Luboil handpump suction from storage tanks.
I am not 100% sure, but I assume the smaller suctionpipes of the handpumps connects to the main suction pipes from port and starboard storagetanks somewhere before the two portside valves shown on the picture below, the two small suctionpipes goes to the stb and comes up underneath the black table (driptray) just below the handpump. I guess you should find the changeovercock ( port/stb storagetanks) right under the table as well.
Tore