LiftMaster LM21XPBB Extended Performance Release Device with battery backup — a stand-alone fire door release for fire-rated rolling, single-slide and center-parting doors on level or inclined track. It holds the door open with a normally energized, fail-safe release; on a smoke detector alarm, a fire alarm panel signal or loss of power it drops the fusible-link assembly and the door closes. Battery backup is built in, UL 864 Rev 9 compliant.
LM21XPBB or LM21XP? The LM21XPBB carries its own 12 V batteries (72-hour standby) and runs from 120 VAC, 24 VAC or 24 VDC. The LM21XP has no battery and must run from a UL 1481 regulated 24 VDC supply on an alarm system that has its own battery backup.
Specifications
| Part number | LM21XPBB (LM21XPBBVB = 24-hour standby version) |
|---|---|
| Function | Fail-safe fire door release; alarm, trouble and door-closed monitoring |
| Doors | Fire-rated rolling, single-slide and center-parting doors, level or inclined track |
| Power | 120 VAC, 24 VAC or 24 VDC (24 VDC may not come from a fire alarm panel or UL 1481 supply) |
| Battery | 12 V 4.5–5.0 Ah sealed lead-acid, 72-hour standby; replace every 2 years |
| Inputs | Up to 4 smoke detectors; fire alarm control panel |
| Outputs | Up to 2 horn/strobes (0.5 A at 24 VDC), 24 VDC 0.5 A auxiliary, Form C alarm and trouble relays |
| Release load | 40 lb maximum |
| Alarm delay | 10, 20, 30 or 60 s by DIP switch |
| Listing | UL 864 Rev 9 |
| Environment | Indoor, dry locations |
| Size / weight | 9.7 × 7.5 × 5 in; about 18 lb with batteries |
| Condition | Genuine LiftMaster, new |
Common questions
Does it replace a fire alarm panel?
LiftMaster describes it as providing the functions of a stand-alone fire alarm system for the door. Where a building fire alarm panel exists, the alarm and trouble relays report to it. Your fire marshal and the door's listing decide what is acceptable on site.
Will it release a door that is already closed?
No — it senses the door is closed and does not release spring tension on an alarm.
Send the door type and alarm panel details to parts@gatehousesupplies.com or call 866-965-5599 and we will confirm the right release device.
