This video and its contents are being prepared as a collaboration between mekanizmalar.com and ALTAROS. In this video we will focus on the inner workings of ALTAROS's air pressure boosters. We want to thank ALTAROS for their technical contributions and generous support for making this animation possible.
Pressure boosters are important components in many applications where high pressure is required, such as high pressure hydraulic presses; CNC water cut machines, and intense air pressure requirements of certain applications. Altaros company offers their pressure boosters especially for air gun shooters, paintball players and scuba divers to fill their high-pressure air tanks at home.
At first the inner workings of the air pressure booster may seem very complex, intimidating and hard to understand. However, this is not the case. What makes this device so elegant is its simplicity and the high-quality workmanship used in its production. It is uses two main circuits called the Reciprocation Circuit and Pressure Boosting Circuit. A third circuit, which is an extension of the Reciprocation Circuit, is called the Cooling Circuit. Now let's describe the details of each of these circuits.
The Reciprocation Circuit.
The compressed air coming from the workshop compressor is connected to the P port of the control valve
and it is called an inlet pressure. This compressed air is diverted to A and B ports of the large
pneumatic cylinder, which can handle pressures between 5 to 10 bar, or 75 to 145 P S I. The control
unit sends the appropriate signals to the solenoid of the flow valve, which controls the direction
of the inlet pressure to A or B ports of the air cylinder. If the inlet pressure is diverted to the
A port of the large cylinder, the air in the B port must be exhausted to the atmosphere at point R,
which stands for right. On the other hand, if the inlet pressure is diverted to the B port of the
large cylinder by the flow control valve, the air in the A port must be exhausted to the atmosphere
at point L, which stands for left. It is being said that the air should be exhausted to the atmosphere
at points R and L, but they are not exhausted to the atmosphere there, we will explain the reasons
behind it later in this presentation. The pressure of the air at point L and R are between 1 and 2
bar or 15 to 30 P S I.
The Pressure Boosting Circuit.
The pressure Boosting Circuit starts its journey at point C. Point C is the point where the shop air
is split into two paths, the first continuous flow path is connected to the P port of the control
valve to feed the reciprocation motion. The second intermittent flow path is connected to the Medium
Pressure cylinder through check valve at point D. During the leftward motion of the large piston,
the air coming from point D is sucked into the medium pressure cylinder by the Medium Pressure piston.
During the rightward motion of the medium pressure piston, the check valve at point D is closed and
the air inside the medium pressure cylinder begins to increase. When the pressure reaches 20 to 60
bar or 350 to 800 P S I the check valve at point E opens and the medium pressurized air begins to
flow toward point F. At that time, the high pressure piston is also travelling rightward and this
causes the check valve at point F to open and air to flow into the high pressure cylinder. This
process continues as long as the large cylinder makes the rightward journey. Once this journey is
completed and the leftward motions starts, the check valve at point F closes. This causes the pressure
inside the high-pressure cylinder to begin to increase. When the high pressure reaches 100 to 300 bar
or 1500 to 4500 P S I, the check valve at point G opens and the pressurized air reaches its final
destination in the High Pressure Tank.
Now the question is, why is the exhaust air not expelled from the large cylinder at points L and R? To answer this question we need to first explain that when gas is compressed their temperature increases and when gas is cooled their pressure is reduced. Everyone who has fixed a flat tire on a bike knows that when the air is pumped into the tire by a hand-held compressor it gets hot. Since Medium pressure and high pressure cylinders are always compressing the air, the temperature of the cylinder walls will get hot. This will increase the temperature of the air coming to the medium and high cylinder chambers. When the air temperature rises before the compression, the efficiency of the pump will decrease. The reciprocation circuit air is cooler, since it is coming from a large tank from workshop compressor. Furthermore, the air expands very rapidly when the large piston reaches the end of its journey during its exhaust processes. This causes the exhaust air temperature to reduce further. Rather than wasting this cool air by expelling the air to the atmosphere at points L and R, it can be used to cool medium and high pressure cylinders. The air coming from point R is directed to R1 with the plastic tubing, this is because plastic has a poor heat transfer rate and we want to keep the air cool. From point R1 to R2, the exhaust air travels between the medium pressure cylinder and the pipe jacket surrounding the medium pressure cylinder. I assume this jacket also has low heat transfer rate, since we do not want to cool it. The air moves between the medium pressure and the jacket in a spiral motion to increase cooling efficiency. While the medium cylinder cools, the air gets hot and expelled from point R2 to the atmosphere. The same can be said for points L, L1, and L2 for the high pressure cylinder.
The inner working of the control unit is beyond the scope of this presentation; however it is important to know that the control units detect the location of the large cylinder from left switch L S and the right switch R S when the large cylinder has contact with them. You can observe this event when the connecting wires glow. When the control unit receives this signal it sends the appropriate signal to the solenoid of the control valve.
I hope this explanation helps you to better understand the inner workings of the ingenious pressure booster.
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