A Wind vane is used for indicating the Direction from which the wind is blowing. A Wind vane consists of a horizontal Arm carrying a rectangular flat fin mounted by means of thrust rod and brass bushes in a support. The horizontal arm is balanced about its axis of rotation by counter weight
attached to the end opposite to the fin. The vane and eight direction rods are supported on a suitable galvanized iron pipe threaded into a base casting Four direction arms carry the letter N, E, S & W which point towards the corresponding true direction while four direction rods indicate the intermediate directions. The position of the counter weight with respect to the eight direction arms indicate the wind direction and may easily be
determined by interpolation to the nearest sixteen points of the compass.
The aluminium material is used for the fabrication of the instrument so it may
withstand permanent exposure in the open and has a long life. The fin is securely fixed to the horizontal arm at one end and on the other end of the arm counter weight is fixed in such a way that the complete assembly is accurately balanced about the spindle. The horizontal arm is perfectly straight and the top end of the spindle projecting up from the horizontal arm is held firmly by a nut. The bearing housing cap is locked to the spindle by a steel pin.
The spindle is a straight rod turned and finished accurately such that it revolves in the bearings with the minimum friction. The spindle is locked to the bearing by means of a steel pin. The mounting ring for direction arms is made of aluminium metal and carry the eight cardinal and inter-cardinal direction arms. It is fixed to the top of the main support tube by screws. The mounting ring has rest level over a collar at the top of the main support is a straight galvanized steel pipe with standard pipe threads at one end for
screwing into the base. The other end takes the collar and mounting ring for direction arms. The main support tube is locked to the base by a suitable steel pin. The base is cast from aluminium material and has three holes for taking the foundation bolts. The external surface is suitably protected with primer and finishing paint. The four directions letters N, E, S and W is painted with red colour. The complete instrument is packed by dismantled the fin from the horizontal arm and the direction rods from the mounting ring in a strong
wooden case to withstand all possible transit risks.
PACKING :- Each instrument is marked and packed separately as per the Section 8 and 9 of IS: 5912-1970.