Description
The Scully WL-170 Whistler Fill Signal 00401 is a ventpipe mounted over a fill warning insert used in fuel storage tanks to indicate when the tank has reached its fill level in HVAC systems. Installed inside a 1-inch vent line, it produces an audible whistle as incoming liquid displaces air during filling, the sound stops once the liquid level reaches the calibrated point, signaling that filling should end. This mechanical indication helps reduce overfill incidents and supports safer delivery operations in storage tank filling applications. The unit is part of a vent signal system commonly used in liquid fuel handling setups.
