The device comprises a pump (10) for delivering a liquid with a foaming agent from a container (R). The displacement of a rigid push-button (14) causes a variation in the volume of an annular chamber (13), and a return air inlet valve (22) allows for the inflow of air into this chamber. The end of the...http://www.google.com/patents/US5289952?utm_source=gb-gplus-sharePatent US5289952 - Device for dispensing foam, and push-button for a device of this kind
