Varec Series 221 Emergency Pressure Relief Manway Covers

Description

The Varec Series 221 Emergency Pressure Relief Manway Covers are designed to provide emergency venting for low-pressure storage tanks and vessels, protecting them from rupture or implosion due to excessive internal pressure or vacuum conditions.

This series includes:

• 221P Model – Emergency pressure relief only, with vacuum relief provided by a separate breather valve.

• 221PV Model – Combines both pressure and vacuum relief, featuring a spring-loaded vacuum relief valve integrated into the cover assembly.

The cast metal cover enhances durability and longevity, while the hinged design ensures proper reseating, improved safety, and prevents cover separation from the base. The cover is easily lifted open, providing a large, unobstructed passage for easy access to the tank.

For added protection, the weather hood and screen shield the venting system from environmental elements. The non-metallic seat insert on the pallet minimizes leakage, while the reinforced fabric diaphragm and compressible non-metallic pads provide enhanced sealing performance and reduced leakage.

This series offers custom material options to suit various chemical and industrial applications.

Key Features

• Emergency Venting Protection: Prevents rupture or implosion in low-pressure storage tanks.

• Multiple Models Available:

  • 221P for pressure relief only.

  • 221PV for both pressure and vacuum relief.

• Strong & Durable Construction: Cast metal cover ensures extended service life.

• Hinged Cover Design: Provides a fixed pivot point, ensuring proper reseating and increased safety.

• Secure Installation: Cover remains attached to the base to prevent loss or misalignment.

• Large Unobstructed Passage: Easy access for tank maintenance and inspection.

• Spring-Loaded Vacuum Relief (221PV Model): Built-in vacuum relief valve for dual protection.

• Weather-Resistant Design: Includes a weather hood and screen for added protection.

• Leakage Minimization:

  • Non-metallic seat insert for tight sealing.

  • Reinforced fabric diaphragm with cellular non-metallic pads for extra cushioning.

• Material Customization: Available in various materials for compatibility with chemical applications.

Technical Specifications

1. Materials & Construction

• Base Materials:

  • Carbon Steel (with Stainless Steel Seating Surface – Standard)

  • Aluminum (Optional)

  • 316 Stainless Steel (Optional)

• Cover Materials:

  • Low Copper Aluminum (Standard)

  • Carbon Steel (Optional)

  • 316 Stainless Steel (Optional)

• Diaphragm & Seating Pads:

  • Standard: Nitrile (NBR) diaphragm with Neoprene (CR) pads

  • Optional:

    • PTFE diaphragm with Neoprene (CR) pads

    • Fluorocarbon (FKM) diaphragm with Fluorocarbon (FKM) pads

    • PTFE diaphragm with Expanded-PTFE pads

• Vacuum Insert (221PV Only):

  • Standard: Nitrile (NBR)

  • Optional: PTFE or Fluorocarbon (FKM)

• Vacuum Pallet Assembly (221PV Only):

  • Standard: Aluminum

  • Optional: 316 Stainless Steel

• Hardware: 304 Stainless Steel (spring retainer, hinge pin, fasteners, etc.)

2. Available Sizes & Connections

• Sizes: 18", 20", 24" (450 mm, 500 mm, 600 mm)

• Flange Drilling:

  • Standard: API 650 dimensions, flat face flange

  • Optional: ANSI 150# dimensions, flat face flange

  • Custom: DIN, JPI, JIS available upon request

3. Pressure & Vacuum Relief Settings

• Pressure Settings: ½ to 6 oz/in² (22 to 264 kg/m²)

• Vacuum Settings (221PV): ½ to 1 oz/in² (22 to 44 kg/m²)

4. Flow Capacity & Performance

• Tested per API Standard 2000

• Designed for high flow capacity, allowing rapid pressure equalization to prevent tank damage.

Applications

• Low-Pressure Storage Tanks & Vessels

• Emergency Pressure & Vacuum Relief Systems

• Chemical & Petrochemical Processing Facilities

• Oil & Gas Storage

• Pharmaceutical & Industrial Processing Plants

• Tank Farms & Refinery Applications