Wikipedia about valves control
Many valves are controlled manually with a handle attached to the stem. If the handle is turned ninety degrees between operating positions, the valve is called a quarter-turn valve. Butterfly, ball valves, and plug valves are often quarter-turn valves. If the handle is circular with the stem as the axis of rotation in the center of the circle, then the handle is called a handwheel. Valves can also be controlled by actuators attached to the stem. They can be electromechanical actuators such as an electric motor or solenoid, pneumatic actuators which are controlled by air pressure, or hydraulic actuators which are controlled by the pressure of a liquid such as oil or water. Actuators can be used for the purposes of automatic control such as in washing machine cycles, remote control such as the use of a centralised control room, or because manual control is too difficult such as when the valve is very large. Pneumatic actuators and hydraulic actuators need pressurised air or liquid lines to supply the actuator: an inlet line and an outlet line. Pilot valves are valves which are used to control other valves. Pilot valves in the actuator lines control the supply of air or liquid going to the actuators.
The fill valve in a toilet water tank is a liquid level-actuated valve. When a high water level is reached, a mechanism shuts the valve which fills the tank.
In some valve designs, the pressure of the flow fluid itself or pressure difference of the flow fluid between the ports automatically controls flow through the valve.
Plumbing facts - about activities
Years of training and/or experience are needed to become a skilled plumber; some jurisdictions also require that plumbers be licensed.
Some needed skills, interests, and values
Reading drawings, and specifications to determine layout of water supply, waste, and venting systems
Detecting faults in plumbing appliances and systems, and correctly diagnosing their causes
Installing, repairing and maintaining domestic, commercial, and industrial plumbing fixtures and systems
Locating and marking positions for pipe connections, passage holes, and fixtures in walls and floors
Measuring, cutting, bending, and threading pipes using hand and power tools or machines
Joining pipes and fittings together using soldering techniques, compression fittings, threaded fittings, and push-on fittings.
Testing pipes for leaks using air and water pressure gauges
Awareness of legal regulations and safety issues
Ensuring safety standards and build regulations are met.
When it is necessary to support the service hydraulic?
Hydraulics are often enough and require emergency repairs carried out by good professionals. Some failures are very serious, others less problematic, but each time should be conducted very fairly and professionally. These smaller faults often we will be able to fix yourself, but if you've become something more serious, you should call a good service hydraulics. Not every failure will end up pretty large costs or cause difficulties, but if not repaired properly, things can get complicated. So it is better to rely here on the knowledge of experienced plumbers, than to rely on luck, because they often can we make this more difficult.