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Hydraulic Engineering

A DIY Automatic Aquarium Water Evaporation  Replenisher Device

(Some Welding Used to Fabricate a Part of System)

This web site focuses on understanding gas flow and the physics of pressure versus volume in compressible flow.   We learned about Compressible Flow theory from scientists like Bernoulli and Reynolds.  Centuries ago they learned how to quantify mathematically the phenomena around them.  This report will cover understanding the lack of gas (a vacuum) and non compressible, liquid, flow. 

We had an occasion to need a water make-up device so investigated ways to accomplish the objective.  The principle used is sometimes called the "Torricelli Vacuum."  This device used some Stainless Steel Tack Welds to fabricate one of the components

Historical Perspective

We learned for this exercise that another scientist from the 1600'reds was responsible for developing our understanding of how gases behave.   Evangelista Torricelli (1608 - 1648) is credited with developing our understanding of barometric pressure, what causes wind and the invention of the Barometer.  In fact he is honored by having a unit of pressure named for him, the Torr.  He is also credited at measuring the perfect vacuum often referred to as the "Torricelli Vacuum."  That principle is what were using to make our automatic "water replenisher."

Torricelli, a professor of mathematics in the Florentine Academy, tested many liquids defining how high a column would remain in a closed end glass tube when it was inverted in a dish of that liquid.  He produced the first sustained vacuum in his laboratory.  The reason for his experiments was that pumps could only lift water about 30 feet and it was not understood why.  These pumps were being used for irrigation to drain water from mines so it was very important to understand why this limitation  existed.  Galileo was commissioned to investigate the problem.  He got other scientists involved in solving this mystery.  Torricelli took a sealed glass tube filled with Mercury and inverted in a dish of Mercury.  He measured the column height (distance BC in sketch right) as 76 cm.  He was credited at understanding that the void above the Mercury column (distance AC) was a perfect vacuum.   He realized the height of the liquid column was the maximum atmospheric pressure pushing on the surface of the Mercury in the dish could hold-up. 

Since Torricelli measured a Mercury column being sustained at 76 cm in the tube; he is quoted at predicting  that water would go up 10 m (32.8 feet) on the basis of the ratio of the liquid densities.  (The density of Mercury is 13.534 gr/cm3 versus water at 1, therefore 76 cm of Hg actually calculates to 10.29 m of water! That translates to 33.75 feet not 32.8. feet!  34 feet is the accepted approximate value.  Since scientists of the day were very careful and I suspect weight measurement was very accurate using a balance he no doubt knew densities accurately enough to get the number correctly and we're probably just translating the 10 m from the length measures they used in Italy at the time, the "Florentine Yard." The Florentine yard is based on the Roman foot. It has been determined that the "Offcial foot is that of Cossutin" and when measuring the length of his foot in a statue it is 0.967 British inches. Therefore the actual 33.75 times 0.967 = 32.6 feet. Therefore that speculation is quite proably correct!

I can only guess what Torricelli and Bernoulli would think today as they saw most of the world using the very logical base10 metric (or SI) system of measurement while one of the most "advanced" technical societies, the USA, is still employing the "foot'' with 12 Inches to the foot and the yard with 3 feet to the yard and  having to use fractions in a ruler!

Free PDF Download with More Details - See Below

Automatic Aquarium Water Level Control

Photo left is the makeup water  storage tank.  Photo right is the tube coming from the tanks and held in the aquarium with a tube open end set at the desired water level.  When water evaporates it is automatically replaced .

This simple system has no moving parts, pumps or electrical connections.  A FREE PDF Report is available as a download outlining the key elements of the system, how it works and the math defining the pressure (or vacuum) that develops in the tank.  We also cover two other attempts that didn't work!
In addition to this automatic water control the FREE report covers:
bulletAutomatic Fish Food Feeder
bulletSimple Way to Drain and Add Aquarium Water
bulletInexpensive Battery Powered Emergency Air Pump
bulletDiscus Tank Set-up
bulletBuying Discus by Mail


Click to Download PDF- 

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