The thermal relief valve is part of many industrial systems, playing a dual role in safety and efficiency during operation. Basically, it relieves pressure built up due to thermal expansion. This normally occurs when fluids are heated in a system and start to expand. In the absence of such valves, the pressure may rise to dangerous levels and lead to equipment failure, system breakdown, or accidents.
Wien Technologies has industrial valve solutions, including a full line of thermal relief valves to suit different application requirements. It includes Flowsafe relief valves and Crosby thermal relief valves, designed to perform almost anywhere: from a chemical processing plant through HVAC systems, oil/gas pipelines, and water treatment facilities. Each type of valve is designed to operate within specified pressure and flow capacity ranges, so there will always be the best solution for any given situation.
This article will consider various thermal relief valves, their functions, and benefits. We will also see how they are applied across different industries, which shall help in choosing the correct valve for your needs. Be it for enhancing safety, increasing efficiency, or complying with any regulations, this guide will arm you with information to make informed decisions pertaining to thermal relief valves.
What are Thermal Relief Valves?
Thermal relief valves are protective devices that vent off the overpressure created in a system by temperature increase, which then expands the fluid inside that particular system. This prevents probable equipment destruction and assures safe operation. Such valves turn out to be quite important in systems where liquids may be heated, consequently causing over-pressurization.
Types of Thermal Relief Valves
There are three primary types of thermal relief valves:
- Direct-Acting Thermal Relief Valve
- Pilot-Operated Thermal Relief Valve
- Balanced Bellows Thermal Relief Valve
Let’s explore further into the specifics of each type.
1. Direct-Acting Thermal Relief Valve
The direct-acting thermal relief valve is the fundamental simplest configuration, symbolising simplicity in design and operation.
- Construction: Comprises a flat diaphragm or bellows.
- Operation: The valve opens directly under the pressure of the expanding fluid.
- Applications: It finds its best applications for medium and low flow amounts.
- Accuracy: Generally to +/- 10% of the set point downstream.
Key Features:
- Compact and Economical: Requires no external sensor line, making it the smallest and most cost-effective option.
- Ease of Installation: Simple to install due to its independent structure.
Feature | Description |
Structure | Flat diaphragm or bellows |
Application | Medium and low flow amounts |
Accuracy | +/- 10% downstream set point |
Installation | No external sensor line required |
2. Pilot-Operated Thermal Relief Valve
In the pilot-operated thermal relief valves, there is an increased complexity in the design, where a pilot valve is combined with a main valve.
- Structure: Comprises a pilot valve controlling the main valve.
- Operation: Pressure is exhausted through the pilot valve onto a piston opening the main valve.
- Applications: Applications relating to higher capacity requirements
- Accuracy: They are more accurate than the direct-acting valves, typically within +/- 5%.
Key Features:
- Higher Capacity and Accuracy: Capable of handling larger flow rates with increased accuracy.
- Integrated Design: The inlet pressure is utilised to assist in opening the main valve.
- No External Sensor Line Needed: Pressure is sensed internally.
Feature | Description |
Structure | Pilot and main valve combination |
Application | Higher capacity requirements |
Accuracy | +/- 5% downstream set point |
Installation | No external sensor line required |
3. Balanced Bellows Thermal Relief Valve
The balanced bellows thermal relief valves have a double diaphragm instead of the piston in the inner pilot valve.
- Construction: Double diaphragm construction.
- Operation: Pressure across a larger diaphragm area opens a larger main valve.
- Applications: Application requiring the ultimate in accuracy and capacity.
- Accuracy: Highest available, +/- 1%
Key Features:
- High Sensitivity: Since the diaphragm is under more changes in pressure.
- Greater Capacity: Greater main valve opening capacity compared to other types
- External Sensor Line: Mounted outside the valve, the component aids in diminishing turbulence for better accuracy.
Feature | Description |
Structure | Double diaphragm design |
Application | High accuracy and capacity needs |
Accuracy | +/- 1% downstream set point |
Installation | External sensor line required |
Applications of Thermal Relief Valves
Applications of thermal relief valves span across industries and include the following:
- Chemical Processing: Controls pressure in reactors and storage tanks.
- Oil and Gas: Protection to pipelines and storage systems from over-pressurization within industries.
- HVAC Systems: Protects heating and cooling systems from over-pressurization.
- Water Treatment: Maintains the balance of pressure within the water distribution system.
Benefits of Using Thermal Relief Valves
- Safety: It protects equipment from damage and provides personal safety from over-pressurization.
- Efficiency: It allows the release of the excess pressure and maintains the ideal condition required for the plant’s operation process.
- Cost-Effective: It reduces frequent maintenance and repairs through the prevention of damages.
Choosing the Right Thermal Relief Valve
When selecting a thermal relief valve, consider the following factors:
- Flow Capacity: The valve shall be designed for the highest flow rate that your system can achieve.
- Accuracy Requirements: The selected valve should be capable of providing a suitable accuracy for its application.
- Installation Conditions: Consider whether the installation is easy and an external sensor line is needed.
- Material Compatibility: Valve materials are compatible with the fluids flowing through the system.
Summary Table
Type | Structure | Application | Accuracy | Sensor Line Requirement |
Direct-Acting | Flat diaphragm or bellows | Medium and low flow amounts | +/- 10% | No external sensor line |
Pilot-Operated | Pilot and main valve | Higher capacity requirements | +/- 5% | No external sensor line |
Balanced Bellows | Double diaphragm | High accuracy and capacity | +/- 1% | External sensor line |
Conclusion
The thermal relief valve is one of the most integral components in industrial processes. Now, understanding the classification of Thermal FlowSafe relief valves, you at your disposal have direct-acting, pilot-operated, and balanced bellows valves to choose from for any specific application. Wien Technologies offers a line of complete thermal relief valves able to handle a variety of application needs for the perfect performance and safety of your systems.
Want more information or have specific needs you’d like to discuss, Crosby, or Flowsafe Relief Valves Catalog? Contact Wien Technologies today.