Because quality is measurable.

Europe's leading specialist for density measuring instruments

About Gefo

What is Gefo?

Are you looking for specialists for density gauges? Then you have come to exactly the right place! Please allow us to introduce ourselves: Gefo, the market leader in the sector of high-quality frost protection and storage-battery acid testers in Germany and Europe. We are in constant dialogue with the leading manufacturers of antifreeze products. That lets us respond quickly and correctly to our customers' demands, which we implement expediently. And in line with our motto “Quality made to measure” we have been proving this successfully for more than 70 years.

It should last and last!

High-quality materials, sophisticated design techniques and regular monitoring ensure the long service lives of Gefo devices even with daily use. It’s no coincidence that meanwhile our products are sought after around the world. To preserve this lead all our density gauges will continue to be “Made in Germany”. Only then can we guarantee the continuous quality of our products and be able to quickly analyse any potential error sources.

Thank you, dear customers!

The long-standing loyalty of our customer proves that with our high standards we are on the right track. And we would naturally welcome you to soon rank among our customers also. Please do not hesitate to knock on our door with your specifications and requests. We look forward to hear from you. Your Gefo Team.

Our products are used by automobile accessory dealers, battery manufacturers, automobile manufacturers, procurement organisations, official institutions, DIY-stores and importers and exporters.

Applications

Anti-freeze-tester

Battery Acid Tester

Multifunctional Application

refractometer

Did you know?

  • What does the density determination of liquids mean?

    Our density measuring devices are based on the principle of buoyancy (discovered over 2,000 years ago by Archimedes). With our flotation scales and areometers, we can determine the density of liquids down to a difference of 0.001 (one thousandth) of a gram in weight. This is done in an environmentally-friendly way without electrical energy sources, purely mechanically and accurately due to the relevant design features. The concentration of anti-freeze for example can be determined from the density. From this concentration, the anti-freeze properties are derived and displayed on the scale. Only this above accuracy enables the determination of the required anti-freeze reliability of water/coolant mixtures. Our measuring devices meet these quality requirements, as well as the robustness required for workshop use.

  • How does temperature affect the measurement accuracy?

    Measuring devices are usually set or calibrated at a temperature of
    20°C. Liquids expand as the temperature increases, thereby changing the density to be measured. The flotation scale in our glycomat (for MEG + MPG) compensates for these effects within the normal range by its own expansion.
    Glass areometers cannot expand, and only produce accurate measurements at 20°C. Corresponding value correction tables can be used for the different media to be measured. Our coldomat anti-freeze tester has an integrated thermometer and a value table for MEG. The gefo s/th acidity tester has a built-in thermometer.

  • What are anti-freeze agents, and how do they differ?

    Anti-freeze agents for cooling circuits

    Coolant additives plus water produce the anti-freeze agent which is filled into the radiator. The coolant additive is a corrosion/anti-freeze agent (concentrate), which contains corrosion inhibitors (approx. 5%), anti-freeze agents (approx. 93%, MEG or MPG) and water. Such agents include:

    Monoethylene glycol (MEG)
    Synonyms: Ethylene glycol, MEG, monoethylene glycol, ethylene glycol, ethandiol

    MEG is generally used for vehicle cooling systems.

    The freezing point of this anti-freeze agent falls, depending on the manufacturer, from approx. -10°C to -40 °C with a water proportion of approx. 20 to 50 Vol% and then rises again on further concentration. At maximum concentration, the freezing point is approx. -13°C!

    and

    Monopropylene glycol
    Synonyms: Propylene glycol, MPG, propandiol

    MPG is used in the area of solar systems, heat pumps, in the foodstuffs industry and pharmaceuticals.
    The freezing point falls continuously to approx. -59°C at maximum concentration.

    Anti-freeze agents for the windscreen washer system

    High-quality anti-freeze agents primarily provide cleaning performance, then anti-freeze protection, material compatibility and minimum stress on people and the environment.

    The windscreen washer fluid (concentrate) consists of ethanol (approx. 79%) and monoethylene glycol (approx. 8%) for anti-freeze protection and to prevent rapid icing or icing of the nozzles. It also contains anionic and non-ionic tensides for cleaning, the removal of insects and salt in winter. The remainder consists of dyes, scents and water.

    The ideal mixing ratio is approx. 30 Vol% windscreen washer fluid and 70 Vol% water, which ensures anti-freeze protection down to approx. -18°C.
    If the concentration is increased, this increases the stress on paintwork, front and rear lights, SRF pipes etc. A sufficient amount of water is also required in order to clear the dirt released by the tensides from the windscreen.

  • How important is corrosion protection in the cooling circuit?

    Next to the electrical system, the cooling system in the car is most susceptible to problems.

    Anti-freeze agents with their corrosion inhibitors reliably protect all metals found in the cooling system against corrosion and deposits. This increases the functional reliability and the service life of the cooling system components such as the radiator, heat-exchanger, water pump, cylinder head and engine.

    Aluminium engines place higher requirements on corrosion protection. All automotive manufacturers research continually and intensively into further development, in co-operation with the manufacturers of anti-freeze agents. The approval conditions of the automotive manufacturers for common anti-freeze agents must also be observed.

  • Can concentrated anti-freeze agents freeze?

    Yes! Concentrated MEG freezes at approx. -13°C, and should not be stored at lower temperatures. Concentrated MPG only freezes at approx. -59°C, and in most regions can be stored in the open without any problem.

  • Should the coolant be replaced regularly?

    Coolants age differently, depending on the stress, and regular replacement is therefore necessary for safety purposes. Anti-freeze protection is primarily corrosion protection, so that coolant is used worldwide and is an all-year-round subject from the point of view of maintenance. When replacing metal components in the cooling circuit, the new components have many reactive surfaces. In order to provide these with a sufficient quantity of organic or inorganic corrosion protection inhibitors, regular replacement of the coolant is also advisable for this reason.

  • Why does the cooling circuit need anti-freeze protection?

    When water freezes, it increases in volume (at 0°C by approx. 9%).
    Cooling circuits cannot withstand this pressure, and can be severely damaged.
    Depending on their concentration, anti-freeze agents can reduce the freezing point to -40°C and below, thus offering adequate protection against damage.

  • What happens to the boiling point?

    The boiling point of anti-freeze/water mixtures is increased to approx. 110°C, and therefore also offers protection against overheating of the cooling circuit.

  • How is a charged battery tested?

    Measuring devices are usually set or calibrated at a temperature of
    20°C. Liquids expand as the temperature increases, thereby changing the density to be measured. The flotation scale in our glycomat (for MEG + MPG) compensates for these effects within the normal range by its own expansion.
    Glass areometers cannot expand, and only produce accurate measurements at 20°C. Corresponding value correction tables can be used for the different media to be measured. Our coldomat anti-freeze tester has an integrated thermometer and a value table for MEG. The gefo s/th acidity tester has a built-in thermometer.

  • What do coolants do as the engine temperature increases?

    Measuring devices are usually set or calibrated at a temperature of
    20°C. Liquids expand as the temperature increases, thereby changing the density to be measured. The flotation scale in our glycomat (for MEG + MPG) compensates for these effects within the normal range by its own expansion.
    Glass areometers cannot expand, and only produce accurate measurements at 20°C. Corresponding value correction tables can be used for the different media to be measured. Our coldomat anti-freeze tester has an integrated thermometer and a value table for MEG. The gefo s/th acidity tester has a built-in thermometer.

Contact

We want to make sure that consulting, sales and the supply of our products are all under one roof.

That lets us respond to individual customer requirements and answer your questions promptly.

Please feel free to get in touch with us!

Hella Weiland-Jacob

Hoffeldstr. 104
D-40235 Düsseldorf
info@gefo.de

Cornelia Vössing

Hoffeldstr. 104
D-40235 Düsseldorf
info@gefo.de