Pipe Flow Engineering Toolbox
Margarita Lovvorn
The Darcy-Weisbach equation with the Moody diagram is considered to be the most accurate model for estimating frictional head loss for a steady pipe flow. Since the Darcy-Weisbach equation requires iterative calculation an alternative empirical head loss calculation like the Hazen-Williams equation may be preferred:
200 gal/min of water flows in a 3 inch PEH pipe DR 15 with inside diameter 3.048 inches. The roughness coefficient for PEH pipe is 140 and the length of the pipe is 30 ft. The head loss for 100 ft pipe can be calculated as
Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro. Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse!
The fluid flow velocities in water systems should not exceed certain limits to avoid noise and damaging wear and tear of pipes and fittings. The table below can be used as a guide to maximum velocities:
Note! - be aware that there are two alternative friction coefficients present in the literature. One is 1/4 of the other and (1) must be multiplied with four to achieve the correct result. This is important to verify when selecting friction coefficients from Moody diagrams. The Colebrook friction coefficient calculator corresponds to equation (1).
The Darcy-Weisbach equation is valid for fully developed, steady state and incompressible flow . The friction factor or coefficient - λ -depends on the flow, if it is laminar, transient or turbulent (the Reynolds Number ) - and the roughness of the tube or duct . The friction coefficient can be calculated by the Colebrooke Equation or by using the Moody Diagram .
Air flows with velocity 6 m/s in a duct with diameter 315 mm . The density of air is 1.2 kg/m3 . The friction coefficient is estimated to 0.019 and the length of the duct is 1 m . The friction loss can be calculated as
Note! - in the equation above the head is related to water as the reference fluid. Another reference fluid can be used - like Mercury Hg - by replacing the density of water with the density of the reference fluid.
The Darcy-Weisbach equation with the Moody diagram are considered to be the most accurate model for estimating frictional head loss in steady pipe flow. Since the approach requires a trial and error iteration process, an alternative less accurate empirical head loss calculation that do not require the trial and error solutions like the Hazen-Williams equation , may be preferred.
Pump and Plumbing Sizing for Solar Water/Space Heating Systems Pump and Plumbing Sizing for Solar Water or Space Heating SystemDetails on solar pump/pipe sizing... This page covers the details of sizing the pump and the plumbing for a solar space or water heating system so that the system efficiently transfers heat from the collector to the storage tank without being excessively large.Details on solar pump/pipe sizing... How to Determine Collector Flow Rates This page takes you through how to determine flow rate for your collector, and what the tradeoffs are ... HVAC Pipe Flow Calculations
Air duct pressure drop calculator...Pipe pressure drop calculator... Some nicely done and generally easy to use calculators for water pipe and air duct pressure losses, channel flow, fan laws, ...
Air Duct Friction Loss Calculator
From The Engineering Toolboxwww.engineeringtoolbox.com/...
An easy to use chart to look up friction losses for flex ducts.I find this one simple chart answers most of my duct loss questions -- it even has a correction for bends at the bottom. Flex Duct Loses Due to Compression and Sags...
Static Pressure Losses in
6, 8, and 10 Non-Metallic Flexible Duct... Flex ducting is subject to extra losses compared to rigid metal ducts when it has sags between supports and when it is not fully stretched out. These extra losses can be quite larger.
This paper measures extra losses for flex ducting with sags and with compressed ducts.
Stack Effect Ventilation Calculator Estimates airflow for thermal stacks Friction loss in round or rectangular ductswww.engineeringtoolbox.com/ ...
Note: The Engineering Toolbox site has a lot of useful stuff, but also has some very scummy popup windows -- so beware. A very simple air duct pressure loss calculator.The duct calculator at the link just above is will handle a wider variety of conditions, but is more complex to use. Temperature Drop Calculator for Air Ducts...
Calculates air density for the temperature and altitude you input. Reynolds Number
Re Calculator...
A nice and flexible calculator for Reynodls number -- accepts a wide variety of units and flow conditions.
The fluid viscosity inputs that are needed can be looked up on the Engineering Toolbox website. Borst Engineering and Construction Calculators
Many Calculators... Borst Engineering has a whole raft of calculators -- HVAC, solar position, shading, and incident heat, water wheels, pipe sizing, ... Pipe Flow Copper Pipe Pressure Drop
Calculators for pressure loss in pipes and ducts, steam tables, and a Psychrometric Calculator Hydronic Heaters -- Baseboard, ... SlantFin Hydronic Baseboard Radiator OutputBaseboard output at low temps... SlantFin manual on their hydronic baseboard units showing output at lower temps that might be typical of what you would get on efficient solar heating systems.
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Process engineering starts after the process design. The latter is usually done with a help of free software for the UF/RO membrane selection and performance prediction, data normalization, and the re-hardening sizing. All three calculator types are specific to water treatment.
Calculators for process engineering are generic; they are valid in any industry. To build such calculators, the engineer should leave the "comfort zone" of water treatment and dive into the pool of disciplines ranging from hydraulics to electrical circuits. As this task is beyond the core desalination business, process engineering toolbox is still a dream come true.
How does the engineer interact with such sophisticated calculators? In most cases the interaction is script-based. It is not a mistake. Instead of numbers, the engineer uses words to describe the task. "Select the piping for this pump discharge" is enough to make calculations. Calculator extracts the fluid type, its pressure and flowrate from "this pump" and uses the "discharge" directive to select the proper velocities and sizes. The "suction" word produces absolutely different results!
Advanced calculators (which we may call smart ones) do not need any directives. The engineer does not use them explicitly. They lurk in the background and once the information is ready, they do their job.
"Job" and "calculation" differ. The latter is finite, its purpose being to get output. Job means repeated calculations for the whole project with the purpose to create secondary information for its next phase. Job is iterative and may be initiated by the project update.
Initiation starts from data validation - calculators are the project auditors. They ruthlessly block the project progress if some piece of information is corrupted. In real life auditors are the most experienced designers.
The PP's core implements procedures described extensively in the "Piping Sizing" guidelines prepared by me for real mega-project. As PP is tied to the P&ID context and has access to the database, it does not require from the user any input. She/he may ask PP to size the accompanied devices like valves, meters, blind flanges, static mixers, etc.
When the user presses the reset button, PP fetches its suggestions, which the user may edit. Normally the "reset" means returning the dialog state to the beginning or no-data state. As process engineering does not have no-data state (it is replaced with intuitive assumptions mentioned earlier), it turns into logical hurdle for engineering software architecture.
Unlike general-purpose industrial pumps, the desalination ones are built for efficiency. But it comes at a price: the higher the efficiency the narrower the preferred operation range is. The narrower the operation range of the pump the less the number of potential customers is.
The manufacturers' marginal interest topped with the requirements for hard-to-handle corrosion-resistant materials like superduplex, hastelloy, and silicon carbide makes the selection of desalination pumps non-trivial at all.
So cornerstone principle of desalination pumps selection is their reusability. In other words, the desalination plants should be engineered around near-fixed capacities of the high-pressure feed pumps (installed before RO membranes).
Similarity in SWRO plant configurations and pump names (low pressure booster, ERS booster, high pressure pump) makes it possible to select the pump based not on its requested head, but its service. Here the objective is to accelerate the bid preparation and implement the "reset" mode.
For example, to assess the pressure drop in the plug valve with full-size port one may use published data labeled as "general valve", or "butterfly valve" or "ball valve" and accidentally hit the nail on the head.
For detailed option the isometrics sketch shall be prepared. The user builds a sequence of hydraulic resistances with varying flowrates. It may include the pump and be chained to another sequence. This sequence may be merged with PU calculator as well to build so-called "installed pump characteristics".
HY is in permanent extension, new use cases being adapted from Handbook of Hydraulic Resistance (I.E. Idelchik). It is a real treasure box containing hundreds of them and waiting its time for digitization.
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