Hydrometer Analysis | IS 2720 (Part 4) | Geotech Lab

Hydrometer Analysis | IS 2720 (Part 4)

Sample & Corrections

Hydrometer Readings

#Time (min)Hydrometer Reading (R)Temp (°C)Action

Particle Size Distribution

Computed Parameters (IS 2720)

Time (min)Corrected Rdg (Rc)Eff. Depth L (cm)Diameter D (mm)% Finer
Enter readings to compute
D10 — mm
D30 — mm
D60 — mm
Soil Classification —

Visual Guide & Schematic

Hydrometer Soil suspension
  • 1. Prepare: 50g soil + dispersant
  • 2. Hydrometer readings: at elapsed times
  • 3. Apply corrections: temp, meniscus, zero → Rc
  • 4. Stokes' law: D = K √(L/t) , % finer = (Rc/Ws)×(Gs/(Gs-1))×100
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About This Tool

Introduction

This web application performs Hydrometer Analysis of soil according to IS 2720 (Part 4). It automates the calculation of particle size distribution from hydrometer readings, applying necessary corrections (temperature, meniscus, zero) and Stokes’ law. The tool is designed for geotechnical engineers, students, and researchers to quickly obtain accurate results, visualize the particle size distribution curve, and export data for reporting.

Features

  • Dynamic Input Table – Add/remove hydrometer readings with auto-indexing.
  • Automatic Calculations – Corrected reading, effective depth, particle diameter (Stokes’ law), and percentage finer.
  • Corrections – Temperature, meniscus, and zero corrections per IS 2720.
  • Particle Size Distribution Curve – Interactive log‑linear plot with tooltips, zoom, and export as PNG.
  • Key Metrics – D10, D30, D60, uniformity coefficient (Cu), coefficient of curvature (Cc), and soil classification hint.
  • Export & Print – Download results as CSV or print a PDF‑friendly report.
  • Demo Data & Reset – Load sample data or clear all inputs with one click.
  • Dark Mode Toggle – Switch between light and dark themes for comfortable viewing.
  • Responsive Design – Works seamlessly on desktop, tablet, and mobile devices.

Documentation

Formulas Used (IS 2720 Part 4):

  • Corrected Hydrometer Reading (Rc): Rc = R + Cm + Cz – Ct
    where R = observed reading, Cm = meniscus correction, Cz = zero correction, Ct = temperature correction.
  • Effective Depth (L): L = a – b·R (a, b are hydrometer constants).
  • Particle Diameter (D): D = √[ (18·η·L) / ((Gs – 1)·g·t) ] × 10 (mm)
    η = dynamic viscosity of water (poise), g = 981 cm/s², t = time in seconds, Gs = specific gravity.
  • Percentage Finer (%): %Finer = (Rc / Ws) × (Gs / (Gs – 1)) × 100
    Ws = dry soil mass (g).
  • Uniformity Coefficient (Cu): Cu = D60 / D10
  • Coefficient of Curvature (Cc): Cc = (D30)² / (D60·D10)

How to Use:

  1. Enter sample details and correction parameters.
  2. Add rows for each hydrometer reading (time, observed reading, temperature).
  3. Results appear automatically in the computed table and graph.
  4. Key grain size parameters are displayed at the bottom.
  5. Export data or print the report for documentation.

Note: All calculations follow IS 2720 (Part 4) guidelines. Ensure that hydrometer constants (a, b) are calibrated for your instrument.