Can anybody explain me the main disadvantage of tilting Disc Check valve over a swing Check valve?

tilting disc check valves are a lot smaller and lighter so for a given pipe size they don't cost as much.  Since the tilting disc is partially balanced, the cracking pressure is less-Particularly for vertical upward flow.  Neither will work well for vertical downward flow, and neither will be happy if they are not installed right-side up.  

If your velocity is not high enough to hold the disc fully open both the swing check and tilting disc valve will experinece bushing/hinge pin wear.  Once difference between tilting disc and swing check is that the TD is very intolerant to any wear and will result in seat leakage.  Swing checks with moderate hinge/bushing wear may still seat tightly at high DP.  

If your velocity is below 10-12 fps water, expect disc oscillation for a swing or TD valve.  These are ballpark numbers and differ based on the specific desings.

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