Vacuum Breakers – Reliable Underpressure Protection

Vacuum breaker for industrial systems – reliable protection against negative pressure in pipelines

PRODUCT CONFIGURATOR

Our product range: Vacuum breakers for every requirement

Our portfolio comprises two primary designs, which differ in terms of installation, pressure range and area of application.

Sleeve vacuum breaker for threaded installation

These compact valves are designed for direct installation in threaded sockets (sockets) and are ideal for smaller nominal diameters and standard pressure ranges.

VB 14 – The economic standard made of brass: The VB 14 is a vacuum breaker made of brass (Cu Zn 39 Pb3) with a stainless steel ball (Z 100 CD 17). With a Rp 1/2" socket connection and an Rp 1/8" outlet bore in accordance with DIN EN 10226-1, it is designed for general applications in condensation steam or liquid systems. It opens at a low differential pressure (Δp) of only 6 mbar and is intended for vertical installation. A drip line can be connected to the outlet as an option.

VB 21 – The corrosion-resistant stainless steel solution for more demanding media or environments, we offer the VB 21 – a vacuum breaker made of stainless steel. Its housing is made of 1.4305 (AISI 303) stainless steel, and the ball is made of AISI 440 C. With the same functionality and connection standard as the VB 14, it impresses with its higher chemical resistance and a maximum operating pressure of PN25.

Interflange vacuum breaker for industrial processes

Gestra's intermediate flange vacuum breakers are the first choice for higher pressures, larger nominal diameters and direct installation in flanged pipes. The RKE 86 series combines the function of a non-return valve with that of a vacuum vent valve.

Highly flexible and robust: The valves are suitable for installation between flanges of the PN10, PN16, PN40 and ASME Class 125, 150 and 300 standards. Thanks to their short overall length in accordance with EN 558, Series 49, they are particularly space-saving.

For the most demanding conditions: They have a metal seat and are designed for continuous use in demanding steam and liquid systems. The body of the standard series is made of chrome steel 1.4317, the valve plate and spring are made of stainless steel 1.4571.
Stainless steel version: For maximum corrosion resistance, the RKE 86A series is available with a housing made of 1.4408 stainless steel.

Typical areas of application for vacuum breakers

Steam pipes and condensate systems: Prevents air from being sucked into condensate pipes after shutdown and protects steam traps.

Tanks and containers: Protects against implosion during cooling or emptying (e.g. in chemical tanks).

Cooling and process water pipes: Prevents negative pressure when valves are closed quickly, or pumps are stopped.

Medical and food processing equipment: Ensures hygienic processes by preventing the backflow of contaminated media.

Your partner for safety fittings

As a reliable partner to industry, we offer not only a wide range of high-quality vacuum breakers but also expert technical advice. Many of our products, including the tried-and-tested Gestra interflange vacuum breakers, are available from stock, guaranteeing short delivery times.

Are you unsure which vacuum breaker – whether brass, stainless steel or as an intermediate flange variant – is the right choice for your application? Our team of experts will be happy to assist you in making your selection. Contact us for a no-obligation consultation or request a quote directly.

Frequently Asked Questions – Vacuum Breakers

A vacuum breaker – also called a vacuum relief valve, anti-vacuum valve, or vacuum vent valve – is a fully automatic safety fitting that protects pipeline systems and plant components against the consequences of uncontrolled negative pressure (vacuum or sub-atmospheric pressure). The operating principle:

In normal operation the vacuum breaker is closed – the system operates at working pressure and no medium escapes.
If the system pressure falls below a defined threshold (opening pressure), atmospheric pressure from outside prevails and opens the valve automatically.
Ambient air flows in a controlled manner into the system and equalises the negative pressure – rapidly and without any external control signal or energy supply.
Once the pressure returns to the normal range, the vacuum breaker closes automatically and remains sealed.

The opening pressure of the FERGO socket vacuum breakers (VB14, VB21) is Δp 6 mbar – a very low threshold that detects and compensates even the smallest pressure differentials. The Gestra RKE 86A series additionally protects against backflow (combined check valve and vacuum relief valve). Installation is vertical, with the system connection at the bottom.

Negative pressure develops in pipeline systems faster than expected and can have serious consequences:

Condensation and cooling of steam – When steam in a pipeline condenses and the resulting condensate drains away or is pumped out, the volume collapses abruptly. Without pressure equalisation, a vacuum forms that squeezes the pipeline from outside – potentially causing deformation or implosion.
Abrupt closure of valves – When shut-off valves close rapidly (e.g. quick-closing valves), a pressure drop can form downstream of the valve, causing cavitation, pipe vibration, and damage to pumps and plant components.
Draining or siphoning of liquids – In pipelines carrying liquids that drain from an elevated position, a siphon effect develops. Without a vacuum breaker this can lead to complete emptying of the pipeline and pump damage.
Back-siphonage of contaminated medium – The negative pressure draws contaminated liquids, wastewater, or other undesired media back from the downstream system into the supply line – with serious consequences for product quality, hygiene, and plant safety (particularly critical in drinking water, food, and pharmaceutical applications).
Damage to heat exchangers – Condensed steam in heat exchangers creates negative pressure that compresses the thin heat transfer surfaces, causing permanent damage.

A vacuum breaker prevents all these damage scenarios reliably, fully automatically, and without any external energy supply.

FERGO offers 11 vacuum breaker models in two product families:

VB14 – Socket vacuum breaker in brass (Rp½", PN16) – Compact vacuum breaker with female thread Rp½" to DIN EN 10226-1 for general applications in condensing steam and liquid systems. Body in brass (CuZn39Pb3), ball in stainless steel (1.4408). Opening pressure Δp 6 mbar. Outlet bore Rp1/8" for drip connection. Vertical installation, system connection at bottom. Cost-effective solution for standard applications in heating, refrigeration, and general process engineering.
VB21 – Socket vacuum breaker in stainless steel (Rp½", PN25) – Identical design to VB14, but body in stainless steel 1.4305 (AISI 303) and ball in stainless steel AISI 440C. Opening pressure Δp 6 mbar. For higher corrosion requirements, aggressive media, steam applications, and installations where brass is not permitted (e.g. due to drinking water regulations or chemical compatibility requirements).
Gestra RKE 86A – Wafer vacuum breaker/check valve – The high-performance solution for demanding industrial processes. The RKE 86A combines two functions: vacuum relief valve + check valve in a single wafer-pattern body. Simultaneously protects against negative pressure and undesired backflow. Available for DN15–DN100 with flanged connections PN10/16/25/40, ANSI Class 125/150, and ASME B16.5 Class 300. Stainless steel body. For industrial steam systems, process plants, power stations, and wherever high pressures, demanding operating conditions, and combined vacuum and backflow protection are required.

Vacuum breakers are used wherever negative pressure can develop and pipelines, vessels, or process components need to be protected:

Steam systems and condensate networks – Protection of steam lines, heat exchangers, radiators, and jacketed vessels against vacuum formation when steam condenses. Frequently used in combination with steam traps.
Heating systems (HVAC) – Protection against negative pressure in hot water heating circuits, particularly in elevated pipelines or with fast-closing thermostatic valves.
Drinking water installations – Legally required backflow protection to DIN EN 1717 / DVGW. Vacuum breakers prevent back-siphonage of contaminated water into the drinking water network during sudden pressure drops.
Food and pharmaceutical industry – Hygienic stainless steel versions protect process lines against vacuum formation and prevent back-siphonage of non-permitted media into purified water or product lines.
Irrigation and garden technology – Protection of irrigation systems, borehole installations, and garden distribution networks against back-siphonage from lines or water storage.
Industrial process plants – Gestra RKE 86A for demanding processes in chemicals, petrochemicals, power generation, and wherever high pressures and temperatures and combined vacuum and backflow protection are required.
Refrigeration and cooling systems – Protection against negative pressure during rapid temperature changes and refrigerant condensation in closed systems.

FERGO offers socket vacuum breakers in both materials. The choice depends on the medium, pressure, and application-specific requirements:

Brass (VB14, PN16) – The more economical standard solution for general applications with neutral media such as water, steam, and non-aggressive liquids. Good corrosion resistance to soft and hard water; not suitable for aggressive chemicals or media that attack brass (ammonia, certain acids). Note for drinking water: Depending on the local drinking water regulation and lead content, brass fittings may be restricted or not permitted in drinking water engineering – check applicable regulations before installation.
Stainless steel 1.4305 / AISI 303 (VB21, PN25) – For higher requirements: aggressive media, steam applications, food and pharmaceutical installations, systems with elevated hygiene standards, and wherever brass is not permitted due to material specifications. Stainless steel is more corrosion-resistant, more durable, and safe for food contact. Higher pressure rating (PN25 versus PN16 for the brass version).
Gestra RKE 86A – stainless steel, wafer-pattern – For the most demanding industrial applications with high pressures (up to PN40 / ASME Class 300) and temperatures. Stainless steel body for maximum robustness and corrosion resistance in steam, process, and power plant installations.

The Gestra RKE 86A is the solution for industrial processes that combines two protective mechanisms in a single compact wafer-pattern body:

Vacuum relief valve – Opens automatically under negative pressure and admits air to protect the pipeline and downstream components from vacuum damage – exactly like a standard vacuum breaker.
Check valve – Simultaneously prevents undesired backflow of medium from the downstream system into the supply line. A check valve and a vacuum breaker in a single component saves installation space, reduces pipework complexity, and eliminates an additional potential leak point.

Technical specifications of the RKE 86A:

Design: Wafer-type – compact installation directly between existing pipe flanges; no additional pipe bends or flange adapters required
Nominal sizes: DN15 to DN100
Pressure ratings: PN10, PN16, PN25, PN40, ANSI Class 125/150, ASME B16.5 Class 300
Body: Stainless steel – for steam, hot liquids, and aggressive process media
Typical applications: Steam systems, condensate networks, power plants, chemical and petrochemical process plants, cooling water systems, and wherever high pressures and combined vacuum/backflow protection are required

Correct installation is critical for reliable vacuum breaker performance. The key installation rules:

Vertical installation mandatory (VB14 / VB21) – Socket vacuum breakers must be installed vertically (upright), with the system connection (Rp½") at the bottom. Only in this orientation does the internal ball valve operate correctly: under negative pressure, incoming air lifts the ball and opens the passage; under positive pressure, the ball rests on its seat under its own weight and system pressure, sealing the valve. A horizontal or inverted installation would impair or prevent correct function.
Drip connection (optional) – A drip line can be connected to the outlet bore Rp1/8" to safely drain any condensate or minor leakage – recommended for steam applications and installations where dripping water would be problematic.
Installation position in the system – The vacuum breaker should be installed at the highest point or near the end of the pipeline sections to be protected, where negative pressure is most likely to develop. In steam systems, typically downstream of the last heat exchanger or radiator, before the steam trap.
Gestra RKE 86A – Wafer installation between existing flanged connections. Check manufacturer's instructions for installation orientation.
Ensure accessibility – Install the vacuum breaker in a location that remains accessible for visual inspection and any maintenance.

FERGO stocks 11 vacuum breaker models in two product families, all available from stock:

VB14 (brass, Rp½", PN16) – Socket vacuum breaker for general condensing steam and liquid systems. Opening pressure Δp 6 mbar. Outlet bore Rp1/8".
VB21 (stainless steel 1.4305, Rp½", PN25) – Identical design to VB14, in stainless steel for higher requirements. Opening pressure Δp 6 mbar.
Gestra RKE 86A (stainless steel, wafer-pattern) – Combined vacuum relief valve + check valve. Nominal sizes DN15 to DN100. Pressure ratings: PN10, PN16, PN25, PN40, ANSI Class 125/150, ASME B16.5 Class 300. Multiple size/pressure variants for virtually all industrial pipeline systems internationally.

While the range is compact (11 models), the RKE 86A's breadth of pressure ratings from PN10 to Class 300 and nominal sizes from DN15 to DN100 covers the majority of all industrial vacuum protection requirements. For special requirements outside these parameters, the FERGO team is happy to advise.

Vacuum Breakers (Vacuum Relief Valves) – Reliable Protection Against Negative Pressure