Sana'a University Faculty

of Engineering
Mechatronics Engineering Department
.

Hydraulics & Pneumatic Systems lap

Function Test on a Check Valve & Fumction test on a

pilot operated check valve &Door operation

Supervised by:

Prof. Hamood Al_nahari

Eng. Mohammed Al_maswary

Done by:

Mohammed AL_Dawliy

AC.NO:

202370303
Contents
Experiment 1:.................................................................................................................3
Check valve function..................................................................................................3
Introduction.............................................................................................................3
Equipment...............................................................................................................4
Simulation...............................................................................................................4
Questions................................................................................................................4
Experiment 2............................................................................................................................. 5
Pilot Operated Check Valve......................................................................................5
Introduction.............................................................................................................5
Equipment...............................................................................................................6
Simulation...............................................................................................................6
Questions................................................................................................................7
Experiment3.............................................................................................................................. 5
Door Operation...........................................................................................................5
Introduction.............................................................................................................5
Equipment...............................................................................................................6
Simulation...............................................................................................................6
Questions............................................................................................................................6
Experiment 1:

Check valve function:

Introduction:
A check valve, also known as a non-return valve or one-way valve, is a
mechanical device commonly used in fluid systems to allow flow in one direction
while preventing backflow in the opposite direction. It serves as a crucial component
in various applications where it is necessary to control the flow direction and prevent
fluid from flowing back into the system.

The main function of a check valve is to ensure that fluid flows in a single specified
direction, typically from the inlet to the outlet, while blocking or significantly
reducing flow in the reverse direction. It accomplishes this through a mechanism that
opens and closes based on the pressure difference across the valve.

When the pressure on the inlet side of the check valve is higher than the pressure on
the outlet side, the valve opens, allowing fluid to flow freely in the desired direction.
This enables the fluid to move through the system and reach the desired components
or outlets.

However, when the pressure on the outlet side exceeds the pressure on the inlet side
or when there is a reverse flow attempt, the check valve closes, preventing fluid from
flowing back into the system. This action helps maintain system integrity, prevents
backflow-induced damage, and ensures the efficiency and effectiveness of the fluid
system.

Check valves are found in a wide range of applications, including plumbing systems,
HVAC systems, hydraulic systems, water treatment plants, and many other fluid
handling systems. They provide essential protection against backflow, prevent the
reversal of flow, and maintain the intended flow direction, contributing to the overall
functionality and safety of the system.
Equipment:
 1 off Check valve.
 1 off 4/3 directional control valve.
 1 off Flow meter.
 1 off Pressure relief valve.
 1 off Distribution manifold pressure/tank.
 Connection hoses as required.

Simulation:

? (Is ? (Is)

0
L/min
Questions:
1- Give another names for a check valve:

 Non-return valve
 One-way valve
 Backflow preventer
 Clack valve
 Retention valve
 Reflux valve
 Reverse flow preventer
 Check back valve
 Stop-check valve
 One-directional valve

2- What is the term given to the ‘pressure’ required to start to open a check valve?

The term given to the pressure required to start opening a check valve is commonly
referred to as the "cracking pressure." The cracking pressure is the minimum pressure
that needs to be exerted on the inlet side of the check valve to overcome the valve's
spring tension or internal resistance and initiate the opening of the valve. Once the
cracking pressure is reached, the check valve will start to open, allowing fluid to flow
in the desired direction.

3- What is the function of a check valve?

 Allows fluid flow in one direction.

 Prevents backflow in the opposite direction.
 Protects system integrity and prevents potential damage.
 Maintains the desired flow direction.
 Ensures efficiency and effectiveness of fluid systems.
 Experiment 2:

Pilot Operated Check Valve:

Introduction:

The pilot-operated check valve is an essential component in hydraulic systems,

providing a controlled flow of fluid in one direction while blocking flow in the
opposite direction. This valve is commonly used in applications where it is necessary
to control the movement or hold the position of hydraulic actuators, such as cylinders
or motors.

The pilot-operated check valve consists of two main sections: the main valve and the pilot
valve. The main valve allows or blocks the flow of hydraulic fluid based on the
pressure difference across it, while the pilot valve controls the opening and closing of
the main valve.

When the pressure on the inlet side of the valve is higher than the pressure on the outlet
side, the pilot valve closes, preventing flow in the reverse direction. This creates a
blocked or closed position, ensuring that the actuator remains in its current position or
does not move unintentionally.

Conversely, when the pressure on the outlet side exceeds the inlet pressure, the pilot valve
opens, allowing fluid to flow in the reverse direction. This enables the actuator to
move or allows for controlled motion.

The pilot valve is typically operated by a separate pressure control line connected to the
valve. By adjusting the control pressure, the opening and closing characteristics of the
pilot-operated check valve can be precisely controlled.
Equipment:
 1 off Pilot operated check valve.
 1 off 4/3 directional control valve.
 1 off 4/2 directional control valve.
 1 off Flow meter.
 1 off Pressure relief vale.
 1 off Distribution manifold pressure/tank.
 Connection hoses as required.

Simulation:

Questions:
1- On the P.O. check valve in the tutor case, does the pilot open or close the
check valve?
In the scenario of a P.O. check valve in the tutor case, the pilot is responsible for
opening the check valve, not closing it.

2- The line from port A of the 4/2 way DCV to the P.O. check valve is a dashed
line, why?
The dashed line represents a pilot line used to transmit a control signal or pilot
pressure from the 4/2 way DCV to the P.O. check valve. It allows for precise control
of the P.O. check valve's operation independent of the main flow path. The dashed
line visually distinguishes it as a signal line, separate from the solid lines representing
fluid or air flow.
3- Whenever using a check valve in a circuit, what must we be aware of?
When using a check valve in a circuit, important considerations include:

 Flow direction: Install the check valve in the correct orientation to maintain
desired flow direction.
 Pressure and flow ratings: Select a check valve that can handle the system's
pressure and flow requirements.
 Installation location: Place the check valve appropriately for effective flow
control and accessibility for maintenance.
 Water hammer: Be aware of the potential for hydraulic shock when a check
valve closes rapidly. Consider using dampening devices or slow-closing check
valves to mitigate this issue.

Experiment 3:

Door Operation:
Introduction:
In this experiment, our objective is to simulate the operation of a door using
pneumatic components. The purpose is to gain a comprehensive understanding of the
principles underlying door operation and explore the potential applications of
pneumatic systems in automating and controlling door movements.

Doors are integral components of buildings and structures, serving purposes such as
providing access, ensuring security, and regulating airflow. Understanding the
mechanisms behind their operation is crucial for designing efficient and reliable door
systems.

Pneumatic systems offer advantages in terms of simplicity, reliability, and ease of

control. By using compressed air, we can simulate the forces and motions involved in
opening and closing doors.
Equipment:
 1 off Single acting cylinder.
 1 off 3/2 way lever actuated, directional control valve.
 1 off Pressure relief valve.
 1 off Distribution manifold pressure/tank
 Connection hoses as required
 (Option) 4kg weight

Simulation:

Questions:
1- Draw the symbol, for a Single Acting Cylinder, with spring return, according
to the I.S.O. 1219-1 standard: -
2- List two (2) disadvantages of a Single Acting Cylinder, with spring return: -

 Limited control and restricted bidirectional force.

 Slower retraction speed in comparison to the extension stroke.

3- Draw the symbol for a 3/2 way N/C push button operated, spring return
valve, according to the I.S.O. 1219-1 standard: