# Calculation and design fabric ducts

## Primary factors taken into account in air sock design

For air sock calculation, we use the TEXAIR-S unified tool. Since each air sock distribution system is calculated for each immediate, specific facility, technological objective, and the parameters of the studied equipment, at the design stage we take the following factors into account: the temperature of the air supplied, the temperature of the air in the facility, the excess pressure, the speed of the air in the duct, the distance to the work area, the facility’s configuration, and other components. Using TEXAIR-S, the engineers calculate the optimal air duct diameter and the optimal diameter for the perforated holes as well as the quantity of them and the duct’s placement relative to the axes and the suspension details. This provides a basis for the relative air velocity in the work zone.

The TEXAIR-S unified software tool provides a means to model the air distribution system, taking its purpose into account. In the event of air heating and conditioning, the movement of the air flows is different, so we have to take into account all of the thermodynamic parameters in order to avoid layering (stratification) and air dead zones at various elevations in the facility.

At certain facilities, due to the technological processes, local zoning of air flows is required; meanwhile, often times augmented air volumes must be emitted while observing the air velocity requirements in the work zone. The TEXAIR-S unified software tool provides a means to compute the corresponding calculations and correctly choose the corresponding emission components for the system.

## Emission of heat energy through air socks

The main requirement stated for air socks is a continuous, even air flow throughout the entire length of the line. And TEXAIR air ducts handle this objective miraculously.

However, if the line is significantly long, the air passing along the fabric duct may lose heat energy due to heat losses caused by a difference in temperature of the air being supplied and the air located in the facility. Thus, the air temperature in the textile air duct will differ from the temperature at the end segment.

This can be seen in Graphic No. 1, which exhibits a 60-meter duct consisting of 6 segments equal in length.

Distribution of heat energy with continuous air flow

In order to ensure event distribution of the heat energy, the air flow must be augmented in proportion to the heat losses along the entire length of the duct, which is shown in Graphic No. 2.

Air emission for even energy distribution

If the length of the line is not great or it features a complex configuration, then zonal air distribution will be the best option for optimal cooling or heating.

## Pressure

Lying at the foundation of the textile air distribution’s operation principle is the principle of continuous static pressure. Thanks to that, we could achieve even air distribution along the entire length of the system.

Because the air speed reduces inside toward the end of the duct, a resulting increase in static pressure is thus observed. It is for this specific reason that we take this size into account during the design phase in order to ensure equal distribution of area along the entire length of the line.

The recommended static figure recommended by TEXAIR’s experts is between 60 and 500 Pa. However, since the aspiration systems operate at a much greater pressure level, we calculate such projects as well.

## Selecting the air duct diameter

The fabric air duct diameter is chosen based on two primary parameters: the air flow and the required current velocity within the duct. This speed is usually regulated by the SNiP construction rules and regulations for metallic ducts, but for textile ducts the upper limit of the air velocity figure may be augmented, since the amount of noise they emit is substantially lower than in the case of metal. The acceptable air velocity of textile ducts is from 6 to 10 m/s.