This document discusses components used in control engineering like sealing devices, filters, and regulators. It describes how seals work to prevent leakage in fluid systems by filling irregularities between mating surfaces. Common causes of leakage are improper mating, wear and tear, vibrations, and contamination. The document classifications seals into static seals like gaskets and dynamic seals like packings used between moving parts. It also discusses properties of sealing materials, types of seals and filters, functions of pressure regulators, and how regulators work to maintain a constant downstream pressure.

1. CONTROL ENGINEERING
Made by :- Mechanical-2-B
Roll no:-24,25
Mustafa Lokhandwala , Viken Sherdiwala

2. COMPONENTS OF PRESENTATION
 Sealing Devices
 Filters and Strainers
 Regulators

3. LEAKAGE OF OILS
 Whenever there is a joint
mating surfaces may not
match properly. Instead the
surface irregularities of both
the surface together form a
small group through which the
oil can leak out easily.
 Seal is inserted between
joints and pressure is applied
by tightening of bolts.
 Seal materials flows into
irregularities of mating parts
due to its plasticity and closes
the flow path of oil and stops
the leakage

4. CAUSE OF LEAKAGE
 Irregularities in surface leading to improper
mating of joints
 Increase in clearances due to wear and tear of
mating parts
 Loosening of joints due shock and vibrations
 Excessive operating pressures
 Fluid contamination
 Damaged or worn out seals

5. INTRODUCTION TO SEALING DEVICES
 In any fluid transmission system the transmission of fluid
between two points is possible only if the device applying
pressure like a piston can apply pressure without any
leakage of fluid.
 In eighteenth century Joseph Brahmah invented an
effective piston seal, the cup packing.This led
to development of the hydraulic press.
 The packing was probably the most important invention in
the development of hydraulics as a leading method of
transmitting power.The development of machines to cut
and shape closely fitted parts was also very important in
the development of hydraulics.

6. CLASSIFICATION OF SEALS
 The packing materials are commonly referred to as seals or sealing devices.
The seals used in fluid power systems and components are divided into two
general classes:-
(a) Static Seals
(b)Dynamic Seals
 Static Seal :- The static seal is usually referred to as a gasket.The function of a
gasket is to provide a material that can flow into the surface irregularities of
mating areas that require sealing.To do this, the gasket material must be
under pressure.This requires that the joint be tightly bolted or otherwise held
together.
 Dynamic Seal :- The dynamic seal, commonly referred to as a packing, is
used to provide a seal between two parts that move in relation to each other.
 Many of the seals in fluid power systems prevent external leakage.These seals
serve two purposes—to seal the fluid in the system and to keep foreign
matter out of the system. Other seals simply prevent internal leakage within a
system.

7. PROPERTIES OF SEALING MATERIALS
 Hardness
 Resistance to indentation, measured using
durometre.
 Softer materials are used for low pressure
applications while hard materials for high
pressure applications.
 Scale of hardness is given in ‘Shore A’
Scale from 0 to 100(degree). Shore A 70
scale is sufficient.
 Permanent set
 It represents permanent distortion of
rubber after elongation (150% for 10 min
at room temp).

8.  Volume change – Swelling and Shrinkage
 Increase/decrease in size of elastomer as a result of
continuous contact with hydraulic medium.
 Swelling is desirable to some extent, as it causes
better sealing. But excessive swelling can cause
friction.
 Allowable is 20%for dynamic seals and 40-50% for
static seals
 Adhesion
 Susceptibility of rubber to stick to contact surface.
 Aniline point
 It is the temperature at which fresh aniline may react
with oil.

9.  Compression set
 Tendency of elastomer to loose it resilience.
Compression set = loss in thickness * 100
Original thickness
 Permanent distortion of elastomer after compression
at a specified temperature for a period of time.
Final squeeze = Initial squeeze + Swell - Compression set
 Squeeze
 Diametric compression of O ring between two mating
surface of Gland.

10.  Tensile strength
 Tensile strength, elongation and tear strenght
affect the operation of seal due to physical
contact and relative moment which tend to
stretch, abrade, tear and wear of seal.
 Ultimate elongation of seal is defined as
maximum length to which an elastomeric seal
may stretch before failure and seperation.
Ultimate elongation= separation length * 100
free length

11. COMMONLY USED SEALING MATERIALS
 Cork
 Leather
 Metal
 Rubber
 Asbestos
 Elastomeric seal material

13. TYPES OF SEALS
 T seals
 V-rings
 O-rings

14. FILTERS AND STRAINERS
 A filter is a system of fine gauge meshes with
depth. When fluid passes through these meshes
or any other medium, the filter element will retain
the insoluble impurities.
 The particle size removed by filter is in microns,
known as micron rating of a filter.
 Strainers are similar to filters but without any
depth. Their efficiency is less than the filters.
Strainers are also called as coarse filters.

15. TYPES OF FILTERS
 Based on filter material
 Metal elements (Porous type) Sintered particles
 Mesh and cloth type media
 Edge type or Filter media
 Non metal element filters

16. TYPES OF FILTERS
 Based on construction and flow
 Simplex filters
 Duplex filters
 Full-flow filters
 Proportional flow filters
 Filter/separator
 Indicating filters
 Inline or cone filters

20. LOCATION OF FILTER
 Return line filter
 Intake filter or Suction Line filter
 Pressure filter

23. REGULATORS
 A pressure regulator is a normally-open valve that
takes a high inlet pressure and converts it to a lower,
pre-set downstream pressure.
 To prevent constant opening and closing (chatter),
the regulator is designed to open at a pressure
somewhat lower than the closing pressure.
 A regulator is open when it is directing fluid under
pressure into the system. In the closed position the
fluid in the part of system beyond the regulator is
trapped at the desired pressure, and the fluid from
the pump is bypassed into the return line and back to
reservoir.

24. Why is it important to regulate Pressure
in a Piping System?
Pressure is one of the
most important aspects
of ANY piping system. If
pressure is too low, for
example, the system is
powerless. And if it is
too high…

25. Just as high blood
pressure damages the
vital organs in your “piping
system,”
overpressure affects
filters, tools, sprayheads,
instruments…any vital tool
in a liquid piping system.

26. PURPOSE OF A PRESSURE REGULATOR…
Imagine having an
employee who
continuously monitors a
single pressure gauge,
and constantly tweaks a
valve as downstream
pressure rises or falls
past a pre-determined
point.

27. USES OF A PRESSURE REGULATOR:
1. As a control element, to ensure that downstream
pressure does not exceed a set point.
2. As a safety device, to protect equipment from harmful
overpressure.
3. Regulate to the correct pressure range so that a flow
system or piece of equipment can operate safely and
effectively.

28. HOW IT WORKS…
INLET OUTLET
A Set Screw
is used to set the desired pressure. It does
this by controlling the force of non-wetted
steel springs
The springs are attached to main shaft, and
the force of the springs presses down, the
main shaft
The valve seat
is part of the main shaft, and thus is held
“open” by the force of the springs.

29. While the spring is holding the valve open and liquid is flowing through, a small tube
near the valve outlet – called the “sensing orifice” – transmits downstream pressure
into a chamber.
Because pressure is equal in all directions, the pressure
in the chamber is identical to downstream pressure.
SENSING
ORIFICE
PRESSURE
CHAMBER

30. SENSING
ORIFICE
PRESSURE
CHAMBER
VALVE OUTLET
ROLLING
DIAPHRAGM
The key to this pressure chamber is a large Rolling Diaphragm. It rolls upward as
pressure increases, and back down as pressure decreases…
In other words, it moves up and down in direct response to changes in downstream
pressure.

31. SENSING
ORIFICE
PRESSURE
CHAMBER
VALVE
OUTLET
ROLLING
DIAPHRAGM
The Rolling Diaphragm is attached to the Main Shaft that we mentioned earlier –
which as you recall, is held down by spring force, which in turn holds the valve open.
SPRING
FORCE
M
A
I
N
S
H
A
F
T
VALVE IS
HELD OPEN
But when pressure at the outlet increases…

32. …as downstream pressure increases, the force on the rolling diaphragm increases, in
direct opposition to the spring force...

33. When downstream pressure exceeds the spring force, the rolling diaphragm
overpowers the springs.
This compresses the springs and forces up the main shaft...

34. The valve seat, as part of
the main shaft, closes
against the main internal
orifice, preventing
additional pressure
downstream.
It will remain closed as
long as downstream
pressure exceeds the
set point, as determined
by the set screw
controlling the force on
the springs.

35. When downstream
pressure falls below the
set point, the valve begins
to re-open as the springs
again force the main shaft
down. Flow resumes.
.

36. • Most pressure regulators impede flow
while sensing pressure. The sensing orifice
and pressure sensing chamber in a
regulator are not in the flow path – flow is
unrestricted and much higher than
competitive designs.
• Large sensing area of the rolling
diaphragm provides smoother, more
accurate control.
ADVANTAGES OF PRESSURE REGULATORS

37. • U-cups used in place of o-rings provide smooth, non-
sticking movement of the main shaft.
• Greater accuracy & repeatability achieved via springs
matched to the pressure range of the application.
• Overall design – large flow path, large sensing area, more
sensitive springs – all combine to provide the best
performing pressure regulators since 1967.
• No wetted metals. All-plastic wetted designs are
essential for corrosive and ultra-pure applications.
ADVANTAGES OF PRESSURE REGULATORS