Hydraulic valves, pure mechanical hydraulics at water service.
On the path of water, from its origin (reservoir, tank, etc…) to the crops, it circulates through the pressure pipes, until it meets the hydraulic valves.
The hydraulic valves are an essential part in irrigation systems, as they are intended to interrupt the water circulation when the irrigation time is over, or to isolate one or more sections of the pipeline, to carry out repairs or maintenance work. In addition, they can also regulate the pressure and flow of the irrigation water. To carry out all these functions, they use the energy of the water that circulates through them, so the energy expenditure is zero. However, in the case of those that incorporate solenoids for their control, electrical orders are necessary, through these low-consumption electrical devices.
What are the different parts of a hydraulic valve?
A hydraulic valve is made up of three main parts:
- The body or basic valve: element in charge of modulating the passage of water.
- One or several pilots in charge of directing the basic valve.
- The control circuit: which includes manual keys, the protection filter, mini tubes, regulation devices and all the connections of these elements with the basic valve, the pilots and the pipe network.
“The hydraulic valves are autonomous, so they do not need any external energy input to operate”
The operation of a hydraulic valve is very simple. The pilot receives the information about the flow rate, pressure, or the parameter to be controlled, from the control circuit. If there is a variation in the data received, the valve diaphragm reacts on the pilot’s command, repositioning itself so that it complies with the pre-set command.
What type of hydraulic valves are used in irrigation systems?
Hydraulic valves can be classified according to the operating system, the number of chambers they contain and the shape of their body.
Depending on the drive system, they can be diaphragm or piston. The latter are not recommended for working with water that is not very clean, such as irrigation water, since the impurities contained in the water can be introduced between the piston and the jacket that surrounds it, eliminating the watertightness and requiring a great deal of maintenance. Therefore, for an irrigation system, the diaphragm valves will be used, where the driving system is a diaphragm.
Depending on the number of chambers they contain, they can be single or double chamber. The chambers are independent spaces used to, with the help of the hydraulic pressure of the circuit, position the valve’s operating system and therefore vary its degree of opening. Each of these has its advantages and disadvantages, and understanding them will help us to choose more appropriately:
The double chamber valves:
- Very low opening pressure (2 or 3 mca) They are the only ones recommended to work at low or very low pressure.
- Short and smooth closing time.
- No contact between the diaphragm and the liquid.
- True control of opening and closing speed.
- Relatively complicated design.
Single chamber valves:
- Medium-high opening pressure (7 to 12 mca, depending on model).
- Long and progressively accelerated closing time.
- There is contact with the diaphragm and the liquid.
- Limited opening and closing speed control.
- Simple and easy maintenance.
According to the shape of its body, in agricultural irrigation we will generally find valves with a “Y” shape, with a “balloon” shape or with an “angle”.