Centrifugal principle Centrifugal is actually the manifestation of the object's inertia, such as water droplets on an umbrella. When the umbrella slowly rotates, the water droplets will follow the umbrella rotation. This is because the friction between the umbrella and the water droplets serves as a centripetal force for the water droplets. But if the umbrella rotates faster, the friction is not enough to make the water drop in circular motion, then the water drop will move away from the umbrella toward the outer edge, just as a rope pulls the stone to make a circular motion. If it is too fast, the rope will Disconnected, the rocks will fly out. This is called Centrifugal. Centrifugal pump works: Centrifugal pump is able to send out the water is due to the role of centrifugal force. Pump before work, the pump body and the inlet pipe must be full of water to form a vacuum state, when the impeller rapid rotation, the blade to promote rapid water rotation, rotating water in the centrifugal force from the impeller, the pump water After being thrown, the central part of the impeller forms a vacuum area. The water of the water source is pumped into the inlet pipe through the pipework under the action of atmospheric pressure (or water pressure). This endless cycle, you can achieve continuous pumping. It is worth mentioning that: before starting the pump must be filled with water to the pump shell before starting, or the pump will not be able to complete the suction liquid, causing the pump heat, vibration, no water, resulting in "idling" Equipment damage caused by the pump (referred to as "gas tied"). Many types of centrifugal pumps, classification methods are common in the following ways 1 by the impeller inhalation points: single suction centrifugal pump, double suction centrifugal pump. 2 according to the number of impeller points: single-stage centrifugal pump, multistage centrifugal pump. 3 according to the structure of the impeller: open impeller centrifugal pump semi-open impeller centrifugal pump closed impeller centrifugal pump. 4 according to the working pressure points: low pressure centrifugal pump medium pressure centrifugal pump high pressure centrifugal pump side vertical centrifugal pump. Impeller installed in the pump housing, and fastened to the pump shaft, the pump shaft directly driven by the motor. The pump housing has a liquid suction inlet and suction pipe connection. Liquid enters the pump through the bottom valve and suction tube. The liquid discharge port on the pump housing is connected to the discharge pipe. Before starting the centrifugal pump, the pump housing is filled with liquid being transported; after starting, the impeller is driven by the shaft to rotate at a high speed, and the liquid between the blades must also rotate along with it. Under the action of centrifugal force, liquid is thrown from the center of the impeller to the outer edge and gains energy, leaving the outer edge of the impeller to enter the scroll casing at a high speed. In the volute, the liquid due to the gradual expansion of the slowing down, but also part of the kinetic energy into static pressure, and finally to a higher pressure into the discharge pipe, to the required place. When the liquid flows from the impeller center to the outer edge, a certain vacuum is formed in the center of the impeller. Since the pressure above the liquid level in the sump is greater than the pressure at the inlet of the pump, the liquid is continuously pressed into the impeller. Visible, as long as the impeller constantly rotating, the liquid will be continuously inhaled and discharged.
Venous Cannula
Venous cannula is also a deep venous puncture catheter. The method is to select the appropriate puncture site and insert the needle under the skin, and insert the needle with negative pressure until the dark red blood is absorbed, indicating that the needle has entered the vein, and the guide wire is inserted. Withdraw the puncture needle to leave the guide wire in the blood vessel, and then insert the venous catheter that needs to be indwelled along the guide wire, then exit the guide wire, inject diluted heparin saline and fix the catheter, the deep venous catheterization is completed. The veins for puncture and catheterization are usually selected clinically, including the subclavian vein, internal jugular vein, and femoral vein. After the puncture catheter is indwelled, attention must be paid to the care of the puncture site to avoid infection with thrombus or catheter falling off.
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