Electronics versus plumbing?

[Panrock]

As was mentioned earlier, oscillators are possible. When I lived in 'digs' in a Victorian house in Evesham, the elderly plumbing system would act as an organ. Tunes were played by manipulating the wash basin taps and the resulting music could be heard throughout the house. The landlady didn't appreciate my musical taste.

Steve

[OscarFoxtrot]

Originally Posted by M0FYA Andy

Yes there is, the sewage system!

And if you don't connect to the sewage return you can just run to earth ...

The best example (and predating 'fluidics' by some time) is probably MONIAC

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

[peter_scott]

Originally Posted by Panrock

As was mentioned earlier, oscillators are possible. When I lived in 'digs' in a Victorian house in Evesham, the elderly plumbing system would act as an organ. Tunes were played by manipulating the wash basin taps and the resulting music could be heard throughout the house. The landlady didn't appreciate my musical taste.

Presumably sine waves? You can have square waves too, water hammer.

Peter

[Panrock]

Presumably sine waves? You can have square waves too, water hammer.

Well, let's just say they were "rich in harmonics". As were the utterances from the landlady's mouth!

Steve

[Radio Wrangler]

THere's a simpler view.

Plumbing pays more!

Two ex-Agilent went on a training course and got CORGI/GASSAFE registered. As they say, they never looked back.

David

[The Philpott]

In my head a pipe is a better analogy/visualisation than a river, since gravity is less of a consideration. I started to think of waterfalls, dams and weirs, (in association with potential difference) and depth of water versus speed and volume, but then you have volume competing against gravity/potential energy for the title of 'voltage'...so i reverted to a good old pipe as a model.

Dave

[G6Tanuki]

Plumbing can be a good analogy at times, but I'm stumped as to what would be the plumbing-equivalent of a neon-tube or a LED!

[Argus25]

Originally Posted by Panrock

What is a plumbing inductor?

The thing to remember when equating fluidic and electrical circuits, is that elements such as a compliant chamber (accumulator or capacitor) and the plumbing equivalent of inductance (fluid inertia) are only active when there is a dynamically changing flow rate. Just as in electrical circuits, the effects of capacitance and inductance are zero, if the current is constant. However when the flow rate or current is changing, that is when the effects of compliance and fluid inertia (or capacitance and inductance equivalent) come into play.

"An inductor opposes a change of current flow, the faster the current attempts to change value, the greater the reactive or opposing voltage (or electrical pressure) generated by the inductor. A mass of fluid on the other hand opposes a change in velocity or flow rate, the greater the
attempted flow rate change the greater the opposing or reactive forces".

Flow Resistance (energy to heat dissipation) exists in both systems. In electrical systems the resistance, for most cases like common resistors we use, is independent of the flow rate. In fluid mechanics, resistance is also independent of the flow rate only if the flow is laminar. If it is not, and the fluid flow is turbulent (which it is often negotiating a constriction or the flow rate is high in small tubing), the flow resistance then increases with the flow rate.

In the case of fluid filled compliant chambers, they act very similarly to capacitors and again the equation systems are practically identical in both systems.

So as the OP noted, plumbing systems make good analogies, but as we know for AC circuits, the math is more complicated than the for DC circuits.

For example, if fluid is transported in plastic tubing, the tubing has compliance per unit length, the fluid in it inertia per unit length and it has flow resistance per unit length, so wouldn't you know it, it has the mathematics and performance of a transmission line, just like coaxial cable. So, if the flow is abruptly stopped and started there are transmitted and reflected waves. Plumbers know this as the "water hammer" effect.

[boxdoctor]

Pressure regulator valves = constant current sources? Tony

[Argus25]

Not really; pressure regulator valves are the analogy of a regulated voltage source.

A constant flow rate valve is the analogy of a constant current source.

In reality these valves exist, they have a piston and return spring, and a side port where the edge of the piston cuts off a bypass hole. The flow direction there is perpendicular to the piston motion. So the flow rate equilibrates to a uniform value where the piston is just partially blocking the exit hole and then the flow rate becomes nearly completely independent of the applied pressure, after flow regulation begins.It is exactly like a current source that is independent of the applied voltage.

[G4_Pete]

It is also interesting to note that fluid flow in the form of pneumatics is a highly practical and useful study. There are all sorts of innovative designs from 3 term proportional , Integral and derivative controllers to logic and even square root extractors.
Many still in use today as they need no electrical power are non sparking and highly reliable (if you keep the air clean and dry).

I guess a standard remote pressure operated pressure regulator with feedback is a bit like a bootstrapped FET.

Pete

[GMB]

Originally Posted by Argus25

For example, if fluid is transported in plastic tubing, the tubing has compliance per unit length, the fluid in it inertia per unit length and it has flow resistance per unit length, so wouldn't you know it, it has the mathematics and performance of a transmission line, just like coaxial cable. So, if the flow is abruptly stopped and started there are transmitted and reflected waves. Plumbers know this as the "water hammer" effect.

Ah yes, and so from this we can deduce the fix to water hammer - namely terminating the line correctly. Since a terminating resistor would be from the "live" conductor to earth (for coax) then by analogy the cure for water hammer is to drill a small hole (=resistor) at each end of the pipe so it flows to "earth" and thus provides the correct termination.

I think I know a plumber that tried that solution.

[G6Tanuki]

I'd suggest the nearest electrical equivalent to water-hammer would be 'arcing' at a switch contact when it's opened.

Just as you put a capacitor across the contacts to 'catch' the pulse energy and reflect it back into the line in a controlled way (perhaps aided by a snubber resistor), on pipework you put a diaphragm-chamber next to the valve.

[Sidenote: why do we talk about 'opening' a switch to inhibit electron-flow, but the same action in plumbing would be to 'close' a tap?]

[Sinewave]

Originally Posted by Steve_Bell

A basic observation: there is no return circuit needed in plumbing (e.g. neutral wire)...

Unless it's central heating or hot tap water supplies in large buildings.

[Sinewave]

Originally Posted by Radio Wrangler

THere's a simpler view.

Plumbing pays more!

Two ex-Agilent went on a training course and got CORGI/GASSAFE registered. As they say, they never looked back.

David

Someone I know who was a gas fitter, retired in his 50s and drives a newish Aston Martin. He's done very well.

[G6Tanuki]

Originally Posted by Sinewave

Unless it's central heating or hot tap water supplies in large buildings.

Yes - and without a 'return' line, where does it all go when you flush your 'water-capacitor's tank ??

In my case the 'wide-area' plumbing's 'return circuit' is essentially earth: everything here runs into a septic-tank and percolation-bed. Is this the equivalent of a "single-wire" earth-return system

https://en.wikipedia.org/wiki/Single-wire_earth_return

as used in Orstrayla etc ??

[Biggles]

I did also ponder about lamps and LEDS, G6Tanuki, but couldn't come up with anything like an equivalent either. Some sea creatures emit a phospor glow but this isn't strictly caused by water flow I guess.
Alan.

[Electronpusher0]

There was of course the Phillips Economic Computer built in 1949 by Bill Phillips, which used hydraulics to model the national economy. One of his early machines is in the Science Museum. Terry Pratchett used this as his inspiration for the "Glooper", an analogue liquid based computer in his book "Making Money"
Peter

[Argus25]

Originally Posted by G6Tanuki

Yes - and without a 'return' line, where does it all go when you flush your 'water-capacitor's tank ??

This is the issue that confused a lot of people when trying to model fluidics as electrical circuits which are a closed loops. If the fluidic loop can be
"conceptually closed" then all of the useful theories for electrical circuits can be applied to fluidics ones; the notable examples being Ohms Law, Kirchoff's law and the Thevenin Theorem & Transmission line equations and circuit node theory.

In most cases fluid starts out at atmospheric pressure in some container (or close to that depending on the depth where it is extracted) , is raised to some higher pressure by pumps (or gravity if taken from the tank bottom), work is done on it and ultimately the fluid returns to atmospheric pressure (or close even if in a different physical place to the origin of the fluid). So this pressure is the analogy of the "earth" or common connection, even though its not obvious because the fluid (unlike the electrical current) does not physically return to where it originated, but it returns to an identical pressure field, like a current returning to a place of identical potential to where it started. This concept solves the problem and allows fluidic circuits to be drawn as electrical ones, complete with L, C, R equivalents and pressure sources and to be analyzed in exactly the same manner. Especially useful for this are Spice Simulations with transisent analysis where the fluid flow (current) stops & starts. I always wondered why Anasoft didn't re-package Spice with a different GUI for fluidics.

[Argus25]

Originally Posted by GMB

Ah yes, and so from this we can deduce the fix to water hammer - namely terminating the line correctly. Since a terminating resistor would be from the "live" conductor to earth (for coax) then by analogy the cure for water hammer is to drill a small hole (=resistor) at each end of the pipe so it flows to "earth" and thus provides the correct termination.

I think I know a plumber that tried that solution.

That was one very smart Plumber !