De dietrich CONDUCTIGLASS BROCHURE

ConductiGlass

®

Lining

Note that grounding through

a Tantalum plug does not

solve the problem. As the

medium is non conductive,

the “lightning conductor”

effect of any electrode
is only efficient a couple
of centimetres around it.

grounding with

a Tantalum plug

is not efficient

Working principle

The principle of the ConductiGlass®solution consists in increasing
the conductivity of the glass-lining to a value high enough to allow
the discharge to the ground of the electrostatic charges as soon as
they are created in the reaction medium, prohibiting then their
accumulation up to dangerous voltages.

Practical realisation

This is achieved by adding to the glass a small quantity of very thin
Platinum fibres, continuously dispersed in the whole thickness of
the glass-lining.
The fibres are not joined, but the glass thicknesses which are in­between them are extremely small and can be compared to a network
of micro-condensers discharging in line to let the electrostatic charges
flow gently to the ground without any damage for the glass-lining.

The opposite sketch compares the behaviours of ConductiGlass

®

and conventional DD 3009 glass-linings when applying them an
increasing voltage (at 150 °C). Let’s have a look on the DD 3009
curve : a very weak leak current appears around 5 kV and grows
regularly up to the breakdown of the glass-lining occurring around
15 kV. As far as ConductiGlass®is concerned, the leak current
starts at a higher value from low voltage, then grows quickly pro­hibiting the voltage to increase :

the flow to the ground of the electrostatic charges
is then as fast as their creation,

integrity of the glass-lining is preserved,

risks of explosion are dismissed.

The probleme of
electrostatic charges

The mixing of non conductive products
in a glass-lined reactor may lead to the
development of electrostatic charges in
the heart of the reaction medium.
In a glass-lined reactor, insulating
properties of the lining prohibit these
charges to flow to the ground and enhance
their accumulation up to very high voltages
that become really dangerous for the
operators and the equipment. All the
operators are nowadays perfectly aware
of the safety rules and incidents very
rare. But these rules are unfortunately
not applicable to all processes, and very
often the accumulation of electrostatic
charges cannot be avoid.
This phenomenon is accelerated by the
temperature as shown on the picture :
for a glass thickness of 1 mm, the break­down voltage which is 40 kV at 22 °C
falls down to 14 kV at 150 °C.

This major problem which was one of
the last remaining in glass-lining techno­logy is solved from now on by the use
of a new kind of glass-lining named

ConductiGlass®.

Working principle of

CONDUCTIGLASS®

0

50

100

150

200

250

300

350

400

450

500

34567891011121314151617181920

Voltage (kV)

Leak current (µA)

CONDUCTIGLASS®

3009 GLASS

damage !

ConductiGlass

®

Delete any risk of
electrostatic damage
on glass-lined
equipment

INFLUENCE OF THE TEMPERATURE

0

5

10

15

20

25

30

35

40

45

0 0,2 0,4 0,6 0,8 1 1,2 1,4

Email Thickness (mm)

Breakdown Voltage (kV)

150 ∞C
22 ∞C