To take a glance at all pocketEngineer software and OS requirements, click Software List.

For common gases pressure drop calculations, see Gases Hydraulics (Windows OS).

There are many situations where you want to determine the pressure drop in the compressed air ring main (loop) pipe in a simple and effective way. This app helps you to do that. 

This program solves the flow (Q) and Pressure drop (Pdrop) in a single loop ring main pipe network. The loop configuration shall be only a single-input supply source with 1 or more discharge outlets.

Hardy Cross method is used in solving the single-looped pipe network. The widely used formula to determine the pressure drop is

Pdrop (bar) = K * L * Q^1.85 / (P * d^5)

where K=1.6 x 10^8, L=pipe length (m), Q=free air flow rate (m3/s), P=pipeline pressure (bar absolute), d=pipe diameter (mm).

Note: Any pipes in series that join the loop (upstream and/or downstream) shall be calculated separately (not provided in this program).

For pipe sizing and pressure drop in straight pipe, see  CompAir.

Important to note: This program is designed with one set of units system for all calculations. For input simplicity, built-in units conversion tools are available.

Various selection and calculation tools are provided, making calculation experience more simulating. They are:

• Flow unit converter, Diameter & Length unit converter, Pressure unit converter, Velocity unit converter.

• Valve & Fitting selection (Equivalent length Le method).

Example: Pressure drop in compressed air ring main looped pipe

For the purposes of illustrating the program capability, the following calculation is done as an example. It is assumed that for the worst case, all the tools are anticipated to operate simultaneously.

Service: Pressure = 7 bar (gauge)

Pipe length: A-1 (Pipe No.101)=10m, 1-2 (Pipe No. 102)=10m, 2-3 (Pipe No.103)=20m, 3-4 (Pipe No.104)=40m, 4-5 (Pipe No.105)=20m, 5-6 (Pipe No.106)=20m, 6-7 (Pipe No.107)=20m, 7-8 (Pipe No.108)=20m, 8-9 (Pipe No.109)=40m, 9-10 (Pipe No.110)=20m, 10-A (Pipe No.111)=10m.

Pipe fittings equivalent length: Le/D=20 for tee flow through run, Le/D=20 for long radius 90oelbow. (Note: Le = equivalent length for valves and fittings, D = pipe diameter, Le/D is dimensionless)

CFM required: Tools 1=25 CFM, 2=25 CFM, 3=50 CFM, 4=30 CFM, 5=40 CFM, 6=50 CFM, 7=50 CFM, 8=25 CFM, 9=35 CFM, 10=12 CFM

Results:

Using 40mm diameter ring main pipe, Pressure drop (Pdrop) = 0.0929 bar = 1.3468 psi.

If the ring main pipe size is changed to 50mm diameter, the Pressure drop (Pdrop) = 0.0309 bar = 0.4475 psi. 

Final Thought: Think about it, how do you properly size your compressed air pipework? Many people use charts. The objective is to size the ring main piping to transport the maximum expected flow with minimum pressure drop. Obviously, the lower the pressure drop, the lower the operating cost.

Instead of using charts and conventional assumption that half of the total flow in half of the ring main pipework, this program will transform the way you perform pressure drop calculation in the ring main pipe network.