Natural Gas Pipe Size for iPhone

Pipe sizing and pressure drop calculation for natural gas installations, on your iPhone or iPad

Natural Gas Pipe Size is an app that lets you quickly determine the recommended pipe diameter for natural gas installations. Additionally, it lets you calculate pressure drop, volume flow rate and velocity for the selected pipe section. Natural Gas Pipe Size for iPhone Download on the App Store:
Download on the App Store


  • minimal user input
  • selectable pipe material
  • wide range of conditions
  • small, fast and accurate
  • no internet connection required
  • no ads
  • metric and imperial units
  • Universal app: works on iPhone and iPad
  • available in English, German, Italian and Slovenian languages

Technical Details

  • Heating value of natural gas can be adjusted to suit conditions
  • Gas working pressure can be adjusted
  • Altitude and working temperature can be adjusted
  • Contains pre-defined fittings and valves with their minor pressure loss coefficients
  • Contains pre-defined pipe materials with their respective roughness, including steel, copper
  • Starting point is heat output of appliances; volume flow rate is always calculated based on conditions
  • First result is recommended pipe diameter
  • Other results are based on diameter, chosen by the user, and include volume flow rate at standard and working conditions, velocity, pressure drop for entire pipe section and pressure drop per one unit of pipe length
  • If the chosen diameter is definitely too small, the app notifies the user to choose a larger one


  • Calculation is always performed for one pipe section. Different pipe sections should be calculated separately and pressure drop should be checked manually for entire installation

The Story

Back in 2012 our company was selected to conduct a replacement of several heating oil burners with ones that burn natural gas. Burning natural gas has some advantages compared to heating oil: the first advantage is cost, the second energy efficiency, and the third is convenience as the owners do not have to order large amounts of heating oil a few times a year. As for the plant itself, this is a rather large bakery in its geographical context.

So the work started in 2012, but the preparation started almost two years before that. The then-existing burners were thoroughly scrutinized, as was the consumption of heating oil. Our company checked every parameter and determined exactly what types of natural gas burners would be needed to best replace the old ones. The heat output of most burners was chosen so that it matched the heat output of the old ones. In some cases, however, the heat output of the new burner was chosen to be smaller than that of the old one. One such case was the burner of the steam boiler, where the oil burner had been severely oversized for its purpose. This way, we achieved an even better energy efficiency of the new burner, as it now has much fewer ignitions and operates more constantly throughout the day. All the new burners also have a modulating heat output, ranging from about 30 % to 100 %. Under 30 % of output, however, they operate as a normal on/off burner, and this is exactly the reason why they should not be oversized.

After the heat outputs of all the burners were determined, we needed to size the natural gas line. We had some tools that helped us do that. They were mostly created on our own, using tools like Microsoft Excel. They surely did the job, but that was the moment when I thought it would be great if I could do this on my iPhone. In fact, I started searching the App Store for an app that would do that. It was not there. So I guessed it was time to write one myself. I knew exactly where I had to start in order to make the calculation workflow as quick as possible. First section, heat output, pipe length. Second section, heat output, pipe length. And so on. Then I had to make sure the app can do better than that: it should be able to work properly with different pipe materials, include options for some common fittings and valves and, most of all, it should be able to take natural gas pressure as input. The resulting required pipe size is in fact highly dependent on gas pressure. And as we normally work with gauge pressure, the app needed to determine atmospheric pressure as well (gauge pressure is relative to atmospheric pressure). There are also things I knew the potential users should not have to enter as input: I was determined to avoid using volume flow as input, and certainly the user should not be expected to know properties of natural gas such as molecular mass, viscosity at different temperatures and so on. So I built-in all these things and after an extended period of testing the app at different conditions, comparing results to some professional calculation suites, tuning properties and confirming that the results were accurate, I decided it was time to put the app on the App Store.

The app was downloaded quite a few times and with every update I saw that the users actually updated it, which meant they were using it. The updates were quite important, as I added features for the calculation of air pressure and subsequent gas pressure from location altitude and I localized the app into German and Italian languages, for which I thank my wife. The review that I received from a German user in December 2013 was the most beautiful thing that can happen to an app developer: the user wrote that they use the app regularly with success and also that they test the app against other calculation suites and the results always match. I got a five-star review which really made all the work worthy.

I also got a one-star review from a user in the US. They were mostly right: the app was using only metric units and was useless for the user who is accustomed to work with imperial units. So I made a quick decision: I had to make the app available in imperial units, too. So I quickly began writing code, improving the overall feel of the app while I was at it. I finally released the update and the app now works with imperial units, too. And it was a free update to all existing users of the app.

Since I wrote the app I haven't looked back to our old tools. I always use the app when I have to do some calculations. The app is suitable when on the go, when I have to determine a pipe section diameter instantly. But it is also completely suitable for performing calculations in the office.
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