Fluorine-lined butterfly valve is expensive or titanium butterfly valve is expensive

Butterfly valves lined with fluorine are more expensive or more expensive. Butterfly valves of the same caliber titanium alloy are much more expensive than those lined with fluorine. At least 3 times higher. The butterfly plate of fluorine F4 is white, and the butterfly plate of F46 is transparent, which is best to distinguish, both can be acid and alkali resistant