A valve is an important component of refining and chemical pipeline systems and plays an important role in petroleum processing. Valves are used to connect and cut off the medium, prevent the medium from flowing backwards, adjust the medium's pressure and flow rate and distribute the medium.
Selection of valves
The selection of valves is mainly based on the trouble-free operation and low cost. Generally, the following principles should be considered.
(1) Characteristics of the transported fluid Valves are used to control fluids, and the characteristics of fluids are diverse. There are fluids including gas, liquid and steam, and there are also fluids with solid particles, dust and explosive, toxic and other characteristics. Therefore, we need to know the characteristics of the fluids when selecting a valve.
(2) Operation functions
Using functions of valves should also be considered when valves are selected. Whether or not valves is used for cutting off, preventing the medium from flowing backwards, adjusting the medium's pressure or flow rate and distributing the medium? If valves are only applied to cutting off the flow, requirements of rapid opening and closing should be taken into account. Does the valve have zero leakage requirements? Each valve has its characteristics and applications, and the right valve should be selected according to the functional requirements.
(3) Sizes
The size of the valve is determined based on the flow rate of the fluid and the allowable pressure loss. Generally, the valve's size is consistent with the size of the pipe.
(4) Resistance loss
A significant portion of the pressure loss of the pipeline's fluid is caused by the valve. Some valve structures have large resistance and some have small resistance. However, all valves have their inherent functional characteristics. You should think twice when choosing a valve.
(5) Temperature and pressure
The material and pressure rating of the valve should be determined based on the pressure and temperature of the valve. When a soft-sealed valve is used, the temperature limit of the sealing material should be paid attention to. For example, the soft-seal butterfly valve and the ball valve are affected by the soft sealing material, and the actual operating temperature of the soft sealing material should be considered.
(6) Materials
The appropriate material should be selected according to the pressure and temperature of the valve and the characteristics of the medium. Different parts of the valve such as valve bodies, valve clacks and valve seats may be made of different materials, and suitable, economical and durable materials should be selected.
(7) Driving methods
Driving methods of valves are manual, gear transmission, pneumatic, hydraulic, electric driving methods. The purpose of using the actuating drive is to make the operation of the valve labor-saving, convenient, quick and reliable, or to achieve automatic control and remote control. Driving methods of valves which are appropriate, economical and easily operational should be chosen.
