Flowmeters

All flowmeters have various units of measure available (not just GPM).
Most variable area flowmeters have a dual scale of GPM and LPM.See example (PDF file size 22k)

F-300 , D-300 and U-300 Acrylic block, machined Saddle connections, impact tube From 5 to 1900 GPM (F-300) 1" through 8" pipe  (F-300)     F-300 D and U-300 F-400 , F-410 , F-420 , F-430 Acrylic tube, machined In-Line connection (vertical) From .025 to 100 GPM 1/4" through 2" pipe   F-440, F-450, F-451, F-452N Polysulfone, molded In-Line and panel mount Polycarbonate shield available From .025 to 175 GPM 3/8" through 2" pipe   F-460, F-461, F462: Rib Guided Polysulfone molded All plastic, No metal In-Line connection (vertical) From .1 to 80 GPM 1/2" through 2"  pipe       F-550: Acrylic block, machined Panel mount connection From .025 to 20 GPM 1/4" through 1" pipe   F-650 , F-670 Glass tube with shield Panel mount connection (F-650) In-Line connection (F-670) 1/4" , 3/8" , 1/2" pipe     F-650 F-670 F-750: PVC, molded Panel mount connection From .25 to 70 OZ/Min 1/4" tubing