How does this pump work without moving parts?

[My Username]

I have a question about how something works.

 

I work in a shop that uses coolant. The coolant comes in a barrel, and it's mostly just oil. It needs to be combined with a lot of water before being used for the machines. To get the mixed coolant, we just turn the water valve on, point a hose, and mixed coolant comes out. What I don't understand is how the "pump" works. It's just one small plastic part with no moving parts and no energy source other than the water line.

 

I drew a crappy picture to help explain how the setup looks. A copper water pipe (orange), with a shut off valve, connects to one side of a plastic piece that looks like a T (black). The other side of the T connects to a hose (green) that we use to aim the coolant into containers. At the bottom of the T there is another hose (yellow) which goes into the barrel (blue) of unmixed coolant.

 

To get mixed coolant, all you have to do is turn the water valve on. But I can't quite figure out what is happening here.

 

Edited January 26, 2017 by My Username

[arc]

It's called a siphon.

 

https://en.wikipedia.org/wiki/Siphon

 

Your device is called a siphon mixer injector that uses the moving water to create a vacuum (lower pressure) in the coolant siphon tube which is at a lower atmospheric pressure then what is in the coolant's reservoir. This lower pressure in the siphon tube is what draws, or more properly, allows the higher atmospheric pressure to force the coolant out of its reservoir and into the stream of passing water at the T fitting.

Edited January 26, 2017 by arc

[Strange]

Is this an example of the Venturi effect?

https://en.m.wikipedia.org/wiki/Venturi_effect

[My Username]

Thank you for responding. I'm glad I have a name for it now. Is the whole system called the siphon, or just that one T looking part?

 

I don't understand how the vacuum is created in it though. In a "regular" siphon (is it called a gravity siphon??) liquid in part of the hose is being pulled by gravity, creating a vacuum behind it. But in this one the water is being pushed out with water pressure from the water source.

 

Is the water's momentum causing it to pass through the "T" and continuing to the other side, rather than the water splitting ways and some water flowing out through the barrel? If that is what's happening, then is the friction between the moving water and coolant inside the T causing some coolant to flow with the water, and creating a low pressure spot behind it to continue this same cycle? I don't know if that's right or not, but it's the only explanation I've been able to make sense of so far.

[Bender]

Bernoulli's equation is what you need: if a fluid flows at a higher speed, the pressure is lower.

 

See Strange's link above for a good explanation.

[studiot]

Nice short input arc that hits the nail. +1

[swansont]

Is this an example of the Venturi effect?

https://en.m.wikipedia.org/wiki/Venturi_effect

 

 

Yes.

[My Username]

Oh, I didn't see the post by Strange. Maybe posted while I was writing my response. Thank you, I believe that explains it.

[RiceAWay]

Everyone else has done a good job of explaining the theory behind this but the practice is rather more complex.

 

You see the height of the barrel is a problem. As the siphon begins emptying the barrel there is a very small head and consequently the flow of the barrel fluid is high. At the barrel begins emptying rapidly but as the barrel empties the barrel "head" increases the pressure necessary to hold the same barrel fluid flow for the same mix of water and fluid.

 

There are several ways of correcting for this.

 

1. You can always empty and entire barrel at a time and set the initial siphon rate so that the higher initial flow and the lower final flow ends up with the correct mix at the end.

 

2. Another way is to use an expandable membrane in the siphon so that the greater pressure required to lift the barrel fluid at a known mixture rate reduces the size of the venturi thereby generating a greater draw (reducing the Bernoulli pressure more). With the constant initial pressure this has the effect of reducing flow of the water and increasing flow of the fluid.

 

3. And the most common method is to have a fluid that simply isn't effected strongly by the admittedly pretty small difference in mixture ratios.

 

In an automobile when they were using carburetors the venturi pressure was extremely sensitive to mixture ratios and the design of the float chamber was such that it minimized these effects - not from head since the float chamber was filled via a pump, but from g-forces accelerating and braking and cornering.An automobile carburetor was quite a complex mechanical computer.

[Endy0816]

I think this is the same thing, though referred to as an eductor here.

 

http://www.foxvalve.com/lt_liquid_eductors.aspx

 

 

Edited January 26, 2017 by Endy0816

[sethoflagos]

I think this is the same thing, though referred to as an eductor here.

 

http://www.foxvalve.com/lt_liquid_eductors.aspx

 

 

 

+1

 

The 'big daddies' of these, much used in the process industries, are steam ejectors (see http://croll.com/vacuum-systems/applications/chemical-processing/24-2/).

 

There are subtle differences in the equations for liquid and gas driven eductors, but the basic idea is the same.

 

Those born before the widespread use of fuel injection systems may remember that carburettors use a similar principle to 'suck' fuel through atomising jets into the inlet airstream.

[Externet]

Pictures of actual venturi tees in the market, or how to make them:

 

----> https://duckduckgo.com/?q=ventury+t+plumbing&t=canonical&iax=1&ia=images

[Endy0816]

 

+1

 

The 'big daddies' of these, much used in the process industries, are steam ejectors (see http://croll.com/vacuum-systems/applications/chemical-processing/24-2/).

 

There are subtle differences in the equations for liquid and gas driven eductors, but the basic idea is the same.

 

Those born before the widespread use of fuel injection systems may remember that carburettors use a similar principle to 'suck' fuel through atomising jets into the inlet airstream.

 

Thank you. I remember being impressed that the same water used for fighting fires could be utilized to combat flooding. Pumping water with water.

[sethoflagos]

 

Thank you. I remember being impressed that the same water used for fighting fires could be utilized to combat flooding. Pumping water with water.

 

I did my apprenticeship in a paper mill laboratory that had a small liquid eductor we could rig up to one of the water taps with rubber tube to create a partial vacuum. It was good enough to boil water at room temperature (not that high in the hills outside Halifax), which was moderately entertaining. Or maybe indicative of how fulfilling a paper mill job in the Yorkshire pennines was in those days

Edited January 29, 2017 by sethoflagos