What this tool does
Prevents readings from being scheduled faster than the entered flow can displace the measured equipment volume.
When to use it
Use after measuring internal tubing diameter and length and obtaining wetted volumes for the installed pump, chamber and flow cell.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
Minimum interval = total equipment volume × entered exchanges ÷ flow
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
For 6 mm ID tubing over 20 m plus 100, 250 and 50 mL components, total equipment volume is about 0.97 L and one exchange takes about 3.86 minutes at 0.25 L/min.
Assumptions
Well construction, water levels, equipment dimensions, flow and field readings are site-specific measurements entered in consistent units. All comparison criteria are supplied by the user from the governing plan or authority.
Limitations
These tools calculate geometry, displacement and numeric variation only. They do not select a sampling method, prove sample representativeness, establish laboratory requirements or authorize collection or disposal.
Sources
- U.S. EPA — Groundwater Sampling Operating Procedure (EQASOP-GW4)
- U.S. EPA — Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures
- U.S. Geological Survey — Purge Analyzer Tool (PAT)