Prihoda products are generally ducting as well as air distribution devices (or return devices) all at the same time. We offer positive pressure air dispersion systems (fabric ducting & diﬀusers) as well as negative pressure ducting for exhaust or returning air to the unit from the space served.
1/ Air dispersion / distribution options for fabric diffusers
Flow V brought into the diffuser through any of the ends or through the entry adapter may exit in the following manners:
A - through a permeable fabric
B - through microperforation – 0.2 – 0.4 mm holes in the fabric
C - through perforation – holes with a diameter greater than 5/32” (4mm)
D - through a small nozzle
E - through a large nozzle
F - through an adapter – air is guided off into another ducting branch (Fabric or metal)
G - through the second end – air leads to another diffuser or ducting (such as back to metal duct, etc.)
It always holds true that: V = A + B + C + D + E + F + G (certain values of A, B, C, D, E, F, G may be zero)
2/ Air inlets for negative pressure ducting
Perforations are currently the only air inlet option used for negative pressure ducting.
3/ Transporting air with fabric ducting
Ducting made from impermeable fabric or insulated ducting feeds air to the point where it needs to be distributed. We can manufacture nearly any fitting required such as a “T”, reducer, radius elbow and many other custom fittings.
Air is distributed from fabric diﬀusers through various sizes, patterns, and types of openings. The combination of size, spacing, and grouping of holes together with various outlet flow models provide an infinite number of combinations and solutions for air distribution requirements for today’s project challenges.
Microperforation - Tiny laser cut holes with a diameter of 0.2 – 0.4 mm, intended for low velocity / laminar air dispersion (Very low throw, not recommended for heating unless directional microperforation is used).
Perforations - A series of 5/32 inch (4mm) or larger holes, provide directed air supply (low to medium throw for heating, cooling, and ventilating).
Nozzles - 3/4” diameter and up, very long throws or when a high velocity or spot cooling/heating is required.
* When calculating the throw/velocity at different distances from the duct, the temperature difference between the delivered air and the room (Delta T) must be considered along with the air speed from the outlets.
Fabric diﬀusers are an extremely versatile air distribution device which cover the entire spectrum of applied flow models used today. We achieve the desired throw by selecting the correct air diﬀuser outlet method, or quite often, a combination of methods.
Note: Throws will vary and depend on static pressure in the diﬀuser, temperature of air delivered vs room temperature, environment, heat sources, obstacles, etc. Please contact us for design or layout assistance.
We tailor make all of our products to meet the needs of each individual project. Due to every project’s specific needs and the numerous combinations of flow models we decided years ago to develop design software to better assist our customers and to insure a proper solution is achieved on every order we deliver.
Our software provides throw velocities at various distances from the diffuser (isothermal or corrected for heating / cooling), pressure loss calculations, and sound generated. Generally the design parameters are static pressure available to the diffuser, volume of air, flow model, fabric type, installation height, throw needed (space dimensions), temperature difference, sound sensitive or not, and mounting method.
Examples of airﬂow patterns created by PRIHODA design software and confirmed by Ansys Fluent CFD software
Many years of continuous software updates, lab/field testing, and thousands of installations world wide gives us complete confidence that our products will accomplish the solution your project requires. On very large or critical airflow applications we also offer the use of Computational Fluid Dynamics software from one of the leading CFD software companies, Ansys Fluent (formerly Fluent Airpak).