Roots blower, also known as Roots blower, belongs to the category of volumetric rotary blowers. Its working principle is based on the relative movement of two bladed rotors in the cylinder, thereby achieving gas compression and transportation. This blower is compact and easy to manufacture, and is very suitable for gas transportation and pressurization tasks under low pressure conditions. It can also be used as a vacuum pump.

Basic principle
The working principle of Roots blower, a volumetric rotary blower, is the synchronous meshing movement of two bladed rotors in the cylinder. The two rotors are kept in precise meshing state by the synchronous gears at the ends of the rotor shafts. In the working volume formed by the concave curved surface of the rotor and the inner wall of the cylinder, the gas is sucked in during the rotation of the rotor, and then when it moves to the vicinity of the exhaust port, the pressure in the working volume increases sharply due to the reflux of high-pressure gas, and finally the gas is transported to the exhaust channel. It is worth mentioning that there is no direct contact between the two rotors, but they are sealed by a strictly controlled gap to ensure that the discharged gas is not contaminated by lubricating oil.

Main features
When the Roots blower is adjusted within the allowable pressure range, the flow rate changes very little, showing a wide range of pressure selection and forced gas transmission characteristics. Its conveying medium is pure and does not contain oil. In addition, the blower has a simple structure, convenient maintenance, long service life, and low vibration of the whole machine.

However, due to the air flow velocity and pressure pulsation generated by the Roots blower during periodic suction, exhaust and instantaneous isochoric compression, a certain amount of gas dynamic noise will be caused. At the same time, the gap between the rotor and the cylinder may also cause gas leakage, which in turn affects the efficiency. Its exhaust volume range is 0.15 to 150 cubic meters per minute, and the speed is 150 to 3000 rpm. The single-stage pressure ratio is usually less than 1.7 and can reach up to 2.1, and the performance can be further enhanced by multi-stage series connection.

Main medium
Roots blowers mainly convey clean air, clean coal gas, sulfur dioxide and other inert gases. In the transportation of special gas industries such as coal gas, natural gas, biogas, carbon dioxide, sulfur dioxide, etc. and under high-pressure conditions, it performs well and becomes the preferred product. Therefore, this blower is widely used in many industries such as metallurgy, chemical industry, fertilizer, petrochemical industry, instrumentation, building materials, etc.

Structure
The structure of Roots blower can be divided into two-leaf type and three-leaf type according to the shape of the rotor. When the three-leaf rotor rotates each time, the two rotors work together to complete three suction and exhaust processes. Compared with the two-leaf type, its gas pulsation is smaller, and the vibration and noise are also reduced accordingly.

Parameters
The speed range of Roots blower is 150-3000 rpm, the flow range is 0.15-1200 cubic meters/minute, and the pressure range is 9.8-196 kPa. The power and unit weight can reach 0.75-1000 kW and 100-9000 kg respectively.