What is Pressure drop: Definition and 160 Discussions

Pressure drop is defined as the difference in total pressure between two points of a fluid carrying network. A pressure drop occurs when frictional forces, caused by the resistance to flow, act on a fluid as it flows through the tube. Pressure drop increases proportionally to the frictional shear forces within the piping network.
There are a number of factors that impact on the degree to which pressure drop occurs in a piping system, including the following:
The nature of the product being pumped, including its density, heat capacity, temperature, viscosity, and the velocity at which it is moving.
Mechanical components in the piping system, including valves, flow meters, adaptors, and couplings. All of these remove energy from the piping system, contributing to pressure drop.
Changes in the elevation of the piping. If the starting elevation of a pipe is lower than its end elevation, the rise in elevation will cause pressure drop as the fluid moves through the pipe. Conversely, if the starting elevation is higher than the end elevation, there will be a pressure gain as the fluid moves through the pipe.

View More On Wikipedia.org
Recent contents Top users
  1. L

    How do i relate pressure drop with h ?

    How do i relate pressure drop with "h"? http://www.2shared.com/document/L4fH2kdT/HES_2340_Assignment_1.html Homework Statement Hi, Regarding to the link above, I have a question on my homework on Q2 and Q4. In Q4, What pressure shall i consider in this situation? Shall i include the...
  2. M

    Pressure drop due to friction and condensation

    Hello, I'm struggling with the following problem. We have a dryer in our plant which evaporates acetone and with a blower the vapour is driven to a scrubber. However the efficiency of the scrubber is not sufficient and that is why I want to place a plate heat exchanger in the vapour line to...
  3. D

    Problem with pressure drop in pipeline

    Hi Folks; As we all knew, and I used to experimentally observe it, as the temperature of water increases, pressure drop through pipeline (kPa/m) decreases. Now, I am getting the opposite, while the results are so consistent and reproducible ! As the water temperature increases, pressure drop...
  4. S

    Calculating Pressure Drop in Two-Phase Flow

    Hi folks, my prof gave us some problems calculating pressure drop in two phase flow. She did some examples and somehow she got the density of water-liquid and water-vapor from steam tables, but she did not explain how. I have never used these. I am especially stumped on the density of...
  5. S

    Pressure drop problem (using the darcy law)

    Homework Statement Estimate the pressure drop in a tower packed with porous support. This tower is an integral part of a water oxygenation system and will need to operate over extended periods without cleaning. From the following data estimate the pressure drop you expect to see on...
  6. A

    Pressure drop through an orifice in a pipe

    Hey all, I'd need help with determining the pressure loss over an orifice in a pipe. I have an equation for the friction factor so no problem there, and I know the Reynold's number as well. What confuses me is choosing the suitable velocity for the pressure drop equation; \frac{Δp}{ΔL} =...
  7. J

    Pressure drop w.r.to time through a orifice dia(D) in a container of volume (V)

    Let initial preasure (P) = 10 bar,volume of container (V)=100000 cubic cm. At what time period pressure will become 5 bar.
  8. B

    Pressure drop along a water pipe

    Along a horizontal pipe I am getting a pressure drop of roughly 10-20 kPa every 20 metres in a 6.5" (OD) water pipe. This seems much to high and I am thinking the pipe may be stuffed and thus there is to much friction which is reducing the pressure of the water. Just wanted to get some other...
  9. S

    Why does blood pressure drop as you get farther from the left ventricle?

    Blood is in continuous contact with itself. Thus any pressure on artery blood is pressure on vein blood. So they have the same pressure. What am I missing here?
  10. T

    Control valve downstream pressure drop

    Hello, I have abnormal situation on a site, there are installed 3 valves in parallel (cascade) in Fuel gas skid, upstream pressure of the valve is 30 bar, downstream pressure 25-26 bar, when 2 GTG starts up to load 40 MWt (100 %) the downstream pressure of the control valves decreses to 21 bar...
  11. T

    Pressure drop across an array of different nozzles?

    I have a question about calculating the pressure drop in a large flow meter across an array of nozzles. Basically its inside of a tunnel... air flows in this tunnel until it reaches a "gate" which is blocked off except for six nozzles of different size, which discharge back into an open...
  12. P

    Pressure drop for viscous fluid in conducts with an obstacle at the outlet

    Hello, I have the following system (see enclosed figure): A viscous (non Newtonian) fluid at high temperature is going trough a tube at a known mass flow, at the exit there is an inclined plane at a given angle (b). I would like to estimate in some way how the inclined plane at the exit...
  13. D

    Test to find pressure drop through valve?

    Hi all I am trying to design a test that can be carried out on a valve to calculate the pressure drop and flow coefficient through said valve. i need to have a 6 bar inlet pressure into the valve and the ID of valve will be 50mm. the fluid i am proposing to use is water. My design is to have...
  14. F

    Compressed Air System Dynamics: Calculating Pressure Drop & Cv

    I want to work out the dynamics of a compressed air system consisting of a filter/regulator unit some spool valves and a rotary actuator with all the associated fittings. Essentially I have a 2" nominal bore compressed air line at roughly 7.5 bar, I have a system which feeds off this air main...
  15. D

    Calculate the flow coefficient and pressure drop through valve?

    Hi I am wondering would ye be able to help me out? I am instructed with the task of calculating the pressure drop and flow coefficient for a valve. Please see basic diagram attached for layout of valve. I need to find the pressure drop and flow coefficient when the ram is closed at different...
  16. A

    Concentrated pressure drop in tube having 90 round bend

    Hi i want to calculate the concentrated pressure drop in a tube having 90 round bend and other one having 180 round bend. The equation that i know is: dP (concentrated) = 1/2 * b*r*v^2 where: b=specific coefficient for concentrated pressure drop r = liquid density (kg/m³) v = average...
  17. M

    Pressure drop across butterfly valves

    Hi, I'll make a valve open and close for some degrees that I have to calculate, the valve motion will produce a pressure wave in the pipeline. I have to know how many degraus I must open the valve to produce a pressure drop that I want. Someone know how I can calculate it? Is there an equation...
  18. A

    Pressure drop profile calculation

    I am so tired I tried many times to calculate the pressure drop profile. What is the right equation? Please help me
  19. T

    Pressure drop across a small section of pipe.

    Hello everyone. I have natural gas (methane) flowing through some piping, and the last little part of pipe is where I'm concerned. The gas goes through a drawn aluminum tube, about 5.08 mm ID (it's a very small tube). The tube has three 90 degree bends where it ejects out of an orifice. It...
  20. M

    Need help to find average velocity and pressure drop in duct

    Homework Statement 1. the average velocity of the air to meet the required volume flow rate, 2. the pressure a fan needs to produce to overcome the frictional losses in the duct, 2. Relevant Information Duct size - 600 mm x 600 mm which operates at 3 Pa/m. The air path is 87 meters from...
  21. N

    Question: Pressure Drop Across A Bed Of Stone

    Dears, I am going to find out the required pressure for the air to pass through a bed of stone in a cooling tower. I have read the book: Handbook of pneumatic conveying engineering (by David Mills) and it said that it can be determined by permeability of the stones (15-20mm size). The...
  22. M

    PWR Pressure Drop: Plenum to Plenum Pressure Drop

    For pressure drop of PWR, what is the plenum to plenum pressure drop?
  23. A

    Pressure drop in pipe due to bends and/or pressure reducing valves ?

    I am currently doing my final year project and have a few queries. I would be really grateful if someone could answer the following questions for me as soon as possible. • The requirement is to drop the pressure from 140-150 bars at the inlet of a pipe to 2 bars at the outlet of the pipe. •...
  24. Q

    Pressure drop in pipeline in a bend or elbow

    I wonder if there is no table or graph with which I can make a quick estimation of the pressure drop in relation with pipe diameter and flowrate ( for 90° bends only ) ... can anyone help me with that ?? Thanks !
  25. K

    Calculating Pressure Drop in Fuel Systems with Complex Geometry: A Case Study

    Hello. I have been asked to calculate the pressure drop across our fuel system. It is a large system with many fittings and bends. My numbers don't seem to make sense to me Please help... Before I begin, I use equation dp=(K*density*MeanVelocity^2)/(2*g) to calculate pressure drop. To...
  26. K

    A couple questions regarding pressure drop

    First, I am very confused as to the difference, if any, between head loss and pressure drop/loss. Can someone help me? Also, I know that the Darcy-Weisbach equation for head loss due to friction is hf=fL/D*V2/2g and you can plug that into get an equation for delta p that is dp=fL/D*pV2/2...
  27. E

    Pressure Drop experiment

    Homework Statement I'm dealing with dimensional analysis in subject called Petroleum Engieering Fundamentals. I was told do devise the apparatus to gain the values of constants a1,n2,n5 stated below.( they are all the members of real numbers) here is the task "Your challenge is to devise an...
  28. A

    Understanding Pressure Drop in Parallel Piping Systems

    I have a question about network flow pressure drop. In a piping system with several identical components in parallel, is the pressure drop across the supply and return header equal to the pressure drop across one of the components? Or is it the inverse of the sum of the inverses? To use...
  29. T

    Pressure drop across orifice , calculation help

    Homework Statement A fluid of relative density 0.86 and viscosity 0.003 pa flows through a pipe of 12cm diameter. The flow rate is measured using an orifice plate with a 6cm diameter orifice, with pressure tapping connected to a differential U-tube manometer using mercury (density = 13600 kg...
  30. B

    Understanding Pressure Drop in Pipes

    Hi, This isn't actually a homework problem, but rather I'm just trying to understand a few things. It's pretty simple though, so I thought this would be the best place to post. I don't care so much that I'm getting the correct answer, as much as I care that I'm understanding the situation...
  31. D

    Pressure drop in a water manifold

    Hi all, This is what I currently have. Water chiller with a flowrate of 2GPM (Choked to 2GPM) Ti= 50F H20 Pi=55-60psi It is a closed loop system. I am looking to split 1 line at 2 GPM (55-60psi) into 8 smaller lines that will run into my cooling jacket. All 8 lines are same length...
  32. S

    How can hydrostatic pressure drop to zero?

    Hello everyone, If this is a vessel the hydrostatic pressure would drop along the vessel due to resistance. My question is why does hydrostatic pressure drop if hydrostatic pressure is due to gravity. Gravity is always there, even if the molecules lose hydrostatic energy, they would gain it...
  33. Valour549

    Air pressure drop in Space ( )

    Air pressure drop in Space (please help!) Homework Statement A space capsule, which may be treated as a sphere of radius 10 m, is hit by a micrometeorite which makes a hole of diameter 2mm in its skin. Estimate how long it will take for the air pressure to drop by 30%. (Answer should be...
  34. S

    Rate of air pressure drop in a reservoir with a hole to a vacuum

    Homework Statement A space capsule, which may be treated as a sphere of radius 10m, is hit by a micrometeorite which makes a hole of diameter 2mm in its skin. Estimate how long it will take for the air pressure to drop by 30%. Avogadro's number is about 6 \times 10^{23} Homework Equations...
  35. P

    Orifice design for pressure drop

    When designing an orifice plate to reduce the pressure of a constant flowing liquid, is it best to have one large hole in the center or multiple smaller holes? One example: Pipe diameter = 10 inches, Flow = 2800 gpm water, pressure drop = 150 psi, temperature = 115 F. The hole diameter...
  36. S

    Blood Pressure Drop: Understanding Mechanisms

    Hello! Ive been trying to understand mechanisms of blood pressure and so far the more I read the more confusing it gets. What I really don't understand is this - why does the pressure drop is largest in arterioles? The physiology book I use says that they constitute a high resistance and as...
  37. C

    Pressure drop expansion valves

    I'm having trouble understanding expansion valves. Gas leaving a diffuser increases its pressure as the cross-section increases (i.e as the gas expands), like in a compressor. We convert kinetic energy in potential energy. That I understand. But in a expansion valve, pressure drops as the...
  38. A

    Calculate air-flow using pressure drop

    At what speed (flow/volume for that matter) does air leave an outlet when you know it holds x bars in the pipe? (It goes from x to zero (or athmospheric) -- you know the pressure difference) I assume you can neglect relative roughness, resistance, and so on as the pressure drop is over...
  39. A

    How to find the flow rate trough a pipe using pressure drop

    Hi, I want to know how high the flow rate trough a pipe is (outlet), but I only now the pressure difference (0.7MPa or 7 bar), and the diameter of the pipe. At what speed (or for that matter volume) does air leave a pipe when the pressure difference is 7 bar, and the diameter is 25.4mm...
  40. B

    What is the formula for finding pressure drop in pipe flow?

    Hi, Which equation should i be using to find the pressure drop across a channel. I know the length of the channel, the hydraulic diameter and the reynolds' number. Thank you
  41. A

    Pressure drop across valves

    Hi guys, i want to ask why is there pressure drop across valves? Because if you look at bernoulli's equation, the head will be the same in 3 points, before the valve, at the valve and after the valve. The only thing changes when a fluid flow through a valve is its pressure and velocity at the...
  42. M

    Pressure Drop vs Velocity in a Rectangular Pipe

    Hi guys I am currently using Comsol to model a single rectangular channel, a typical one found in a fuel cell (with symmetry boundary). Dimension of the inlet and outlet area is of the order 10e-3 and the length of the pipe is 0.1 m. I am having difficulty getting the expected result. The...
  43. P

    Calculating Pressure Drop Across Valve in Horizontal Pipe

    Hi, 20m straight length horizontal pipe (60 mm internal diameter), steam flows at rate 0.5 kg/s, at midpoint there is a valve in the line. inlet pressure to this section of line is 5 bar (gauge), pressure at end of line is 3 bar (gauge). mass quality of steam is 0.8 and 2 phase flow occurs in...
  44. J

    Equation relating mass flow rate to pressure drop

    Hi I am designing a heat exchanger. I know the mass flow rate required for cooling. I have calculated the pressure drop for current design. How do I work out if the size if the heat exchanger can handle the flow rate ? Does the mass flow rate depend on the size of the heat exchanger tubes ...
  45. S

    Pressure drop across a packed bed

    I have a packed bed with an inlet pressure of 108psig and an outlet pressure of 88psig to give a total pressure drop of 20psi. The packing is becoming damaged due to the 20psi pressure drop. I have thought and looked for an answer for a long while, why does the packing only experience the...
  46. K

    Pressure Drop Across Radiator And Air Flow

    Hello all, I have some performance data on a particular radiator, and I want to model the system and see if I can't get a simple analytical model to match the data. The problem I'm having is with the air flow rate through the radiator. The only relevant data made available to me is the...
  47. Y

    How Does a 90-Degree Bend Affect Pressure Drop in Pipes?

    I have a centrifugal pump that gives flow of 56 lit/min at 50 psi. Media: clear water, Temp. ambt The discharge pipe size: 1 1/2", Material: SS Total pipe length: 14 feet At 3 feet from pump discharge there is 90 degree bend and again at 6feet there is 90 degree bend. My question is what...
  48. M

    Pressure Drop Due to Combining Flow in a Water Pipe System

    Hello, I am wondering how to determine the pressure drop due to fittings such as Tees and "Y's" when there are two flows coming in and one coming out. So for example there is a Tee where there are two flows coming in opposite directions (180 degrees from one another) and they combine and exit...
  49. M

    How to use flow rates (GPM) and pressure drop to determine if a valve is usefull

    I need to determine if a valve can handle a flow rate of 50 GPM, this valve being: 2/2 Way, Normally closed, w/ 2-pilot control, and coupled solenoid. I also need to determine pressure drop... it is a burkhert model - 457361D the valve specs indicate: Cv = 35.1 pressure...
  50. S

    Compressed Air Pressure Drop Across a Restriction

    I would like the formula that describes the reduction in pressure that results when a constant flow (cfm) of compressed air travels from a 3" diameter pipe through a bell reducer that provides a smooth transition to a 1.5" diameter pipe. Also, in the same piping configuration as described...
Back
Top