Vent Valves & Flame Arrestors

Vent valves and flame arrestors are essential safety and environmental control components for underground storage tanks (UST) in fuel retail and commercial fueling facilities. These devices regulate tank pressure and vapor flow, prevent hazardous overpressure or vacuum conditions, and block flame propagation into the tank, ensuring safe, compliant fuel storage and dispensing operations. Leading manufacturers such as OPW, EMCO Wheaton, and Franklin Fueling (EBW) deliver a wide range of industry‑tested venting solutions. 

Role of Vent Valves and Flame Arrestors in UST Systems

Vent valves provide controlled ventilation for underground tanks by regulating the escape of vapors and the entry of air. They maintain the balance between internal pressure and external vacuum during normal operations and fuel delivery. Flame arrestors, when combined with vent valves or installed independently, protect tanks by extinguishing flames and preventing fire or explosion hazards. Together, they play a critical role in operational safety, environmental compliance, and equipment longevity.

Core Components and Functions
1. Pressure/Vacuum (P/V) Vent Valves

Pressure/vacuum vent valves are designed to allow controlled venting of vapors from the tank while preventing excessive pressure or vacuum buildup that can damage tank structures or compromise seals. The internal mechanism typically uses diaphragms or poppets calibrated to specific cracking pressures for various regions and standards. 

Key Roles:

Permit controlled release of vapors at preset pressure thresholds

Allow air intake when internal vacuum exceeds safe limits

Help maintain tank structural integrity and prevent vapor lock or collapse

Design Highlights:

Rolling diaphragm or poppet mechanism ensures precise opening/closing

Sealed construction minimizes leakage and environmental emissions

UV‑resistant materials extend service life in outdoor conditions

Options to support in‑line grade level maintenance and testing without equipment removal 

2. Vent Valves With Built‑In Flame Arrestors

When local codes require additional fire safety measures, vent valves can be equipped with integrated flame arrestors. These devices use fine mesh or engineered internal structures to prevent flames from propagating down into the tank upon exposure to external ignition sources. 

Common Features:

Flame‑resistant screens or mesh that block flame fronts

Combined pressure/vacuum regulation and flame suppression

Designed to comply with fire safety standards such as EN ISO 16852

Configurations suitable for various regional cracking pressure requirements (e.g., US, UK, China) 

3. Open Atmospheric Vent Valves

Open atmospheric vents allow unrestrained venting of vapor to the atmosphere and are typically used where controlled PV venting is not required or as auxiliary venting. They are simple in construction and include screens to block debris, insects, and water. 

Typical Characteristics:

Always open path to atmosphere

Screened outlet reduces contamination or clogging

Often made from zinc/aluminum or cast iron with corrosion‑resistant mesh

Leading Manufacturer Technologies
OPW Retail Fueling

OPW provides a wide range of venting solutions, including pressure/vacuum vents with corrosion‑resistant bodies and brass mesh flame arrestors. Their vents often incorporate precision‑machined poppets and factory‑preset pressure/vacuum settings to protect tanks and reduce vapor loss. 

Examples Included:

OPW pressure/vacuum vents with flame arrestor options

Open atmospheric utility vents for diesel and motor oil storage

Emergency vents that provide high‑capacity relief in fire or blockage events 

EMCO Wheaton

EMCO Wheaton offers pressure/vacuum venting solutions integrated into UST manhole assemblies or sold as stand‑alone devices. Their vents are designed for high‑flow vapor regulation and long‑term reliability. EMCO may also include debris screens and weatherproofing to protect vent paths. 

Franklin Fueling (EBW)

Franklin Fueling (EBW) provides a series of extractor and vent valves engineered to fit standard tank openings and support manifolded tank piping and vapor recovery systems. EBW vent products are electrocoated for broad fuel compatibility, including alcohol and biodiesel blends, and are designed to integrate easily into retail fueling infrastructure. 

Additional Notes:

EBW vent valves support Stage II vapor recovery installations

Extractor vent fittings allow efficient vapor extraction from multiple outlets 

Applications

Vent valves and flame arrestors are essential for:

Retail service station underground storage tanks

Commercial and industrial fueling terminals

Fleet fueling infrastructure

Environmental compliance and emission control programs

Proper venting ensures tanks breathe safely during changing liquid levels, prevents excessive pressure/vacuum events, and protects against external fire hazards.

Advantages of Using Advanced Venting Solutions

Pressure and Vacuum Regulation: Prevents structural damage and vapor lock

Fire Protection: Integrated flame arrestors enhance safety in high‑risk zones

Environmental Compliance: Minimizes vapor emissions and meets global standards

Durability: UV‑resistant materials and corrosion‑resistant screens for long service life

Serviceability: Grade‑level maintenance options reduce downtime