When the rotor rotates, the springs continue to push the vanes outward so the vanes will follow the contour of the compression chamber. When the pump starts, the rotor is going to move across the inlet and expose an area inside the compression chamber.
This area will be at a lower pressure compared to the pressure inside the system; so the air and moisture inside the refrigeration system is going to rush in to try and fill this empty region. Pressure always flows from high to low, so if we connected for example; two balloons of different pressures, the gases will move from the high pressure side into the low pressure side until both are of equal pressure.
Gases want to equalise and will flow from a high pressure to a low pressure. Gases try to equalise pressure across connected regions. Therefore we use a vacuum pump to create a region of lower pressure so that the unwanted gases inside a refrigeration system will rush out of the system to try and fill this lower pressure region.
In our scenario, the connection hose and the new low pressure area within the compression chamber become an extension to the refrigeration system so the gases in the system are going to rush to fill this and try and make the pressure between these two equal. The other vane passes across the inlet and creates another lower pressure region so more gases rushes in to fill this void again and again. This decrease in volume is going to compress the gases into a tighter space, that will increase the pressure and temperature.
It continues to rotate into a smaller volume until the pressure becomes high enough that it forces the reed valve at the exhaust to open and the gases are discharged. The compressor continues to rotate and as it does so the next batch of gases is pulled into the system and this cycle continues. Most vacuum pumps will be two stage which means there are two compression chambers linked in series, with the exhaust from the first compressor linking directly into the inlet of the second chamber.
This design allows the pump to achieve a deeper vacuum. When we have a single compressor; the outlet is pushing against atmospheric pressure, as detailed above. But with the two stage design, the outlet is pushing against a much lower pressure which is simply the inlet of the second rotating compressor and the low pressure region it creates during that rotation. As the vacuum pump continues to run, it will eventually pull the gases out of the closed system which will reduce the pressure down below the pressure of the atmosphere that surrounds the outside of the system.
As the pressure reduces, any moisture in the system will become easier to boil and evaporate. We can add a little heat with a heat lamp or heat gun to help it vaporise. Thank you for this excellent webpage showing how a vacuum pump functions. I am super interested in understanding this topic. And when I see the animation of a single stage rolling piston vacuum pump functioning and read the accompanying description, something really puzzles me.
Could you possibly tell me,. I can understand why an exhaust valve would be required, and need to be closed, if the vacuum pump is slowing down, so that the vacuum attained in the system is retained. What happens if the exhaust valve is held open during continuous operation of the rolling piston vacuum pump? I am guessing the vacuum pump would at least be very noisy, with atmospheric air rushing in for each cycle. Would the atmospheric air rushing in disturb the smooth rotation of the rotor?
While both momentum transfer and entrapment pumps are used to create high and ultra-high vacuum conditions, they require a great deal of energy and maintenance and are, therefore, costly to operate.
On the other hand, a large majority of industrial and commercial vacuum pump uses are fulfilled by means of positive displacement pumps, like the rotary screw vacuum pumps made by Kaishan. In addition, our vacuum pumps serve an integral part of metal processing, glass and stone cutting, printing, plastic injection molding and aviation equipment manufacturing — to name but a few of the modern processes that rely on Kaishan equipment and technology.
To learn more about our vacuum pumps and other quality Kaishan products, contact us today. Here are the various types of positive displacement primary vacuum pumps:.
Oil Sealed Rotary Vane pumps compress gases with an eccentrically mounted rotor that turns a set of vanes. Due to centrifugal force, these vanes slide out and form chambers between themselves and the housing. The pumped medium is trapped inside these chambers. During further rotation, their volume is constantly reduced. Thereby, the pumped medium is compressed and transported to the outlet.
Rotary vane vacuum pumps are available in single- and two-stage versions. Liquid ring pumps have an off-center impeller with vanes bent towards rotation that form a moving cylindrical ring of liquid around the casing from centrifugal acceleration.
The vanes create crescent shaped spaces of different sizes as they rotate and are sealed by the liquid ring. Near the suction or inlet, the volume becomes larger causing the pressure in the each one to drop and draw in gas. As it rotates, the volumes between each vane decreases because of the eccentrical positioned impeller and liquid ring formation. This compresses the gas as it discharges, creating a continuous flow.
Diaphragm pumps are dry method positive displacement vacuum pumps. A diaphragm sits on a rod connected via crankshaft that moves the diaphragm vertically as it rotates.
When the diaphragm is in the low position, volume in the chamber increases, lowering the pressure and pulling air molecules in. As the diaphragm moves up, the volume is decreased, and gas molecules are compressed while flowing to the outlet.
Both the inlet and outlet valves are spring loaded to react to the pressure changes. Scroll pumps use two non-rotating scrolls in a spiral design, where the inner one orbits and traps a gas in the outer volume space. As it orbits the volume of gas gets decreasingly smaller and smaller, compressing it until it reaches minimum volume and maximum pressure allowed and is expelled at the outlet located at the center of spiral.
Root pumps push gas in one direction through two lobes that mesh without touching as the counter rotate. This counter rotating creates maximum flow rate as the volume increases at the inlet at the simultaneously decreasing at the outlet compressing the pressure.
A trapping pump, also known as a capture pump, is usually located in the container that is being evacuated. The pump removes the gas molecules by sorption or condensation on the internal surface. If the gas molecules come in contact with the refrigerated surface of the pump, the gas will be condensed and removed as a liquid. Vacuum pumps can be damaged over time and basic maintenance is needed to keep the equipment up and running.
Vacuum pump repair is offered throughout the country and a number of different companies may operate in your area.
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