Standards


UL 325 - Entrapment Protection for Operated Gates

 

Underwriters Laboratories (UL) issued UL 325 to provide a common objective in providing products that are safe for the public.  This standard contains qualifying features for products and applications that should be tested by a nationally recognized testing laboratory.  However, a product that is “UL 325 Compliant” or “UL 325 Ready” only relates to the product.  That product must then be installed properly to qualify for UL 325 compliance. 
 
NOTE:  Before specifying a UL 325 requirement on a barrier system, please consult a Barrier Integrator to first discuss the FULL requirements of this standard.  Some security functions that a facility requires may not be compliant with ALL specifications of the UL 325 standard, and should therefore not be used.  A Theory of Operation should be thought out and discussed, taking into account pedestrian traffic, vehicular traffic, security requirements, budget, threat assessment, etc.
 
The UL 325 standard classifies various types of systems:
Class I
Residential Vehicular Gate Operator
A vehicular gate operator (or system) intended for use in a home of one to four single family dwellings, or garage or parking area associated therewith
Class II
Commercial / General Access Vehicular Gate Operator
A vehicular gate operator (or system) intended for use in a commercial location or building such as a multi-family housing unit (five or more single family units, hotel, garages, retail store or other building servicing the general public.
Class III
Industrial / Limited Access Vehicular Gate Operator
A vehicular gate operator (or system) intended for use in an industrial location or building such as a factory or loading dock area or other locations not intended to service the general public.
Class IV
Restricted Access Vehicular Gate Operator
A vehicular gate operator (or system) intended for use in a guarded industrial location or building such as an airport security area or other restricted access location not servicing the general public, in which unauthorized access is prevented via supervisions by security personnel.
 
After the classification is determined, the application type must then be chosen. This is typically determined by available space, security level, traffic patterns, aesthetics, budget, etc.
 
For Horizontal Sliding Gate, Vertical Lift Gate, or Vertical Pivot Gate:
Classification
Required Primary Device Type
 
Required Secondary Device Type
Class I
A
AND
B1,  B2,  D
Class II
A
AND
B1,  B2,  D
Class III
A,  B1,  B2
AND
A,  B1,  B2,  D,  E
Class IV
A,  B1,  B2,  D
AND
A,  B1,  B2,  D,  E
 
For Swing Gate, Vertical Barrier (Traffic Arm):
Classification
Required Primary Device Type
 
Required Secondary Device Type
Class I
A,  C
AND
A,  B1,  C,  D
Class II
A,  C
AND
A,  B1,  C,  D
Class III
A,  B1,  C
AND
A,  B1,  C,  D,  E
Class IV
A,  B1,  C,  D
AND
A,  B1,  C,  D,  E
 
Safety Device Types:
A
Inherent entrapment sensing system
An automatic sensor system that senses the entrapment of a solid object and “responds” to that entrapment within two (2) seconds.  The system must be incorporated as a permanent and integral part of an operator.
B1
Non-contact sensor
Provision for connection of or supplied with a device that senses a potential obstruction of the gate without actual contact between the obstruction and the gate being required; i.e., a photo-electric or photo-reflective sensor or equal.
B2
Contact sensor
Provision for connection of, or supplied with, a device that senses an obstruction of the gate when actual contact between the obstruction and the device or gate is detected; i.e., an edge device or equal.
C
Inherent adjustable clutch or pressure relief device
Incorporation of a mechanical clutch mechanism that can be adjusted such that the clutch “slips” when there is contact between the gate and an obstruction, thereby stopping the gate’s travel. 
Incorporation of a hydraulic relief valve system that can be adjusted such that the hydraulic fluid pressure “bleeds off” when there is contact between the gate and an obstruction, thereby stopping the gate’s travel.
D
Continuous pressure to maintain opening or closing motion of the gate
Provision for connection of, or supplied with, an actuating device (such as a push button) requiring continuous pressure to maintain the opening or closing travel of the gate.
F
Inherent audio alarm
Incorporation of an audible alarm device of at least 100dB that sounds just prior to the gate beginning to travel and during the gate’s travel.

Not only are the above safety measures required, the UL 325 standard lists other requirements that may or may not be compatible with the security needs. For example:

  • Class I and Class II operators must have an audio alarm that shall function if two (2) sequential activations of the entrapment protection device(s) occur.
  • Class I and Class II slide gate operators cannot run the gate at a speed that exceeds one (1) foot per second.
  • When a non-contact or contact sensing device is used as the primary safety device, the system shall monitor for the presence and correct operation of such a device, including the wiring to it, at least once during each open and close cycle of the gate.
  • An obstruction must be sensed within a maximum of two (2) seconds and, when such an obstruction is sensed, the gate operator shall stop the travel of the gate and reverse it a minimum of two (2) inches.
  • If the gate operator senses a second sequential obstruction, the operator should stop the gate travel and go into a “lock down” condition that requires an “intended” input is received.
  • After any obstruction reversal caused by either an inherent entrapment sensing system or contact sensing device, any timer-to-close system is disabled until manually reset since both of these systems sense direct contact with an obstruction.
  • In the case of swing gate operators utilizing inherent adjustable clutch or pressure relief protection, the gate cannot exert more than forty (40) pounds of force after the initial start-up.
  • Slide gates must have a protective cover from the bottom of the gate, up to a height of four feet for the entire length of the gate exposed in the fence opening.  The portion of the adjacent fence that the gate and/or back frame covers in the open position, shall be similarly covered.  The protective cover must prevent a 2-1/4 inch diameter sphere from passing through the openings.
  • Requires a renewed, intended input in the line-of-sight of the operator, once the entrapment sensing system detects a second sequential obstruction.

In summary, security barrier configuration is different depending on barrier type, traffic patterns, and security level.  UL 325 requirements are to protect pedestrians and vehicles using primary and secondary methods, and are targeted towards normal garage door and vehicle gate application.  If UL 325 is required on crash rated gates for vehicle attacks, compliance can make the system easier to defeat.  However, safety devices and some UL 325 concepts can still be effectively integrated into the theory of operation for a safer system.

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