Antifreeze Refractometers

Low temperatures leading to freezing conditions can, if not managed correctly, often result in serious damage to plant and equipment, chillers and engine cooling systems. System blockages, cracked pipes and unwanted fluid loss can be expensive both in terms of operational down-time and ultimate repair or replacement costs. It is therefore essential that systems are properly protected and antifreeze levels are periodically tested. Testing of antifreeze concentrations for automotive and industrial applications has been made easier by the use of antifreeze refractometers.

The antifreeze/battery refractometer is designed for testing the refractive index or concentration of battery fluids, antifreeze liquid and cleaning fluids that works on the critical angle principle. Antifreeze refractometers utilize lenses and prisms to project a shadow line onto a small glass reticule inside the instrument, which is then viewed by the user through a magnifying eyepiece.

In use, a sample is sandwiched between a measuring prism and a daylight plate. The reading is taken when a shadow line crosses the scale from the shadow line formed between the illuminated area and the dark area then a shadow line crosses the scale. With the indication of the percentage you may know which temperature the fluid will be frozen for both propylene glycol and ethylene glycol. It can also be used for checking the strength of electrolyte solution batteries.

Refractometers represent the most accurate conventional testing method available for determining freeze point and concentration of engine coolants and antifreeze solutions. Don't be misled by hydrometers or freeze-point test strips, which are not accurate enough to be useful.

One of the best instruments to test these solutions is the ATAGO Antifreeze Refractometer model Master BCF. This refractometer has an exclusive scale for measuring specific gravity of battery fluid and for checking the freezing temperature of ethylene glycol and propylene glycol which are used as antifreeze mixture in automobiles, thermal catalyst for solar power systems and other industrial applications. The Master BCF is easy to use and accurate for testing in the field

Author Name: Rowland Brasch : Nationalmicroscope.com

Antifreeze Refractometers

Inverted Microscopes

Most microscopes that you see in a typical laboratory environment are compound microscopes. They are designed with objectives on a rotating nosepiece mounted above the stage, and the light source and condenser below the stage. They are most commonly used for viewing samples that have been fixed to a flat slide.

In certain applications it is necessary to look at live, unfixed samples. A more practical microscope design to use is the inverted microscope. An inverted microscope is a microscope with its light source and condenser on the top, above the stage pointing down, while the objectives and turret are below the stage pointing up. Inverted microscopes are useful for observing living cells, tissues or organisms at the bottom of a large container (such as a tissue culture flask). This allows you to examine the specimen under more natural conditions than on a glass slide, as is the case with a conventional compound microscope. You can place a Petri dish or other container on the stage and view the samples from below, thus not disturbing their more “natural” states. Larger, covered samples are less susceptible to evaporation and increases in temperature, thus preserving suitable living conditions for the specimen you are viewing.

Because of the fact that you have to look through thicker containers you often find the objectives to be long working distance or ultra-long working distance. These objectives have been corrected for observing samples that are further away than what you normally see on a compound microscope. The image may not be quite as clear as when you are looking at a perfectly flat slide. You may want to use a plastic Petri dish rather than a glass one as the plastic dishes are thinner and more uniform. Most inverted microscopes will have objectives that range from 4-40X, with 60X being an added option. You do not usually find inverted microscopes that incorporate 100X objectives.
Inverted microscopes can be configured for work in electrophysiology, in vitro fertilization, micromanipulation, high-resolution DIC, video-enhanced observations, and a variety of advanced fluorescence techniques. Motorized accessories can include shutters, filter wheels, revolving nosepieces, fluorescence block turrets, focus drives, and condensers. Inverted microscopes also allow you to add advanced objectives for water immersion, ultraviolet excitation, and phase contrast. Prices for inverted scopes vary according to the number and types of accessories you add to them, just as in compound microscopes.

The fundamental advantage of an inverted microscope is that it allows you to accept a container with a large and relatively long-lived diverse culture of live organisms without any preparation. This can be invaluable to work which requires the sample to be alive and in as natural an environment as possible.

Author Name: Rowland Brasch : Nationalmicroscope.com

Inverted Microscopes

Used Microscopes

Remember back to your school days when you first saw amoeba swimming around in pond water? You thrilled to seeing the microscopic organisms moving around, bumping into each other. Now you want to share that memory with your children or grandchildren as they grow. But you don’t want to spend their college money on a new high-priced microscope, so what can you do? No problem – you can now find many microscopes that are either used or demo models at a much more reasonable price. But first you need to determine what type of a used microscope you want: compound or stereo/dissecting.

The most common microscope is the compound microscope. It is the one most people visualize when they think about microscopes. It comes with one eyepiece called a monocular; two eyepieces called a binocular or it might have an additional camera tube and is called a trinocular. It has a number of objectives (the lens closest to the object being viewed) of varying magnification mounted in a rotatable nosepiece. It uses a light source beneath the stage to illuminate slides. These microscopes are generally used to view very small objects such as cells or bacterium mounted on slides. Magnification of these scopes range from 40X up to 1000X. Actual magnification can be figured by multiplying the power of the eyepiece by the power of the objective lens.

The other type of microscope is called a stereo or dissecting microscope. It uses two eyepieces and two paired objectives. There are models that have full zooming capability and models that just have only two magnification settings. It is particularly useful for biologists performing dissections, technicians building or repairing circuit boards, paleontologists cleaning and examining fossils or any one who needs to work with their hands on small objects such as rocks & bugs. It may use a built in light source from above, below, or none at all. Magnification is usually from 10X to 40X.

By researching and purchasing used microscopes you open up a much greater range of instruments available to you. You can now purchase an instrument with many more accessories for much less money. Just make sure to do your homework ahead of time so that you know what to expect for the money you pay.

Author Name: Rowland Brasch : Nationalmicroscope.com

Used Microscopes

Abbe Refractometers

Refractometers are measuring instruments which put the phenomenon of light refraction (bending) to practical use. They are based on the principle that as the density of a substance increases (such as when sugar is dissolved in water), its refractive index rises proportionately. Refractometers were devised by Dr. Ernst Abbe, a German/Austrian scientist in the early 20th century. The prism in a refractometer has a greater refractive index than the sample solution. Measurements are read at the point where the prism and solution meet. With a low concentration solution, the refractive index of the prism is much greater than that of the sample, causing a large refraction angle and a low reading. The reverse (lower refraction angle and higher reading) would happen with a highly concentrated solution.
Abbe Refractometers are a type of refractometer used for measuring the refractive index of solid samples, such as glass, plastics and polymer films. There are two detection systems for refractive index: transparent systems and reflection systems. Hand-held refractometers and Abbe refractometers use transparent detection systems, and digital refractometers use reflection detection systems. Abbe refractometer readouts can be either digital or analogue. Abbe refractometers are used most often to measure solid samples – something that standard digital refractometers cannot do. Circulating water baths can be added to control instrument and fluid temperature in Abbe refractometers.
Newer versions of Abbe refractometers have recently been upgraded to include solid state Peltier elements to both heat and cool the refractometer so that you no longer need to use a waterbath. Another modern feature is the ability to link the Abbe refractometer to a computer to control the instrument and to record readings. Some Abbe refractometers can measure at wavelengths other than the standard 589 nanometers, using filters on up to the near infrared range. They are referred to as Multi-wavelength Abbe refractometers. Multi-wavelength Abbe refractometers can be used to easily determine a sample's Abbe number, which is a measure of the material's dispersion (variation of refractive index with wavelength) in relation to the refractive index. These multi-wavelength Abbe refractometers can be used to test eyeglass lenses, contact lens materials, optical plastics for optical communication, compact disk materials and insulating oil. Other accessories that are available include digital printers, extra filters and near-IR viewers.

Author Name: Kathy Brasch : Nationalmicroscope.com

Abbe Refractometers

Brix refractometers

You often hear the term brix and brix refractometer when testing samples for sugar content. Just what is a refractometer? A refractometer is an instrument that measures the refraction of light through a substance. The refractive index becomes higher in a substance of higher concentration.

A refractometer has a wide variety of uses such as measuring sugar concentrations and liquid concentrations. Refractometers are sometimes called “Sugar concentration meters” or “Density meters” depending on the application.
Brix and refractive index are common measurement scales for refractometers. A refractometer that measures brix is referred to as a Brix Refractometer. When measuring solutions that have multiple ingredients the Brix value equals the total concentration of dissolved solids.
About the Brix (%) Scale

Brix (%) shows the concentration percentage of the soluble solids content in a sample (water solution). The soluble solids content is the total of all the solids dissolved in the water, including sugar, salts, protein, acids, etc., and the measurement reading is the sum total of these. Basically, Brix (%) is the number of grams of cane sugar contained in 100g of cane sugar solution. When measuring a sugar solution, Brix (%) should perfectly match the actual concentration. With solutions containing other components, especially when one wants to know the exact concentration, a conversion chart is necessary.

Digital versus Analog Brix refractometers

Brix refractometers are available in hand-held (analogue) or digital models. Hand held units are read by putting a drop of sample on the prism, closing the daylight plate and then reading the scale through an eyepiece as the instrument is held up to your eye. A hand-held/analogue unit determines the refractive index or brix by use of the “Transparent System” which measures light as it passes through the sample and the prism. A low concentration sample has a larger angle of refraction so the boundary line falls on the lower part of the scale, whereas a high concentration sample has a small angle of refraction so the boundary line appears in the upper part of the scale.

Digital Brix refractometers use the “Reflected light system. When you put a sample on the prism and press the Start button, the light that is transmitted from under the sample will travel and refract in multiple directions. The angle of reflection is proportional to the refractive index of the sample, and the reflected light is measured by a sensor and converted into the refractive index or brix readout.

Because of their versatility, brix refractometers are used widely to test sugar content in fruit, vegetables, wine and other food products.

Author Name: Kathy Brasch : Nationalmicroscope.com

Brix refractometers

How a Polarimeter works: A more detailed explanation

Light waves as it travels. As shown in Figure 1, light may seem to travel unidirectionally. In actuality light travels in all directions as shown in Figure 2.


When light, which waves in all directions, goes through a grating placed in its course of travel, only the light wave that oscillates in the direction parallel to the bars of the grating passes through, Light waves that oscillate in other directions get blocked by the bars of the grating. ( Figure 3 ) Such light, which waves in one particular direction, is called polarized light, and the grating is called a polarizing plate.

When polarized light travels through in a polarimeter an observation tube filled with a sample solution that does not make light rotate (water, for example), the light continues to wave in the same direction even after passing through the solution. ( Figure 4 )


In contrast, when it travels through in a polarimeter an observation tube filled with a sample solution that makes light rotate (sucrose solution, for example), the light wave begins to rotate as it passes through the solution. (Figure 5) This is called optical rotation.


Those samples that make light rotate have a molecular formula that contains asymmetric carbon ( indicated by "C" ) . Sugar is the most common. The explanation of the asymmetric carbon can be highly technical. Imagine making a light path by placing a polarizing plate, an observation tube, another polarizing plate, and a sensor one after another. (Figure 6 and 7). The path in Figure 6 has an observation tube filled with water, in Figure 7 a sample solution, such as sucrose solution, that makes light rotate, such as you would find in a polarimeter.



In Figure 6 a certain amount of light reaches the sensor.

In Figure 7 the light does not reach the sensor. (Technically speaking, in terms of a vector an imperceptible amount of light does reach the sensor, but let's assume that the light does not reach the sensor here. )

When the second polarizing plate is rotated as shown in Figure 8, the same amount of light as in Figure 6 now reaches the sensor.


Conducting Zero-Setting on a Polarimeter
Conduct zero-setting in the step shown in Figure 6. In the actual adjustment procedure, the observation tube filled with water is not necessary and zero-setting is conducted by letting light travel through the air. Next, place an observation tube filled with a sample solution that makes light rotate as shown in Figure 8. Rotate the second polarizing plate so that the equal amount of light reaches the sensor as it did when zero-setting was conducted. The measured angle of the rotated polarizing plate is the angle of rotation of the sample solution.

Author Name: Kathy Brasch : Nationalmicroscope.com

How a Polarimeter works: A more detailed explanation