paraphrase (use your own words):

STEP 1- Observe that with NO FLOW, there is zero pressure head difference indicated by the manometers connected to station pairs, A and B.
Note: Ensure bypass valve in the open position.

STEP 2- With a small flow passing through the bend meter, pitot tube meter and the venturi meter, observe the small pressure head difference:
(hA - hB) = h

STEP 3- Record flow rate Q from magnetic flow meter and height of water in the V-notch weir tank (see note below.

STEP 4- Repeat STEPS 2 and 3 for several different flows (up to ~4L/s), recording Q and h in each case.

STEP 5- Repeat STEPS 1 - 4 inclusive for flow passing through the orifice plate. The pressure differences are more sensitive, so the test flow rates will need to be less (up to ~1 L/s).

Note: turn bypass valve in the closed position to force flow through the orifice!