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Self-made instrument KIPA
FEEDING CO 2 TO AQUARIUM
The device consists of a pair of PET bottles of the same capacity ( green color ) and also a plastic tube ( orange ) that is the diameter of the bottle entering the neck. The tube is closed with plastic stoppers on a pair of sides, the upper one in the figure should ensure tightness. In the upper elements of the tube, which is not included in the bottom bottle in any way, a fitting for CO 2 removal ( black color ) is glued in. The cork from the bottle is also attached to it ( black color ), it is sealed by a rubber or silicone ring ( red ). Under the cork there is a spacious cutout for easy loading of chalk or limestone. Even lower, the tube is perforated with a set of holes for the free contact of the acid, also chalk. A polyethylene cocktail tube ( blue color ) is punched through the upper and lower corks. It is also hermetically sealed in the cork of the upper bottle - it is best to insert a plastic hollow rod inside its upper end, which securely sticks the tube into the hole in the cork of the upper bottle. In order to neutralize the acid vapors in the exhaust gas, it is bubbled through the soda solution in a separate bottle.
The production of CO 2 is based on the well-known reaction between chalk and acetic acid. Chalk or limestone is needed in the form of pieces that cannot be passed through the holes of the tube, and especially there should be no chalk dust. The device is filled with a weak solution of acetic acid almost up to the top level. shown in the figure. Chalk pieces fit into the tube of the upper elements of the apparatus; it is inserted inside the bottle and carbon dioxide evolution also begins. It is discharged through the nozzle, it makes its way through the soda solution and is also fed into the aquarium. It is highly desirable to put a check valve on the outlet. If the gas release is in no way extremely turbulent - the device works as if just a container with chalk and acid. But if CO 2 is emitted more than it is necessary either the removal of CO 2 is blocked (by a tap or a valve) by the evolved gas starts to force the liquid out of the bottom bottle, it also goes up to the top bottle through the central tube. The reaction of gas evolution stops, at what time the level of acid in the bottom bottle is made below the perforated tube with chalk. The main capacity of the acid goes into the upper bottle. If you resume the removal of gas, the pressure in the bottom of the bottle drops and the acid again starts to react with the chalk. Thus, according to the Kipp principle, the gas pressure is kept constant within certain limits. This pressure, respectively, a waste of gas, will also depend on the depth of immersion of the sprayer into the aquarium.
The speed of the reaction is highly dependent on the content of calcium carbonate in the chalk or limestone used, the density and the porosity of the mineral. I advise you first to choose the concentration of acid on a small sample - the gas evolution should be quite weak, inadmissibly strong foaming and bubbling. If the slow progress of the reaction does not provide the necessary amount of gas in any way - it is better to reassemble the apparatus by screwing in bottles of larger capacity than using a more concentrated acid. On the other hand, a low concentration of acid can lead to the need to more often bypass the device - it will be extremely quickly to be neutralized. In general, you will need to pick up.
WHAT IS IT FOR
As I see it, there are some benefits - CO 2 is cheaper than brewing from cylinders as well - since the machine itself is also worthless, and the reagents are cheap enough (common limestone is free). The device at the expense of its device allows without any risk to stop the flow of CO 2 at night - the release of gas automatically stops. Disadvantages - you will have to work hard to reliably also hermetically assemble all of this, which is decently more difficult than withdrawing from the bottle with home brew. But you can also buy in the bench of chemical devices also finished such a device made of glass Just do not forget also the outer grid for it - such a device with hydrogen decently smashed in my eyes as glass fragments flying in all directions - not the most pleasant thing.
This device works under a slight pressure, but also with a weak acid.
If you are not at all sure of the strength of the connections made by the elements of the apparatus, place it entirely
in a large container or durable leakproof plastic bag!
Article author: Vadim Lisovsky