In molecular flow, the speed of the pump is directly related to the aperture of the pump's inlet, hence the 10 l/s. Connect it close to your chamber with no bends and it will work fine.
Also don't get to wrapped up in making a fancy fitting for the inlet. Use a very short length of 1.5" id vinyl tubing with hose clamps to connect it to the chamber's outlet nipple.
Steve
Created on Saturday, April 14, 2001 1:50 PM EDT by Steve Hansen