A Pressure & Vacuum Breather Valve (PVRV) — also known as a conservation vent or breather vent — is a safety-critical device installed on storage tanks to protect them from excessive internal pressure or vacuum. It allows controlled venting of gases or air only when preset pressure or vacuum thresholds are exceeded, thereby minimizing product loss and preventing structural damage to the tank.
These valves are essential for maintaining tank integrity, product conservation, and environmental compliance.
Tank Protection: Prevents over-pressurization and implosion caused by thermal expansion, product filling/emptying, or external temperature changes.
Emission Control: Minimizes vapor loss by venting only when required, contributing to environmental protection.
Product Conservation: Reduces evaporation losses of stored liquids.
Improves Safety: Controls and limits hazardous gas release to reduce explosion and fire risks.
Cost Efficiency: Passive device with low operational and maintenance costs.
Regulatory Compliance: Meets standards like API 2000, ISO 28300, and EPA 40 CFR Part 60 (NSPS for storage tanks).
Pressure & Vacuum Breather Valves (PVRVs) are critical safety components installed on atmospheric and low-pressure storage tanks. Their primary role is to maintain safe internal pressure by relieving excess pressure and vacuum that can result from filling, emptying, or ambient temperature changes.
Combined Pressure/Vacuum Valve – Performs both functions in a single unit and is the most common type used.
Spring-loaded Type – Uses calibrated springs to control opening pressure.
Weight-loaded Type – Uses adjustable weights for pressure/vacuum control.
Pilot-operated Type – For more precise set point control and reduced leakage.
With Flame Arrester – Integrated or separate flame arresters for flammable vapor service.
Oil & Gas Terminals – For tank protection and emission control.
Chemical Processing – Handles vapors from solvents, acids, or flammable liquids.
Pharmaceutical Manufacturing – Prevents contamination and vapor loss in sensitive chemical storage.
Food & Beverage Plants – Used in edible oil, syrup, and alcohol storage.
Paint & Coating Industry – To control emissions from volatile organic compounds (VOCs).
Biofuel & Ethanol Facilities – Essential for preventing explosion risks and conserving product.
Wastewater Treatment Plants – Installed on gas-holding tanks or sludge digesters.
| Feature | Specification |
|---|---|
| Design Standard | API 2000, ISO 28300, NFPA, ASME |
| Material Options | Aluminum, stainless steel, carbon steel |
| Pressure Set Points | Typically from 50 mm W.G up to 2500 mm W.G (customizable) |
| Vacuum Set Points | From 25 mm W.G up to 500 mm W.G or more (depending on design) |
| Size Range | 2” to 12” (DN 50 to DN 300) |
| Seal Type | Buna-N, FKM (Viton), EPDM, PTFE (Teflon) |
| Mounting Type | Flanged (ANSI/DIN), threaded |
| Operating Temperature Range | -40°C to +200°C (based on materials) |
| Optional Features | Flame arresters, weather hoods, lifting levers, limit switches |
Mount on the tank’s vapor outlet nozzle, typically on the roof.
Ensure correct orientation (vertical) and match the flange rating and gasket material to the tank and product.
Follow clearance requirements to allow proper valve lift during operation.
Use weather protection (hood or screen) for outdoor installations.
For hazardous areas, include flame arresters or install in conjunction with inert gas blanketing systems.
Inspection Frequency: Every 6–12 months or per regulatory guidance.
Cleaning: Remove dirt, corrosion, or product buildup from seats, pallets, and guides.
Seal Check: Inspect gaskets and diaphragms for cracks or warping.
Function Testing: Perform lift tests or simulated over/underpressure tests to ensure proper actuation.
Calibration: Recheck pressure/vacuum set points during scheduled inspections.
Vapor Emission Reduction: Helps meet VOC emission limits by only venting when pressure thresholds are exceeded.
Supports Product Stewardship: Reduces evaporation and conserves volatile products.
Energy-Free Operation: Operates mechanically without external power.
Long Service Life: Durable construction reduces material waste and replacement frequency.
Recyclable Materials: Aluminum and steel bodies are fully recyclable.
Replaceable Parts: Internal seals and pallets can be replaced without discarding the entire valve.
Low Carbon Footprint: Passive technology, no energy consumption during normal operations.
Leaking Valves can result in fugitive emissions.
Stuck Pallets may cause tank collapse or over-pressurization.
Incorrect Set Points can lead to excessive venting or unsafe pressure buildup.
