Head loss in pipe bends and valves

The three common methods for calculating the head loss in valves and fittings are. This article details the calculation of pressure losses through pipe fittings and some minor equipment using the equivalent length method. Where the length of the pipe is relatively long, the effect of the fitting losses are usually considered as minor losses, and are often ignored during initial analysis of the pipe system. Minor head loss due to components as valves, bends. By know the major head losses due to pipe diameter over a length of pipe and the minor head losses caused by pipe fittings can cut down on cost and raise the overall efficiency of a system. From my dynometer testing days, on race engines, any elbows, bends and restrictions affect the oil pump pressure. Minor loss coefficients for commonly used pipe and tube system components. As fluid moves through a pipe it will experience losses. For horizontal pipe, with constant diameter this loss may be measured by height of the pressure drop. Oct 05, 2012 fittings such as elbows, tees and valves represent a significant component of the pressure loss in most pipe systems. These pipe fittings are installed in a series configuration. A compound pipe which consists of several pipes of different lengths and diameters to be replaced by a pipe having uniform diameter and the same length as that of compound pipe is called as equivalent pipe. The total head at point 0 must match with the total head at point 1, adjusted for any increase in head due to pumps, losses due to pipe friction and socalled minor losses due to entries, exits, fittings, etc. Head loss from pipe friction energy loss resulting from friction in a pipeline is commonly termed the friction head loss hf this is the head loss caused by pipe wall friction and the viscous dissipation in flowing water.

Table 3 friction losses through pipe fittings in terms of equivalent lengths of standard pipe size of pipe small dia. For full table with larger dimensions rotate the screen. If you do the typical kind of pipe flow calculation, pressures due to elevation changes will be included. The strength of the equivalent length method is that it is very simple to calculate. The first type is static head loss due to the elevation of part of a pipeline above its source, such as in the high floors of a building. Minor head loss due to components as valves, fittings, bends and tees. Friction loss as the fluid passes through any pipe fittings, bends, valves, or components. The total head loss h b is expressed by the following equation. In the practical analysis of piping systems the quantity of most importance is the pressure loss due to viscous effects along the length of the system, as well as additional pressure losses arising from other technological equipments like, valves, elbows, piping entrances, fittings and tees. Head losses in pipes, bends and fittings notes for mechanical engineering sudden expansion of pipe. Minor losses to find minor losses, an edibon energy losses in bends module was used with various fittings throughout the system. Bernoulls energy equation is bernoullis equation divided by the fluids specific weight. Fittings such as elbows, tees, valves and reducers represent a significant component of the pressure loss in most pipe systems.

The head loss is inversely proportional to the diameter of the pipe. Pvc friction loss in fittings and equivalent length minor loss in pvc and cpvc fittings as equivalent length of straight pipe. Determine l friction loss in pipe fittings in terms of equivalent length in feet of straight pipe. Head losses in pipes, bends and fittings notes for. Such losses are generally termed minor losses, although they often account for a major portion of the head loss. Each type of loss can be quantified using a loss coefficient k. The objective of this experiment is to determine the loss coefficient k for a range of pipe fittings, including several bends, a contraction, an enlargement, and a gate valve. Therefore, complete head loss or pressure loss in pipe flow will be summation of major head loss and minor head loss and will be. First, loss due to change of direction of the water in the pipe. The resistance coefficient k is considered to be constant for any defined valves or fittings in all flow conditions, as the head loss due to friction is minor compared to the head loss due to change in direction of flow, obstructions and sudden or gradual changes in cross. The head loss coefficient according on the valve opening angle depends on the hydraulic profile of the butterfly.

Pressure losses for fluid flow in 90 degrees pipe bends. Major and minor losses in pipes mechanical engineering. Head loss of hydraulic system is divided into two main categories. It is a loss of flowing pressure in a pipeline due to friction from the pipe walls or as the liquid flows through elbows, valves and fittings. Flow in valves and fittings pipe flow calculations. Friction losses were measured in fully and partially open butterfly and plug valves, bends and unions. Head loss, pipe fittings, frictional factor, minor loss coefficient. Minor loss for pvc and cpvc fittings as equivalent length of straight pipe feet for water. Pressure loss due to a change in elevation of the fluid if the pipe is not horizontal pressure gain due to any fluid head that is added by a pump. Pvc pipes schedule 40 friction loss and velocity diagrams friction loss psi100 ft and velocity for water flow in plastic pvc pipe schedule 40 resistance and fittings equivalent length in hot water systems equivalent length of fittings like bends, returns, tees and valves in hot water heating systems equivalent length in feet and meter. The energy losses due to pressure changes can be seen in every part of a hydraulic system due to the expansions, contractions, bends in pipes, pipe fittings, and obstructions in the pipes. Jan 23, 2018 head of flowing water indirectly depicts the energy content of it.

In industry any pipe system contains different technological elements as bends, fittings, valves or heated channels. Specifically, the head loss across a valve or fitting can be calculated as a function of the velocity of the fluid flowing through the valve or fitting. For relatively short pipe systems, with a relatively large. Dec 30, 2012 minor head loss is due to any pressure drop caused by an elbow, tee, valve, etc. These values are defined as the flow rate through the valve required to produce a pressure drop of 1 psi. For more videos click on playlist link shown below v. Loss of head in each parallel pipe is same where, and are head loss at 1 and 2 respectively. Oct 02, 2015 fittings are common in long pipes, specially when we need to do a specific task such as rotate flow 90. Bend and standard fitting losses the head loss that occurs in pipe fittings such as valves and elbows and at bends is given by.

The loss of head, due to bends in a pipe, depends upon three factors. Diameters of pipes ranged from 25 to 100 mm while the process fluid flow rates ranged from 0 to 50 m3h. There are three types of forces that contribute to the total head in a pipe, which are elevation head, pressure head, and velocity head. For horizontal pipe, with constant diameter this loss may be measured. In fact, in a pipe system with many fittings and valves, the minor losses can be greater than the major friction losses. Major head loss due to friction in pipes and ducts. Major losses, which are associated with frictional energy loss per length of pipe depends on the flow velocity, pipe length, pipe diameter, and a friction factor based on the roughness of the pipe, and whether the flow is laminar or turbulent i. Minor losses are directly related to the velocity head of a pipe, meaning that the higher the velocity head there is, the. Aug 06, 2019 loss of head in each parallel pipe is same where, and are head loss at 1 and 2 respectively.

Impactacademyofficial free engineering video lectures. Resistance and fittings equivalent length in hot water systems equivalent length of fittings like bends, returns, tees and valves in hot water heating systems equivalent length in feet and meter. Select the appropriate k value for such and select d and f for schedule 40 pipe. Each elbow, valve, section of pipe or other fluid restriction is given a resistance coefficient, k. The major head loss is given by the following equation h major f ld v22g the minor head loss is given by the following equation h minor. Check valve head loss pipelines, piping and fluid mechanics. This equation gives best results when the head loss is greater than 1 ft 0. Losses are proportional to velocity of flow, geometry of device. In a previous article i discussed major head loss, which is the pressure drop caused by the fluids friction in relation to the length of pipe. Manufacturers of pipe work fittings and valves often publish a fittings. As pipes get shorter and more complicated the proportion of the losses due to the fittings and valves gets larger, but by convention are still called the minor losses.

Reported herein are explicit and accurate equations for pipe diameter and head loss and a closed form solution for the. Minor losses in pipes losses caused by fittings, bends, valves. The term minor losses, used in many textbooks for head loss across fittings, can be misleading since these losses can be a large fraction of the total loss in a pipe system. Attached is a nice summary of how its done throughout industry. Head loss in pipe flow system due to various piping components such as valves, fittings, elbows, contractions, enlargement, tees, bends and exits will be termed as minor head loss and will be indicated by h lminor. Within the pipe flow wizard software the type and quantity of bends, valves and other fittings associated with the pipe can be set by amending the quantity values on the pipe fittings screen. Minor losses are expressed using the following equation. Friction loss on fittings and valves applied fluid dynamics. Loss is given by 2 h k v g 2 l where k is computed as e k l d f t. Head losses in pipes, bends and fittings notes for mechanical. Friction loss in fittings watts water technologies.

The friction loss in pipes is due to the influence of the fluids viscosity near the surface of the surrounding pipe. Pump head developed is generally a function of the flow through the system, with head rise decreasing with increasing flow through the. This article details the calculation of pressure losses through pipe fittings and some minor equipment using the kvalue method, also known as the resistance coefficient, velocity head, excess head or crane method. Minor head loss head loss or pressure loss due to components as valves, bends, tees and the like in the pipe or duct system. Minor in comparison to friction losses which are considered major. To determine the pressure drop for a given gpm the following formula may be used. Major and minor loss in pipe, tubes and duct systems. K v22g where f is the friction coefficient, l is the length of the pipe.

K minor loss coefficient for valves, bends, tees, and other fittings table of minor loss coefficients. Minor or dynamic loss coefficients for pipe or tube system. The head loss due to resistance in valves and fittings are always associated with the diameter on which velocity occurs. As can be seen, the head loss of piping system is divided into two main categories, major losses associated with energy loss per length of pipe, and minor losses associated with bends, fittings, valves, etc. Hsthe head loss with characteristic velocity distribution in a straight pipe.

In long pipelines most of the pressure drop is due to the friction in the straight pipe, and the pressure drop caused by the fittings and valves is termed the minor loss. To obtain losses in bends other than 90 degree the following. Table 3 friction losses through pipe fittings in terms. Head loss is a loss in pressure head due to the viscosity of a fluid and obstructions to a fluid such as pipe elbows, valves, etc. Pressure drop in pipe fittings and valves equivalent length. These losses are expressed as loss of fluid static head in feet meter of fluid flowing. Figure 1 connected to the armfield hydraulic bench to measure the head loss across different types of pipe fittings such as the bends, expansion and contractions. Minor head loss is due to any pressure drop caused by an elbow, tee, valve, etc. Elbows or bends are available in various radii for a smooth change in direction which are expressed in terms of pipe nominal size expressed in inches. In general, with v1 v2 but z1 6 z2, the head loss is given p1. The normal practice consists in allocating a flow coefficient c v to the different openings.

In a pipe network, the presence of pipe fittings such as bends, elbows, valves, sudden expansion or contraction causes localized loss in pressure head. Friction loss in fittings valves as an aid, liquid sizing constants cv values are shown for valves. Schematic diagram of the energy losses apparatus experimental. Pressure loss from fittings excess head k method neutrium. Along the wall under the chalk board, there is a gate valve. Pressure loss due to a change in elevation of the fluid if the pipe is not. Pipe fitting losses pressure loss in a pipe due to fittings such as elbows, tees, valves, expanders and reducers based on 3k and 2k method. Resistance and fittings equivalent length in hot water systems equivalent length of fittings like bends, returns, tees and valves in hot water heating systems. Losses are proportional to velocity of flow and geometry of device. L e equivalent length length of pipe with same resistance as the fitting valve f t friction factor. When water flows through the pipe then it suffers head loss due to friction.

Pdf friction losses in valves and fittings for powerlaw fluids. Click on the valve button to display the pipe fittings screen. How to calculate flow loss between 90 and 45 degree fittings. The head loss for fluid flow is directly proportional to the length of pipe, the square of the fluid velocity, and a term accounting for fluid friction called the friction factor. The head loss that occurs in pipes is dependent on the flow velocity, pipe length and diameter, and a friction factor based on the roughness of the pipe and the reynolds number of the flow. Pressure losses were determined for nine 4inch steel, 90 pipe bends of radii from. It is the energy loss due to a fitting per unit weight of fluid. Head or energy losses are mainly due to the frictional losses and viscosity. The head loss that occurs in the components of a flow path can be correlated to a piping length that would cause an equivalent head loss. By knowing the head loss, you can successfully modify bernoullis energy equation accordingly.

Major and minor losses due to pipe diameter and fitting. Pipe fittings loss calculations with k factors pipe fittings, valves and bends usually have some associated k factor or local loss coefficient, which allows the calculation of the pressure loss through the fitting for a particular fluid flowing at a specified velocity. The impact of flow rate q on the head loss h l in pipes and fittings was studied on different sizes or diameters d of pipes fitted with gate valve, 45 and 90o bends using water as process fluid. Generally you can assume the valve is a point, without any length and calculate the pressure due to elevation change and frictional loss up to that point, then apply the cv friction loss equation to get the pressure drop across the valve, and lastly, calculate the unknown pressure on. Example lab report losses civl2310 fluid mechanics. Select the appropriate k value for such and select d and f for schedule 40 pipe from the table below where k is the pipe diameter in feet. Pipe pressure drop calculations formula, theory and equations. K value as the bernoulli equation shows, the fluids velocity in a pipe contributes to the total energy of the fluid. Pvc plastic pipe fittings add a head loss factor, too.

Friction loss on fittings and valves applied fluid. These additional components add to the overall head loss of the system. Head losses are a result of wall friction in all types of pipelines and of local resistance to flow, for example in valves and fittings see also pressure loss. Look up the pressure loss data for 3inch schedule 40 pvc plastic pipe in the industry data chart. If the piping design contains a partially open valve then the effect and head loss through the valve should always be included since the valve head loss may turn out to be significant. Table 3 friction losses through pipe fittings in terms of. Values of loss coefficients k f were calculated and correlated as a function of the. Head loss along the pipe wall is called friction loss or head loss due to the friction. Minor loss in pvc and cpvc fittings as equivalent length of straight pipe. Minor loss losses caused by fittings, bends, valves etc. Head loss and pressure loss represent the same phenomenon frictional losses in pipe and losses in hydraulic components, but they are expressed in different units. With the pipe being made of copper, the roughness value is 0. In a bend, in addition to the head loss caused by pipe friction, a loss caused by the change in flow direction is also produced. Pvc friction loss in fittings and equivalent length.