The minor losses in valves can be measured by finding “the ratio of the head-loss through the device to the velocity head of the associated piping system.”, K is the dimensionless loss coefficient The problem states that using the Velocity through the valve will give a better K value. Minor loss coefficients for commonly used components in pipe and tube systems. The minor loss a ball valve with flow velocity 2 m/s with water with density.
Minor Head Loss Coefficients for Valves
Minor Head Loss Coefficients for Valves
Hello,
I am working on a problem where I'm trying to approximate the minor head loss in a scenario where one branch includes a mostly-closed globe valve. I say 'mostly-closed' because there is an obstruction keeping the valve-seat from being fully engaged with the valve plate. I can't find any information that would give a good estimate of the minor head loss coefficient for that valve. I saw that a ball valve 2/3 closed is about 200, so I would think a leaking globe valve would be closer to 400. Does anyone know where I could find a more exact approximation for a mostly-closed, 6 inch globe valve? Thanks for your help.
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. Manufacturers of pipe work fittings and valves often publish a fitting's associated 'K' factor. I am working on a problem where I'm trying to approximate the minor head loss in a scenario where one branch includes a mostly-closed globe valve. I say 'mostly-closed' because there is an obstruction keeping the valve-seat from being fully engaged with the valve plate. I can't find any information that would give a good estimate of the minor head loss coefficient for that valve. I saw that a ball valve 2/3 closed is about 200, so I would think a leaking globe valve would be closer to 400. Does anyone know where I could find a more exact approximation for a mostly-closed, 6 inch globe valve? Thanks for your help.
Pipe Fitting Loss Formula
Fluid head loss through a fitting can be calculated by the following equation:
h = K x v² / 2g
where
h = pressure loss in terms of fluid head, i.e. fluid head loss
K = manufacturer's published 'K' factor for the fitting
v = velocity of fluid
g = acceleration due to gravity
h = K x v² / 2g
where
h = pressure loss in terms of fluid head, i.e. fluid head loss
K = manufacturer's published 'K' factor for the fitting
v = velocity of fluid
g = acceleration due to gravity
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.
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.
Pipe Fittings and K factors database
Our Pipe Flow Expert software has a database that contains the K factors for many different types of valves and fittings. It also has special wizard helpers that can calculate the K factor for special types of fittings such as:
- gradual enlargements
- gradual contractions
- sudden enlargements
- sudden contractions
- rounded entrances
- long pipe bends
Addition information about losses through pipe fittings is published in 'Flow of Fluids through valves, fittings and pipe' - Crane Technical Paper No. 410.