Part Description:

1. Rainproof Hat 2. Birdscreen Cover 3. Telescopic Handle 4. Locking Bolt 5. Pressure Relief Plate 6. Valve Seat 7. Positioning Ring 8. Sling Ring 9. Connecting Flange 10. Casing Section 11. Diaphragm 12. Negative Vacuum Valve Assembly

I. Product Overview

The AD6220 type overpressure/vacuum emergency relief manhole is a safety emergency ventilation device installed on the storage tank roof, commonly used with breathing valves to prevent damage to the tank and accidents due to sudden overpressure inside the tank caused by unexpected reasons. It is particularly suitable for flat-top storage tanks sealed with nitrogen, used for storing materials.

Features include pressure-regulated exhaust, flexible opening and closing, compact structure, excellent sealing performance, and safety reliability. The product employs a 24/7 sealed structure and is a safe exhaust device that regulates the opening and closing of the exhaust cover through the use of counterweights or springs.

II. Operating Principle

Under normal operation of the breathing valve, the emergency vent is basically kept in a sealed state, with the tank at normal pressure. In the event of a malfunctioning breathing valve or fire inside the tank, causing the tank to rapidly overpressurize, the valve disk of the emergency vent will automatically lift to release pressure urgently, maintaining the tank pressure at a normal level. After the pressure release is complete, the valve disk will automatically seat back, maintaining a sealed state.

Section 3: Emergency Relief Manhole Selection Table

Gravity operated-----For operating conditions with a set pressure less than 6.9 KPa, the pressure relief manhole opening pressure can be adjusted using counterweights; generally, a selection of ≤5.0 KPa is used.

Spring-loaded — For operating conditions with a set pressure of ≥6.9 KPa, spring-loaded control can be used for the relief manhole opening pressure. Generally, ≥5.0 KPa is selected.

Vacuum Suction Pressure Setting: -0.2~2.0 KPa.

Section 4: Product Advantages

1. Provide professional emergency venting manhole calculations and CAD drawings based on the data sheet and operating conditions provided by the customer.

2. Eddie summarizes years of design and manufacturing experience, optimizing the emergency vent manhole sealing form, sealing material, pressure set point, flow coefficient, and return-to-seal characteristics. As a result, the emergency vent manhole achieves zero-leakage sealing at 80% of the set pressure.

3. Utilizes an independent valve seat structure and imported FEP diaphragm technology to achieve 10% overpressure technology.

4. FEP film sheets feature resistance to chemical corrosion, adhesion of liquids and steam, extreme temperature resistance, and bonding due to valve seat freezing.

5. Prior to shipment, each unit undergoes testing on a pressure testing platform for opening pressure and leakage, and is released for production upon passing the inspection.

6. Carbon steel valve bodies are internally and externally coated with anti-rust primer, with an epoxy topcoat applied; stainless steel valve bodies are sandblasted.

7. Packaging is uniformly done in standard wooden crates.

5. Installation Precautions

1. Ensure the emergency relief manhole is in an upright position during installation to prevent tipping or excessive tilting that could affect component operation.

2. During hoisting, the ropes should be secured to the four hoisting rings above the emergency relief flange, not on the head or any other part, to prevent deformation of the component.

3. During installation, consider the placement of the breathing valve and nitrogen supply valve; they should not be too close together. Generally, the breathing valve is positioned at the *** level, while the emergency vent valve is located at the second highest level.

V. Relevant Standards for the Products

• API 2000-2014 ------- Ventilation Atmosphere and Low-Pressure Storage Tanks

• SY/T0511.1-2010----"Petroleum Storage Tank Accessories - Part 1: Breathing Valve"

• SH/T3007-2014——Petroleum & Chemical Storage and Transportation System Tank Farm Design Specification

• GB50160-2018-------"Design Fire Protection Standard for Petrochemical Enterprises"