# What is Volumetric flow rate: Definition and 30 Discussions

In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, rate of fluid flow, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol Q (sometimes V̇). The SI unit is cubic metres per second (m3/s). Another unit used is standard cubic centimetres per minute (SCCM).
In hydrometry, it is known as discharge.
In US customary units and imperial units, volumetric flow rate is often expressed as cubic feet per second (ft3/s) or gallons per minute (either US or imperial definitions).
Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m3/(m2·s), that is, m·s−1. The integration of a flux over an area gives the volumetric flow rate.

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1. ### Volumetric flow rate ratio calculation

I'm using two tanks of nitrogen and oxygen and mixing them in different ratios to change the oxygen partial pressure in the system. System is opened to the atmosphere through the venting pipe which therefore sets the total pressure of the system to 1 bar. System is opened and gases flow through...
2. ### Volumetric flow rate of nitrogen through relieving pressure regulator

Hello all, I'm having trouble figuring out the volumetric flow rate upstream of a relieving pressure regulator used on a 1/4" OD nitrogen line. Upstream of the regulator P=100 PSIG and T=70F, while downstream P=80 PSIG and T=70F with downstream consumption at q=4 L/min or 0.91 SCFM (at std...
3. ### Volumetric Flow Rate through a Venturi Meter

Hi, I have designed a simple Venturi meter to measure pressure differential across to section of the pipe as pictured. However in calculations I am not sure if I am doing something wrong. I am trying to calculate Volumetric flow rate in L/s. I am using Bernoulli Equation of the Venturi meter as...
4. ### Mass and Volumetric Flow rate of Natural Gas

Hi. I am currently doing my internship in the oil and gas industry (contractor) as process engineer. My supervisor give me a task to do some reverse engineering where i need to study how a spreadsheet (calculation) construct by other process engineer was been constructed. Ok the situation is the...
5. ### Volumetric flow rate of a pipe

Hello kind people of PF I am looking to mount a fan on one end of a pipe but I'm not sure how much air can the pipe transfer. (Volumetric flow rate) The pipe is vertical and 15 meters long.It has a diameter of 10 cm. I'm looking to push air from top to bottom using a fan. Need to know the...
6. ### Finding Velocity of Water Flow: A0 to A

a) so Q=V/t = Av Q is constant ( same At A0 and A). That means I have to find the velocity of the water either at A0 or at A. But how can I find it? I thought there must be a reason that h is given but the only way I can use it is to assume the velocity is 0m/s at A0 but actually it is not...
7. ### Relationship between volumetric flow rate and pressure

Hello everybody, This is my first post. I've been working on a liquid rocket engine for a while, but I have never gotten to work on its feed system (fluid mechanics), until recently. We are using a very simple pressure fed system, and its main goal is to deliver the propellants at a specific...
8. ### Volumetric flow rate in a PFR reactor

Hi pf, I have a reaction ## aA → bB ## in a PFR reactor. The simplest equation to write is: ## \frac {dF_A} {dV} = -R ## where ##F## is the Molar flow rate. ##F = C_A*Q## where ##Q## is the volumetric flow rate and ##C_A## is the molar concentration of A. My textbooks says that if ##a=b##...
9. F

### I Volumetric flow rate and Force

Does Pressure multiplied by volume multiplied by volumetric flow rate equal Force?
10. ### Volumetric flow rate conversions

I'm trying to learn more about how air compressors work (not how they mechanically function - how they're input/out pressures and flow rates work) and I'm having a lot of trouble getting a specific questioned answered even after a lot of google searching. Suppose I have a compressor that the...
11. ### Calc Volumetric Flow Rate of Free Air: 0.841 m3/s

Homework Statement Air is to be compressed from a pressure of 1 bar and a temperature of 20°C to a pressure of 15 bar in a two stage compressor with intercooling. After intercooling the air temperature returns to 20°C and the polytropic index of compression is 1.28. If the input power per...
12. ### Convert Volumetric Flow Rate to Mass Flow Rate: A Guide

How to convert volumetric flow rate to mass flow rate?
13. ### How to find force from volumetric flow rate and pressure

1. Homework Statement Hi. This is a problem related to designing a RC hover craft. We are given a datasheet for a fan used as thrust. http://imgur.com/6liZSid Sorry image post no working, url: http://imgur.com/a/6XLwL We have to approximate the equation to a straight line through the curve...
14. ### Volumetric flow rate of bubble out of the straw

Homework Statement Imagine that you are blowing air through a straw in a cup of water and the root of the straw was connected through a rectangular box with empty base and every side of the rectangular box was cut into "teeth" shape. Bubbles will come out from the teeth of the rectangular box...
15. ### Have mass flow rate, want superficial vapour velocity

Hi guys, quick simple question. Lets say I have a pipe separated into 3 sectoins (all horizontal), all have the same flow areas. In the first section it is all liquid water. I know the mass flow rate in this. In the second section the water is heated. And I can work out the steam quality...
16. ### Mechanics -- Converting volumetric flow rate to nozzle velocity

Homework Statement A hose with a nozzle 80 mm in diameter ejects a horizontal stream of water at a reate of 0.044 m3 s-1. With what velocity will the water leave the nozzle? What will be the force exerted on a vertical wall situated close to the nozzle and at right-angles to the stream of...

How to calculate how much flowrate from blower i can push water pool 2,75m*1,8m down by 1,25m in 1 sec? Note : Blower Pressure 0.03 bar - 0.035 bar There is an empty room above the water pool with dimension of 2.75m*1.8m*1.7m This process happen in a closed chamber...
18. ### Finding volumetric flow rate from pressure?

Hello everyone, I am quite new to Fluid dynamics, so I would like to ask for your help. Is it possible to calculate volumetric flow rate from the instantaneous pressure? We need to know the flow rate of the air entering the cylinder in the engine due to the suction pressure. It is required to...
19. ### PV=nRT to PQ=ṁRT where Q - volumetric flow rate?

Homework Statement Hello, I have really hard time to express the gas law PV=nRT to PQ=ṁRT where Q is volumetric flow rate and ṁ- mass flow rate. Is it possible ? Teacher told me, it is ... Homework EquationsThe Attempt at a Solution
20. ### Confused about Volumetric Flow Rate & Valves?

I'm new here, and I have a question that might be easy but really confuses me. Does the volumetric flow rate of incompressible fluid change across a valve?. Based on my analysis, no it can not change since the mass is conserved, and since it's incompressible fluid. I know that the velocity will...
21. ### How to find the volumetric flow rate?

With a given 2kW pump That pumps a liquid with a density of 820kg/m³ from one tank to another that's 30m higher. With a calculated change in pressure to be 241.3kpa. Find the volumetric flow rate. I feel like there are not enough given variables for this problem. What do you think?
22. ### Volumetric flow rate through a pipe vented to atmosphere

My chemical engineering is a little rusty after 25 years and I could use a little help with this real world problem. This isn't my project but I've been asked to advise. Sorry for the limited information. We have a 30 gallon tank with 75% hydrogen/25% nitrogen mixture at 100 psig. From the...
23. ### Low volumetric flow rate measurement

Hi everyone, I'm currently a mechanical engineer interning at an HVAC company. I need to measure the resistance of a fluid through ductwork. The CFD shows a linear curve through a plenum when plotting R vs volumetric flow rate. For example, a straight rectangular box 1 1/16” by 2.5” and 3ft...
24. ### Calculating Volumetric Flow Rate (Q) of Non-Water Liquids

Hey, I was wondering how to calculate the volumetric flow rate (Q) of a liquid other than water through a hole at the bottom of a tank. I know that Q= V.A and 1/2.ρ.V^2 = ρ.g.h Where, V: Velocity of the liquid coming out of the hole A: Area of the hole h: Height of the...
25. ### Volumetric flow rate of air into a tank - Fluid Mechanics

Hi all, I am stuck on a problem, and it's been a while since I took fluid dynamics. I have a cylindrical tank of know capacity with an inlet, where a vent is attached, and an outlet, the fluid gets sucked. The tank has fluid in there with known volume and density. If I know the usage rate of...
26. ### The Equation for Volumetric Flow Rate?

I'm not sure how to clearly express my query, so I'll round up the gist of it. I understand that this is an entry level question. I was told that, in order to calculate Volume Flow Rate (VFR), I would use these equations: * Q = Velocity * Area [EQUATION 1] * Q = Volume / Time [EQUATION 2]...
27. ### Volumetric Flow Rate Calculation - Tank Drain & Pump Input | DE Forum Help

I posted this in the DE forum as well since it is related. --------------------- Hi all, I've got a fairly straight forward problem to solve here regarding flow rate out of a tank with uniform cross-sectional area. I am treating this is a volumetric flow problem since there is assumed...
28. ### At what volumetric flow rate will air fill a space vacuum at Earth's STP?

At atmospheric pressure of 14.2 psi, if I had a 1 ft square hole through a 5 foot thick wall into an endless space vacuum, I am trying to find out the the final maximum volumetric flow rate that our atmospheric pressure would push air through the hole. I tried using Poiseuille's Equation...
29. ### Volumetric flow rate (simple?)

Volumetric flow rate (simple?) Assuming reservoir level stays constant, and friction losses are negligible compared to gravitational effects, which overflow config achieves a higher volumetric flow rate? http://boards.420chan.org/tesla/src/1311021903815.jpg --------------------- Now...
30. ### Calculating Volumetric Flow Rate Without Cross-sectional Area

hi , I have a question that if you answer it I would be so thankfull, Q is: "Can we calculate volumetric flow rate without knowing cross-sectional area? If,yes,How?" I have this Q because I see a portable Thermometer,volumetric flow rate meter ,which show it without giving any area size...