Pressure Vacuum Relief Valves & Related Safety Equipment

Ensuring the safety and compliance of storage tanks, chemical plants, oil & gas installations, and industrial pipelines in Pakistan demands high-quality equipment. Leading suppliers in Pakistan offer a full suite of essential components:

Pressure Vacuum Relief Valves (PVRVs)
Emergency Vents & Manways
Flame Arresters
Gauge Hatches
Free Vents & Rim Vents
Float Gauges

These components prevent overpressure, vacuum collapse, and flame propagation and ensure operational visibility and safety. This guide provides in-depth insights into products, applications, standards, and local suppliers.

🔧 Pressure Vacuum Relief Valves (PVRVs)

What they do: PVRVs, also known as breather valves or conservation vents, maintain safe internal pressure on storage tanks and vessels. They open at set positive or negative pressures to protect against rupture or implosion.

Technical Specs:

Operating Range: From low vacuum to high pressure (e.g., Sewon models: –45 °C to +120 °C, set pressure from 22 to 10,000 mmWC)
Construction: Typically spring/weight-loaded, with flanged ANSI B16.5, SS304/SS316 bodies.
Standards: Manufactured per API 2000 / ISO 28300, ASME, EN norms

Benefits:

Prevent structural failures caused by pressure/vacuum buildup.
Minimize product vapour losses, preserving environmental compliance.

Top Local Suppliers:

Bliss Flow Systems distributes API‑2000 certified valves in South Asia
Karachi-based industrial valve vendors via directories such as Go4WorldBusiness.

🚨 Emergency Vents & Tank Manways

Purpose: Emergency vents (rupture panels) and manways act as fail-safe openings to rapidly relieve pressure in explosions or thermal events.

Rupture Discs: One-time-use thin metal panels that burst at preset pressure, preventing catastrophic failure.
Tank Manways: Provide personnel access for maintenance, hydrostatic testing, and emergency escape routes.

Compliance: Often installed per ASME VIII or EN 764‑7 standards.

🔥 Flame Arresters

Functionality: Passive safety devices installed in vents to stop flame propagation while allowing gas flow.

Typically coupled with PVRVs to prevent ignition through the relief system.
Constructed of stainless steel with fine mesh internals.

Local Presence: Global manufacturers like Sewon/Valmatic specify integrated flame arresters for PVRVs; local implementation follows suit.

📊 Gauge Hatches (Level Indicator Ports)

Use: Provide visual inspection points for internal liquid levels, especially in storage tanks.

Include transparent sight glass or bolted manway designs.
Available in various ANSI flange standards and materials like SS316 or aluminium.

Benefits: Enable safe level checks without disrupting tank integrity.

🌬️ Free Vents & Rim Vents

Free Vents: Simple vent ports for equalising pressure, used in non-hazardous service.

Rim Vents: Mounted at floating roof tank rims to prevent hydrostatic collapse during rainwater accumulation.

May include screening or flame arresting elements.
Kept open during normal operation; closed under abnormal pressure scenarios.

💧 Float Gauges (Level Measurement Devices)

Operation: Float gauges measure liquid levels via buoyant floats linked to indicators on the outside of tanks.

Provide continuous level monitoring: open/close switch signals or mechanical indicator rods.
Common materials: stainless steel, brass, or aluminium.
Rated for chemical compatibility and high-pressure service.

⚙️ Technical Standards & Material Considerations

API 2000 / ISO 28300: Governing design and testing of PVRVs, making sure leakage <1 SCFH at 90% set pressure.
ASME B16.5, API 526, 527: Define flange dimensions, seat tightness, set pressure, blowdown, etc. .
Materials: SS316/SS304, aluminium, carbon steel, ductile iron; elastomers like Viton or Teflon ensure chemical resilience.

🛠️ Choosing the Right Equipment

Product	Key Parameters	Applications
PVRV	Set pressure/vacuum, leak tightness, material	Tank breathers in petrochemical and LPG storage
Emergency Vent	Burst disc rating, panel area	Pressure surge/emergency relief
Flame Arrester	Mesh specifications, flow rating	Vent lines, PVRV protection
Gauge Hatch	Glass type, flange rating	Level inspection in storage units
Float Gauge	Float material, pressure rating	Continuous liquid level monitoring
Rim Vent	Rain prevention, screen mesh size	Floating roof tanks

🛒 Where to Buy & What to Consider

Compare local stock vs. imported inventory based on lead time.
Ensure certifications: ISO, API, ASME for safety compliance.
Ask for testing reports: factory leak tests and material traceability.
Arrange after-sales services: installation support, calibration, and periodic maintenance.

✅ Final Takeaway

Pakistan’s industrial and petrochemical sectors rely heavily on robust safety hardware like pressure vacuum relief valves, flame arresters, gauge hatches, free/rim vents, and float gauges. By sourcing certified, locally available products from Mirha International, OTC, and Silver String Chemicals, businesses can safeguard assets, personnel, and compliance. Integrating API/ISO/ASME-certified systems ensures both performance and peace of mind.

For personalised consultation, request datasheets or get quotes — connect with suppliers in Karachi and Lahore today.