Pressure Drop Analysis in Fluid Flow Apparatus
Jermaine Angela B. Prieto, BSChE – 3B
Bicol University, jermaineangelabersabe.prieto@bicol-u.edu.ph
Abstract
Fluid flow mechanics is a crucial aspect of
chemical engineering, shaping how liquids and gases move
in various processes. This study focuses on understanding
how pipes and fittings affect pressure in a fluid flow
system. By remodeling a 2006 apparatus with PVC pipes,
we aimed to explore how different components impact
pressure. Our findings shed light on the importance of
smooth flow and minimizing obstacles like bends or
narrowings, which can cause pressure to drop. Despite
some issues with the apparatus, our experiment highlights
the enduring significance of fluid flow mechanics in
chemical engineering. The researcher hope to address
these challenges to improve efficiency in future studies.
Index Terms – fluid mechanics, pressure drop, friction factor
INTRODUCTION
Fluid Flow Mechanics is a branch of fluid dynamics that deals
with the behavior of fluids (liquids and gases) as they move.
In chemical engineering, understanding fluid flow mechanics
is crucial because it plays a fundamental role in various
processes involved in the production, transportation, and
transformation of chemicals and materials. Involving fluid
statics, or the study of fluids at rest, and fluid dynamics, or the
study of fluids in motion, it serves as the fundamental
principle in several disciplines in science and engineering. It
is also used in the concepts of transport phenomena,
equipment design, process optimization, fluid behavior, scale
up and process intensification, etc. in chemical engineering.
Whether analyzing the flow of liquids through pipelines, the
dispersion of gases in reactors, or the behavior of plasmas in
advanced processes, a profound understanding of fluid
dynamics is indispensable for optimizing efficiency, ensuring
safety, and achieving desired outcomes in chemical
engineering endeavors.
In chemical engineering, the movement of liquids or
gases through pipes and ducts is a common practice,
especially in heating, cooling, and fluid distribution systems.
Typically, fans or pumps compel the fluid to flow through
these conduits, creating a defined flow path. A critical aspect
of this process is understanding and managing friction, which
directly influences pressure drop and head loss within the
piping system. Pressure drop serves as a key parameter for
determining the power required by pumps to maintain the
desired flow rate.
In a typical piping setup, various components such as
pipes of different diameters, fittings, elbows, valves, and
pumps are interconnected to direct and control fluid flow
efficiently. By optimizing these elements and managing
frictional losses, chemical engineers ensure the smooth and
effective operation of fluid distribution networks,
contributing to the overall efficiency and performance of
chemical processes.
In this experiment, the class has remodeled an old fluid
flow apparatus, last operated in 2006, to further understand
the concepts and mechanisms of fluid flow, pressure drop, and
fluid dynamics. In these types of apparatuses, the mostly used
pipe types are the circular ones. Compared to noncircular
pipes, these can withstand large pressure differences between
the inside and the outside without undergoing significant
distortion. Noncircular pipes are usually used in applications
such as the heating and cooling systems of buildings where
the pressure difference is relatively small, the manufacturing
and installation costs are lower, and the available space is
limited for ductwork.
The combined energy dissipation in a pipe system
consists of both major and minor losses. Major losses result
from frictional energy dissipation, attributed to the viscous
nature of the fluid and the surface roughness of the pipe.
These losses lead to a pressure drop along the pipe as the
pressure is expended to overcome the frictional resistance.
The Darcy-Weisbach equation stands as the predominant
method for quantifying energy loss in pipe flow. Within this
equation, a dimensionless quantity known as the friction
factor (f) characterizes the frictional losses within the pipe and
it is given by:
∆𝑃𝐿 = 𝑓
2
𝐿 𝜌𝑣𝑎𝑣𝑔
𝐷
(1)
2
2
𝜌𝑣𝑎𝑣𝑔
Where
is the dynamic pressure and 𝑓 is the Darcy
2
friction factor. It is also called the Darcy–Weisbach friction
factor, named after the Frenchman Henry Darcy (1803–1858)
and the German Julius Weisbach (1806–1871), the two
engineers who provided the greatest contribution in its
development.
Minor losses, on the other hand, arise from various
factors such as pipe fittings, alterations in flow direction, and
modifications in flow area. Given the intricate nature of
piping systems and the multitude of fittings employed, the
head loss coefficient (K) is empirically determined as a
convenient method for swiftly estimating minor head losses.
𝑃
𝑣2
𝛾
2𝑔
[ +
+ 𝑧]
𝑃
𝑣2
𝛾
2𝑔
=[ +
𝑖𝑛
+ 𝑧]
𝑜𝑢𝑡
+ ℎ𝐿
(2)
Bernoulli’s equation provides a means to assess energy
loss within a pipe system, as expressed by Equation (2). Here,
𝑃
𝛾
+
𝑣2
2𝑔
and z represent pressure head, velocity head, and
potential head, respectively. The comprehensive head loss,
denoted as ℎ𝐿 , encompasses both major and minor losses.
Assuming constant diameter through the pipe fitting results in
equal inlet and outlet velocities 𝑣𝑖𝑛 = 𝑣𝑜𝑢𝑡 Consequently,
when disregarding changes in elevation head, the manometric
head difference equates to the static head difference, defined
as ∆ℎ through the fitting, as delineated in Equation (3).
𝑃
𝑃
𝛾 𝑖𝑛
𝛾 𝑜𝑢𝑡
[ ] −[ ]
= 𝐻1 − 𝐻2 = ∆ℎ
(3)
𝐻1 𝑎𝑛𝑑 𝐻2 denote manometer readings pre- and postfitting. The energy loss in a pipe fitting can be quantified as a
fraction (K) of the velocity head through the fitting, as
represented in Equation (3), where K denotes the loss
coefficient and v signifies the mean flow velocity into the
fitting.
∆ℎ = 𝐾
𝑣2
2𝑔
(4)
Due to the intricate flow dynamics within various
fittings, K is typically empirically determined. The head loss
coefficient (K) is computed as the ratio of the manometric
head difference to the velocity head, elucidated in Equation
(4). Notably, in fittings involving alterations in pipe crosssectional area, the difference in velocities cannot be
disregarded, leading to an additional change in static pressure.
This value assumes a negative value for contractions and a
positive value for enlargements. To gauge the pressure
difference ∆ℎ pre- and post-gate valve, a pressure gauge
directly measures it, subsequently converting it to an
equivalent head loss using the conversion ratio: 1 bar= 10.2
m water. The loss coefficient for the gate valve can then be
computed using Equation (4). To determine the flow regime
through the fitting, the Reynolds number is calculated using
Equation (5), where v represents the cross-sectional mean
velocity, D denotes the pipe diameter, and \nu stands for the
fluid kinematic viscosity.
𝑅𝑒 =
𝑣𝐷
𝑣
(5)
Another equation imperative for the computation of flow
is the Poiseuille's Law, named after the French physicist Jean
Léonard Marie Poiseuille, describes the steady, laminar flow
of a Newtonian fluid through a cylindrical pipe or vessel. It
relates the flow rate of the fluid to various parameters such as
the pressure difference, viscosity of the fluid, length of the
pipe, and radius of the pipe. This is given by:
𝑄=
𝜋∆P r4
8𝜇𝐿
(6)
Where Q is the volumetric flow rate, ΔP is the pressure
difference between the two ends of the pipe, r is the radius of
the pipe, μ is the dynamic viscosity of the fluid, and L is the
length of the pipe.
In this activity, the researchers are to describe how the
fluid flows in the apparatus, explain the principles behind the
flow, relate the process to its real-life applications (large-scale
scenarios), and determine how efficient the apparatus is.
METHODOLOGY
This section of the paper shows the processes done, and
the materials used in the experiment.
I.
Checking and Preparation of the Apparatus
Before conducting the experiment, the researchers made
sure to check the equipment first for malfunctions and
abnormalities, considering the time it was last used and
operated. Since dated back in 2006, the apparatus was
expected to have multiple leaks, and malfunctions. To resolve
this problem, majority came up with the following proposed
solutions:
1. Replace old gauges and buy adhesives and epoxy to
stop the leaks
2. Reconstruct the fluid flow apparatus excluding the
upper and the lower tanks (using plastic pipes such
as the PVC pipes)
The first proposed solution was rejected since the pipes
were all faulty, the gauges weren’t reading any pressure, and
there were still leaks. Therefore, the second proposed solution
was used and the apparatus was remodeled.
II.
Raw Materials Used
In this experiment, the materials used to mirror the old
model were the following:
 PVC pipes of sizes 1-in (with length of 142.5in), 1.5-in (L=50-in), 1.75-in (L=70-in), 2-in
(L=99.5-in), with 2 pcs 1/2/1 reducer, 6 pcs 1-in
elbow reducer, 1/2/1.75 elbow and 1 pc 1.75-in
elbow
 2 gate valves
 Pipe adhesives and solvents
 Epoxy
 Submersible pump
 Water
III.
Installation of Reconstructed apparatus
The installation of the remodeled fluid flow apparatus
involves a meticulous process, utilizing PVC pipes of varying
sizes to ensure optimal performance. Beginning with the
foundation, PVC pipes sized at 1-inch, 1.5-inch, 1.75-inch,
and 2-inch are selected to facilitate the fluid's journey through
the system. To accommodate transitions between different
pipe diameters, two pieces of 1/2/1 reducers are integrated
strategically along the pipeline. Additionally, six 1-inch
elbow reducers are incorporated to facilitate directional
changes where necessary, ensuring smooth flow dynamics.
Furthermore, precise curvature adjustments are made with a
1/2/1.75 elbow and a singular 1.75-inch elbow, enhancing the
efficiency of fluid movement within the apparatus. Each
component is meticulously positioned and secured, adhering
to industry standards and safety protocols. The result is a
meticulously crafted fluid flow apparatus, meticulously
designed and installed to optimize performance and reliability
in various applications.
The apparatus was remodeled without altering both the
upper and bottom tanks. There were also gate valves installed
before the opening of the last bottom pipe, and after the first
gauge. All the gauges were properly sealed to the pipes,
making sure that there is no leakage of fluid.
Before using the apparatus, it was first washed and
cleaned to prevent clogging and more malfunctions.
any changes in pressure or flow behavior within the system.
Subsequently, the valves were reopened for another 10second interval to resume the flow.
The process was repeated once more, with the valves
closed for an additional 10-second duration, followed by their
reopening for another 10 seconds. Throughout these intervals
of opening and closing the valves, data on pressure drop and
flow rates were collected and analyzed to understand the
effects of pipes and fittings on the overall performance of the
system.
By employing this experimental methodology,
researchers could systematically investigate how different
pipe materials and fittings influenced pressure drop and flow
characteristics, providing valuable insights for optimizing
piping systems in various engineering applications.
V.
Post-Experiment
After completing the experimentation phase to assess the
effects of pipes and fittings on pressure drop using the
remodeled 2006 apparatus with plastic pipes, some postexperimental procedures were followed. The equipment was
drained with water, the area was cleaned, and the submersible
pump was removed from the water at the bottom tank.
After noticing pressure differences because of the
differences in pipe sizes and fittings, the data are now
gathered for interpretation, comparison, and analysis.
RESULTS AND DISCUSSION
FIGURE I
RECONSTRUCTED FLUID FLOW APPARATUS
Figure 1 shows the remodeled imitation of the original
apparatus wherein PVC pipes were used for cost efficiency.
IV.
This section of the paper explains what happened during,
and presents the data acquired from the experiment.
Table 1 below shows the readings of the Pressure gauges
(in Psi) during the experimentation proper. The pressure
gauges read very low pressures and kept fluctuating.
TABLE I
Experimentation Proper
The experimentation process for assessing the effects of
pipes and fittings on pressure drop using a remodeled and
reconstructed 2006 apparatus involved several steps. Firstly,
the apparatus was set up, comprising plastic pipes instead of
traditional materials. Two tanks were utilized: an upper tank
and a bottom tank. Inside the lower tank, a submersible pump
was placed to pressurize the water, which was then propelled
upwards to the feed.
Once the apparatus was prepared, the experimentation
procedure commenced. Initially, the valves were closed for
the first 30 seconds to allow the water to start flowing steadily
through the system. After this initial period, the valves were
opened for a duration of 10 seconds. This allowed for the
observation of the pressure drop and flow characteristics
during this interval.
Following the 10-second open period, the valves were
closed again for 20 seconds to momentarily halt the flow of
water. This interruption in flow facilitated the examination of
PRESSURE READINGS IN EACH GAUGE
Pressure Gauge
PG1
PG2
PG3
PG4
PG5
PG6
PG7
PG8
PG9
PG10
PG11
PG12
PG13
Pressure Reading (in Psi)
8
8
10
9
10
10
8
10
0
12
10
Interpreting the data obtained from the experiment earlier
entails a comprehensive analysis of the pressure readings
recorded by the pressure gauge at various key points
throughout the fluid flow system. Each pressure gauge (PG1-
PG13) represents a specific location within the system where
pressure measurements were conducted, providing crucial
insights into the pressure distribution and dynamics within the
system. The pressure readings, measured in pounds per square
inch (Psi), serve as indicators of the pressure conditions at
each respective gauge location, shedding light on the
performance and behavior of the system under different
operational scenarios.
Examining the provided data reveals several noteworthy
observations:
PG2 to PG4 consistently exhibit pressure readings
ranging from 8 to 10 Psi, suggesting a relatively stable
pressure environment at these points in the system. These
consistent readings imply uniform pressure distribution and
flow characteristics within this segment of the piping
network.
PG5 registers a pressure reading of 9 Psi, aligning with
the preceding measurements, and indicating continued
uniformity in pressure levels along the system.
Similarly, PG6 and PG7 record pressure readings of 10
Psi, mirroring the trend of consistent pressure levels observed
in earlier measurements. This further corroborates the notion
of a well-maintained pressure regime within the system.
However, a significant deviation from this trend is
observed at PG11, where a pressure reading of 0 Psi is
recorded. This abrupt drop in pressure suggests the presence
of a flow obstruction, valve closure, or potential fault within
the system, warranting further investigation to identify and
address the underlying cause. PG12 and PG13 subsequently
display pressure readings of 12 Psi and 10 Psi, respectively,
indicating a recovery in pressure levels following the
observed drop at PG11.
This recovery may suggest the resolution of any transient
issues or disturbances affecting the system. PG10 records a
pressure reading of 10 Psi, consistent with the preceding
measurements, reaffirming stable pressure conditions at this
location within the system. Notably, PG11 mirrors the
anomalous reading observed at PG8, registering a pressure
reading of 0 Psi. This recurring occurrence may indicate a
persistent issue or fault at this specific point in the system,
necessitating thorough troubleshooting and corrective action.
In essence, the data garnered from the experiment offers
valuable insights into the pressure dynamics and performance
of the fluid flow system, highlighting areas of potential
concern and prompting further analysis to optimize system
operation and reliability.
There are factors that affect pressure drop which are;
frictional resistance, changes in flow direction, flow reduction
or enlargement from fittings, obstruction and blockages,
material and roughness. Each of which contribute to pressure
drop of the apparatus and in the experiment, not everything
was given focus on since the focus were mostly for the repair
of the apparatus.
Nevertheless, the conducted experiment proved that the
outdated model can still work but with lesser efficiency than
when it was first used for operation.
RECOMMENDATIONS
To obtain accurate results, the researchers suggest to
follow the following procedures:
- Use a pressure gauge that can read the slightest
amount of pressure.
- Make sure that no leakage shall happen by securing
all fittings and pipes were sealed,
- Measure the amount of feed and recycle
- Calculate the flowrate of the fluid inside the pipes
ACKNOWLEDGMENT
I would like to express gratitude to our professor, Engr.
Junjun Pajara, for letting us explore the use and mechanism
of the equipment ourselves. With that, we established
teamwork, collaboration, and also independence.
Thanks is also given to my family and of course, my
friends for helping me with the parts I lacked knowledge
about, and the data I failed to take note of.
Lastly, to Father Almighty for keeping me sane and
guiding me always through this semester.
REFERENCES
[1] Habib Ahmari, & Shah. (2019, August 14). Experiment #4: Energy
Loss in Pipes. Pressbooks.pub; Mavs Open Press.
https://uta.pressbooks.pub/appliedfluidmechanics/chapter/experiment
4/
[2] Central States Industrial. Central States Industrial.
https://www.csidesigns.com/blog/articles/what-is-pressure-drop-andhow-does-it-affect-your-processing-system (accessed 2024-03-08).
[3] FLOW IN PIPES. (n.d.).
https://www.kau.edu.sa/Files/0057863/Subjects/Chapter%208.pdf
[4]. McGillivray, R. (2022, January 22). Pressure Gauge Calibration.
Tameson.com. https://tameson.com/pages/pressure-gauge-calibration
CONCLUSION
AUTHOR INFORMATION
After the experiment, it was concluded that there were
flaws on the fluid flow apparatus, making it unable to produce
the desired outcomes. Pipes and fittings can significantly
impact pressure drop in a fluid flow system due to their
geometrical characteristics and flow obstruction properties.
Jermaine Angela B. Prieto, 3rd Year Student, Department of
Chemical Engineering, Bicol University College of
Engineering..