The manager shall serve as purchasing agent and as such shall:
(1) make or approve all purchases of material, equipment and supplies authorized by the council:
(2) establish sets of standards and specifications to control purchases by the city;
(3) prepare and publish specifications and notices to bidders;
(4) advise the council as to anticipated needs for purchases and make purchases in advance of needs as authorized by the council;
(5) store material, equipment and supplies in advance of actual need;
(6) keep records of all purchases made by him and of the destination or ultimate use of the material, equipment and supplies; and
(7) cause to be kept an inventory of all city property in his custody and of all city property in the custody of the other officers and employees of the city.