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What Is A Steam Distributing Coil?
Dec 28, 2017

Steam distributing coil

The whole idea behind steam distribution coils is to insert the inner tube along the entire length of the outer tube. Steam is evenly distributed along the inner tube. 

The inner tube has a pitch of about 9 "to 12". As the steam becomes condensate (as it travels along the inner tube), the condensate is released through these holes to the outer tube. No matter what the steam will not become condensed water, will eventually be discharged from the open end of the inner tube to the outer tube.

The outer tube is "capped" and there is no return elbow, so the condensate under pressure is nowhere to go, but the manifold from which the steam originally came along the outer tube.

The idea behind the coil's original design was to distribute steam and condensate evenly throughout the distribution coil so there were no "dead spots" or "cold spots" in the coil. After several tests, one side effect was found to be that this type of coil is more difficult to freeze than a standard, conventional steam coil. Therefore, the name "not frozen" surfaced. Steam traveling along the inner tube causes the condensate to reverse run in the outer tube without freezing.

Today, it is a generally accepted practice to install these coils in industrial practice in applications where the air temperature is 40 ° F or below. Keep in mind that non-freezing coils do not freeze easily, but they can be frozen under the proper conditions and often occur.5/8 "outer tube and 1" outer tube steam distribution

Many companies sell and build 5/8 "or 1" non-freezing steam coils as if they were interchangeable. No matter what faster or cheaper they use, it depends on the job. We are here to tell you that the structure of these coils is very different when you use them depending on the application. 5/8 "outer 3/8" tube

Most steam distribution coils have 5/8 "outer tubes of 3/8" inner tubes. This leaves 1/4 "space between the tubes, but the real space is 1/8" on each side of the tube. From this 1/8 "you have to subtract the thickness of the outer tube, as you can see, there is only a small amount of space between the outer tube and the inner tube to allow the condensate to flow back through the outer tube 1" The outer 5/8 "inner tube . Steam Distribution 1 "The true outer diameter of the steam distribution coil is 1/8" and the inner is a 5/8 "tube. As you can see, there is more than twice as much room for 

condensate to pass through the outer tube. The wall thickness is also .035 "instead of .025".

Whenever a large amount of outside air is used in the non-freezing coil, the temperature rises and the amount of B.T.U. becomes larger. As a result, you need more pounds. Steam per hour, you get more pounds. Condensate must pass through the coil every hour. If you want a high air temperature or low air intake, you need to use a 1-inch non-freezing steam coil. If you are using mainly circulating air or if you only need a 30 ° F or 40 ° F air temperature rise, 8 "non-freezing coil is usually OK

The real problem here is the cost. As you might expect, 1 "steam coils are more expensive than 5/8" and some companies do not even build them. So, regardless of the conditions, installing a 5/8 "steam coil often does not work, and on a long coil above 72", you can diagnose this problem by moving the far end of the coil away from the manifold. If the coil feels cold, that means the condensate is trapped and stops the steam from coming down from the coil. Coils may be the incorrect design of the application and need to be replaced.