a second valve seat 162 again of a truncated conical nature is formed as part and parcel of the intermediate cap 156 as shown and operates as the seat for an outlet valve as will become apparent below an annular recess or cavity 164 is provided about the interior wall surface of the cap 156 to provide a ring like passage between an aperture 166 provided through the wall of the cap 156 and the aperture 168 provided through the wall of the collar 150 accordingly there is a passage for communication between the air chamber cavity 132 and the liquid chamber cavity 158 through the apertures 146 166 and 168 by means of the annular recess or passage 164 as can be seen with respect to fig3 and fig4 apertures 168 are in fluid communication with the atmosphere fig3 when the refill unit is not mated with the air compressor portion 118 and are in fluid communication with compressor 118 fig2 when the refill unit and liquid pump 116 are mated together a nozzle 120 is received by and closes the end of the intermediate cap 156 as shown in fig4 a cavity 170 is thus defined between the nozzle 120 and the intermediate cap 156 this outlet chamber or cavity 170 receives an appropriate sponge screen mesh assembly or.