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Technical Information
The chemical composition and properties of SIMAX glass place
it in "group 3.3" of clear "hard" borosilicate glasses, characterised by their high
heat-resistance and chemical stability, as defined by the international standard
ISO 3585 and the Czech standard CSN ISO 3585. It fully complies with the
requirements which these standards place on its properties.
SIMAX glass is used to produce a wide range of technical and
laboratory glass products, industrial apparatus and heat-resistant household glassware,
whose characteristics and practical value have made them much sought-after products in
many countries throughout the world.
Because of its properties, SIMAX glass is used in situations
which place the highest demands on the heat-resistance and chemical stability of
products as well as their neutrality with respect to the substances or preparations
with which they come into contact, i.e. in chemistry, petrochemistry, the food, energy
and metalworking industries, health care, microbiology, pharmacy, mechanical engineering
and laboratories.
Products made from SIMAX glass are smooth, non-porous and perfectly
transparent, with no catalytic action, and are corrosion-resistant even in demanding
operating conditions up to 300°C without sudden changes of temperature.
SIMAX glass is an environment-friendly product and is completely
harmless from an ecological point of view.
Chemical composition of SIMAX glass
| Component | Amount (% by mass) |
|---|
| SiO2 | 80,4 |
| B2O3 | 13,0 |
| Al2O3 | 2,4 |
| Na2O + K2O | 4,2 |
Chemical Properties of SIMAX Glass
Products made from SIMAX glass are chemically stable,
practically inert and characterised by high resistance to the effects of water,
water vapour, acids and salt solutions and relatively high resistance to alkalis.
The glass is etched by hydrofluoric acid and concentrated
trihydrogenphosphoric acid and corroded by hot concentrated alkaline solutions.
Constant alternation of acid and alkaline environments increases corrosion.
The chemical resistance of SIMAX glass is specified by
the ISO 3585 and CSN ISO 3585 standards and is evaluated precisely by the international
standard testing methods defined by ISO and DIN ISO standards.
Chemical resistance of SIMAX glass to
| water at 98 °C (in accordance with ISO 719) | HGB 1 |
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| water at 121 °C (in accordance with ISO 720) | HGA 1 |
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| acids (in accordance with ISO 1776) | 1 |
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| effects of a boiling aqueous solution of mixed alkalis (in accordance with ISO 695) | A2 or better |
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Physical Properties of SIMAX Glass
The physical properties of SIMAX glass are evaluated precisely
by the international standard testing methods defined by ISO and DIN ISO standards.
The physical properties of Simax glass, as shown in the following
table, comply with the ISO 3585 and CSN ISO 3585 standards.
| Mean coefficient of linear thermal expansion (ISO 7991) Α20/300 | 3,3 ×10-6 K-1 |
| Density r | 2,23 g×cm-3 |
| Thermal conductivity (at 100 °C)l w | 1,2 W × m-1×K-1 |
| Specific heat capacity at constant pressure cp | 0,8× 103 J× Kg-1 × K-1 |
Temperatures of main points in terms of viscosity h in dPa × s
- 104 working temperature (ISO 7884 -- 2, ISO 7884--5) ..... 1260 °C
- 107,5softening point - Littleton point (ISO 7884--6) ..... 820 °C
- 10 13,2upper cooling temperature (ISO 7884-7) ..... 560 °C
- 10 14,7 lower cooling temperature (ISO 7884-7) ..... 510 °C
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| Transformation temperature (ISO 7884-8) | 525 °C |
| Modulus of elasticity E | 64 × 103 MPa |
| Poisson constant m | 0,20 |
| Tensile strength R m | 35 to 100 MPa |
Viscosity is also an important property of glass, and is significant in all stages of glass production and working. It also affects electrical properties through its effect on the mobility of ions.
SIMAX glass is counted among viscously "shorter" glasses, i.e. it has a relatively narrow temperature range for working.
Mechanical stability of SIMAX glass
The mechanical properties and service life of products made from SIMAX glass are largely determined by the condition of the surface, especially its integrity, i.e. the depth of damage to the surface in handling and secondary heat treatment.
| Scratch hardness of glass on Mohs scale | 6 |
| Allowable tensile stress | 3,5 MPa |
| Allowable bending stress | 7 MPa |
| Allowable compressive stress | 100 MPa |
Thermal Properties of SIMAX Glass
The high resistance of products made from SIMAX glass to sudden changes of temperature - their heat resistance - is due to a low coefficient of linear thermal expansion, a relatively low modulus of tensile elasticity E and relatively high thermal conductivity.
When the glass product is heated or cooled, unwanted internal stress arises. Breaking on rapid cooling of the product occurs when the unwanted internal stress exceeds the allowable limit. Values of resistance to thermal shock (D °C) for Simax glass products are shown in the following table against the thickness of the wall.
| Wall thickness (mm) | Resistance to thermal shock (D°C) |
|---|
| 1 | 303 |
| 3 | 175 |
| 6 | 124 |
| 10 | 96 |
Cooling of SIMAX glass
Cooling is a thermal process whose purpose is to prevent unwanted and unacceptable thermal stress from appearing in the glass, which would weaken the product, or to remove stress which is already present.
The cooling cycle consists of three stages:
Temperature increase (heating of the product) at a given heating rate from the initial temperature to the upper cooling temperature.
Maintenance of temperature (hold, tempering, stabilisation) - the product is kept at the upper cooling temperature for some time while the temperature differences within the product equalise and stress decreases to an acceptable level.
Temperature decrease (initial and final cooling) at a given cooling rate from the upper cooling temperature to the lower cooling temperature (this stage is important, as permanent stress may arise) and from the lower cooling temperature to a final temperature or to the ambient temperature (important for subsequent practical handling of the product).
A specific cooling cycle is shown in the table
Temperature Ranges
| Temperature increase | hold | decrease |
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| Max. wall thickness | 20 -- 550 °C | 560 °C | 560 -- 490 °C | 490 -- 440 °C | 440 -- 40 °C |
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| 3 mm | 140 °C/min | 5 °C/min | 14 °C/min | 28 °C/min | 140 °C/min |
| 6 mm | 30 | 10 | 3 | 6 | 30 |
| 9 mm | 15 | 18 | 1,5 | 3 | 15 |
| 12 mm | 8 | 30 | 0,6 | 1,6 | 8 |
Optical Properties of SIMAX Glass
Simax glass is transparent and colourless and does not show significant absorption in the visible spectrum. Its transmittance at ultraviolet wavelengths allows products to be used for photochemical reactions.
| Refractive index of Simax glass (l = 589,30 nm) nd | 1,472 |
| Photoelastic constant B | 3,6.10-6 MPa-1. |
The optical transmittance of SIMAX glass in the visible area of the spectrum is between 90 and 92% for a wall thickness of 3 mm, and is shown in the following graph.
Electrical Properties of SIMAX Glass
SIMAX glass is non-conductive at normal temperatures - it is an insulator.
| Electrical resistivity in a humidity-free environment (20 °C) | greater than 1013- 1015 W× cm |
| Permitivity e (20 °C, 1 MHz) | 4,6 |
| Loss angle tg d | 4,9 × 10-3 |
Dielectric losses rise sharply with increasing temperature and change with frequency.
Standard tolerance of dimensional parameters of tubes,
rods and capillary tubes SIMAX
Lengths and the end treatment
| Tubes - outside diameter |
length |
end treatment |
| 4 mm £ Ø £ 7 mm |
1500 ± 20 mm |
cut only |
| 7 mm < Ø £ 10 mm |
1500 ± 10 mm |
cut only |
| 10 mm < Ø £ 48 mm |
1500 ± 10 mm |
trimmed and glazed |
| 48 mm < Ø £ 150 mm |
1500 ± 5 mm |
trimmed and glazed |
| Capillary tubes and rods |
| 3 mm £ Ø £ 7 mm |
1500 ± 20 mm |
cut only |
| 8 mm < Ø £ 17 mm |
1500 ± 10 mm |
cut only |
| 18 mm < Ø £ 30 mm |
1500 ± 30 mm |
cut only |
Special lengths of tubes in range of 1000-3000 mm can be delivered on demand
in dependence on outside diameter.
Tubes cut in special way in length of 15-3500 mm can be delivered in dependence
on outside diameter.
Out-of-roundness
Out-of-roundness of tubes, rods and capillary tubes
is related to outside diameter.
Tubes
In any place of tube there the difference of maximum
and minimum diameter must not exceed 2 % of nominal outside diameter.
Rods and capillary tubes
In any place of rod or capillary tube there the difference of maximum and minimum
diameter must not exceed 3 % of nominal outside diameter.
Siding
Siding in any place of the tube cut must not exceed the values as follows:
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25 % of nominal wall thickness for the thin-wall tubes
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15 % of nominal wall thickness for the medium and thick wall tubes medium
wall thickness or these thick-wall ones
Deflection
The tube deflection is related to nominal length L = 1500 mm
| Tubes |
| Ø £ 6 mm |
0,6 % of the tube length |
| 6 mm £ Ø £ 10 mm |
0,4 % of the tube length |
| 10 mm < Ø £ 150 mm |
0,3 % of the tube length |
| Rods and capillary tubes |
| Ø £ 6 mm |
0,6 % of the tube length |
| 6 mm £ Ø £ 16 mm |
0,5 % of the tube length |
| 16 mm < Ø £ 30 mm |
0,15 % of the tube length |
Stones
For tubes with outside diameter of 4 - 20 mm incl. are allowed the following
dimensions and numbers of stones in 1 kg of glass :
| Ø < 0,3 mm |
allowed |
| 0,3 mm £ Ø £ 1 mm |
4 pieces in maximum per 1 kg of glass |
| 1 mm < Ø £ 2 mm |
2 pieces in maximum per 1 kg of glass |
For tubes with outside diameter over 20 mm are allowed the following dimensions
and numbers of stones in 1 kg of glass :
| Ø < 0,3 mm |
allowed |
| 0,3 mm £ Ø £ 1 mm |
2 pieces in maximum per 1 kg of glass |
| 1 mm < Ø £ 2 mm |
1 piece in maximum per 1 kg of glass |
For rods and capillary tubes are allowed the following dimensions and number
of stones in 1 piece of product with length of 1 500 mm :
| Ø < 0,3 mm |
allowed |
| 0,3 mm £ Ø £ 1,0 mm |
3 pieces in maximum per 1 piece of tube Ø < 24 mm |
| 0,3 mm < Ø £ 1,0 mm |
4 pieces in maximum per 1 piece of tube Ø ≥ 24 mm |
Knots, stringy knots
| Tubes |
| Ø < 0,3 mm |
allowed |
| 0,3 mm £ Ø £ 1,0 mm |
4 pieces in maximum per 1 kg of glass |
| 1,0 mm < Ø £ 3,0 mm |
2 pieces in maximum per 1 kg of glass |
| Rods and capillary tubes |
| Ø < 0,3 mm |
allowed |
| 0,3 mm £ Ø £ 1,5 mm |
3 pieces in maximum per 1 piece of tube or rod Ø < 24 mm |
| 0,3 mm < Ø £ 1,5 mm |
4 pieces in maximum per 1 piece of tube or rod Ø ≥ 24 mm |
Capillary bubbles
Capillary bubbles to length £ are allowed.
Total length of capillary bubbles with length > 20 mm is allowed in maximum 1,5 m per 10 m of the tube length.
Width of capillary bubbles is allowed:
| for tubes 4 mm £ Ø £ 40 mm |
max. 0,2 mm |
| for tubes Ø > 40 mm |
max. 0,7 mm |
| for rods and capillary tubes |
max. 0,3 mm |
Notes
- Tubes up to Ø 43 mm are delivered in the not cooled stage, if it is not agreed in other way.
Tubes of Ø 44 mm and bigger are standardly delivered in the cooled stage.
Rods and capillary tubes are delivered in the not cooled stage, if it is not agreed in other way.
- If it is not agreed with customer in other way, tubes of outside diameter 8 – 40 mm are protected on surface with PE cover to increase their resistance against scratches.
- In additional to the standard forms of profiled tubes mentioned in catalogue it is possible to ask for other forms of profiled tubes.
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