Diving is a very popular and widely spread sport and hobby. Many people from different countries go in for diving. It is very interesting and gives you a great amount of positive emotions. But it is not that simple hobby. To take up diving you have to know a lot about the diving and its equipment. That is why, often times a specially trained professional instructor is needed to explain you everything you need to make a first dive. For diving you have to have a special breathing apparatus. It consists of a special mask that allows divers to breathe under water. The rubber tubing connects this mask to a cylinder or a couple of cylinders with the so-called breathing gas. These breathing gas cylinders are usually placed behind the diver's back during the plunge. As a breathing gas regular air or oxygen is used. And in some special cases other sorts of gases or even mixtures of different gases are used. For example, to dive into big depths a special mixture of oxygen and helium is used. It allows breathing easily under water's pressure. Breathing gas in diving cylinders is stored under pressure. Such gas cylinders can also be used in many other fields, for example, to store pressure oxygen for oxygen healing therapy. A special device is used to fill these gas cylinders with gas. The device is called high pressure breathing air compressors. These high pressure breathing air compressors are mechanical devices that allow increasing gas pressure and reducing its volume. There are different models of high pressure breathing air compressors represented on the modern market of diving equipment. All of them have different designs and, thus, different efficiency. So, you can buy a pretty expensive compressor and get a high quality device that will fill your cylinders in several minutes. But usually divers buy one of the cheaper models of high pressure breathing air compressors. Such models allow obtaining just the needed pressure of the breathing gas but they work very slowly. However, that disadvantage is not that serious and easy to overcome. All the diver needs is bigger cylinders to store bigger volumes of breathing gas which can be filled preliminarily. And all the scuba gas cylinders can be filled with them very fast. Most of the divers have several such big cylinders on their boats and these cylinders are usually connected into a cascade bank to make filling of small cylinders effectively. But if you fill a gas cylinder too quickly then the gas inside will get hot and later as the cylinder will cool down the pressure inside will drop, so it is better for you to fill the gas cylinder faster, but not too fast. And it is not all you need to know about diving. Of course, with such knowledge you can make your first dive under an instructor's supervision but if you want to start diving by yourself you need to learn more - much more about diving. Luckily, there is a huge amount of information on that subject. Just go on the internet and you will find a huge list of different links to the web sites dedicated to diving and diving equipment.