Pressure drop through pipe

Piping Systems Equivalent length key pipe components Singularity coefficient key pipe components Partially filled pipe Sonic Velocity Valves types Valves Cv Control valve sizing for gases Pressure safety valves Colebrook correlation Churchill correlation Velocity in pipes Flow regimes Orifice calculations 1. Definition The pressure drop through common fittings and valves found in fluid piping can be calculated thanks to a friction coefficient K. This coefficient must be determined for every fitting. In pre-project, common values are often sufficient. Usual coefficients are given in the tables below. 2. Pressure drop calculation The pressure drop through a fitting or a valve can be calculated thanks to K. Equation 1 : pressure drop through a pipe singularity (valve, fitting...) With ΔPs = pressure drop through pipe singularity (valve, fitting...) (Pa) K = friction coefficient from tables below ρ = fluid density (kg/m3) um = average fluid velocity (m/s) K coefficient in a same pipe section can be added, the pressure drop can then be expressed the following way. Equation 1 : pressure drop through all pipe singularities of a pipe section (valve, fitting...) For compressible fluids, it is important to use the average velocity. If the pressure drop is too important and density and velocity change too much, the pipe section considered must be broken down in smaller sections to keep a good calculation accuracy. 2. K coefficient for additional friction loss due to pipe and fittings The values below are only valid in TURBULENT FLOW Table 1 : K coefficient for calculation of pressure drop through valves and fittings Note : Re>4000 : turbulent regime Source Mecanique et Rheologie des Fluides en Genie Chimique, Midoux, Tec et Docs, 1993, pages 329-331 Perry's Chemical Engineers Handbook, Perry, McGraw Hill, 2008, page 6-18

Technical Information Pressure drop: Pressure drop in pipes is caused by: 1.) Friction 2.) Vertical pipe difference 3.) Changes of kinetic energy Calculation of pressure drop caused by friction in circular pipes First we calculate the Reynolds-Number: If Reynolds number Now we calculate the pipe friction number: Pipe friction number at laminar flow: Pipe friction number at turbulent flow: Now we can calculate pressure drop in circular pipes: Calculation of pressure drop caused by friction in fittings etc. To calculate pressure drop in fittings we use resistance coefficients normally. The resistance coefficients are in the most cases found through practical tests. If the resistance coefficient is known we can calculate the pressure drop: Calculation of pressure drop caused by vertical pipe difference Pressure drop caused by vertical pipe difference we calculate with the formula: Calculation of pressure drop caused by changes of kinetic energy Pressure drop caused by changes of kinetic engergy we calculate with the formula: The element "Dyn. pressure change" calculates these pressure changes. Normally you input the dimension of begin and end of the whole pipe. Pressure drop in gases and vapor Compressible fluids expands caused by pressure drops (friction) and the velocity will increase. Therefore is the pressure drop along the pipe not constant. SF Pressure drop calculates these pressure drops with an approximate equation (pressure drop at arbitrary heat transfer): We set the pipe friction number as a constant and calculate it with the input-data. The temperature, which is used in the equation, is the average of entrance and exit of pipe. You can calculate pressure drops of gases with the same formula as liquids if the relativ change of density is low (change of density/density = 0.02).

Calculation of pressure drop in steam and water lines The pressure drop in a water & steam lines refers to the decrease in pressure that occurs as water/steam flows through a pipe or conduit due to factors such as friction and flow resistance. Several factors influence the magnitude of pressure drop in a water line:Pipe Characteristics: The diameter, length, and roughness of the pipe impact the resistance to flow and consequently the pressure drop. Smaller diameter pipes and longer pipe lengths tend to result in higher pressure drops. Additionally, rougher pipe surfaces create more friction and increase pressure drop compared to smoother surfaces.Flow Rate: The rate at which water/steam flows through the pipe affects the pressure drop. Higher flow rates generally result in higher pressure drops due to increased frictional resistance.Fluid Properties: The physical properties of the water/steam being transported, such as viscosity and density, can influence the pressure drop. However, for water at typical temperatures and pressures, these effects are usually negligible. Pipe Fittings and Valves: The presence of fittings, such as elbows, bends, valves, and other obstructions in the water line, can contribute to pressure drop. These components disrupt the flow and introduce additional resistance. It's important to note that pressure drop calculations for steam lines can be complex and require a comprehensive understanding of steam properties and fluid dynamics. Pressure drop in water line:Head loss in water line for turbulent flow is given asHead loss in meter = 4fLV2 / (2gD) Where, f = Friction loss in pipe, generally varies from 0.005 to 0.007L = Pipe lengthD = Diameter of the pipeg = Acceleration due to gravity, 9.81 m/s2V = Velocity of the fluid Example:A Boiler feed pump is delivering feed water flow 50 TPH to the boiler at a distance of 70 meter.The steam drum height

Pressure drop is decrease in pressure from one point in a pipe or tube to another point downstream. Pressure drop occurs due to frictional forces acting on a fluid as it flows through the tube. The frictional forces are caused by the resistance to flow. The main determinants of resistance to fluid flow are fluid velocity through the pipe and fluid viscosity. Any liquid or gas will always flow in the direction of least resistance (less pressure). Pressure drop increases proportional to the frictional shear forces within the piping network. A piping network containing a high relative roughness rating as well as many pipe fittings and joints, tube convergence, divergence, turns, surface roughness and other physical properties will affect the pressure drop. High flow velocities and / or high fluid viscosities result in a larger pressure drop across a section of pipe or a valve or elbow. Low velocity will result in lower or no pressure drop. Pressure Drop can be calculated using two values: the Reynolds Number, Re (determining laminar or turbulent flow), and the relative roughness of the piping.Where D is the diameter of the pipe, v is the velocity of the fluid, ρ is the density of the fluid, and μ is the dynamic viscosity of the fluid. The relative roughness of the piping is usually known by cross referencing the Reynolds number with the relative roughness, the friction factor, f, is calculated.The velocity of hydraulic fluid through a conductor (pipe, tube or hose) is dependent on flow rate and cross sectional area. Recommended fluid velocities through pipes and hoses in hydraulic systems are as follows:ServiceVelocity (ft/sec)Velocity (m/sec)Pump suction2-40.6 - 1.2Pump return4 - 131.5 - 4Pump discharge7 - 82 - 5.5Use values at the lower end of the range for lower pressures or where operation is continuous. Refer to the flow/velocity nomograms for more information.Alternatively, fluid velocity can be calculated using the following formula: Q × 0.408v = -------------- D2 Where:v = velocity in feet per second (ft/sec)Q = flow rate in US gallons per minute (US gpm)D = inside diameter of pipe or hose in inches

It’s important to understand the fundamentals of pipe parameters when it comes to insulation and heating for your home. Pipes are essential for distributing steam or hot water throughout your home so that each room is kept cozy and warm. However, how are the different parameters of these pipes calculated? There are key formulas and examples that can help you through the process, from diameter to flow rate.Let’s start by discussing pipe diameter. A pipe’s diameter has an impact on both its pressure drop and flow rate. Greater flow rates and lower pressure drops are typically possible with larger diameter pipes, whereas smaller diameter pipes produce slower flow rates and higher pressure drops. A number of variables must be taken into account when determining the proper diameter, including the amount of heat output needed in each room, the length of the pipe runs, and the kind of material the pipes are made of.We then proceed to calculate flow rates. The volume of fluid going through a pipe in a given amount of time is called the flow rate. To guarantee effective heating throughout your house, you must ascertain the proper flow rate. Calculations of flow rate are influenced by various factors, such as the size of the heating system, the quantity of radiators or heat emitters, and the intended temperature in each room. Through comprehension of these elements and application of appropriate formulas, you can accurately size your pipes for maximum efficiency.Another crucial factor to take into account when building a heating system is pressure drop. The term "pressure drop" describes the reduction in pressure caused by frictional losses when water passes through a pipe. Increased energy consumption and decreased heating efficiency can result from excessive pressure drop. Pipe length, diameter, flow rate, and the inner surface roughness all play a part in calculating pressure drop. Knowing the fundamentals of pressure drop calculations will help you make sure your heating system runs smoothly and effectively.Let’s now examine some real-world examples of applying these computations. Useful examples can help demonstrate how to apply the discussed formulas, from figuring out the pipe

Calculate the pressure drop generated by the air at a flow rate of 500 m3 / h through a pipe with an inside diameter of 60 mm and a length of 100 m. The air temperature is 5 C, the roughness of the pipeline is 0.02 mm, and the coefficient of local resistances is equal to zero - there are no local resistances in the pipeline. Pressure on the pipeline start is 4 bar gauge. Solution: Pressure drop is: 95.67 mbar AirFloAirD, L, t, p1, p2, KQ Example #5 Task: Calculate the air flow through a pipe with an inside diameter of 1 inch and a length of 200 m. The available pressure in the air tank from which the pipeline starts is 2 bar gauge. At the end of the pipeline, the air flows out into the atmosphere. The internal roughness of the pipe wall is 0.1 mm. The pipeline has 6 pipe elbows 90 degrees and a radius of 1.5 D. The air temperature is 15 C. Solution: Flow rate is: 90.713 m3/h AirFloAirQ, D, L, t, K, p2Δp Example #6 Task: Calculate the pressure drop that creates air at a flow rate of 1000 cfh through a pipeline with an inside diameter of ½“, and a length of 1000 ft, with an internal roughness of the pipe wall of 0.012 in. The pipeline has 4 elbows 90 degrees and one reduction at the end of the pipeline to ¼“, after which the air flows into the open atmosphere. Solution: Pressure drop is: 7.287 bar Related calculators available for download