Our original design used a rotary vane pump that had 4 vanes. It was rejected by the customer because they prefer flanged connections over threaded NPT connections. The vendor offered a replacement pump that was the same size and had flanged connections, but he doesn't have any curves for that pump with fluid of the same viscosity as we are using. The pumps seem very similar except the original pump had 4 vanes where the replacement pump has 8 vanes.

I'm looking for some kind of calculation I can use to compare the 8 vane versus the 4 vane, or other ways to compare and evaluate the replacement pump. Any help would be appreciated.

Thank You