Polarimeter Tubes

This comprehensive range of polarimeter tubes from Schmidt and Haensch are precision engineered from high quality laboratory grade glass or stainless steel. They have a 30 mm diameter support flange and meet the standards of ICUMSA Class A and the corresponding specifications of the OIML and the Australian Standard K157. The range includes many standard types and models for small samples, continuous measurement, and temperature controlled samples. We can also supply special tubes to meet specific requirements.

Choosing a Polarimeter Tube
Generally speaking longer tubes are better than shorter tubes, because the effects of artifacts such as manufacturing tolerances, contamination from residues and sample heterogeneousness are proportionately lower in a long tube. The most common tube lengths are 100 or 200 mm.. The 400 mm tubes are for visual sugar polarimeters. When testing colored samples it is sometimes necessary to use shorter tubes to reduce light absorption. The amount of absorption varies exponentially with length while the angle of rotation is directly proportional to length. The 190.09 mm and 95.04 mm tubes are for per cent observation for diabetes urine-sugar analysis. They are designed for testing in a circle polarimeter at a wavelength of 589 nm. The unknown glucose concentration in the test solution corresponds directly to the angle of rotation with the 190.09 tube and double the angle with the 95.04 mm tube.

Flow Through Tubes
Flow through tubes are recommended when a large number of measurements are required from solutions of essentially the same type. Flow through tubes are built in versions for manual sample changing with a funnel or automatic sample changing with a pump or dosing system. Flow through tubes work on the principle of completely displacing the current sample in the tube with the next sample to be measured. To do this a minimum sample volume of 60 cc is required.

Reduced diameter tubes ( 3 - 5 mm ) are used when only a small volume of sample is available. The bubble free filling of these narrow tubes is best accomplished with a syringe

Stainless steel sample tubes with center filling cap. Thermostatible

For photoelectric polarimeters the flow tube is held in place by the door of the measuring compartment and a special holder is not necessary. The supply and drain pipes are straight.

For photoelectric polarimeters.

For use with the Saccharomat, Polartronic M and H series Polarimeters. These tubes have an integral temperature sensor that is plugged into the polarimeter to make automatic temperature correction. Shown in sample well of a Polartronic

 The automatic flow through tubes for photoelectric polarimeters have longer connecting pipes so that they can be held in place by the measuring compartment door.

Washers and cover Glasses
Washers and covers glasses form the end seals of the polarimeter tubes. They are available in two sizes 15.5 mm diameter for all tubes except the flared ends of the bubble traps which take 23,7 mm diam glasses. Note that the purpose of the washers is to protect the end of the glass tube from stress when the screw caps are applied, the seal (and the precise length of the tube) is formed solely by the mating of the finely ground surface of the tube with the cover glass. Care should be taken to make sure that the mating glass surfaces of the cover and tube are clean and free of residue as this can lead to leaks. Washers that show signs of hardening or creasing should be replaced and care should be taken not to stress the cover glasses.

Quartz Control Plates
Quartz control plates are measurement standards which serve, mainly in the sugar industry, as test and reference standards for polarimeters. They are plates of optically pure quartz about 0.4 to 1.6 mm thick which are ground with high precision to have parallel surface perpendicular to their optical axis. They are mounted in tubes and their optical rotation is measured to better than 0.01 degrees. Each control plate comes with a test certificate to document its value. It is not possible to manufacture control plates to predetermined rotation values, but we keep stocks of control plates with differing rotation values so it is easy to obtain one with a value suitable to your purpose.