Pumpmaster 2 - 1:1 ratio suction pump.
Pumpmaster pump with 1:1 ratio with a modified air valve to allow a lower upward movement of the piston to improve pump suction capacity and avoid pump cavitation when suctioning fluids like waste oil through small diameter suction canes.
https://samoa.ltd.uk/content/03_BOMBAS%20DIAFRAGMA%20V216_UK_10-end.pdf