Note: This GRYVOZE 3 inch flow meter is factory-tested with white calibration oil before shipment, so slight oil residue or a mild odor may be present when received. This is normal. The oil is colorless, non-toxic, and safe. Simply rinse with detergent if needed. Before use, please confirm that the pipe size matches the flow meter size, the liquid flow rate is within the specified measurement range, and the liquid being used is compatible with this product. The flow meter stores two types of data: Batch Total and Cumulative Total. Press the RESET button once to reset the Batch Total. Hold the RESET button for 5 seconds to reset the Cumulative Total. To switch units, press and hold the RESET button while pressing the CAL button for more than 5 seconds to enter unit setting mode. The default unit is gallons (US gallons). Press the RESET button to switch between GAL, QTS, PTS, L, and m. Then press and hold the CAL button for 3 seconds to save the setting and exit unit setting mode. Note: Previous flow data is not retained when switching units. Please clear the Cumulative Total before changing units to avoid inaccurate readings. The 3 flow meter is suitable for diesel, gasoline, kerosene, methanol, and similar media. Built with a durable, rust-resistant aluminum alloy housing, a PP turbine, and 3 inch NPT threads, it is widely used in swimming pools, hydrants, fire trucks, water trucks, wastewater treatment plants, and tanker trucks. With an IP68 waterproof rating, this 3 inch water flow meter operates reliably even in wet outdoor conditions. Its EMI protection helps ensure stable readings when used near pumps, motors, and other electrical equipment. This 3 flow meter offers measurement accuracy up to 1%, a flow range of 16-343 GPM, a working temperature of -10C to +80C (14F to 176F), and a maximum working pressure of 145 PSI. The LCD screen clearly displays Batch Total, Flow Rate, and Cumulative Total. The Cumulative Total count range is 29,999,999, and the Flow Rate display range is 99,999. It also supports 5 selectable units: QTS, GAL, PTS, L, and m. The panel can be rotated 360 for easier viewing after installation. The screen automatically turns off after 10 minutes of inactivity and turns on again when flow is detected. The battery offers long service life and can last up to 365 days under normal use. A low battery warning alerts you when the battery needs to be replaced. When replacing the battery, you only need to remove the display panel without uninstalling the entire meter from the pipeline. The non-volatile memory retains your data during battery replacement.