ZORN ZFG Light Weight Deflectometer (LWD)

ZORN advantages of the Light Weight Deflectometer | in a few words

...over 10,000 satisfied customers

Proven for decades: Over 70,000 testing devices sold and more than 10,000 satisfied ZFG customers rely on our durable LWD. Robust, reliable and low-maintenance, they accompany construction projects for decades - a guarantee of quality and precision in construction and engineering practice.

Here comes our range of ZORN ZFG models...

ZFG D plus| LWD for wireless operation

ZFG 3.1 | LWD with small handheld device (printer, printer case optional)

ZFG 3000 | Light Weight Deflectometer with compact measuring electronics in a robust case including printer

ZORN Mini | LWD for narrow trenches (broadband, fibre optics, trenching)

Click here for the accessories.

... for rapid compaction testing of soils

The Light Weight Deflectometer is used to determine the compaction quality and load-bearing capacity of soils and unbound base layers in earthworks, foundation engineering and road construction, as well as for soil improvement. Within two minutes, you can perform high-quality measurements in accordance with different international standards (see below) and obtain, among other things, the dynamic deformation modulus Evd [MN/m²] .

This dynamic plate load test can be carried out in confined spaces (e.g. bridge underpasses, pipe trenches) without load vehicles or other aids. With different electronic systems (ZFG 3000, ZFG 3.1 or ZFG D plus), our LWD scores points with its modular design and practical additions. GPS/GNSS and WiFi are of course included. The accompanying ZORN FG WebApp, which can be used free of charge, simplifies data logging. As a quality leader, it is important to us to continue to be the best in service and to work with you honestly and transparently without any hidden follow-up costs.

Get a no-obligation consultation and purchase your reliable drop weight device from the service winner.

The original – durable, sustainable, high quality!

LWD for rapid soil compaction testing

Service leader________________________________________________________________

With our Light Weight Deflectometer, you benefit from an unbeatable service network all around the world. Our calibration centres guarantee fast and reliable maintenance carried out by trained specialists. We provide unbureaucratic and direct assistance – always fair and customer-oriented. Transparent costs with no hidden fees make our service global unbeatable.

Technical expert_________________________________________________________________

Our LWD combines precision, innovative technology and ease of use. Developed for engineers, construction companies and soil testers, it delivers accurate results in compaction tests and ground analysis. Thanks to state-of-the-art technology and practical functions, you are always one step ahead.

Did you already know?

ZORN | innovative, modern, customer-oriented!

Calibration - why is it necessary? Let's have a look.

The reliable and consistent use of the measuring device also called a "drop plate" is regulated in Germany in particular by the Technical Testing Regulations for Soil and Rock in Road Construction (TP BF-StB) Part 8.3, in conjunction with the Zusätzlichen Technischen Vertragsbedingungen und Richtlinien für Erdarbeiten im Straßenbau (Supplementary Technical Conditions of Contract and Guidelines for Earthworks in Road Construction) (ZTV-E StB).

ZORN INSTRUMENTS also operates a calibration stand for the Lightweight Deflectometer. This stand was developed by us for the German Federal Highway Research Institute (BASt) and was the first of its type to be approved by the authorities.

You will find more detailed information on our technical service on the calibration and servicing page.

For decades, highly qualified employees from ZORN INSTRUMENTS have been actively involved in related research and standardisation forums, in Germany and worldwide. Numerous international standards such as ASTM E2835-11 or the Austria test specification RVS 08.03.04 in the meantime permit users to use the dynamic plate load test correctly in their countries and in the related conditions there.



Test specifications and contractual terms and conditions for the
dynamic plate load test.

Dynamic plate load test specifications: the Lightweight Deflecto-
meter from ZORN INSTRUMENTS meets all specifications for the
correct usage of the dynamic plate load test.

TP BF-StB Part B 8.3
Road construction, Part E1 (Statistics)

ZTVE-StB 09
Road construction, base courses, sewer construction

NGT 39 - Eisenbahnbau
Railway construction

RIL 836 Deutsche Bahn AG
Guidelines for the use of the lightweight deflectometer in railway
construction

RVS 08.03.04 March 2008
Compaction verification using dynamic plate load test (Austrian
test specification)

UNE 103 807-2
Spanish test specification

ASTM E2835-11


All certificates at a glance.

Efficient ground control

The “drop plate” enables fast and precise measurements of compaction quality. Its ease of use and quick readiness for use save valuable time on the construction site.

Flexibility in every situation

The compact design makes it particularly mobile and versatile - whether in road construction, bridge building or geotechnical engineering. Wherever fast and reliable results are required, the Light Weight Deflectometer is your first choice.

Sustainability as standard

Our equipment is designed to be durable and environmentally friendly, meeting the highest standards in the construction industry. Durability means less use of resources and less maintenance.

Your advantage: the best global service network

Our global service network ensures that you receive rapid support when needed. With our experienced dealers around the world, we are always on hand to provide maintenance, calibration and technical advice.

General questions about the Light Weight Deflectometer (LWD)

It’s easy. The serial number is engraved on the loading plate, as this is also where the acceleration sensor is located.

The electronic units have a serial number label:

  • On the ZFG 3.1 and ZFG 3.0, the label is located on the outside of the bottom of the unit.
  • On the ZFG 3000, the label is located under the lid, on the rear wall at the top, where the lid is attached to the housing by the hinges.

The weight (more precisely, the loading device) receives a new calibration label after each calibration. Among other information, this label contains a QR code linking to the calibration certificates. The serial number can also be found there.

This allows the loading plate, electronics and loading device to be clearly assigned to the correct instrument.

Not necessarily. If there are voids beneath the loading plate, fill them with dry medium-grained sand to ensure proper contact between the plate and the test surface (see also the German technical testing specification TP BF-StB Part B 8.3).

The test surface must also be level and as horizontal as possible.

In short: Use sand only when needed to compensate for voids and ensure full contact between the loading plate and the test surface.

By default, preloading impacts are detected by the electronic measuring unit.

You can adjust the electonics to suit your requirements in the Settings menu. To do this, first press the <Mode> button to open the menu. Use the <Mode> button to scroll to “Settings” and press <OK> to open it. Then scroll to “Preloading” and press <OK> to switch the preloading function on or off.

The results of the preloading impacts are not included in the measurement result and are not stored.

Tip: If the electronic measuring unit does not detect the preloading impact, you can also perform the preloading with the electronics switched off. To do this, simply deactivate the “Preloading” function.

Preloading impacts are performed in exactly the same way as measurement impacts.

By default, the preloading function is enabled. The results of the preloading impacts are not included in the measurement result and are not stored.

You can display the Evd value in either MN/m² or MPa. You can change the unit directly on the electronic measuring unit:

  1. Press the <Mode> button to open the menu.
  2. Use the <Mode> button to scroll to “Settings”.
  3. Press <OK> to open the settings.
  4. You are now in the “Settings” menu.
  5. Use the <Mode> button to scroll to “Unit”.
  6. Use the <+> and <-> buttons to select the desired unit and save your selection by pressing the <ON/OFF> button.

Note: MN/m² and MPa are numerically equivalent units, so the measurement value itself does not change only the way it is displayed.

Whenever you change the loading device (10 kg or 15 kg), the loading plate (150 mm or 300 mm), or switch to a CBR test, the electronic measuring unit must be manually set to the corresponding test type.

To change the test type:

  1. Press the <Mode> button to open the menu.
  2. Use the <Mode> button to scroll to “Settings”.
  3. Press <OK> to open the settings.
  4. In the “Settings” menu, use the <Mode> button to scroll to “Type”.
  5. Use the <+> and <-> buttons to select the desired test type and save your selection by pressing the <ON/OFF> button.

Important: Always make sure that the test type selected in the electronics matches the actual loading device and loading plate being used. Otherwise, the measurement results may be incorrect.

Yes, of course. It can happen that the language is accidentally changed and the display suddenly shows a language you no longer understand.

In this case, you can switch back to your preferred language via the “Settings” menu on the ZFG 3.0, ZFG 3.1, ZFG 3000 and other compatible models. It may be a bit of a blind flight, but the following steps will guide you through it:

  1. Switch on the electronic measuring unit using the <ON/OFF> button.
  2. Press the <Mode> button to open the menu.
  3. Press the <Mode> button four times.
  4. Press <OK>.
  5. Use the <+> and <-> buttons to select your desired language.
  6. Save your selection by pressing the <ON/OFF> button.

Still stuck? No problem. Just give our service team a call at +49 3931 25273-27 or mail to sales@zorn-instruments.de.  We’ll be happy to help.

You can quickly check the sensor yourself to see whether it is functioning correctly.

  1. Press the <Mode> button to open the menu.
  2. Use the <Mode> button to scroll to “Calibration”.
  3. Press <OK> to open the menu item.

If the measurement cable is correctly connected between the loading plate and the electronic measuring unit, the value “a” should be around 0.0.

The value of “a” should change by approximately two whole number units when the loading plate is turned upside down, with the centering ball and mounting pin facing downward.

If “a” shows a different value and/or does not change when the loading plate is turned over, there may be a fault in the cable, socket or sensor.

In this case, please contact our service team so we can help identify the source of the problem:

Service: +49 3931 25273-27 or mail to sales@zorn-instruments.de. 

Yes. The electronic box can also save measurement data in its internal flash memory. These data can later be copied from the internal memory to an SD card.

Please note: To avoid problems, we recommend not making any manual changes to the “ZFG” directory. To back up your files, save the entire “ZFG” directory.

If you no longer need the files, delete the entire directory rather than individual files.

Depending on the selected setting, the coordinates can be displayed either as latitude and longitude (Lat/Lon) or using the UTM (Universal Transverse Mercator) coordinate system.

You can change the coordinate format in the “Settings” menu:

  1. Open the “Settings” menu.
  2. Use the <Mode> button to scroll to “Coordinates”.
  3. Use the <+> and <-> buttons to select the desired coordinate format.
  4. Save your selection by pressing the <ON/OFF> button.

Tip: If the GPS values suddenly look completely different from what you are used to, check the selected coordinate system first. The data may be perfectly correct - they are simply being displayed in a different format.

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