Pneumatic valves are key components within control and automation systems on board ships. They use compressed air to control the flow, pressure or direction of air and fluids. These valves are widely used throughout the marine industry due to their reliability, fast response and safe operation. Pneumatic valves are often used within engine room automation, fuel oil systems, boiler control systems, starting air systems and remote operated systems.
Pneumatic valves are devices which utilise compressed air to control the movement of a valve mechanism or the flow of a medium within a pipeline.
Depending on the design of the pneumatic valve it can be used to:
Some pneumatic valves will be fully operated by the air pressure, whilst other pneumatic valves will use compressed air to move an actuator which is connected to another process valve.
This depends on what type of pneumatic valve you have. Most pneumatic control systems will have compressed air supply via an air compressor or instrument air system.
The basic principle is as follows:
As an example, a pneumatic actuated fuel oil valve will use the compressed air to move a piston/diaphragm which will open/close the valve, controlling the fuel flow.
The design will vary depending on the type of valve, however key parts include:
There are a variety of pneumatic valves available, depending on their use and design. The most common are:
Directional control valves are used to control the direction of compressed air. These are often referred to by how many ports and positions they have.
Examples include:
The first number refers to how many ports there are, the second number refers to how many positions.
Pressure control valves are used to control or restrict the pressure within a pneumatic system.
Examples include:
Flow control valves control the flow rate of compressed air in a system. This can be used to control how fast pneumatic cylinders or actuators work.
Non return valves allow air to flow in one direction only. Also known as check valves.
Solenoid operated pneumatic valves use a solenoid (electrically operated) to move the internal spool/poppet. Once an electric signal is sent to the solenoid it will change the position of the valve, controlling the air flow.
These are often used within automated systems.
Pneumatic valves are used within a few systems on board ships due to their reliable remote and automated operation.
Like other components on board ships, pneumatic valves will require regular checking and maintenance.
Issue Possible Cause
Not returning Weak/broken return spring
Before carrying out any maintenance ensure that the air supply is isolated and any trapped pressure is released. Follow the vessel’s safety procedures to ensure that the equipment cannot operate.
Pneumatic valves play an important role within automation and control systems on ships. They utilise compressed air to operate machinery, control the airflow and control the movement of fluids using remote operated valves. Knowing the different types, principles of operation and uses will help marine engineers identify any issues and ensure reliable operation of pneumatic equipment on board
To control the flow, direction or pressure of compressed air within a pneumatic system.
Pneumatic valves are a general term for valves which are operated by pneumatic energy or control air. Solenoid valves use an electromagnetic coil to operate the internal mechanism. Solenoid valves can also be used to control compressed air.
This refers to a pneumatic valve with 5 ports and 2 positions. These are often used to control double acting pneumatic cylinders.
They provide a reliable method of remote and automated control for machinery and fluid systems. They are also useful in situations where it would not be suitable to have electrical equipment.
Low air pressure, blocked filters, blocked pipework, air leaks or damaged components..
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