The Parshall Flume is an open channel flow measurement device designed by American engineer R.L. Parshall in the 1920s. It converts the flow state into a measurable water level difference through a specific structure to calculate flow rate, widely used in water conservancy, agriculture, and environmental protection. Consultation: 176,3318,9946.

II. Core Structure and Components

Contraction Section

: The inlet section gradually narrows to accelerate water flow.

Throat

: The narrowest part, forming critical flow conditions.

Expansion Section

: The downstream gradually expanding structure to restore flow velocity.

Observation Well

: Installed upstream (point H) and at the throat (point h) for water level measurement.

III. Working Principle
Based on the critical flow principle and Bernoulli's equation:

When water flows through the throat, it reaches critical velocity (surface waves cannot propagate upstream).

The upstream water depth (H) and throat water depth (h) form a fixed relationship, with flow rate calculated using an empirical formula:
Q = K × H^n
(K is the flume size coefficient, n is determined by the throat width).

IV. Typical Application Scenarios
? Agricultural irrigation: Precise control of field water usage
? Sewage treatment plants: Monitoring inflow and outflow rates
? Hydrological stations: Long-term flow observation in rivers/channels
? Industrial circulating water systems: Cooling water usage statistics

V. Advantages and Limitations
? Advantages:
? No moving parts, operates without electricity
? Strong sediment passage capability, not prone to clogging
? Wide measurement range (common throat widths 0.076m~15m)
? Limitations:
? Requires standardized installation (leveling error ≤ ±3mm)
? Upstream requires a straight section ≥5 times the channel width

VI. Selection and Maintenance Points

Select throat size based on estimated flow rate

Regularly remove sediment deposits (recommended inspection after flood season)

Water level sensors require annual calibration

Prevent frost heave deformation in cold regions

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For installation parameters or flow calculation tables in specific scenarios, provide more detailed requirements for further clarification.