Patent ID: 7303096

Claim:
A liquid delivery system comprising: a first reservoir having a first outlet, a lower portion, an upper portion, and a liquid delivery means for delivery of liquid from the first reservoir via the first outlet, the first outlet located at the lower portion of the first reservoir, the first reservoir having a vent enabling the upper portion of an interior of the first reservoir to be open to atmosphere, a second reservoir located above the first reservoir and having a second outlet and a lower portion, the second outlet located in the lower portion of the second reservoir, a first delivery conduit connecting the second outlet to the first reservoir, a second delivery conduit interconnecting the upper portion of the interior of the first reservoir with an upper portion of an interior of a second reservoir located above the level of liquid in the second reservoir, a vent valve controlling communication through the second delivery conduit, a level sensor provided with the first reservoir and adapted to sense the level of the liquid in the first reservoir, the sensor associated with the vent valve to cause the vent valve to open upon the level of the liquid in the first container falling below a first predetermined level, and to close the vent valve on the level of liquid in the first reservoir rising above a second predetermined level, and wherein the first predetermined level is lower than the second predetermined level.