5 Differences between round ducts and square ducts-Part One

Advantages of circular air ducts

Advantage 1: High air tightness. As we all know, no matter whether it is conveying gas or relying on gas for material transportation, the gas conveying pipeline is the most forbidden to leak. So, how does the round duct do this? It turns out that the pipe fittings of the round air duct and other parts connected to the duct have factory-assembled airtight joints. When installing, just insert them into the round duct to achieve a high degree of airtightness. According to the international CEN pipeline airtightness standard, it can reach Class C leakage level. The airtight joint is composed of two rubber sealing rings (see picture). When the joint is connected with the pipe fittings, the sealing ring is compressed and can withstand a positive pressure of 3000Pa and a negative pressure of 5000Pa, thereby ensuring the degree of airtightness. The circular straight pipe with spiral bite will not produce leakage. After using the sealed joint, the air leakage rate of the entire air duct system will be minimized. The leakage of the ventilation pipeline is caused by the connection of a large number of pipe fittings. Compared with the rectangular pipeline, the typical length of the round pipe is 3-6 meters, while the length of the rectangular air duct is only 1-1.5 meters. The gasket of the rectangular air duct is made by hand and installed roughly, it is impossible to be installed by the factory like the round pipe fittings. The circumference of the sealing part of the circular pipe fitting is relatively short. For the same section, the circumference of a rectangle with an aspect ratio of 1:3 is 41% longer than that of a circle, so the air leakage area is greatly reduced.

Advantage 2: Low installation cost Under the same resistance conditions, a rectangular pipeline of 250×250 mm can be replaced by a circular pipeline with a diameter of ∮ 200 mm in the same installation space, and its overall installation cost is lower than that of a rectangular pipeline by 50 %. Replacing one rectangular pipe with two or several circular pipes also reduces costs.

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Installation technical measures: on-site installation process

(1) When installing the air duct, first install the supports and hangers according to the design elevation of the air duct, arrange them in order, and number them. When hoisting, safety measures should be taken to prevent damage caused by collisions. The installation of the air duct should be carried out in accordance with the position of the equipment and the position of the tee, elbow, etc., and the sequence of the equipment connection pipe and then the main pipe; the vertical air pipe is generally installed from bottom to top. 

(2) According to the center line of the air duct, find out where the suspenders are to be laid. The single suspenders are on the center line of the air duct; the double suspenders can be installed symmetrically according to the distance between the bolt holes of the supporting plate or the center line of the air duct, and the distance between the hangers is ≤ 4m. When the air duct is long, a row of hangers needs to be installed. The positions of the two ends can be determined first, and then based on the determined supports at both ends, use the pull wire to find the position of the middle support for installation. Fixing supports and hangers should also be added at appropriate positions to prevent swinging. (HVAC Nanshe) 

(3) Reinforcement of the air duct: a. Reinforcement measures should be taken in the following cases: a.1 The diameter of the spiral air duct is greater than or equal to 800mm, and the length of the pipe section is greater than 1250mm or the total surface area is greater than 4m2. Reinforcement measures. b. The reinforcement of the air duct shall comply with the following regulations: b.1 The reinforcement of the air duct may be in the form of corrugated ribs, vertical bars, angle steel (inner and outer reinforcement), flat steel, reinforcement ribs and pipe inner supports, etc. 

To be continued.

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