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Cells by Hellma Analytics for all applications

As an authorised dealser we offer more than 1,000 cells by Hellma Analytics online; here you can find cells for all applications and suitable for use with all analytical instruments. With more than 75 years of experience Hellma is known as the worldwide leader for the design and production of high-precision cells produced from optical glass and quartz.

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Cells

 

Material of the cells

Hellma Cells are manufactured from different types of glass. The most important criterion for the choice of a particular type of glass ist the spectral range for which the cell is intended. Basically, we differ between two ranges of material: 

Quartz Glass and Optical Glass

Quartz consists exclusively of silicon dioxid (SiO2)and shows some remarkable properties:

  • Quartz displays a high UV transmission, in highly purified synthetic Quartz down to well below 200 nm
  • The thermal expansion of quartz is extremly low
  • Quartz is chamically very resistant and maintains its shape, even at high temperatures up to approximately 1000°C

Common criteria for all types of Optical Glass are:

  • the cells made from it are used in the visible range of the spectrum
  • the glasses Hellma uses are characterised by relatively low values of refractive index and dispersion
  • the display good resistance to chemicals

Application and handling of cells

The Hellma precision cells are manufactured from glass and quartz and possess all the benefits of this material. Hellma generally recommends that cells are cleaned and dried immediately after use and returned to their storage cases. Do not keep the cells in the open in a corrosive atmosphere, and do not leave the polished windows in contact with liquid over long periods of time. Both conditions could lead to formation of deposits or stains and could render the cells unusable.

To avoid scratches on the precision-polished windows, the cells should never come into contact with objects made of hard materials like glass or metal.

  • Care is required when inserting the cells into a metal cell holder.
  • When filling the cells with liquids using a pipette, never touch the polished windows with the pipette.
  • Never use metal tweezers or pliers for carrying or holding the cells.

Handling Cells with Stoppers

Use caution when handling Cells with Stoppers: Cells that contain liquid and are sealed with stoppers may crack as a result of increased inner pressure. The most common cause of such a pressure increase is the expansion of the liquid within the cell due to an increase in temperature.

A temperature increase can be caused by:

  • heat conducted from an exterior source
  • a chemical reaction within the liquid
  • radiation absorption within the liquid

You can avoid the destruction of the cell by too much pressure in the following ways:

  • Fill the cell just high enough so that the light beam can pass through the liquid. The liquid can expand into the remaining cell volume when its temperature increases.
  • Should you fill the cell to the brim, only put the stopper on loosely so that the extra liquid can escape.
  • Do not try to force the stopper into place, as this will inevitably result in damage to the cell.
  • Use stoppers with a pressure release capillary.

Please note that high pressure may destroy some other kinds of cells as well. This occurs if the liquid contained is subjected to extreme changes in temperature. For
example, cells for anaerobic measurements may be affected. On the one hand it is possible to cool an empty cell down to just few Kelvin without destroying it, but the same cell, even if it is not sealed will burst, if filled with water and brought to a temperture a few degrees below the freezing point. The reason for this is the fact that water does not only expand upwards when it freezes, but in all directions equally which can cause the cell to burst.