how to install oil tank vent whistle when vent pipe is welded to tank
The whistle is to be heard while the delivery guy is filling, while filling, it vents air and whistle can be heard, whistle stops when fuel fills to cover whistle. The vent needs to be vented to outside and near fill pipe, the whistle can be heard very clear; like an old ship communication system.
Since it is welded, you can buy a 4-6" long threaded black pipe that matches existing diameter. Cut the nipple in half, screw each half (with teflon tape on threads 3 layers thick) into the whistle. Hacksaw out this whistle unit length from vent. Use fuel rated hose and dbl hose clamps on both ends of hose. 8 clamps total. This is automotive fuel filler hose (2 - 2" pieces.). Put whistle just above tank, so it goes quiet as soon as tank is full. Not that much expansion of fuel when minimal temp extremes.