Patent ID: 6857367

Claim:
A method of operating equipment for coating printing materials in a printing press, the method which comprises: providing equipment including at least one metering system and a circulating line system associated with the metering system for at least one liquid medium received in at least one container, the circulating line system having a pump subsystem including at least one feed pump for feeding the liquid medium from the container to the metering system, and at least one return pump for returning the liquid medium from the metering system into the container, and a feed line disposed between the metering system and the feed pump; and at least partially emptying at least the feed line by carrying out the steps of: shutting off a medium connection between the feed pump and the container; and connecting a suction side of the feed pump to a space having a gaseous medium, for sucking in the gaseous medium by the feed pump and, as viewed in pumping direction of the feed pump, for pumping the gaseous medium into the feed line; and during the step of at least partially emptying at least the feed line, sucking in ambient air as the gaseous medium by the return pump via a bypass disposed between the feed line and a suction side of the return pump and via the feed line.