| Membranetype 3 - mesh reinforced silicone |
The mesh is embedded directly into the
silicone membrane. Metallic or plastic meshes are available.
The membrane thickness is conditioned to mesh structure.
Advantages of this membrane type:
| - |
Thin silicone films are
easier to handle
|
| - |
Mechanically very stable
- pressure resistant up to 600 bar
|
| - |
Mechanical cleaning is
possible, because of the embedded mesh. Also, this membrane
is more resistant to scratching. Deep scratches will
only penetrate up to the mesh, leaving the silicone
layer behind undamaged.
|
| - |
Improved rigidity of the
membrane because of the embedded mesh, (therefore allowing
fixed distance between membrane and electrode.
|
| - |
this membrane type is
also available with additional antifouling protection |
|
| The high-grade steel
membranes are now available in layer thickness 150 µm. |
|
 |
| sensor membranes - Basics |
|
Dense membranes (so called solubility membranes)
have their applications in different underwater gas sensors
i.e. oxygen-sensors or the CAPSUM METS .
The chosen membrane-polymer and its characteristics are therefore
specialised for the gas detected. Silicone is often used because
of its high permeability for different gasses. Compared with
other materials, the silicone surface is very resistant to
fouling. The membrane is used here as a phase separation between
the liquid and the gas detection room. The transition of gas
out of the water in the detector room takes place via gas
diffusion through the membrane.
The membrane type chosen is dependant upon the measuring principle
and construction of the sensor head. There are three types
of membranes available for these purposes.
|
| Membranetype 1 - silicone- und teflonfilms |
pure silicone:
|
layer
thickness: 100 µm to several 100 µm.
|
|
Application:
For use with oxygen sensors either directly, or on a teflon
membrane to utilise the antifouling effect of the silicone.
Because of the high gas permeability of silicone compared
to teflon, there is no negative impact on the sensor response
time. This type of membrane is also available including antifouling
protection. (please see the separate Antifouling membrane
spec sheet for further information).
|
 |
| NOTE: Teflon membranes are currently not available. |
| Membranetype 2 - silicone composite |
|
This membrane type consists of three layers.
Because of the special construction, extremely thin silicone
films are possible, thus enabling very short response times.
Due to the three-layer construction, the membrane can adapted
to the needs of the application by varying the individual
thickness and structure of each layer.
|
 |
|
This membrane is used in the METS methane
sensor and is pressure resistant up to 400 bar bzw. 600 bar
with the corresponding membrane support. It can also be adapted
for other sensors with similar membrane support and measurement
to deliver shorter response times.
Additional equipment with antifouling protection is still
in development.
|
silicone
coating thickness:
Top
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between less than 1 and up to 100 µm
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