By accuracy we mean corresponding to the average value of a series of measurements adjusted for temperature and pressure with the desired value.

Borosilicate glass differs from soda lime glass by using a higher proportion of sand (SiO₂). The composition of this glass contains 70-80% silicon dioxide (SiO₂), 7-13% boron trioxide (B₂O₃), 4-8% Na₂O and K₂O, as well as 2-7% aluminia oxide (Al₂O₃). Glass with such composition is characterised by a high resistance against acidic attack, low thermal expansion and excellent temperature stability. This glass is particularly suitable for laboratories and chemical use where contact with aggressive materials is likely to be prolonged.

We recommend washing all laboratory glassware before it is used for the first time, because it cannot be completely excluded that it has not been contaminated during transport.

Cleaning by hand
The common cleaning method is to wipe and rub the glassware with a cloth or sponge soaked in a cleaning solution. Abrasive cleaners and sponges should not be used because they can damage the surface of the glass.

Machine cleaning
Cleaning in a machine is more gentle for glassware than soaking it. The glass only comes into contact with the dishwashing liquid for relatively short periods when it is being sprayed onto the surface of the glass.

To ensure proper operation and life of the OPTIFIX® dispensers, we recommend the following cleaning procedure to provide you with years of trouble free service.
Prepare a standard cleaning solution and hot water.
Remove the piston from the Cylinder via the volume setting knob.
Remove discharge tube, intake tube and adapter.
Put all parts into the cleaning solution for 2-4 hours or over night to allow a good soaking.
After soaking, use a clean glassware brush to remove any further dirt if necessary.
Rinse all dispenser parts with distilled water and air dry.
Reassemble the unit and put the OPTIFIX dispenser back into service.

Calibration of Volumetric Glassware

Volumetric glassware is either calibrated to deliver (EX) or to contain (IN).

• EX calibrated to deliver. The delivered liquid corresponds with the volume indication.
  The liquid that remains on the wall or in the tip of the glassware is taken into consideration.
• EX + s calibrated to deliver after a waiting time (for pipettes 5 or 15 seconds, for burettes 30 seconds).
• Keeping to the waiting time is important to avoid mistakes in measurement.
• IN calibrated to contain. The contained liquid corresponds with the volume indication. Example: flasks and cylinders.
• 20°C The calibration has been done at 20°C. Volumetric glassware changes volume about 0,1 % each degree Celsius.

The coefficient of variation is the % value of the precision

Graduation: All graduation marks are either white ceramic fired onto the glass or amber stain fired into the glass.

Colour coding is used to distinguish various sizes on graduated and volumetric pipettes

The revised version of the German metrology calibration law published in August 1988 includes conformity control and approval of volumetric measurement instruments made of glass. This means that the manufacturer himself may certify the conformity on the basis of the PTB standards. The maintainance of these specifications is monitored at regular intervals by national bodies. Volumetric measuring instruments, which have been checked in accordance with these guidelines, are marked by the conformity sign ‘H’ , which includes the manufacturer’s own designation within it.

• A tolerance according to DIN, ISO and BS. Class A is the most precise class. Glassware of class A is suitable for official calibration, that means it can be tested by either the German or the UK Weights and Measures Offices. This is useful for the control of the measuring instruments according to DIN ISO 9001. The same applies to Class AS
• While AS is the same as class A, t for pipettes and burettes has faster delivery. The waiting time is much shorter than for class A.

Disinfection Laboratory equipment that has been in contact with infectious material should be disinfected before use, for the protection of laboratory workers. It can be washed by hand with a cleaner/disinfectant. Further it can be cleaned by using physical or thermal methods (for 10 minutes at 93°C as required by the BGA). If necessary the glassware can be steam sterilised.

Steam sterilisation Steam sterilisation refers to the DIN 58 900,Pt.1,1986 ‘the destruction or irreversible inactivation of all micro-organisms of 120°C and 2 bar’. At a sterilisation temperature of 121°C the glassware should be sterilised for 20 minutes minimum effective application time. Laboratory equipment should be always cleaned carefully before steam sterilisation, otherwise any soiling will bake on during the steam sterilisation. If there are any chemicals on the surface of the glassware during the sterilisation they can damage the glass due to the high temperatures. Containers should be opened during the sterilisation to avoid a build-up of pressure. The steam has to have unrestricted access to all contamined points to ensure an effective steam sterilisation.

Soda Lime glass finds its use in the foodstuffs industry as bottle and preserve glass as well as in the laboratory industry. The chemical composition of this glass consists of 71-75 % sand (SiO2), 12-16 % soda and 10-15 % of lime. Soda lime glass is subject to acute stress under heat shock and has a relatively high coefficient of expansion. It is particularly resistant to alkline liquids.

Borosilicate glass differs from soda lime glass by using a higher proportion of sand (SiO2). The composition of this glass contains 70-80% silicon dioxide (SiO2), 7-13% boron trioxide (B2O3), 4-8% Na2O and K2O, as well as 2-7% aluminia oxide (Al2O3). Glass with such composition is characterised by a high resistance against acidic attack, low thermal expansion and excellent temperature stability. This glass is particularly suitable for laboratories and chemical use where contact with aggressive materials is likely to be prolonged

Cerium glass is a variant of soda lime with cerium oxide. It is very useful when looking to sterilise with gamma rays which you cannot do with ordinary soda lime glass.

We distinguish between two different graduation types:

• for Class A or AS products: complete ring marks
• for Class B products: short graduations

Dispensers (compiled from BS ISO 8655: Part 1-6: 2002)

Test Lab should contain:

Lab should ideally be air conditioned.
Temperature and air pressure should be stable.
Air movement should be minimised.
Weighing/balance surface should be free of vibration.

Test Lab Equipment:
Air pressure barometer• Certified Class A thermometer
Accurate (5 decimal place)balance properly calibrated to National Standards
Distilled water at stable room temperature.

Measurement of volumes is part of to the routine work in a laboratory. The most common volumetric glassware such as bulb and graduated pipettes, burettes, volumetric flasks and graduated cylinders form part of the basic equipment in a laboratory. Inscriptions and graduations on volumetric glassware should be easy to read, acid and alkali resistant. The complete range of FORTUNA® and VOLAC® volumetric glassware fulfils these requirements.

Meniscus We read value at the lowest point of the surface, which means when the lowest point of the meniscus touches the upper line of the graduation mark (See Picture 1).

For burettes with Schellbach stripes the reading has to be made at the level where the wedge-shaped two points are touching (See Picture 2). When reading the scales it is important that one‘s eyes are at height of the fluid level. Otherwise it results in reading errors (parallax errors).

For further information please see technical information section in our catalogue.

Tare a container on the balance.
Using a wetted tip, pipette/dispense into the tared container on the balance.
Read weight of dispensed water.
Read temperature of distilled water.
Read the air pressure.
For setting calibration test 4 times at each volume,for checking/certifying calibration test minimum 10 times and for testing co-efficient of variation test 30 times.

Use high quality tips preferably of a brand to match the pipettor. Ensure tips do not leak (hold pipettor verti cally with tip filled with liquid without dripping for at least 20 secs).
Always rinse and pre-wet each tip with distilled water at least 3 times before use.
Always fill and dispense slowly and smoothly.
Always fill with pipettor tip not more than 3-4 mm below liquid surface and pipettor held vertical.
Always dispense with pipettor tip against wall of container and pipet tor held at 45° to the vertical; always draw tip up the container wall one or two seconds after second blow out pressure of the thumb press.

PP – Polypropylene When polymerising, propylene develops a product which contains methyl side groups of monomers of the paraffin chain. The volume requirement due to the regular methyl side chains is relatively large. For this reason polypropylene is the plastic with the lowest specific weight in compact form. It is similar to polyethylene, and may be used instead of polyethylene, where it particularly depends on good heat resistance, high impact strength, inherent stability during stress or particularly low specific weight. Polypropylene also has a good resistance to many inorganic reagents as well as the less aggressive organic solvents.

Precision is a measure of the variation from the nominal value achieved through a series of measurements at one setting.

PTFE – Polytetrafluorethylene PTFE has no thermoplastic characteristics although it consists of linear, chemical chain molecules which are not linked. It is not possible to handle or form PTFE in the usual thermoplastic way. Nevertheless PTFE is a thermoplast because it can be sintered. For the production of shaped parts from PTFE the polymer is cold pressed as powder under high pressure into the desired form and sintered at temperatures around 380°C. PTFE is attacked only by elemental fluorine and chlorine tri fluoride at higher temperatures and pressures as well as by melting alkali metals. Otherwise it is resistant to all chemicals. A further advantage of polytetrafluorethylene: it has got the lowest coefficient of friction of all solids. However above 350°C PTFE burns in air to form noxious gases.

What is understood by quality? In general usage the term ‘Quality’ has a number of meanings. Glass products of first class quality might be called this because the finish is good, the raw material used is good, the packaging is good, the appearance is good or the accuracy is good. Quality is defined as having all those characteristics and features of a product, which refers to its suitability for the fulfilment of given requirements, that is ‘fit for purpose’. So Quality is related to the need and the specification set.

The Quality Management of Poulten & Graf Product quality is directly dependent on the quality of process. Quality assurance must begin in the very first phase of the product creation process and cover all following phases. This global view of quality assurance, involving all aspects of production, design, testing, packing and conformity with both internal standards and externally set specifications, is the basis of our quality management. This is reflected in the approvals of DIN EN ISO 9001/2008, which we have achieved and which we maintain.

Important safety instructions:

1. In the context of the inspection of incoming goods, users should check laboratory instruments before application to ensure proper functioning.

2. Within the daily laboratory routine, laboratory instruments should always be examined for damage in order to avoid risk of injury. Damaged laboratory instruments will be dangerous for the user due to the risk of cuts, burns and infection.

3. Damaged volumetric glassware such as volumetric flasks, pipettes and measuring cylinders should never be repaired. The effects of heat can leave stress in the glass (high risk of breakage!) and changes the volume.

4. Avoid sudden changes of temperature during handling of the glassware (especially, thick walled glassware has to be cooled down slowly).

5. Before using glass equipment in a vacuum or under pressure it must always be inspected visually. Damaged glassware (e.g. with scratches) should not be used for work under pressure or in a vacuum. Glass equipment that is under pressure or in a vacuum (e.g. filter flasks) must be handled with care to avoid damaging the surface.

7. Avoid sudden changes in pressure, that means vent items that are in a vacuum, smoothly. Laboratory glassware with flat bottoms, e.g. Erlenmeyer flasks, should not be used under pressure or in a vacuum.

Please note that we offer plastic coated volumetric glassware to minimise risks when using glass in the laboratory.

Current discussions on environmental protection, dangerous materials etc. have made laboratory technicians more sensitive in the selection of laboratory instruments. The primary concern remains the safety aspects, because while handling dangerous or hazardous materials, laboratory equipment must be extremely safe and reliable. For the protection of humans and the environment all valid regulations of official organisations must be observed. For a number of products we offer a repair service:

• bottle top dispenser POLYFIX®, OPTIFIX® and VOLAC ULTRA,
• electronic burette OPTIFIX® titrier,
• automatic dosing system OPTIMAT® 2, VOLAC pipettors.

Please remember that when returning any instrument for repair it must be accompanied by its packaging.

Soda Lime glass finds its use in the foodstuffs industry as bottle and preserve glass as well as in the laboratory industry. The chemical composition of this glass consists of 71-75 % sand (SiO₂), 12-16 % soda and 10-15 % of lime. Soda lime glass is subject to acute stress under heat shock and has a relatively high coefficient of expansion. It is particularly resistant to alkline liquids.

Steam sterilization refers to the DIN 58 900,Pt.1,1986 ‘the destruction or irreversible inactivation of all micro-organisms of 120°C and 2 bar’. At a sterilisation temperature of 121°C the glassware should be sterilised for 20 minutes minimum effective application time. Laboratory equipment should be always cleaned carefully before steam sterilisation, otherwise any soiling will bake on during the steam sterilisation. If there are any chemicals on the surface of the glassware during the sterilisation they can damage the glass due to the high temperatures. Containers should be opened during the sterilisation to avoid a build-up of pressure. The steam has to have unrestricted access to all contamined points to ensure an effective steam sterilisation.

To define the different classes (Class A, Class AS,. for glass or ‘performance’ for pipettors and dispensers) the following terms are used: ‘accuracy’ and ‘coefficient of variation’ (precision). Sometimes we also speak about ‘tolerances’ which are specified in the ISO  or DIN standards. This means the permitted deviation of the measured values from the nominal volume. By accuracy we mean corresponding to the average value of a series of measurements adjusted for temperature and pressure with the desired value. Precision is a measure of the variation from the nominal value achieved through a series of measurements at one setting. The coefficient of variation is the % value of the precision.

When manufacturing pharmaceutical products or intermediates which may either be exported into US markets or which are made by companies being audited by US authorities, such as the Food and Drug Administration (FDA), it is a written requirement of the FDA that volumetric glass used in laboratories for control purposes must conform to the standards laid down within the US Pharmacopoeia.

The standards of accuracy for volumetric glass laid down by the US Pharmacopoeia are not always the same as those laid down by ISO. DIN standards are never the same as USP. Each individual piece of USP Class A glass is individually tested and carries its own individual number. Not only does this offer full traceability, but it also permits all laboratory work to be done with identifiable and identified equipment. Accuracy to USP Class A standards is guaranteed. A WAC certificate is supplied.

All VOLAC Class A glassware is batch tested.. Test records are kept in-house with the manufacturing records.

individual Works Certificates of Accuracy can be provided for each piece if required; each piece of glass has its own individual number engraved on it and the Certificate supplied will have the corresponding number, the date and the relevant test results.

Works Certificates of Accuracy (look for the designation WAC in the product codes) should not be confused with Certificates of Con­formity which refer to batch testing only.

All VOLAC and FORTUNA® conformity approved volumetric glassware is delivered with theVOLAC or FORTUNA® Batch Certificate of Performance. A regular control of all testing equipment is claimed in the DIN EN ISO 9001. The demand for traceability is fulfilled with theVOLAC or FORTUNA® lot number and the batch certificate.

In addition to the conformity sign all VOLAC and FORTUNA® volumetric glassware is marked with the individual lot number that allows an exact traceability back to the batch certificate. If your certificate is lost, you may ask for a copy by informing us about the product details and the batch number.

AllVOLAC andFORTUNA® conformity approved volumetric glassware has a downloadableVOLAC or FORTUNA® Batch Certificate of Performance. A regular control of all testing equipment is claimed in the DIN EN ISO 9001.