Introduction: technical callability for production reliability
Hydropneumatic systems are the basis of many production processes, especially in the industrial automation sector. Choosing the right type of valve—proportional or servo—affects the system's efficiency, cost-effectiveness, and longevity. This article examines the technical aspects of choosing between proportional and servo valves, including speed of response, control accuracy, and economy.
Fundamental principles: physics and electromechanics
Proportional and servo valves are used to control fluid flow in hydropneumatic systems. Proportional valves receive a signal from an electromagnetic sensor, which proportionally affects the opening of the valve. Servo valves, in contrast, use an electric motor to precisely control the position of the piston.
Proportional valves conform to ISO 281 and DIN 51825 and servo valves conform to ISO 10628 and IEC 60947-2. Both types of valves use the principle of proportional control, but servo valves provide higher accuracy and smaller deviations.
Technical specifications and standards
Proportional valves are manufactured according to EN 13600 and DSTU 4137:2019 standards, which set requirements for accuracy, service life and electrical characteristics. Servo valves comply with ISO 10628 and IEC 60947-2 standards, which ensure high control accuracy and stability in working conditions.
The table below shows the main technical parameters of the valves:
| Parameter | Proportional valves | Servo valves |
|---|---|---|
| Maximum pressure | 250 bar | 350 bar |
| Maximum flow | 100 l/min | 150 l/min |
| Control precision | ±5% | ±1% |
| Ambient temperature | -20°C to +60°C | -20°C to +80°C |
| Mass | 1.5 kg | 2.2 kg |
Selection and calculation guide
Valve selection depends on requirements for accuracy, power and cost effectiveness. Here are the criteria for selection:
- If you need high control accuracy, choose servo valves.
- If cost is critical, choose proportional valves.
- If high power is required, choose servo valves.
- If environmental conditions require high stability, choose servo valves.
The formula for calculating valve power:
P = (Q * ΔP) / η where:
- P — power, kW
- Q — flow, l/min
- ΔP is the pressure difference, bar
- η is efficiency, a relative value
Installation and debugging recommendations
For effective operation of the valves, it is necessary to correctly install and adjust the system. Here are the main recommendations:
- The valve connection must comply with the ISO 10628. standard
- Ensure the purity of the working fluid (level of contamination no more than 10 µm).
- Valve adjustment must be performed using measuring equipment according to the EN 13600. standard
- Carry out regular checks for tightness and working pressure.
Modal modes and analysis of the causes of knock-out
Proportional and servo valves can fail for various reasons. Here are the main modal modes:
| The reason | Indicators | The solution |
|---|---|---|
| Clogging | Increase in cost, decrease in accuracy | Regular cleaning of the filter |
| Incorrect setting | Output instability | Adjustment using measuring equipment |
| Electrical instability | Complete shutdown | Checking the power supply |
Knockout prediction and condition monitoring
The following methods can be used to predict valve knock-out:
- Temperature monitoring using sensors according to the ISO 10628. standard
- Flow control using flow sensors (ISO 10628).
- Knockout analysis using measuring equipment (EN 13600).
Using condition monitoring can reduce downtime and repair costs.
Comparison table
Below is a comparison table of the three valve options:
| Indicator | Proportional valve | Servo valve | Combined valve |
|---|---|---|---|
| Accuracy | ±5% | ±1% | ±2% |
| Mass | 1.5 kg | 2.2 kg | 1.8 kg |
| Maximum pressure | 250 bar | 350 bar | 300 bar |
| Cost | €350 | €600 | €500 |
| Term of service | 10,000 hours | 15,000 hours | 12,000 hours |
Conclusion and reference to the catalog
Choosing the right valve plays a key role in ensuring the reliability and efficiency of hydropneumatic systems. Proportional valves are an economical option for routine applications, while servo valves provide high precision for complex systems.
United-D is a reliable supplier of components for hydropneumatic systems. Consult our e-catalog for detailed specifications and technical support.
Refer to our e-catalogList of sources
- ISO 281:2017 — Dynamic compliance of hydropneumatic systems
- DSTU 4137:2019 — Requirements for hydropneumatic valves
- IEC 60947-2:2016 - Electrical devices for control
- EN 13600:2020 — Technical requirements for hydropneumatic systems
- ISO 10628:2018 — Quality control of hydropneumatic valves
