A pneumatic immersion lubricant pump, including a primary piston sliding in a sealed manner in contrast to at least one spring inside a cylindrical body together with which the primary piston defines a chamber provided on an opposite side of the primary piston with respect to that where the at least one spring is positioned, a body of the pump including at least one channel in which an element projecting from the primary piston is slidably housed in a sealed manner. The body of the pump including a plurality of cylinders each equipped with a loading port open on the outside of the pump body. Each cylinder housing a secondary piston axially constrained to the primary piston. The projecting element and the channel defining a pressurization duct of the chamber.

A pneumatic immersion lubricant pump, including a primary piston sliding in a sealed manner in contrast to at least one spring inside a cylindrical body together with which the primary piston defines a chamber provided on an opposite side of the primary piston with respect to that where the at least one spring is positioned, a body of the pump including at least one channel in which an element projecting from the primary piston is slidably housed in a sealed manner. The body of the pump including a plurality of cylinders each equipped with a loading port open on the outside of the pump body. Each cylinder housing a secondary piston axially constrained to the primary piston. The projecting element and the channel defining a pressurization duct of the chamber.

Exemplary two chamber foam pumps, refill units and dispensers utilizing the same are disclosed herein. An exemplary refill unit includes an inverted container having a neck located at the bottom of the container and a foam pump secured neck. The foam pump includes a first air pump chamber, a liquid pump chamber and a second air pump chamber. In addition, the pump includes a piston. The piston has a hollow central portion. A first air inlet aperture is located through a wall of the piston between the first air pump chamber and the hollow central portion. A liquid inlet aperture is located below the first air inlet aperture and between the liquid pump chamber and the hollow central portion. A second air inlet aperture is located through the wall the piston located below the liquid inlet aperture and between the second air pump chamber and the hollow central portion.