A removable mullion is a temporary, vertical support structure placed between a pair of doors, offering enhanced security and functionality while allowing for a complete, unobstructed opening when removed.
Understanding Removable Mullions
A mullion, in the context of doorways, is a vertical bar or post that divides the panes of a window or, more commonly, separates the individual doors in a double-door system. While fixed mullions are permanent parts of the frame, a removable mullion offers the unique advantage of being easily installed and detached. This flexibility makes it an invaluable component for specific architectural and functional requirements.
The Mechanism: How a Removable Mullion Functions
Essentially, a standard removable mullion is designed to attach securely to the head of the door frame. Once in place, it sits precisely at the meeting edges of the double doors, acting as a critical stop for both door leaves. This structural element also efficiently covers the gap created where the two doors meet. For enhanced performance, such as improved weatherproofing, sound insulation, or fire ratings, a mullion seal is often installed along its length.
Here's a breakdown of its operational mechanism:
- Attachment Points: Removable mullions typically feature mounting brackets at the top (connecting to the door frame head) and a floor socket or pin at the bottom.
- Door Stop and Security: When installed, the mullion provides a robust vertical element against which the inactive door leaf latches or secures. This significantly enhances the security of the doorway, as both doors effectively become single-acting units secured to the mullion.
- Gap Coverage: By fitting snugly between the doors, it eliminates the vertical gap that would otherwise exist, preventing drafts and maintaining privacy.
- Quick Release: A key feature is its quick-release mechanism, which might involve a specific latch, lock, or lever. This allows the mullion to be disengaged from its top and bottom mounts and lifted away, clearing the entire doorway.
Benefits of Utilizing a Removable Mullion
The versatility of removable mullions makes them a popular choice for various applications:
- Unrestricted Egress: When removed, the full width of the doorway becomes available, which is crucial for moving large equipment, furniture, or for high-traffic situations requiring a wide clear opening.
- Enhanced Security: Provides a strong, central point for securing double doors, especially when paired with vertical rod exit devices or deadbolts.
- Building Code Compliance: Allows flexibility in meeting egress requirements for clear opening widths while maintaining security during normal operation.
- Improved Environmental Control: The optional mullion seal helps to reduce air infiltration, improving energy efficiency, and also contributes to sound attenuation.
- Aesthetic Integration: Modern designs allow them to blend seamlessly with the door frame when installed.
Typical Installation and Removal
Installing and removing a mullion is generally a straightforward process designed for ease of use:
- Installation:
- A top bracket is secured to the door frame's head.
- A floor socket is installed directly below the top bracket.
- The mullion is angled into the top bracket and then lowered into the floor socket, often with a simple locking action.
- Removal:
- A release mechanism (e.g., a lever, push-button, or key-operated lock) is engaged.
- The mullion is lifted out of its floor socket.
- It is then disengaged from the top bracket, allowing it to be stored away.
Removable vs. Fixed Mullions
Understanding the core difference between these two types of mullions helps in choosing the right solution:
| Feature | Removable Mullion | Fixed Mullion |
|---|---|---|
| Opening Width | Allows for a full, unobstructed clear opening when removed | Permanently divides the opening, always restricts full clear passage |
| Flexibility | High; adaptable for temporary large object passage or emergency | Low; static structure |
| Security | Provides robust central latching point for double doors when installed | Integral part of the door frame, permanent latching point |
| Installation | Designed for easy, temporary installation and removal | Permanently installed as part of the frame structure |
| Primary Use | Commercial spaces, warehouses, or large entryways needing occasional wide access | Standard double doors, fire-rated assemblies, continuous security needs |
Applications and Considerations
Removable mullions are commonly found in:
- Commercial buildings: Retail stores, convention centers, and factories where large deliveries or equipment movement is periodic.
- Educational institutions: Gymnasiums or auditoriums needing wide access for events.
- Healthcare facilities: For moving large medical equipment or beds.
When considering a removable mullion, it's important to evaluate the frequency of removal, security requirements, and compatibility with the existing door hardware, such as vertical rod exit devices.
