|
Diaphragms
are hermetically sealing flexible elements dividing two volumes of
interchanging dimensions, interchanging pressure, and usually of
different media. Outstanding feature of a diaphragm is its ability
to flex in both directions vertical to the sealing flange plane,
within predetermined stroke limits, flexing effected either by
mechanical actuation or by reaction to differential pressure.
Flexibility and stroke limits of a diaphragm depend on properties
of material used, its dimensions, and in the larger stroke ranges
- on the extent of pre shaping provided in its manufacture.
Important properties of diaphragms materials:
- Flexibility for dynamic
function)
- Resiliance (for sealing function)
- Mechanical strength (for pressure resistance)
- Chemical resistance (for media exposure)
- Low permeability (for diffusion resistance)
These
properties must be maintained for longest possible duration within
the temperature range, under the differential pressures, and in
permanent contact with the media specified in accordance with
application conditions. Basic materials used under these aspects
in the manufacture of diaphragms are
- Elastomers
- Elastomer coated fabrics and for additional reinforcements
- Fabrics
- Metals
- Thermo and Duroplasts as well as
- PTFE (Teflon foil)
For
surface protection against extremely aggressive media. Dimensions
and if necessary three dimensional shape of a diaphragms must be
determined in accordance with specific criteria as to installation
and function and with due consideration to the limits set by
material characteristics and manufacturing technology.
|
;)
