Product Support - Testing Supplies
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      FORNEY Moisture Tester (Model LA-3405) – Accurate, On-Site Moisture Analysis

      The FORNEY Moisture Tester, proudly made in the USA, delivers quick and reliable moisture content readings for a variety of materials, including:

      How It Works

      The FORNEY Moisture Tester uses a chemical reaction between a calcium carbide reagent (sold separately) and water in the sample to generate acetylene gas. The integral analog pressure gauge measures gas pressure, which correlates directly to moisture content.

      1. Weigh the sample – 20 g of representative material (10 g for high-moisture proportional testing)

      2. Add reagent – 2–3 scoops of calcium carbide into the cap

      3. Seal the vessel – Keep horizontal to avoid premature mixing

      4. Agitate – Shake for 5 seconds, rest 1 minute, and repeat up to three times

      5. Read the gauge – Moisture is displayed directly from 0–20% in 0.2% increments

      Tip: Halving the sample doubles the effective measurement range

      Key Features & Benefits

      ✅ Quick & Reliable – Delivers immediate, on-site results
      ✅ No Complex Calculations – Integral analog gauge provides direct readings
      ✅ Versatile Applications – Construction, mining, soil, and materials testing
      ✅ Durable & Portable – Heavy-duty, watertight, and dustproof case
      ✅ Complete Kit – Includes vessel with gauge, digital scale, sample scoop, cleaning tools, and steel pulverizing balls
      ✅ Standards Compliant – Meets ASTM, AASHTO, and Florida DOT standards

      Testing Guidelines

      • Ensure the vessel and cap are clean and dry before testing

      • Prepare the material:

        • Sands/fines – no prep needed

        • Clays/soils – use steel ball pulverizers

        • Ores and coal – grind or pulverize if needed

      • Keep the sample and reagent separate until sealed

      • Test in environments near 70°F (20°C) for best results

      Proportional Method: For high-moisture materials, use half the sample weight and double the gauge reading

      Conversion Chart: Wet Weight % to Dry Weight %

      Certain industries (e.g., civil engineering and DOT testing) require moisture content expressed as a percentage of dry weight, not wet weight as shown on the gauge.

      To make this easy, Forney provides a downloadable Conversion Chart that allows users to convert Wet Weight % (W.W.%) to Dry Weight % (D.W.%) with no math required. Example:

      Gauge Reading Dry Weight %
      10.0% W.W. 11.0% D.W.
      20.0% W.W. 25.0% D.W.
      30.0% W.W. 42.8% D.W.
      40.0% W.W. 66.6% D.W.
      50.0% W.W. 100.0% D.W.
       

      👉 Download the Moisture Content Conversion Chart (PDF)

      Common Troubleshooting

      • Negative Reading: Ensure reagent was added and sample contains moisture

      • Low Reading: May result from poor mixing, cold vessel, expired reagent, or premature contact between reagent and sample

      • High Reading: Check weighing accuracy, gauge orientation, or allow cooling between tests

      • Slow Reading: Pulverize sample further or use the steel ball method

      Safe Disposal of Test Residue

      The reaction produces acetylene gas and calcium hydroxide. After testing:

      1. Empty contents into a disposable container

      2. Spread residue outdoors and allow to oxidize in air

      3. Optionally, spray with water to accelerate decomposition

      Never dispose of residue in indoor waste bins

      Ordering Information

      Questions? Visit www.forneyonline.com or call (800) 367-6397