::DETONATION & FLAME ARREST::

With Dynapore^® Sintered Wire Mesh Laminates

How is Dynapore® 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:

• Repeatability

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.

• Controlled Permeability

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.

• Ease of Assembly

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 alloys.

• Mechanical Strength

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.

• Structural Integrity

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 Dynapore® compare with other media?

• Versatility

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.

• Volumetrically Compact

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.

• Calculation of Effective Hydraulic Diameter of MKI Dynapore® Wire Mesh Laminates



• Basics of Dynapore® Laminate Design for Spark, Flame & Detonation Arrest

If two 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.