Sliding Door Operators for Blast Resistant Doors

A recent project required sliding door operators for several blast resistant doors weighing 30,000 lbs. The weight of each operator is supported by an S beam and hanging trolleys (supplied by others).

Project Requirements:

• Door operator shall control movement of a 30,000 lb door.
• 27’ travel distance
• Door operator to be mounted on the exterior (safe side) under a weather canopy
• Controls panel: upgraded to 220VAC single phase supply voltage and rated for exterior use
• Manual override

Our Solution:

The standard NB-4120-DC operator is rated up to 700 lbs horizontal operating force. After reviewing the frictional data for the hanging trolleys, we added the necessary acceleration forces and determined that the 700 lb rating provides a reasonably high factor of safety for moving the doors once in service.

The 27’ travel was accomplished by increasing the timing belt length and upgrading the rotary position transducer. The door position can now be adjusted using the handheld HMI without external limit switches.
Although the drive train is mostly protected from direct exposure from the canopy, the ¾ hp DC motor was upgraded to a washdown version. At the heart of the drive train is the maintenance free 2” steel reinforced polyurethane timing belt, which is an ideal fit for this application.

The supply voltage was upgraded to 230VAC single phase and the control panel to a NEMA 4 rated enclosure. All penetrations, including cord grips and seals were upgraded to NEMA 4.

Although the manual override feature is standard on all NB-4120-DC, the enclosure and penetrations were upgraded to NEMA 4. The door operators were shipped on schedule and the end user successfully completed the installation of all units.

> Please view the NB-4120-DC Specification and Manual for a complete product description.