The HTTP portable transit time ultrasonic flow meter clamps onto the outside of a pipe and does not contact internal liquids. It also provides instantaneous rate and accumulated flows for efficient fluid measurement. The easy to mount portable meter includes bi-directional flow capability to measure forward total, reverse total, and net total; pipe sizes that range from1/2 in. and higher; and non-invasive meter clamps. It has no moving parts for a maintenance-free operation. Communication with the HTTP meter is achieved via a PC serial communications port and infrared serial adapter, allowing the user the convenience of no interconnection wires. This portable flow meter uses UltraLink Windows software, allowing for configuration, calibration, and troubleshooting. The unit is packaged in a compartmentalized and padded carrying case along with the transducer set, a 20-ft interconnection cable, one tube of acoustic couplant, mounting hardware, AC power converter, an auto-style 12 VDC converter, an infrared adapter, a 4-20 mA interface cable, and an operations manual.