The vacuum chamber has 12 flanges (four 4-5/8 and eight 2-3/4 flange size). For the pump down test I will attach the pumping station to the 4-5/8 flange and close down the other three flanges with blank flange. Similarly out of the eight smaller flanges (2-3/4 size) five will have Tees (for 2 gauges), up to air valve, two optical windows, cryo-feedthrough and the remaining with blank flanges (or else I can change them with other feedthroughs to test them out for vacuum leakage). Just for information - the pumping station is attached to a reducer which will house the rotary valve. Reducer is requred to match the flange size of the pumps (4-51/2 siz - CF63 size) and the vacuum chamber (4-5/8 size). The rotary valve will be attached to the hose which will then be attached to the flange of the vacuum chamber.