HEROSE safety valves - functions, types and applications

The relief (safety) valve is a key component of any pressure system that serves to protect the equipment and operator from dangerous overpressure. It automatically opens when the pressure of the medium (e.g. air, steam or liquid) exceeds a set safe value, thereby releasing excess medium outside the system. When the pressure is reduced, the valve closes again. Without a safety valve, there is a risk of serious damage to the equipment (bursting of the tank, pipes, etc.) or even endangering the health and life of the operator. Therefore, safety valves in pressure assemblies are mandatory according to standards and laws and their correct functioning is essential for safe operation.

Safety valves can be found on compressors, pressure vessels, boilers, heating systems, piping and many other devices. Everywhere they ensure that the pressure does not exceed the permissible limit. The design of these valves is most often spring-loaded (inside there is a spring pressing the cap to the seat, which loosens at the set pressure and the medium leaks out). The great advantage is that the valve operates fully automatically and requires no power supply or manual operation - it works purely on the principle of the physical force of pressure. Thanks to the safety valve, you can easily and safely "blow off" excess pressure and prevent accidents. Below we look at the different types of safety valves, their features, advantages and practical applications. We will also answer the most common questions customers have and provide advice on how to select the right relief valve for your needs.

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Overview of types of safety valves and their characteristics

There is a wide range of safety valves differing in material, construction, certification and application. Each type is designed for a specific medium and conditions. Below is an overview of the most common safety valve designs available on the market. For each type, we mention what certifications it usually has, what media it is suitable for and what its typical design is (material, construction, connection method).

Brass threaded safety valves

This type of relief valve is most common in smaller applications and for compressors or smaller volume pressure vessels. They are affordable and easy to install on standard threads.

Characteristic: Brass valves withstand moisture and common non-corrosive media well. They are usually set to lower to medium pressure ranges (e.g. 3-40 bar, depending on the model). It is suitable as a fuse for compressors, air handlers, pumps, domestic boilers and generally where the medium is air or water. The advantage is the easy installation directly into the threaded hole of the vessel or pipe. Thanks to their compact dimensions, they can also fit into tight spaces. The disadvantage can be limited chemical and temperature resistance - brass valves are not suitable for very hot steam or aggressive substances.

Stainless steel and steel safety valves (threaded)

Stainless steel valves are designed for harsh conditions, higher pressures or aggressive media. They are often used in industry where brass is no longer sufficient in terms of strength or durability.

Characteristic: Stainless steel relief valves are highly resistant to corrosion, high temperatures and can handle media such as saturated steam or chemicals where brass would corrode. They are used, for example, in steam generators, chemical apparatus, food processing equipment (where hygienic stainless steel is required) or gas cylinders. They are usually capable of operating at medium and higher pressures (tens of bar or more). Some models have a manual pull rod/lever for manual blow-off or function test (this is typical for boilers, for example). Compared to brass valves, they are more expensive, but offer longer life and reliability in demanding conditions.

Flanged relief valves (cast iron/steel)

For larger pressure systems and industrial plants, safety valves with flanged connections are used. These valves have a higher flow capacity and durable cast iron or steel construction to handle large media volumes and high pressures.

Characteristic: Flanged valves are used e.g. in steam boilers and heat exchangers, in large compressor stations, on large pressure vessels and wherever large quantities of medium need to be discharged quickly. Thanks to the flanges, they can be firmly screwed onto larger pipe diameters and sealed even at high pressures. Cast iron is common for hot water and steam systems (can withstand high temperature), steel or stainless steel flanged valves are used for more aggressive media and gases. These valves often meet strict standards (they have TÜV type numbers for gas, steam or liquid) and must be supplied with complete documentation. Their installation requires professional installation between the pipe flanges. The disadvantage is the higher weight and the difficulty of installation, the advantage is the high reliability in industrial applications and the ability to safely release high pressure.

Special safety valves (cryogenic, pilot, etc.)

In addition to standard spring valves, there are also specialised designs for specific purposes:

Characteristic: Cryogenic relief valves are designed to operate reliably at extremely low temperatures (freeze-resistant materials, elimination of friction by freezing). They are used, for example, in liquid nitrogen, oxygen or LNG storage tanks. Pilot valves, on the other hand, are used for large installations where the direct opening of a large valve requires relief by a pilot valve - typically in refineries, the chemical industry or at very high pressures. These special valves are always subject to stringent certifications and often international standards (they may have ISO 4126, ASME VIII, etc. approvals in addition to the European TÜV). They are not that common for the average customer, but it is good to know that they exist for very non-standard conditions. If you need a valve for non-typical environments (extreme temperature, food service, explosive environments), stainless steel or special designs are the right choice.

Summary of types: When selecting a relief valve, focus not only on the correct pressure setting range, but also on the medium and material. Each valve should state in the description what medium it is designed for (air, steam, water, oil, inert gas, etc.) and what certifications it has. All quality safety valves must comply with the requirements of the European Pressure Equipment Directive ( CE marking according to PED) and are usually also TÜV approved and certified for the type of application. In our range , you always get a valve with complete documentation - set to the required pressure and sealed with TÜV certificate and attestation. So you can install and operate it immediately without any worries. Below, we look at the advantages and disadvantages of using relief valves in various applications and advise further practical information.

Advantages and disadvantages of safety valves in various applications

There is a huge safety benefit to having a safety valve in a pressure system, but it is good to know the potential disadvantages or limitations. Here is an overview of the main advantages and disadvantages of using relief valves across different applications:

Benefits of using a safety valve

• Protection of equipment and persons: the safety valve reliably protects against explosion or bursting of the pressure vessel or pipeline. In the event of a hazard, it automatically drops the media to prevent an accident, protecting property and human health.

• Automatic operation without the need for power: The valve operates independently based on pressure, no electricity or other actuator is required. This ensures protection even in the event of a power failure or control system failure.

• Repeatable function: unlike disposable safety valves (e.g. bursting diaphragms), the safety valve can be used repeatedly. After the pressure drops, it closes and is ready to intervene again at the next overpressure. You don't have to change it after one blowout (unless it's been damaged).

• Wide applicability: there are valves for different media and conditions, so there is a solution for most applications - from a small compressor in the workshop to a large steam boiler or cryogenic storage tank. Safety valves are universal and customizable.

• Compliance with legislation: most pressure equipment is legally required to have an overpressure relief device. By installing a certified safety valve, you will meet the relevant standards (e.g. ČSN, PED) and the inspection engineer finds the equipment safe for operation.

Disadvantages and limitations

• The necessity of making the right choice: An improperly selected valve can cause problems - for example, if it has too low a relief capacity, it will not release pressure fast enough; or conversely, if it is set to a higher pressure than the design limit of the device. Selecting the correct type and setting is therefore critical (see section below on How to select the correct relief valve).

• Maintenance and inspection: Although the valve operates automatically, it is not completely maintenance-free. Regular inspections are recommended, especially in demanding operations. Sediment, corrosion or dirt can cause leakage (the valve will leak even under operating pressure) or prevent the valve from opening. The valve should therefore be checked, cleaned or tested for functionality from time to time (many valves have a test lever for this purpose).

• Possible medium leaks and noise: when the valve opens, the medium is released into the surroundings - this can be noisy (hissing, whistling under pressure) and in the case of steam or hazardous gases, potentially dangerous for the surroundings. Therefore, in sensitive applications, the valve is sometimes piped to a safe zone or to the outdoors. However, a short-term spill is usually the price of averting a major accident.

• Wear and limited service life: Prolonged exposure to pressure can cause fatigue of the spring or valve seal. Aging of the material (e.g. rubber bands) can cause the valve to leak perfectly or change its opening pressure slightly after a few years. Therefore, manufacturers often state that the valve should be reconditioned or replaced after certain years of operation (typically after 5-10 years, depending on conditions, or even sooner for very frequently stressed valves).

• Higher purchase cost for large valves: for very high pressures or flows, certified relief valves can be a relatively expensive part of the system. However, this investment is necessary and worthwhile compared to the cost of potential damage.

In general, the advantages far outweigh the disadvantages - the safety valve is a safety feature that the pressure system cannot do without. Disadvantages can be minimized by proper selection, installation and maintenance. Next, we will focus on specific examples of the use of safety valves in practice.

Areas of application - practical examples

Safety valves are used in many industries. Below are some typical application areas, accompanied by specific examples:

Compressor stations and air systems

Each reciprocating or screw compressor usually incorporates a safety valve on the air tank (compressed air pressure vessel). If the automatic pressure monitoring fails, or if the power goes out, for example. if the mains supply fails and the compressor continues to run, the valve will react and blow off the excess air. In industrial compressor stations where there are multiple compressors and large storage tanks, larger high flow relief valves are also used. An example would be a compressed air distribution system in a factory - there is a safety valve on the main line set at e.g. 1.1 times the working pressure to protect the network from exceeding the limits. The advantage in these systems is that the valves prevent damage to expensive compressors and pneumatic equipment; the disadvantage is perhaps the need for occasional checks to see if dusty air has caused the valve seat to become damaged.

Pressure vessels and tanks

Each individual pressure vessel (air receiver, gas tank, expansion tank, fire extinguishing cylinder, etc.) must have its own pressure safety equipment. The relief valve on the vessel is usually calibrated to the maximum allowable pressure of the vessel. For example, process nitrogen storage tanks will have a stainless steel relief valve set to a pressure that the vessel design can withstand. Should overheating or overfilling occur and the pressure rises, the valve will drop the medium. In practice, you will see safety valves on domestic boilers (water heaters) - these protect the boiler from excessive water pressure during heating. Similarly, gas cylinders have an integrated safety diaphragm or valve to prevent overpressure at higher temperatures. In the pressure vessel sector, the valve is a necessity; its correct functioning is regularly verified during inspections of pressure equipment.

Steam distribution and heating plants

In heating and industry, saturated steam is widely used for heating or technological processes. Steam boilers and piping are extremely dangerous if over-pressurised - that's why they have robust safety valves. Steam relief valves tend to be large cast iron or steel valves with flanges, often fitted with a manual lever for occasional testing (required by standards for boilers). For example, at the outlet of a steam boiler with a pressure of 10 bar, there may be a safety valve set to about 11 bar, which in the event of a burner failure will discharge excess steam into the exhaust pipe. Additional valves can be located at critical points in the steam distribution system (e.g. upstream of heat exchangers). The advantage is obvious - prevention of boiler or pipe explosion. The disadvantage can be hot steam escaping when the valve is hit, which requires safe routing away from people. Relief valves in these applications are usually checked very frequently and must be in top condition.

Industrial refrigeration and air conditioning systems

Refrigeration circuits in industry (e.g. large freezers, food processing plants) use compressors and condensers with refrigerant under pressure. A common medium is ammonia (NH₃) or other refrigerant, which increases the pressure considerably when the temperature rises. There are safety valves on all pressure parts of such systems (compressor, condenser, refrigerant tank). For example, when the condenser cooling fails, the pressure rises sharply and the valve opens to protect the system. For refrigerants, it is important that the valve is suitable for the medium - e.g. for ammonia, steel valves are used (brass would be chemically compromised). Care should also be taken to vent the fumes outside the room as the refrigerant can be toxic or smell unpleasant (ammonia). Similarly, large R410a or CO₂ air conditioners have their own safety valves. These applications show that safety valves protect not only the equipment but also the surroundings from leakage of hazardous substances - even if some controlled leakage occurs when the valve is operated.

Other industrial applications

Special cases can also be mentioned: oil and gas industry (oil tanks, gas tanks - safety valves prevent overpressure in case of fire or failure, often in conjunction with safety diaphragms), chemical industry (reactors, autoclaves with the need to release pressure during exothermic reactions), pharmaceuticals (sterilization equipment), etc. In all these areas, relief valves play the same role - to safely and quickly release dangerous overpressure. At the same time, each sector places specific demands on the valve design (chemical resistant material, food certification, frost resistance, etc.), so manufacturers offer different variants for each sector.

Frequently Asked Questions and Answers (FAQ)

Customers often ask us about the practicalities of safety valves. Here are the answers to the most common questions:

• How do I know the right type of relief valve for my application?
  When selecting, be guided by the type of media and the operating parameters of your system. It is important to determine the medium for which the valve is intended (e.g. whether it is suitable for steam, gas, water, etc.), the pressure it should be set to and the flow capacity (capacity). Also take into account the connection (thread or flange size) and material - for corrosive media choose stainless steel, for normal air just brass etc. All these details can be found in the product description. The correct type of valve is therefore selected by comparing the parameters of the device (pressure, medium, flow) with the parameters specified for the safety valve. If you are in doubt, we will be happy to advise you; see also our detailed article How to choose the right safety valvewhere the selection is explained step by step.

• How often does the safety valve need to be changed or checked?
  A regular functional check at least once a year is highly recommended - ideally in conjunction with a review of the entire pressure system. For smaller valves (e.g. on a boiler), preventive replacement is often recommended after 3-5 years of operation, as water deposits and material fatigue can affect the tightness. In larger industrial systems, safety valves are checked during pressure vessel inspections (usually once a year to once every few years depending on legislation) and replaced or repaired according to condition - for example, every 5 years or if the valve fails a test. It is important to follow the manufacturer's instructions and local regulations. Remember that the valve is a safety feature - if it shows a fault (leaks, jams), do not delay replacement.

• What is the approximate life of the safety valve?
  Lifetime varies according to type and operating conditions. Quality brass or stainless steel valves often last for many years (5-10 years or more) if not frequently activated. However, materials such as springs and seals age - for example, rubber seals can harden over time. If the valve frequently drains (operates close to the opening limit), it will wear out faster. In general, after 5 years of continuous operation, it is advisable to inspect or service the valve. Some manufacturers also specify a maximum recommended service life after which the valve should be repaired or recertified. However, with careful operation and good maintenance, the valve can last more than 10 years. The key is to regularly test its function (occasionally manually blow out debris with lever valves) and check for leaks.

• Can I set the valve opening pressure myself?
  Normally not - the settings are made by the manufacturer or supplier during calibration. The safety valves in our offer are delivered already set to the pressure you require (within the valve specification) and sealed. This ensures that the settings have not been tampered with. Home pressure adjustment is not recommended because it requires special equipment (pressure sources, calibrated gauge) and knowledge. Incorrect settings can be dangerous and illegal. If you need a different opening pressure, please specify this when ordering or consult us - we will arrange the setting professionally. The exception to this is some small safety valves on heaters/boilers which may have an adjusting screw, but even there it should only be handled by a knowledgeable technician.

• What to do if the relief valve is "blowing" or leaking when it shouldn't?
  If the valve is leaking fluid when the system pressure is below the valve setpoint, this indicates a leak or malfunction. This may be a small leak caused by dirt on the seat - try a short gentle blow off (clean the seat) on valves with a hand lever. If the valve is still leaking, it is probably worn or damaged (broken spring, defective seal, etc.). In this case, the valve must be replaced or reconditioned. Operation with a leaking relief valve is not suitable - the system loses medium (air leakage reduces compressor pressure, water leakage from the boiler increases consumption, etc.) and the valve may not hold pressure properly in the event of a crash. The solution is to disassemble and repair/replace the valve. If you are unsure of the cause, we recommend calling a professional service centre.

More useful information for customers

Filter by Parameters On this page you can further filter the range of safety valves by type, certification or media. This means that you can easily select only TÜV-certified valves, for example, or view only brass valves for air. Using the filter will save you time when searching for a suitable product.

Advice and professional help: If you are unsure about your choice or need help with technical details, please visit our online advice (articles section). In addition to the aforementioned guide to selecting a safety valve, you will also find other useful hints and tips from the field of pressure technology. Alternatively, you can contact our customer support team - we'll be happy to help you design a tailored solution.

Installation and maintenance: always read the manufacturer's instructions carefully before installation. The valve is usually mounted directly on the highest point of the pressure vessel or pipe (to prevent possible liquid leakage) and vertically, unless otherwise specified. Ensure that there is sufficient space around the valve for servicing or inspections. Visually inspect the valve periodically (e.g. once a year) and for models with a lever, perform a test blow-off to ensure that it is not rusted and that the passage is not blocked. Entrust the maintenance of larger industrial valves to a specialist company as part of periodic inspections.

Related equipment: in addition to the relief valves, it may be useful to check other components of the pressure system. These include pressure reducing valves (maintain the working pressure, reducing stress on the relief valve), pressure gauges (pressure gauges to monitor whether you are approaching the opening pressure), or bursting diaphragms for critical applications (as additional protection). These elements, together with the safety valve, can increase the safety and reliability of your equipment.

Finally, remember that safety always comes first. A properly selected and maintained relief valve will ensure a restful night's sleep and long-term reliable operation of your pressure equipment. In our e-shop you will find all safety valve designs - from small brass pieces to large industrial valves - and we provide expert advice on all of them. We hope that this detailed category description will help you to navigate the range and choose the right safety valve for your needs. Have a safe trip!

Thanks for the warning! Here is the edited text for the main category of safety valves, which clearly links to both the parametric categories by certification and by medium - all with internal linking within the domain:

🔍 Looking for a safety valve by media or certification? Simply choose based on what you are dealing with in your system:

✅ Safety valves by medium:

• For compressed air - compressors, air blowers, pneumatic systems
• For water - heating circuits, hot water, boilers, solar systems
• For steam - steam boilers, heat exchangers, sterilizers
• For oil - hydraulics, lubrication systems, gearboxes
• Pro inertní plyny (např. N₂, Ar, CO₂) - laboratory, food and process applications
• For nitrogen - pressure vessels, cryogenic storage tanks, laser technology
• For cryogenic gases (LIN, LOX, LAR, LNG) - liquid technical gases, freezing technology
• For diesel and fuel oils - pumping stations, heating, storage tanks

🔒 S afety valves according to TÜV certification:

• TÜV-SV.1048 - for liquids and gases in normal operation
• TÜV-SV746 D/G - for liquids and gases, pressure systems
• TÜV-SV581-F - certification for liquid media (e.g. water, oil)
• TÜV-SV749 D/G - universal use for steam, gases and liquids
• TÜV-SV1090 S/G - certified solution for steam and gases in industry

💡 Not sure about your choice? Check out the advice center:
👉 How to choose the right safety valve - A clear guide with practical tips for selecting a valve according to media, pressure and operating conditions.