UL-325

Introduction

Automatic vehicular gate operating systems provide convenience and security to the end user. The popularity of these systems has grown greatly over the past few years. With that growth has come increasing awareness of the inherent dangers of an improperly designed, installed, used or maintained system. In some applications, gate operators must use high level of force to move the gate. In others, pedestrians are mixed with vehicular traffic. In still others, inadequate safety features are specified or installed for the system.

Persons coming into contact with a moving gate are in danger of “pinching” a portion of themselves or, even worse, becoming “entrapped” by the gate. If a system is not properly designed, specified, installed, used and maintained, serious injury or even death can result to someone in the vicinity of a moving gate.

Over the past thirty months, the standard, UL 325 – Standard for Door, Drapery, Gate, Louver and Window Operators and Systems, has undergone substantial revision in response to growing concerns over the safety of automatic vehicular gate operating systems. This information is provided in an effort to help you understand the current automated gate-related contents of this standard and its impact on the gate and gate operator industry. It will also advise you of some of the possible changes pending for this standard.

Underwriters Laboratories (UL) & Its Standards

Underwriters Laboratories, Inc. (UL), a not-for-profit organization established in 1894, is self-described as “the leading third-party certification organization in the United States and the largest in North America.” UL’s primary stated mission is “to evaluate products in the interest of public safety.” Note that while UL declares it is the “leading” organization of this type, it is not the only one. There are several other testing laboratories and certification organizations in the United States but UL remains the one most people recognize and think of in this area.

UL standards are voluntary standards that establish minimum requirements for many products on the market today. The term “voluntary” in this respect means that the standards are not initiated through any government or similar regulatory agency mandate. The term “minimum” also has specific meaning to this discussion in that the industry and those who developed the standard believe that all participants affected by the standard should meet the requirements and that some in the industry may adopt more stringent provisions.

As you can see, these standards are developed via an open, non-exclusionary process involving UL scientists, industry members and other interested parties. In addition, a number of UL Standards have undergone a “canvass” or ballot process in order to obtain recognition by the American National Standards Institute (ANSI) as an American National Standard. This designation garners those standards a wider awareness and acceptance by the public. The canvass process typically includes interested individuals and organizations that may have direct or material interest in a particular standard. UL 325 is one of the standards that has used this process to attain ANSI designation.

What is the UL 325 Standard?

The first edition of UL 325 was released in 1973. That edition primarily focused on the electric operation of garage doors and did not contain any provisions related to gates or gate operators. After federal laws were enacted in the early 1990’s that cited the provisions of UL 325 as applicable to garage door operation, the gate operator industry initiated inclusion of electric gate operator provisions in UL 325. These provisions of the Standard were established, for all intents and purposes, in September of 1998. Some government agencies and other interested groups monitored the standard’s progress and provided input on the final format of the provisions of the standard that relate to gate operators as they were developed. As of March 1, 2000, all manufacturers that desired UL listing and labeling for their gate operator products were required to comply with the changes that UL identified as requiring “substantial redesign and retest” of the affected equipment. Additionally, March 1, 2000 was the operative date for compliance with the revised instructions governing installation. It is important to remember that continual compliance with the standard is a requirement of maintaining a listing and labeling program.

For products within the scope of the standard, UL 325:

• Contains the basic qualifying factors that products must meet in order to be documented (listed) and marked (labeled) as complying with the requirements of the UL 325 Voluntary Listing and Labeling Program;

• Provides methods for testing products, primarily related to safety performance;

• Covers installation of the products in accordance with the National Electric Code, which is maintained by the National Fire Protection Association and is in force nationwide (UL 325 is to be “harmonized” with this code) and

• Addresses safety concerning potential fire and electrical hazards as well as the safety of the general public.

Based on this, UL 325 is used as a basis to test products at a nationally recognized testing laboratory. Gate operator manufacturers that choose to participate in the listing and labeling program must submit their products for testing. If the laboratory finds them to be in compliance with the UL 325 standard, they are listed and receive a mark (label) indicating that compliance.

It is very important to remember that there are laboratories other than UL that are capable of listing and labeling products; however, only products tested by UL can receive a UL label. Therefore, a UL label is not a generic term and should not be used in that manner. It is also important to understand that UL and the other laboratories do not “approve” products. Approval implies acceptance of responsibility for compliance with the standards when this responsibility ultimately lies with the applying manufacturer and not with the laboratory (the burden of proof of compliance always lies with the manufacturer).

In general, UL 325 contains of the following highlights as regards gate operators:

1. A glossary that defines each type of operator,

2. A separation of gate operators into “classes;”

3. Entrapment protection criteria for each class of operator;

4. Entrapment alarm criteria;

5. Requirements for gate construction and installation and

6. Instructional requirements placing increased responsibility on the installers of gates and gate operators.

The term “entrapment,” as used in relation to gates and gate operators in UL 325, is defined as “the condition when an object is caught or held in a position that increases the risk of injury.”

A key part of the UL 325 Standard is the table that summarizes the entrapment device options for the different classes of gate operators of the various types of gate included in the standard. A copy of this table can be obtained from UL but we will attempt to summarize its structure and provisions in the following sections.

Gate Definition and Types According to UL 325

To begin with, we need to know what a “gate” is for purposes of this standard. UL 325 defines a gate as “a moving barrier such as a swinging, sliding, raising, lowering, rolling or like, barrier that is a stand-alone passage barrier or is that portion of a wall or fence system that controls entrance and/or egress by persons or vehicles and completes the perimeter of a defined area.” Based on this, UL 325 goes on to address these main types of gate operators/systems:

Vehicular Barrier (Arm) operator or system – an operator (or system) that controls a cantilever type device (or system), consisting of a mechanical or barrier that moves in a vertical arc, intended fro vehicular traffic flow at entrances or exits to areas such as parking garages, lots or toll areas;

Vehicular Vertical Pivot Gate operator or system – a vehicular gate operator (or system) that controls a gate that moves in a vertical plane that is intended for use for vehicular entrances or exits to a drive, parking lot or the like;

Vehicular Horizontal Slide Gate operator or system – a vehicular gate operator (or system) that controls a gate which slide in a horizontal direction that is intended for use for vehicular entrances or exits to a drive, parking lot or the like;

Vehicular Vertical Slide Gate operator or system – a vehicular gate operator (or system) that controls a gate which moves in the vertical direction and is intended for use for vehicular entrances and exits to a drive, parking lot or similar location and

Vehicular Swing Gate operator or system – A vehicular gate operator (or system) that controls a gate which swings in an arc in a horizontal plane that is intended for use for vehicular entrances and exits to a drive, parking lot or the like.

It is important to note that, after the initial definition of a gate, all gates and gate operator systems included in UL 325 are defined as vehicular gates and not pedestrian gates. A key provision of the design and installation of any gate system desiring UL 325 listing is the provision of a separate entrance gate for pedestrian access that is located outside the area used by the automatic gate operating system.

UL 325 Gate Operator Classifications

As mentioned above, UL 325 separates gate operators into “classes”.” For purposes of the standard, there are four classes of gate operators as follows:

Class I – Residential Vehicular Gate Operator – operator to be used in a residential setting of one to four single-family dwellings;

Class II – Commercial / General Access Vehicular Gate Operator – operator to be used in a commercial setting where general public access is expected such as a public parking lot or garage, a gated community or multi-family housing (five or more dwellings) unit or development;

Class III – Industrial / Limited Access Vehicular Gate Operator – operator to be used in an industrial setting that is not intended for use by the general public such as a warehouse, factory or loading dock area and

Class IV – Restricted Access Vehicular Gate Operator – operator to be used in a guarded industrial setting that is not intended for use by the general public and in which unauthorized access is prevented via supervision by security personnel such as a prison or airport security area.

Entrapment protection requirements vary dependant upon the class the operator falls into based on it intended usage. UL 325 requires that all classes have primary and secondary entrapment protection provisions and that the primary and secondary provisions cannot be satisfied by the same device or system. The type of primary and secondary entrapment protection required varies from class to class.

Entrapment Protection Provisions by Operator Type & Class

Remember that the type of gate operator used combined with the class of the application will determine the type of entrapment protection device or system required for both the primary and secondary protection provisions. Horizontal Slide Gate Operators and Vertical Lift or Pivot gate operators have different entrapment protection requirements from Swing Gate Operators and Vertical Barrier Gate Operators in all of the classes. The exact requirements are summarized below (note that these terms do not always reflect the exact term used in the standard but are our interpretation of these terms in some cases):

Horizontal Slide, Vertical Lift or Vertical Pivot Gate Operators:

Swing Gate or Vertical Barrier (Arm) Gate Operators:

Entrapment Protection Devices Defined:

UL 325 defines, in general terms, how each of these entrapment protection devices or system should operate:

Inherent Entrapment 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.

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 photoelectric or photo-reflective sensor or equal.

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.

Inherent Adjustable Clutch – 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.

Inherent Pressure Relief – Incorporation of an 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 gates’ travel.

Continuous Pressure Activating Device – 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.

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.

Other Important Provisions of UL 325 Regarding Gate Operators

Some special provisions extracted from the UL 325 impact gate operator installations beyond the type of operator and the class of the installation. Specifically, UL 325 requires that:

1. 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. This should not be confused with the Inherent Audio Alarm entrapment protection system defined above.

2. Class I and Class II slide gate operators cannot run the gate at a speed that exceeds of one (1) foot per second. It is hoped that this speed strikes a balance between the security needs (prevention of a second party entering the gated area before the gate closes) and the safety issues of someone being struck by the gate.

3. Anytime 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.

4. In most conditions, 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. The purpose of this provision is to prevent a person from being entrapped in a stationary position by the gate system.

5. 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. This intended input must be generated by a person within the line of sight of the gate using a hard-wired device to reset the operator once the obstruction has been resolved; it cannot come from a timer or other automatic device.

6. 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.

7. 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; the reasoning here is similar to that of the speed limitation on slide gate systems.

8. 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.

9. Contact Sensors such as edge devices are not permitted to satisfy either primary or secondary protection provisions on swing gate systems at the present time. Many interested parties disagree with this provision and are working to have it modified at the present time.