::DETONATION & FLAME ARREST::
Dynapore® Sintered Wire Mesh Laminates
How is DynaporeŽ better than loose stacked screens?
When multiple layers of woven wire screen are
sintered together, the resulting Dynapore laminate takes on a completely
different and superior character as compared with a stack of the same
number and type of loose screens. Some of these advantages are as follows:
The geometry of a mesh laminate, once specified, is extremely
stable and repeatable. Once a particular Dynapore disc is tested, thousands
more may be reliably produced at any time without fear that the production
parts will vary from the original test articles in mass, surface area,
pressure drop or permeability to flow.
- Fixed Angular Orientations
The angular bias of each respective layer in any particular
laminate specification is fixed, and does not vary from pack to pack.
For example, in a Dynapore laminate, all layers can be oriented uniformly
with parallel wires, or can be oriented in a fixed sequence of angular
biases such as 0°,30°,60° etc. This stability of angular
orientation cannot be achieved by manual stacking. Loose stacked screens
with randomized orientations will exhibit a wider variance of pore sizes
within a stack as well as between stacks.
Dynapore packs may be designed with any number of layers using
one or more mesh weaves oriented in parallel or in any fixed sequence
of angular rotations. This versatility allows the design and production
of packs with any specified effective hydraulic diameter, thickness
and permeability. As a consequence of having a fixed repeatable geometry,
once a particular pack is found to exhibit the desired characteristics,
the pressure drop and permeability of that pack will be repeated within
a tight deviation in the production of thousands of packs.
As a stable monolithic structure, a Dynapore disc is much
easier to handle or install than a stack of loose screens. Dynapore
comes cut to size, clean, and ready to install in the arrester housing.
Dynapore packs may be supplied with bolt holes for gasketed flange installation.
Dynapore may also be welded or brazed. Martin Kurz & Co. can offer
vacuum furnace brazing of Dynapore packs into customer-supplied housings
using high-strength corrosion-resistant nickel-chromium-based filler
The sintered Dynapore pack exhibits much greater strength
and rigidity than an unsintered stack. A disc of Dynapore can withstand
higher pressures and gas throughput without deflecting or dishing, and
is therefore more resistant to a detonation shock wave.
The sintered pack will be completely free from medium migration.
No wire fragments can come loose and migrate away from the arrester.
The pack is resistant to rough handling, vibration, or repeated cycling
of bi-directional flow.
- Maintenance of Filtration Rating
The wires in loose screens are not fixed in place and may
tend to shift and separate under pressure. The result is that some of
the pores open up over time, and the effective pore size or hydraulic
diameter of the pack is compromised. In a sintered pack, the wires in
each layer of mesh are securely fused together and will not shift. Therefore
the pore size of the pack will remain constant throughout its life.
- Cleanliness and Cleanability
The sintering process removes all hydrocarbon lubricants from
the mesh wire surfaces, leaving a bright, clean, dry pack with no combustible
surface contaminants. In addition, after use, Dynapore sintered wire
mesh packs can withstand many cleaning processes including pressure
washing, oven burn-off and furnace firing, caustic baths, passivation
baths, solvent cleaning, ultrasonic cleaning and other processes, which
may permit the pack to be reused repeatedly.
How does DynaporeŽ compare with other media?
As mentioned above, Dynapore® packs may be designed with virtually
any specified effective hydraulic diameter, thickness and permeability.
- High Surface Area
- Low Pressure Drop
- Extremely Repeatable Structure
- Reasonable Cost
In production quantities, Dynapore is competitive with other
media in price and delivery.
The same or better flame arrest capacity may be exhibited
by a quarter- or half-inch thick Dynapore laminate as might be obtained
by other materials over a length of many inches. This allows compact
housing design with reduced weight and cost.
Can one predict or model the
performance of a particular type of Dynapore®?
The following papers give methods
for estimating the effective hydraulic diameter of a laminate.
or more screens are stacked, each screen is partially occluded by the
next successive adjacent screen. A formula is developed for estimating
the resultant effective pore size. Martin Kurz & Co. can recommend
pack structures for any given desired critical hydraulic diameter. We
can also calculate the surface area in any pack as required.
In order to model the exact flow characteristics of a gas through a multi-layer
screenpack, an extremely sophisticated fluid dynamics model would have
to be developed. Such a model would be very costly to develop and use,
and it would yield results which are at best rough approximations.
It is our strong opinion, borne out by many years of experience with
laminate structures which are used in a wide range of fluid dynamic applications
such as filtration, that the best research is done by empirically testing
a variety of laminate structures and obtaining actual performance results.
Once actual results are obtained on a group of sample structures, interpolation
or extrapolation can lead quickly to an ideal laminate structure for a
given set of desired performance characteristics. Using our experience,
we can often make a very good educated guess as to the right laminate
structure for a given application.
Martin Kurz & Co., Inc. manufactures and supplies sintered (diffusion-bonded)
wire mesh laminates under the trademark Dynapore® to a wide spectrum
of manufacturers serving many industries. MKI makes no warranty of fitness
for a particular purpose. Application suitability must ultimately be determined
by the end user.