Key Instruments Flow Meter The Key Instruments FR4500 series variable area flow meter measures the gas flow rate of 30L/min to 280L/min. It is a standard, precision-machined, acrylic, flow meter for liquids or gases. It also has direct reading air and water scales. The FR4500 flow meters can be configured with a control valve on the inlet or no valve at all. The O-rings are provided as Buna-N. Note: Mounting screws are required (available separately). Features and Benefits Pipe diameter range is 1/4 in Connection type is 1/4 NPT female Maximum operating pressure is 6.89bar Maximum operating temperature is 65°C It is use for long term trouble free operation Easy-to-read scales Threaded brass inserts for quick installation Easy disassembly and assembly for maintenance Durable, 1-piece, clear, acrylic construction Stable, easy-to-read float Superior quality Mounting inserts 10-32 UNF x 3/8in It has maximum pressure 100PSIG Applications Compatible with most gases and fluids