricting it to a point half the pump would do...

I plan to start small, work my way up to a pump that will deliver the flow rate under beyond normal use circumstances, testing through the full setup to make sure I'm getting what I need out of it, just needed to know what aspect I needed to measure :)