Internal Floating Roof Tank vs. External Floating Roof Tank: Choosing the Right Tank Solution for Your Needs
Created on 08.04
In the world of bulk liquid storage, the choice of tank design is a critical decision that impacts everything from operational safety and environmental compliance to long-term costs. While traditional fixed-roof tanks are still in use, the industry has widely adopted floating roof tanks for storing volatile liquids, thanks to their superior ability to minimize vapor emissions and prevent product loss. Within this category, two primary designs stand out: the Internal Floating Roof Tank (IFRT) and the External Floating Roof Tank (EFRT).
Understanding the fundamental differences between these two tank types is essential for selecting the most suitable and cost-effective solution for a specific application. Both designs are highly effective at their core function, but they are engineered to excel under different conditions and for different purposes. At Shijiazhuang Zhengzhong Technology Co., Ltd, globally known as Center Enamel, we are experts in the design, engineering, and manufacturing of both Internal Floating Roof Tank and External Floating Roof Tank systems. Our role is to provide clients with a clear understanding of the advantages and ideal applications for each, ensuring they receive a tailored, high-performance storage solution that perfectly meets their needs.
What Defines an External Floating Roof Tank (EFRT)?
An External Floating Roof Tank is a cylindrical steel tank with an open top and a floating roof that rests directly on the liquid surface. The roof rises and falls with the liquid level, effectively eliminating the vapor space between the liquid and the roof. A continuous, flexible seal system at the perimeter of the roof, known as the rim seal, bridges the gap between the floating roof and the tank wall.
The EFRT’s main advantages are its simplicity and cost-effectiveness. It is an excellent choice for storing liquids with relatively low volatility and is particularly common in areas with mild climates. The absence of a fixed roof makes the EFRT less expensive to construct initially. However, the floating roof and its seal system are exposed to all environmental conditions, including rain, snow, and wind, which requires a robust drainage system and can make it more susceptible to damage from severe weather.
What Defines an Internal Floating Roof Tank (IFRT)?
An Internal Floating Roof Tank is a fixed-roof tank that houses a floating roof inside its structure. The fixed roof, which can be a dome or a cone, provides a full enclosure. The internal floating roof operates in the same way as an external one, resting on the liquid surface and moving up and down with the liquid level. The seal system also bridges the gap between the floating roof and the tank wall.
The IFRT is typically the preferred choice for storing highly volatile products and for applications where strict emissions control is paramount. The fixed roof provides an essential protective layer, shielding the floating roof and its seals from all external elements. This not only simplifies maintenance but also enhances the longevity of the entire system. While the initial construction cost is higher due to the addition of the fixed roof, the long-term benefits in terms of superior emissions control and reduced maintenance often make it the more economical choice over the tank's lifespan.
A Direct Comparison: Key Differences and Advantages
To help clarify the choice between these two advanced tank designs, here is a direct comparison of their key features:
1. Emissions Control and Regulatory Compliance
External Floating Roof Tank: EFRTs are very effective at reducing evaporative losses compared to fixed-roof tanks. However, emissions can still occur through the rim seal system, especially in windy conditions or if the seal is not maintained properly.
Internal Floating Roof Tank: The IFRT’s fixed roof provides a crucial secondary barrier. It shields the internal floating roof and its seal system from wind and weather, which can otherwise cause seal damage and increased emissions. This makes the IFRT’s emissions control capability superior, particularly for highly volatile liquids or in regions with stringent environmental regulations.
2. Protection from the Elements
External Floating Roof Tank: The floating roof is directly exposed to rain and snow, which must be continuously drained via a roof drain system. Ice and heavy snow loads can pose a risk to the roof's structural integrity. Strong winds can also disrupt the seal system.
Internal Floating Roof Tank: The fixed roof completely protects the floating roof from weather-related issues. This eliminates the need for a roof drainage system, simplifies maintenance, and prevents the buildup of snow or ice. This is a significant advantage for tanks located in regions with harsh weather conditions.
3. Safety and Fire Prevention
External Floating Roof Tank: The open-top design means the tank is susceptible to lightning strikes. While the floating roof itself helps minimize the vapor space, a flammable vapor-air mixture can still accumulate in the rim space, which poses a safety risk.
Internal Floating Roof Tank: The fixed roof provides a robust barrier against lightning strikes and other external ignition sources. The space between the fixed roof and the floating roof can be purged with an inert gas, further reducing the risk of fire or explosion. The IFRT is generally considered the safer option for storing highly flammable liquids.
4. Maintenance and Operational Costs
External Floating Roof Tank: Maintenance is required to inspect and repair the rim seal and the roof's drainage system. The exposure to the elements means these components may require more frequent attention.
Internal Floating Roof Tank: The fixed roof protects the floating roof and seals, reducing the frequency of maintenance. However, access for inspection and repair of the floating roof requires personnel to enter the tank, a more complex and time-consuming process than with an EFRT. Despite this, the reduced maintenance needs over the long term often lead to lower operational costs.
5. When to Choose Which Tank
Choose an External Floating Roof Tank when: Storing low-volatility liquids, operating in a mild climate, and when initial cost is a primary concern.
Choose an Internal Floating Roof Tank when: Storing high-volatility liquids, operating in a harsh climate with heavy precipitation or wind, and when superior emissions control and enhanced safety are the highest priorities.
Center Enamel's Expertise in Floating Roof Tank Solutions
At Center Enamel, we don't just supply tanks; we provide comprehensive, expertly engineered solutions. As a leading manufacturer of both Internal Floating Roof Tank and External Floating Roof Tank systems, we are uniquely positioned to consult with our clients to determine the optimal design for their specific needs. Our expertise in fabricating tanks to meet stringent international standards ensures that every solution we deliver is of the highest quality, safety, and reliability. We understand the nuances of material selection, seal system design, and structural engineering to provide a tank that is perfectly suited to its intended purpose.
A Proven Track Record in High-Stakes Applications
Center Enamel's reputation is built on a foundation of successful projects and a deep commitment to excellence. Our work on challenging industrial applications demonstrates our capability to deliver reliable, high-performance storage solutions.
Project Case Study: Huadong Medicine Zhejiang Hangzhou Pharmaceutical Plant Wastewater Treatment Project
This significant project exemplifies Center Enamel's robust capabilities in providing critical storage solutions for highly specialized industrial applications. For the Huadong Medicine Zhejiang Hangzhou Pharmaceutical Plant Wastewater Treatment Project, Center Enamel supplied multiple storage tanks featuring advanced roofing systems. This extensive installation underscores our expertise in delivering high-performance storage solutions essential for environmentally sensitive operations, ensuring secure containment and effective treatment processes for complex industrial wastewaters in the pharmaceutical sector. This project demonstrates Center Enamel's unwavering commitment to supporting vital industries with high-quality, reliable storage infrastructure where precise containment, material compatibility, and long-term performance are paramount—qualities that are directly embodied in every Internal Floating Roof Tank and External Floating Roof Tank we supply.
The Final Decision: A Strategic Partnership
The decision between an Internal Floating Roof Tank and an External Floating Roof Tank is not about which is inherently "better," but which is the "right" solution for your specific operational, environmental, and economic context. It is a strategic choice that requires careful consideration of all factors. By partnering with a knowledgeable and experienced manufacturer like Center Enamel, you gain access to the expertise needed to make that choice with confidence. We provide the quality, engineering, and support to ensure that your investment in either an Internal Floating Roof Tank or an External Floating Roof Tank delivers superior performance and value for decades to come.