4640-B Surface Thin Layer Density Gauge

About Troxler Products

Troxler Electronic Laboratories, Inc. is a world leader in the manufacturing of testing/quality control measurement equipment for the construction industry. We are recognized worldwide as the industry standard for Nuclear Moisture/Density Gauges. In addition to nuclear gauges, Troxler is also a leader in the production of Gyratory Compactors and Asphalt Ignition Ovens. Troxler continues to set new product standards of quality and precision in the construction industry. For a complete list of Troxler equipment, please review this Products section.

Recognizing the need for an improved method of measuring the density of thin layer asphalt overlays, Troxler, the world leader in nuclear gauge technology, developed the first true thin layer density gauge, the Troxler Model 4640-B.

Designed to measure the density of thin asphalt and concrete layers from 2.5 to 10 cm (1 - 4 inches), the Troxler Model 4640-B Thin Layer Density Gauge accurately measures the overlay density without influence from underlying material. No nomographs or manual corrections are required in order to compute the true density of the overlay. With on-site results available in as little as one minute, the Model 4640-B can provide the user with test results when they are needed, not hours after compaction has been completed.


Gauge Precision ±1 std. deviation at 2240 kg/m3 [140 pcf])

Time (minutes)
2.5 cm (1")
5.0 cm (2")
6.3 cm (2.5")
2.5 cm (1")
5.0 cm (2")
6.3 cm (2.5")
Depth of Measurement 25-100 mm (1-4 inches)
Accuracy of Density Standards: ±0.3%
Calibration Range: 100-170 pcf (1600-2700 kg/m3) Density
Gamma Source 8 ±1 mCi Cesium-137
Troxler Drawing Number

TEL A-102112

Source Housing Stainless Steel Encapsulation (single or double)
Shielding Tungsten and lead
Surface Dose Rates 5 mrem/hr max. top and sides of gauge
15 mrem/hr max. bottom of gauge, gamma in shield position
Shipping Case DOT 7A, Type A, Yellow II Label, 0.2 Transport Index
Sealed source approved for domestic and international shipment CS-127, Special Form Certificate
GB:SFC 140
Stored Energy 30 watt-hours
Battery Recharge Time 14-16 hours (automatic cutoff)
Charge Source

110/220 VAC, 50-60 Hz or 12-14 V DC

Power Consumption 0.1t6 watt-hours

4x16 alpha-numeric LCD

Case Colored polycarbonate top shell with aluminum cast base
Operating Temperature Ambient: -10 to 70°C (32 to 158°F)
Surface: 175°C (350°F)
Gauge size without handles 18.6 x 9.1 x 6.2 inches
(472 x 231 x 158 mm)
Gauge height with handles 9.5 inches (240 mm)
Storage Temperature -55 to 85°C (-70 to 185°F)
Weight 29.7 lbs. (13.5 kg)
Shipping Weight 90 lbs. (40.8 kg) with case


Features & Benefits The Model 4640-B provides you with these advantages: True thin-layer gauge; no nomograph calculations needed No need to measure the density of base materials Stores up to 750 test results Fifty years of Troxler experience and a twelve month warranty give you the confidence you need in your field testing equipment


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