The DR-803K Water Quality Automatic Sampler is a specialized sampler designed and manufactured by Derun Houtian for mixed sampling and retention of exceedance samples in online monitoring systems for water pollution sources. It is widely used at the inlets and outlets of pollution sources and wastewater treatment plants, and is integrated with online monitors for COD, ammonia nitrogen, total phosphorus, total nitrogen, and heavy metals. The sampler features a flow tracking sampling mode that automatically adjusts the sampling flow based on instantaneous flow, enabling continuous sampling to ensure more representative water samples are collected. It also has an A&B drum mixing sample function, providing uninterrupted mixed water samples to online monitors.