Interest is growing in the clinical use of sutureless (SU) valves. However, indications in some anatomical sub-settings, like bicuspid aortic valves (BAV), have been so far limited. We discuss herein our initial experience with the implantation of the 3f Enable SU bioprosthesis in patients with a BAV. Patients with a BAV were selected in our unit between March 2011 and September 2014 for a SU. Respondents' review of the echo-Doppler study report from July 22, 2009, revealed that Mr. Ploss had 'moderate mitral regurgitation that showed insufficiency of the mitral valve due to mitral valve prolapse, rheumatic heart disease, or a complication of cardiac dilation.'
Minor pressure and head loss in pipes, tubes and duct systems
Pressure loss in straight pipes or ducts are called the major, linear or friction loss. Pressure loss in components like valves, bends, tees and similar are called the minor, dynamic or local loss.
Minor loss can be significant compared to major loss. In fact - when a valve is closed or nearly closed - the minor loss is infinite. For an open valve the minor loss can often be neglected (typical for a full bore ball valve).
Minor Loss
The pressure drop or the minor loss in a component correlates to the dynamic pressure in the flow and can be expressed as
Δpminor_loss = ξ pd
= ξ ρf v2 / 2 (1)
where
ξ = minor loss coefficient
pd = dynamic pressure in fluid flow (Pa (N/m2), psf (lb/ft2))
Δpminor_loss = minor pressure loss (Pa (N/m2), psf (lb/ft2))
ρf = density of fluid (kg/m3, slugs/ft3)
v = flow velocity (m/s, ft/s)
The minor loss can be expressed as head water column by dividing the dynamic pressure with the specific weight of water
Δhminor_loss,w = (ξ ρf v2 / 2) / γw
= (ξ ρf v2 / 2) / (ρwg)
= ξ ρfv2 / (2 ρwg) (2)
where
Δhminor_loss,w = minor head loss as water column (m H2O, ft H2O)
γw = ρw g = specific weight of water or reference fluid (9807 N/m3, 62.4 lbf/ft3)
g = acceleration of gravity (9.81 m/s2, 32.174 ft/s2)
- 1 psf = 0.00694 psi (lb/in2)
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 - check Velocity Pressure Head.
If the flowing fluid has the same density as the reference fluid - typical for a water flow - eq. (2) can simplified to
Δhminor_loss = ξ v2 / (2 g) (2b)
where
Δhminor_loss = minor head loss (column of flowing fluid) (m fluid column, ft fluid column)
Minor Loss Coefficient
The minor loss coefficient - ξ - values ranges from 0 and upwards. For ξ = 0 the minor loss is zero and for ξ = 1 the minor loss is equal to the dynamic pressure or head. The minor loss coefficient can also be greater than 1 for some components.
The minor loss coefficient can be expressed by rearranging (1) to
Ploss Valve Pic
ξ = 2 Δpminor_loss / (ρf v2) (3)
The minor loss coefficient can alternatively be expressed by rearranging (2) to
ξ = 2 ρwg Δhminor_loss,w / (ρfv2) (4)
The dynamic loss in components depends primarily on the geometrical construction of the component and the impact the construction has on the fluid flow due to change in velocity and cross flow fluid accelerations.
The fluid properties - in general expressed with the Reynolds number - also impacts the minor loss.
Minor loss information about components are given in dimensionless form based on experiments.
Equivalent Length
The dynamic minor loss in a component can be converted to an equivalent length of pipe or tube that would give the same major loss.
Major loss in a fluid flow can be expressed as
Δpmajor_loss = λ (l / dh) (ρf v2 / 2) (5)
where
Δpmajor_loss = major (friction) pressure loss in fluid flow (Pa (N/m2), psf (lb/ft2))
λ = Darcy-Weisbach friction coefficient
l = length of duct or pipe (m, ft)
v = velocity of fluid (m/s, ft/s)
dh = hydraulic diameter (m, ft)
ρf = density of fluid (kg/m3, slugs/ft3)
If we want the minor loss to be equal to the major loss for a given equivalent length of pipe or duct - then
Δpminor_loss = Δpmajor_loss, eq (6)
or by combining (1) and (2)
ξ ρf v2 / 2 = λ (leq / dh) (ρf v2 / 2) (6b)
where
Δpmajor_loss, eq= equivalent major loss (Pa (N/m2), psf (lb/ft2))
leq = equivalent pipe length (m, ft)
(6b) can be reduced and rearranged to express equivalent length as
leq = ξ dh / λ (7)
The total head loss in a pipe, tube or duct system, is the same as that produced in a straight pipe or duct whose length is equal to the pipes of the original systems - plus the sum of the equivalent lengths of all components in the system.
Interest is growing in the clinical use of sutureless (SU) valves. However, indications in some anatomical sub-settings, like bicuspid aortic valves (BAV), have been so far limited. We discuss herein our initial experience with the implantation of the 3f Enable SU bioprosthesis in patients with a BAV. Patients with a BAV were selected in our unit between March 2011 and September 2014 for a SU. Respondents' review of the echo-Doppler study report from July 22, 2009, revealed that Mr. Ploss had 'moderate mitral regurgitation that showed insufficiency of the mitral valve due to mitral valve prolapse, rheumatic heart disease, or a complication of cardiac dilation.'
Minor pressure and head loss in pipes, tubes and duct systems
Pressure loss in straight pipes or ducts are called the major, linear or friction loss. Pressure loss in components like valves, bends, tees and similar are called the minor, dynamic or local loss.
Minor loss can be significant compared to major loss. In fact - when a valve is closed or nearly closed - the minor loss is infinite. For an open valve the minor loss can often be neglected (typical for a full bore ball valve).
Minor Loss
The pressure drop or the minor loss in a component correlates to the dynamic pressure in the flow and can be expressed as
Δpminor_loss = ξ pd
= ξ ρf v2 / 2 (1)
where
ξ = minor loss coefficient
pd = dynamic pressure in fluid flow (Pa (N/m2), psf (lb/ft2))
Δpminor_loss = minor pressure loss (Pa (N/m2), psf (lb/ft2))
ρf = density of fluid (kg/m3, slugs/ft3)
v = flow velocity (m/s, ft/s)
The minor loss can be expressed as head water column by dividing the dynamic pressure with the specific weight of water
Δhminor_loss,w = (ξ ρf v2 / 2) / γw
= (ξ ρf v2 / 2) / (ρwg)
= ξ ρfv2 / (2 ρwg) (2)
where
Δhminor_loss,w = minor head loss as water column (m H2O, ft H2O)
γw = ρw g = specific weight of water or reference fluid (9807 N/m3, 62.4 lbf/ft3)
g = acceleration of gravity (9.81 m/s2, 32.174 ft/s2)
- 1 psf = 0.00694 psi (lb/in2)
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 - check Velocity Pressure Head.
If the flowing fluid has the same density as the reference fluid - typical for a water flow - eq. (2) can simplified to
Δhminor_loss = ξ v2 / (2 g) (2b)
where
Δhminor_loss = minor head loss (column of flowing fluid) (m fluid column, ft fluid column)
Minor Loss Coefficient
The minor loss coefficient - ξ - values ranges from 0 and upwards. For ξ = 0 the minor loss is zero and for ξ = 1 the minor loss is equal to the dynamic pressure or head. The minor loss coefficient can also be greater than 1 for some components.
The minor loss coefficient can be expressed by rearranging (1) to
Ploss Valve Pic
ξ = 2 Δpminor_loss / (ρf v2) (3)
The minor loss coefficient can alternatively be expressed by rearranging (2) to
ξ = 2 ρwg Δhminor_loss,w / (ρfv2) (4)
The dynamic loss in components depends primarily on the geometrical construction of the component and the impact the construction has on the fluid flow due to change in velocity and cross flow fluid accelerations.
The fluid properties - in general expressed with the Reynolds number - also impacts the minor loss.
Minor loss information about components are given in dimensionless form based on experiments.
Equivalent Length
The dynamic minor loss in a component can be converted to an equivalent length of pipe or tube that would give the same major loss.
Major loss in a fluid flow can be expressed as
Δpmajor_loss = λ (l / dh) (ρf v2 / 2) (5)
where
Δpmajor_loss = major (friction) pressure loss in fluid flow (Pa (N/m2), psf (lb/ft2))
λ = Darcy-Weisbach friction coefficient
l = length of duct or pipe (m, ft)
v = velocity of fluid (m/s, ft/s)
dh = hydraulic diameter (m, ft)
ρf = density of fluid (kg/m3, slugs/ft3)
If we want the minor loss to be equal to the major loss for a given equivalent length of pipe or duct - then
Δpminor_loss = Δpmajor_loss, eq (6)
or by combining (1) and (2)
ξ ρf v2 / 2 = λ (leq / dh) (ρf v2 / 2) (6b)
where
Δpmajor_loss, eq= equivalent major loss (Pa (N/m2), psf (lb/ft2))
leq = equivalent pipe length (m, ft)
(6b) can be reduced and rearranged to express equivalent length as
leq = ξ dh / λ (7)
The total head loss in a pipe, tube or duct system, is the same as that produced in a straight pipe or duct whose length is equal to the pipes of the original systems - plus the sum of the equivalent lengths of all components in the system.
Example - Equivalent Length of Gate Valve
The equivalent length of a 50 mm gatevalve with loss coefficient0.26 when 1/4 closed located in a steel pipe with friction coefficient0.03 can be calculated with (7) as
leq = 0.26 (0.05 m) / 0.03
= 0.4 m
Ploss Valve
Related Topics
- Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time
- Fluid Flow and Pressure Loss - Pipe lines - fluid flow and pressure loss - water, sewer, steel pipes, pvc pipes, copper tubes and more
Related Documents
- Air Duct Components and Minor Dynamic Loss Coefficients - Minor loss - pressure or head loss - coefficients for air duct distribution systems components
- Air Ducts - Friction Loss Diagram - Major loss diagram for air ducts - SI units
- Air Ducts Minor Loss Coefficient Diagrams - Minor loss coefficient diagrams for air ductwork, bends, expansions, inlets and outlets - SI units
- Air Flow and Velocity due to Natural Draft - Air flow - volume and velocity - due to stack or flue effect caused by indoor hot and outdoor cold temperature difference
- Darcy-Weisbach Pressure and Major Head Loss Equation - The Darcy-Weisbach equation can be used to calculate the major pressure or head loss due to friction in ducts, pipes or tubes
- Hydraulic Diameter - Hydraulic diameter of pipes and ducts
- Minor or Dynamic Loss Coefficients for Pipe or Tube System Components - Minor loss coefficients for commonly used components in pipe and tube systems
- Pressure Gradient Diagrams - A pressure gradient diagram is a graphical presentation of the static pressure throughout a fluid flow system
- PVC - Friction Loss in Fittings and Equivalent Length - Minor loss in PVC and CPVC fittings as equivalent length of straight pipe
- Total Head Loss in Pipe or Duct Systems - Major and minor loss in pipe, tubes and duct systems
- Water Flow and Velocity Head in Steel Pipes - Schedule 40 - Velocity head used to calculate minor pressure or head loss in fluid flow systems
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Ploss Valve
- en: minor loss pipe tube duct system
- es: sistema de conductos de tubo tubo de pérdida menor
- de: geringen Verlust Rohr Rohrleitungssystem
One of the diaphragms would be fixed to the patient's chest with an adhesive pad. The other would be placed under the blood pressure cuff. The central part of the device is a three-way valve (also called a switch valve) in which all of the tubes converge. When the blood pressure cuff was inflated, the switch closed the acoustic pickup from the chestpiece. Shown here is an example of the second model, introduced in 1968. It was made by 3M and sold under the trademarked name 'Ploss Monitorscope'. By the 1980s, it had been made obsolete by an increasing number of electronic monitors of patient vital signs.
