Pneumatic valve quality identification

you might know that wenzhou is 'the countryside of Chinese pump pneumatic valve, the production of pneumatic valve in the domestic account for most of the pieces. In spite of this, but production still have good and bad points. That we should be how to identify the quality of pneumatic valve is good and bad?
in the first place: it is a good product must have its own brand, such ability by the mass of love;
2: cast steel ball pneumatic valve has its own standard configuration, you can be in accordance with the standard reference check; Third:
related to manufacturers, a good product with a reputable manufacturer production;
4: you want to have some knowledge of pneumatic valve, unclear circumstances can go online check, such as: the material of the good and bad, pneumatic valve rod, and pneumatic valve seat material problems, be sure to know a little, lest be deceived.