MEGTEC designs and installs permanent total enclosures (PTE) for a wide variety of applications. Permanent total enclosures systems are included as part of turnkey oxidizer installation projects or as upgrades to existing systems.
In the U.S., regulations require Volatile Organic Compound (VOC) control projects maintain an overall Control System Efficiency (CSE) of 95% or greater. In many industries, on new installations, and for some highly toxic chemicals, overall control efficiencies of 98% or even higher may be required. These high levels of VOC control explain the need for well-designed air handling, capture and control equipment to maintain compliance. For many applications, capture hoods and floor sweeps alone will not achieve this level of control. Most state-of-the-art VOC control schemes now include Permanent Total Enclosures (PTEs) as a necessity to meet federal and state regulations.
A PTE can be defined as "a permanently installed enclosure that completely surrounds a source of emissions such that all VOC emissions are captured and contained for discharge to a control device". By definition, a permanent total enclosure constructed to the Agency's specifications is presumed to preclude any fugitive emissions escaping to atmosphere.
Capture systems and PTEs may take many forms, but in essence, every capture system and PTE design must address common challenges such as regulatory requirements, safety and health considerations and operational issues. Each of these focus areas must be viewed separately as well as in conjunction with each other, since each presents a combination of interrelated and unique design challenges. The capture systems or PTE, in conjunction with high efficiency emission control devices, allow companies to successfully comply with EPA regulations*. In many applications the addition of well-designed permanent total enclosures has resulted in better process control, improved quality and reduced waste. Contact us today to learn more about MEGTEC permanent total enclosures, capture systems and our environmental technologies.
*Review of EPA Method 204 Requirements:
The following five criteria, established by the EPA under test Method 204, must be met for an enclosure to qualify as a PTE.
- Any natural draft opening (NDO) shall be at least 4 equivalent opening diameters from each VOC emitting source. An equivalent diameter is equal to the diameter of circle that has the same area as the opening.
- The total area of combined NDO's shall not exceed 5% of the total surface area of the enclosure including the floor and ceiling.
- The average face velocity (FV) of air through the NDO's shall be at least 200 ft/min and the direction of flow shall be into the enclosure.
- All access doors and windows not included as NDOs shall be closed during routine operation of the process.
- All exhaust gases from the enclosure must be directed to a control device.
Most State and local regulatory agencies have adopted these criteria as a basis for PTE design.
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