![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109936_01.jpg)
Materials and tools
- disposable syringes volume 5 ml and 2 ml;
- spring from a fountain pen;
- stationery or penknife;
- hot glue gun.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109940_02.jpg)
Check valve manufacturing process
We disassemble the syringes, cut the piston rod of the smaller one at the place of the first narrowing.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109929_03.jpg)
We cut the stiffening ribs of the rod so that a spring can be put on it.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109918_05.jpg)
Apply glue to the rod and put a spring on it, let the composition dry.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109896_06.jpg)
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109953_07.jpg)
We cut off about half of a five-millimeter syringe and use the front part.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109966_08.jpg)
Using pliers, carefully shorten the spring so that it slightly protrudes from the cut of the 5 ml syringe.
From a 2 ml syringe, cut off a small piece near the spout and liberally apply glue to it.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109955_10.jpg)
We insert the part into a section of a syringe with a valve and let the glue cure for polymerization.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109980_11.jpg)
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109976_12.jpg)
Additionally, fill it with adhesive on top, allow it to dry completely and test it with a syringe. We connect the latter to the valve as shown in the figure and pull out the piston. With a properly functioning check valve, external pressure should return the piston to its original position.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109920_13.jpg)
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109904_14.jpg)
We install a valve at the outlet of the air compressor, and throw the tube into the aquarium, the air is supplied regularly and saturates the water with oxygen.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109961_16.jpg)
At the same time, in the event of a power outage, there will be no reverse flow of water; the valve piston pressed by the spring prevents this.
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109982_17.jpg)
![Check valve made of two syringes](https://i.washerhouse.com/uploads/posts/2020-02/1582109936_01.jpg)