water flow through pipe calculator
With this being the case, they will be accurate to within 10% of the actual results obtained. All formulae for finding the amount of fluid that will flow through a hose at a given time, are approximate. For example, if liquids contain solid particles, engineers try to achieve a higher velocity so that the heavy particles in the liquid dont settle and cause blockage in the pipe. Typical velocities are usually: Cold water velocity - 1.5-2.4m/s or 5-8 ft/s, Hot water flow velocity - 1.2-1.5m/s or 4-5 ft/s, Hot water return velocity - 0.7-1m/s or 2-3 ft/s. Do Not Sell or Share My Personal Information. How to reset a leak controller for a water filtration? for use in every day domestic and commercial use! BYJU'S online water flow calculator tool performs the calculation faster, and it displays the liquid flow rate in a fraction of seconds. Turbulent Flow Rate Calculator. 2023 Hy-Tech Products, Inc. All rights reserved. 5 ft/sec is a somewhat arbitrary velocity threshold that some designers use because beyond that the friction losses, danger of water hammer, and pipe movement due to water momentum changes are deemed to be too high. The flow will happen as long as there is an altitude difference between the source water (upstream source) and the discharge point. The consent submitted will only be used for data processing originating from this website. D is the diameter in inches. Continue with Recommended Cookies. The properties of water flowing in a gravity-fed system can be calculated using the Free Pipe Flow Calculator. The coefficient of velocity (Cv) - Calculator - Cv, or coefficient of velocity, is a measure of the flow capacity of a valve. Multiply the constant pi by the answer to Step 1: 3.142 x 0.0025 = 0.00785. Please click on the tabs below to view the results. Flow rate or discharge of water Q = V A = 6m/sec 0.0044184375sqm = 0.026510625 m 3 /sec . It is measured in m/s, GPM, or l/s and is directly proportional to the pipe flow velocity. Use the second form to calculate the inside diameter of a pipe at a water velocity of 5 ft/sec. We do not guarantee the accuracy of this information. Units that are commonly used to measure volumetric flow rate are: m3/s (cubic meter per second), L/min (liters per minute), ft3/sec (cubic feet per second), ft3/min (cubic feet per minute, or CFM), and gal/min (gallons per minute, or GPM). Understand your return on every ad dollar. Pump Head = 0 if no pump present. How Much Water Can Flow Through A Pipe by Size and GPM or GPH? ): It represents the number of gallons per minute (GPM) of water at 60F that will flow through a valve with a one-inch opening at a pressure drop of one pound per square inch (PSI). Use the Hazen-Williams equation to find the velocity of the gravity flow. 8 to 10 linear feet per second . Volume of piping needed to install an irrigation system for lawns and gardens. Also read: How To Calculate Water Velocity In Pipe? Typical water velocity in a pipe is generally between 0.7-2.4 m/s. Free-Flowing Water Circular Culvert (Pipe) Drawings and Equations. You can embed our Flow Rate Calculator into your own website by copying the code below. Water Flow (GPM/GPH) based on Pipe Size and Inside/Outside Diameters Match the right technician to the right job. ServiceTitans volume of pipe calculator also easily computes: Water capacity of in-home heating systems. P [end] = Pressure at end of pipe. Enter the required amount of volume needed to flow pass per unit of time. Account for every cent with seamless integration. The flow rate depends on the head loss, which again depends on the flow rate. Enter flow rate and velocity in text fields in the calculator and click calculate button to get results. Use the calipers to measure the outside diameter directly instead of estimating inner diameter based on circumference. Water flows to the plant through a 36" diameter pipe @3500m3/h and 220kPa for 9m before teeing out to a 24'' pipe (1.5m high with butterfly valve). Experiment with a leaky water tower to see how the height and water level determine the water trajectory. Valves and Orifices. Q = D^2 * V / .408 Q = D2 V /.408. To get the radius, divide the diameter by 2. V is the velocity ft/s. Have a question or in need of a specific roofing product or drain part? Sign up to our exclusive email newsletter to get the latest news and offers from Copely. Fill in the form below to request a quote for our industrial water treatment services. Plumbers and other contractors need the right tools to solve complex math equations in the field, such as calculating the volume of a pipe to determine how much water it can handle. The tailwater must be known or estimated prior to performing the culvert hydraulic calculations. The water flow rate, along with the pipe diameter can be converted to a velocity using a pipe velocity calculator. Click to calculate the depth of water in the channel. Discharge (flow rate) can be computed for water flowing out of a . At 32F, the normal flow rate is 1 atmosphere (101.3 kPa) or 14.696 psi (0 0C). Our online calculator resource determines the velocity of water in a pipe (when the flow rate and diameter of the pipe are known). Hazen and Williams created an empirical formula to calculate pressure losses for liquids flowing through straight pipes. To calculate internal pipe diameter, you should only enter flow rate and velocity in corresponding fields in the calculator and click calculate button to get results. The unique case of gravity flow, in which water flows via a closed pipe, is taken into account by our water flow calculator. First use the Hazen-Williams equation to find the velocity of the fluid: v = k C R0.63 S0.54. Ozone Generators for Commercial and Residential Water Systems, Tanks, Wells, Hot Tubs, Pools. These fluid flows are applied to transport chemicals, petroleum products, gas products, sewage flows, household water supply, etc. Plumbers and other contractors need the right tools to solve complex math equations in the field, such as calculating the volume of a pipe to determine how much water it can handle. Pressure Loss through Piping. This empirical equation, exclusively applicable to water, allows calculating the velocity or the head loss of a gravity flow. The following formula is used by this calculator to populate the value for the flow rate, pipe diameter or water velocity, whichever is unknown: V = 0.408 Q/D2. Reduce flow by 3% (Multiply by .97) for flow going through Flexible PVC Pipe. The Excel Formulas in the spreadsheet templates that can be downloaded will calculate water flow rates for pipe sizes (diameters and lengths) using the Hazen Williams formula. If you have questions, please call our Drain Wizard at 800-635-0384. This . You can also use this calculator to tally how much the volume of water in pipes weighs. Water Flow Calculator is a free online tool that displays the flow of water for the given pressure. The liquid in the pipe is at an elevation Z 1, has pressure P 1, and has velocity V 1. This is the speed of flow that will be . Use our Pressure Drop Calculator. Yes, because the flow rate is determined by the cross-sectional area of the pipe, it will grow as the pipe diameter squares. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. Need to work out the Pressure Drop of fluids moving through a tube or pipe? If the leak rate is known, the calculator can compute pressure or crack area (and diameter). We have the resources to help you. Leicester, Checks the capacity of drain tile on existing drainage systems. Step 2: To obtain the flow rate, click the "Calculate x" button. An inch = a measurement of length. Pressure Drop Software for Excel: . 5. Gas. Multiply this answer by the pressure drop across the pipe, measured in pascals. Your email address will not be published. HMDigital LBS-10 and SAVANT AS-414. The Hazen-Williams equation is only applicable for water. Common approaches are outlined below. In the case of gravity-fed systems, only gravity is used to transport water (or other fluid) from a source to a final application. Quick pipe diameter calculation in closed, round, rectangular pipes and ducts. This equation only applies to water, and it calculates the velocity of the water by relating the geometric properties of the pipe and the slope of the energy line. Online Pipe Velocity Calculator - Imperial Units. Used to calculate the velocity of water in a pipe. You can also use this calculator to tally how much the volume of water in pipes weighs. This calculator may also be used to determine the appropriate pipe diameter required to achieve a desired velocity and flow rate. Select the 'Water Depth' option. There is a reason we are rated 4.9/5 for customer support on Capterra. As the calculation can be measured in terms ft/second and m/second, there are two different calculation methods to establish pipe velocity: The following equation can be used to calculate the pipe velocity: V = Water velocity inside the pipe (ft/second), Q = Water flow rate inside the pipe (GPM), D = Pipe inside diameter (inner diameter) (in), V = Water velocity inside the pipe (m/second), D = Pipe inside diameter (inner diameter) (m). WaterProfessionals offers a comprehensive suite of industrial water treatment services and equipment, such as water purification, water filtration, process wastewater treatment, wastewater reclaim/recycle and more, for pharmaceutical, medical, industrial, governmental and commercial businesses. This calculator uses this formula to determine the water velocity inside of a pipe. The slope should be 1/4-inch per foot for sewers longer than 50 feet. With this diameter, velocity and flow rate calculator, you can determine the exact flow rate or velocity at which water will flow through any given pipe. Flow-through pipes or fluid flow is a type of flow within a closed conduit with a certain pressure. What is a plastic pipe's roughness coefficient? That's another tool that considers the liquids flowing through pipes. The pressure drop can then be automatically calculated, For example, pipes are generally designed to higher velocities in the USA compared to the UK, For example, stainless steel pipes can generally be designed to higher velocities than copper pipes, For example, if the pipe is above a room such as a bedroom, the pipe velocity should be kept low to avoid undue noise, For example, pipes containing hot water in recirculating systems should be designed to a lower velocity than cold water pipes. PU vs PVC: Which is Best for Your Application? The simple version of the pressure drop calculator uses the following equation to calculate pressure loss due to pipe friction: Pressure Loss = 4.53 x Pipe Length x ( ( (Flow Rate / Pipe Coefficient) 1.852) / (Pipe Diameter) 4.857) The advanced version of the calculator has a number of steps to work out the pressure. As a result, the flow rate decreases as the square of the pipe diameter increases. Therefore, Flow rate or discharge of water = 0.026510625 m 3 /sec x 1000. To strengthen your understanding of the idea, obtain the answers to the solved example questions. Multiply the answer to Step 5 by the fluid's viscosity. Also, the flow of liquid . If I assume that all ur diversion are on a horizontal plane and the Tee split the incoming pipe into two direction of equal diameter than ur flow in each pipe will be half of ncoming flow i.e. A= 0.025434m^2. If the pipe velocity is too high, the fluid flow will be called turbulent flow. 3) Water is flowing through a 2 foot diameter pipe, at a rate of 20 . So this calculation is vital when designing a system. Use the second form to calculate the inside diameter of a pipe at a water velocity of 5 ft/sec. Learn how we calculated this result below. A= r^2. Multiply the area by the answer to Step 2: 0.00785 x 200 = 1.57. You don't need to know the values of CCC, RRR, or SSS in order to use our pipe flow calculator we calculate them for you! This super-helpful tool essentially works as a liquid volume calculator. The HazenWilliams equation is an empirical formula used to calculate water's velocity in a gravity-fed system. Fractures are developed in carbonate rock areas, and the fracture water flow significantly influences the heat exchange between buried pipes and the rock mass by induing heat convection, providing the carbonate rock area a strong heat exchange capacity and preferable conditions for shallow geothermal development and utilization. We need to find the flow through the pipes AB and AC. 2. Bigger pipe is more expensive, but keeping the water velocity low is important to limit pressure losses due to friction, water hammer, and pipe movement due to water momentum changes inside the pipe. How can you find out the volume flow rate in a pipe? We can determine the volumetric flow rate as follows: The flow rate will vary according to the cross-sectional area of the channel: The area of the pipe is 0.349 ft2. For instance, if you calculate flow rate you will receive your answer in m 3 /s, m 3 /h, in 3 /s, in 3 /g, ft 3 /s and ft 3 /h. . Hy-Tech Products10035 Broadview Road, Broadview Heights, OH [email protected], 2023 Hy-Tech Products, Inc. All rights reserved. Divide the drop by the length of the pipe to calculate the slope. There are 3 main types of flat-roofing systems: built-up roof (BUR), modified bitumen and single-ply. The term cross sectional area is often used to describe the area . Enter 10 in the pipe diameter box and choose centimeters from its menu. The Hazen-Williams equation is only applicable for water. Defined as: The flow rate in U.S. gallons per minute (gpm) of water; At a temperature of 60 Fahrenheit ; With a pressure drop across the valve of 1 psi; If the desired flow rate, pressure drop, and media characteristics are known, the minimum required Cv value can be calculated. 5 p. In this pipe flow calculator's Advanced mode, you can view and modify all these parameters (area, perimeter, hydraulic radius). By changing the Material variable of the calculator, you can see different values for the pipe Roughness coefficient. Now we can find the . There can be a difference between the values spreadsheet and values in the H2X result due to the rounding up of multiple decimal places within the calculation. Measure the volume of pipes based on inner diameter and length. 4-STROKE BASIC MAINTENANCE PARTS. Hi. Calculate the inner diameter of the pipe by measuring the distance from one inside edge, across the center, and to the opposite inside edge. Take the radius and square it, or multiply it by itself. If youre unsure how to measure the inner diameter of a pipe, consider investing in a set of calipers that fit around the outside of the pipe. You can then calculate the volume that flows through . Plumbers, irrigation contractors, septic crews, and pool service workers constantly do pipe calc math in the field to figure out the right size of pipe to install, determine water flow and pressure, or work to maximize pump efficiency. Measure the number of liters or gallons in the container, and divide that number by 15. The flow measurement using an orifice plate is based on the application of energy conservation to a flow, measuring the difference in pressure between two points (P1 and P2), at this points the flow has different speeds. Similarly, if the pipe velocity is low, the fluid flow is known as a laminar flow. We can calculate that water flow velocity using the Hazen-Williams Equation. We begin with some results that we shall use when making friction loss calculations for steady, fully developed, incompressible, Newtonian flow through a straight circular pipe. Cross-Sectional Area. The flow discharge Q is calculated using the following formula Q = AV, The Pipe Flow Calculator is a free online application that depicts the flow of liquid through a closed container. In this equation, k is either 0.489 for metric or 1.318 if using imperial units, C is the roughness coefficient of the pipe material, R is the hydraulic radius (cross-sectional area divided by perimeter), and S is the slope of the pipe. Pipe velocity is the speed at which fluid flows through a pipe and is usually measured in terms of m/s or ft/s. Pipe Sizing by Velocity. Calculate flow velocity. The pipe is 12 feet long, and the difference in height between the beginning and endpoints of the pipe is equal to 3 feet. Is the flow rate affected by pipe diameter? This energy could be provided by gravity or/and by a pump. Click the CALCULATE button and the answer is 114.59 centimeters per second AND the answer is in 23 other different units !! This free spreadsheet contains the pipe velocity formula that is used for the H2X calculations. v = k * C * R0.63 * S0.54. Leak Rate Equations and Derivation. Q = (Velocity) * (Diameter)2 * (theta - sin(theta)) / 8, The cross-sectional area of a rectangular channel can be determined as follows:A = (Width) * (Depth), The flow rate (Q), is thus as follows:Q = (Velocity) * (Width) * (Depth), The cross-sectional area of a trapezoidal channel can be determined as follows:A = (Depth) * (Top Width + Bottom Width) / 2, The flow rate (Q), is thus as follows:Q = (Velocity) * (Depth) * (Top Width + Bottom Width) / 2, You may also be interested in our Friction Loss Calculator, A collection of really good online calculators. where. Use our pipe flow calculator to determine the velocity and flow rate of water that flows by gravity. Divide the diameter by 2 to find the radius of the pipe. Water Flow Rate in a Pipe - Calculator. The roughness coefficient is determined by the pipe's material. The formula is similar to this. The objective behind creating the H2X software solution was to use modern technology combined with recognised methods of plumbing engineering to automate the entire plumbing design workflow, including these calculations, so you can save hundreds of hours designing each project while reducing errors, rework, and costs. This calculator may also be used to determine the appropriate pipe diameter required to achieve a desired velocity and flow rate. With a turbulent flow, there is no smoothness in the process. This is a highly practical and reliable calculator which can be simply used for calculating the volume flow rate of a fluid which also is defined as volume of fluid that is passing through a given cross sectional area per unit time. volume flow (US gal/min, gpm) . This flow rate can be converted to velocity with the diameter of the valve. Its speed is influenced not just by the slope and size of the pipe, but also by the material of the pipe. With a laminar flow, a regular and consistent fluid flow is witnessed throughout the pipe. Whether youre in search of roof drain specifications, product catalog, or anything in between, we have the resources to answer your questions. Each system is designed to waterproof the roof and protect it from sun, rain, snow and more. Note: The maximum flow rate through a circular channel occurs when the water depth is approximately 93.8% of the internal diameter of the pipe. The following formula is used by this calculator to populate the value for the flow rate, pipe diameter or water velocity, whichever is unknown: V = Water Velocity; Q = Flow Rate; D = Pipe Diameter. Water Flow Chart #2 Pressure Flow in GPM through pipe ID in inches PSI 1" 1.25" 1.5" 2" 2.5" 3" 4" 5" 20 26 47 76 161 290 468 997 2895 30 32 58 94 200 360 582 1240 3603 40 38 68 110 234 421 680 1449 4209 50 43 77 124 264 475 767 1635 4748 60 .ADVERTISEMENTS: Rise in Pressure of Water Flowing in a Pipe: Diameter, Flow . If you have questions, please call our Drain Wizard at 800-635-0384. Consider a straight horizontal piece of 15 mm pipe (inside), 20 meters in length, with 5 bars static pressure connected to a water main. Do business exactly the way your customers prefer. The water flows through the engine and directly out the exhaust. Flow rate or discharge of water = 26.510625 litre/sec . Notice that the HazenWilliams equation has some constraints (besides water only), making the results relatively accurate only for: Viscosity and density of water are affected by temperature. If the pipe is circular, you will find it according to the following equation: where rrr is the pipe radius, and ddd is the pipe diameter. The pressure is sometimes stated as head of water. The graphs above are generated from calculations assuming the hose to be in good condition and laid in a straight line. As we know, 1cum = 1000 litre. Divide the area by the perimeter to find the hydraulic radius of the pipe. Flow rates are usually measured by the volume of water passing per minute. Interested? The flow rate will increase with pipe diameter squared since it depends on the pipe's cross-sectional area. The effects on the predicted flow rate are then given in three graphs, where in turn two of the variables are kept constant and the flow rate is plotted against a range of values of the third. New version of Online Calculator is available: www.pressure-drop.online. In the following sections, you'll find basic techniques and formulas for calculating flow velocity and flow discharge. Heres a specific example of how to apply the volume of a pipe formula: For a 1-inch pipe that measures 50-feet long: volume = (pi) radius squared length. Need to calculate the flow rate of water through a specific pipe diameter? The Hazen-Williams equation is an empirically derived formula that describes the velocity of water in a gravity flow. Water is flowing through the channel at an average velocity of 16 feet per second. Per the Copper Tube Handbook ( www.copper.org ), once the fluid temperature exceeds 140F, the velocity needs to slow down to 2 to 3 fps, as the water becomes more aggressive the hotter it becomes. The ratio of the pipe's area and perimeter is known as hydraulic radius. The term cross sectional area is often used to describe the area through which something is flowing. A cubic inch = a measurement of volume. find the area of the circular pipe for water flow calculation. The volume of pipe equals the volume of liquid inside it, or the amount of space it occupies. The formula is F = V/T, where F is the flow rate, V is the volume and T is . If you find That said, we put together the following tables to serve as general guides for estimating a pipe's water flow capacity through a pipe or roof drain. Measure each height from the center of the pipe. You can unsubscribe at any time. We and our partners use cookies to Store and/or access information on a device. in different piping and pipeline systems. There is an inverse relationship between the internal diameter of a pipe and the pipe velocity. Where, v is the water flow velocity in the pipe (m/s is for the metric system, ft/s is for the imperial system) ServiceTitans Pipe Volume Calculator improves data accuracy, saves time, and reduces waste, so you know youve chosen the right-sized pipes for the job each and every time. Then, type in its length: length = 6 m. This is where retrofit drains are used, as they replace the broken or corroded roof drains easily with almost no Search our inventory of drains, drain parts, safety and roofing equipment, and accessories. Water Pipe Sizing:This video describes that how you can calculate maximum possible flowrate of water that can be passed through a pipe of certain dia. End depth method. Flat roof drains are often subjected to heavy weathering and regular wear and tear. It is usually denoted by the Q symbol. Here you can find tables with the approximate water flow in a pipe by size. Flow Calculator. The right piping size calculation needed for refilling a swimming pool. You can calculate the flow rate in five simple steps: Shape: If you need to know water capacity in gallons, you'll need to convert the water volume in the pipe calculator metric to cubic inches. We also suggest checking the orifice flow calculator to see another type of liquid flow! Discover your ROI with ServiceTitan: Calculate Now. Be sure to check it out if you're interested! Assume we need to calculate the velocity and flow rate in a system with the following characteristics: A pipe made of steel, with a diameter of 2.5 inches, with a length of 18 feet, and a difference in heights of 3 feet. The values in the UPC are . Helpful Hint: To square a number, multiply the number by itself. Hazen-Williams equation is valid only for the water. Sizes the piping needed on the acreage to . Remember, if you would like some assistance in choosing the right hose for your application or sector, please feel free to contact one of our helpful team members on 0116 240 1500 or email [email protected]. Considering rainfall infiltration, Finite element simulation was performed for studying the water flow through macro-channel of fractured rock in the 4th cave of Yungang Grottoes, where a group of joints with directions . Yes. AXEON Solo I 4-stage 50 GPD Compact Reverse Osmosis System, Ozone Generator JED 103 (120V, 240V, 12V), GRO 5-Stage Reverse Osmosis ready installation kit with Pentair 50 GPD membrane 1:1. versions and U.S. versions of the Hazen Williams equation are presented and discussed. This calculator can also be used for uniform flow in a pipe, but the Manning roughness coefficient needs to be . Second thing is" how to calculate the flow after T-connection), well it basically depends on your end discharge & starting flow condition. Select a Manning coefficient for the pipe material. For instance, 5 = 25. Use this pipe flow calculator to analyze the properties of water flowing in a gravity-fed system. If the set of conditions entered in the model generate negative answers, then clearly it is necessary to adjust the variables as appropriate until a realistic result is obtained. Calculate the radius of the pipe through its diameter. Hydraulic radius R = A/P = r/2r = r/2 = d/4, Divide the pipe length by the drop to get the slope of the energy line. For a typical plastic pipe, its roughness coefficient is 150. Besides the fact that manually calculating pipe velocity is a time-consuming process, any manual calculation opens up the doors for human error. Water Velocity through Piping. Most of the calculations I have found appear to need 2 of these: diameter, flow rate, velocity. Offices in Tennessee, North Carolina, and South Carolina. To find the initial water flow, solve for v 1. The higher the roughness coefficient, the slower the gravity-fed flow through a pipe will be. Let ServiceTitans water pipe volume calculator take the guesswork out of the equation when trying to determine the volume of water in pipes measured in gallons. Choose any diameter and instantly obtain the flow rate (gpm) and head-loss (ft/1,000 ft) results for the design-default velocity of 5.0 fps. You just found the speed and discharge of a gravity flow. The rate at which a liquid flows will vary according to area of the pipe or channel through which it is passing and the velocity of the liquid. Volumetric flow rate . The flow rate of the fluid is the volume of fluid that passes through an area in a unit of time. Enter 9 in the in the flow rate box and choose liters per second from its menu. This flow rate calculator uses flow velocity and cross-sectional flow area data to determine the volumetric flow rate of liquid. Our integrated help button means that a real engineer will assist with any design query, no matter how big or small. Its important to know what your pipe velocity is because it relates closely to frictional losses. A = (Depth) * (Top Width + Bottom Width) / 2, Q = (Velocity) * (Depth) * (Top Width + Bottom Width) / 2, United States Salary Tax Calculator 2022/23, United States (US) Tax Brackets Calculator, Statistics Calculator and Graph Generator, Grouped Frequency Distribution Calculator, UK Employer National Insurance Calculator, DSCR (Debt Service Coverage Ratio) Calculator, Arithmetic & Geometric Sequences Calculator, Volume of a Rectanglular Prism Calculator, Geometric Average Return (GAR) Calculator, Scientific Notation Calculator & Converter, Probability and Odds Conversion Calculator, Estimated Time of Arrival (ETA) Calculator, Select the shape of the cross-section of the channel, Input all the measurements required to compute the cross-sectional area. Fill in known values for any two fields below. WaterProfessionals recognizes your right to privacy and protection of the information you provide us. We regularly get asked about the water flow capacity of different pipe sizes, and which is the best roof drain for a specific pipe size. Back business decisions with real-time data. Also, in the coefficient of discharge calculator, we described the metric related to the theoretical and actual flow rates. Remember that the Hazen-Williams equation is valid only for water applying it for any other fluid will give you inaccurate results. . GR/O Reverse Osmosis System 75 GPD, 3.2 Gal Tank, Faucet. Thurmaston Lane, if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'goodcalculators_com-medrectangle-4','ezslot_5',618,'0','0'])};__ez_fad_position('div-gpt-ad-goodcalculators_com-medrectangle-4-0'); The channel or pipe through which a liquid flows will commonly have a circular, rectangular, or trapezoidal cross-sectional shape. Find this tool useful? 5 ft/sec is a somewhat arbitrary velocity . Read on to discover the formulas we use and to see an easy-to-follow example calculation. A square inch = a measurement of area. Larger pumps and equipment can increase the capital cost of the building and also increase the operational cost to run the building. Copelys Contribution to the UKs Battle With COVID-19, Using Plastic More Sustainably How We Recycle Our Waste Material. How Much Water Can Flow Through A Pipe (GPM/GPH)? All units must be the same when using this formula. The right velocity will allow the system to run smoothly for longer periods. There are 231 cubic inches in 1 U.S. gallon. If the head is given in metres of water, each 1-metre head (3.28 ft) induces 0.1 bar (1.47 psi.) 1) If the flow rate is measured in cubic meters per second, then the area should be in square meters 2) if the flow rate is measured in cubic feet per second, the area should be in square feet.