Differential Pressure Flow Meter shall be of corrosion resistant thermoplastic [specify PVC or Corzan CPVC] body, [EPDM or Viton/FKM] seals with no wetted metal parts. End connections shall be [specify 1/2" or 2" NPT] threads. Differential pressure flow meter shall have isolated spring-loaded diaphragm and magnetic movement to measure the pressure drop across the valves fixed orifice. The gauge shall have a highly visible 3.5" diameter face to read GPM range of [specify 0-10 GPM - ½”, 0-50, 0-100 and 0-200 GPM-2”] flow rate. Gauges to feature a 5:1 turndown ratio; dial starting mark to be 20% of full scale. Overall accuracy to be 2% full scale. All units are to be 100% individually tested at the factory. As manufactured by Plast-O-Matic Valves, Inc., Cedar Grove, NJ USA.