NEBS Standard
Designed to ensure maximum equipment operability for telecommunications equipment and components.
What is NEBS?
The Telcordia Network Equipment Building System (NEBS) GR-63-CORE standard is designed to ensure maximum equipment operability for telecommunications equipment and components. Air filter components are included in this standard to ensure flame safety and improving system performance by reducing harmful airborne contaminants from entering the system.
The standard notes that “accumulation of dust on telecommunications products can provide the potential for electrical breakdown.” Air filters are viewed as important components to help prevent this electrical breakdown: “Forced air-cooled equipment shall be fitted with suitable filters to remove particulate matter that has not yet been filtered out by the return air systems of the building.”
What are the NEBS Requirements Pertaining to Air Filters?
- All fan-cooled equipment shall be equipped with filters [R4-18]
- Fan filters shall meet the minimum fire rating of Underwriters Laboratories UL 900-2004, Standard for Air Filter Units, plus revisions and be marked “UL Classified”. [R4-21]
- Polymer filter media must also meet the fire-resistance requirements per Section 4.2.3.1, Materials/Components Fire-Resistance Criteria. (UL 94 HF-1) [R4-21]
- Minimum Dust Arrestance
- Equipment fan filters used in equipment occupying over 2U of vertical rack space: 80% per ASHRAE 52.1-1992 [R4-19]
- Equipment fan filters used in equipment occupying 2U of vertical rack space or less: 65% per ASHRAE 52.1-1992 [R4-20]
- Equipment shall have a provision for fan-filter replacement without particulate contaminants from the filter being introduced into equipment. Filter designs with rigid frames that are withdrawn from the airflow for removal satisfy the intent of this requirement. [R4-23]
NEBS Standard | Specifications Sheet
Download the NEBS GR63 Issue 5 Technical Specification sheet with notes added by the UAF Engineering team.
NEBS FAQs
Why do you need NEBS certification?
Does the air filter media need to meet any flame safety requirements?
Yes. A polymeric foam or polyester media should meet UL 94 HF-1.
Does the air filter assembly need to be UL Classified?
Yes. The air filter assembly should contain the UL Classification mark.
Does the size of the system determine the air filtration requirements?
Yes. If the system is 2RU high or less, the air filter media should be rated MERV 2 or have an average of at least 65% weight arrestance per ASHRAE 52.2. If the system is 3RU or higher, the air filter media should be rated MERV 4 or have an average of at least 80% weight arrestance per ASHRAE 52.2.
Does a 1RU system require an air filter?
According to the most recent GR-63 Issue 5 release, it is an objective for 1RU systems to contain an air filter. Telecommunications service providers recognize this could present some design challenges, but prefer an air filter in the system.
Are air filters RoHS compliant?
It is recommended to consult the air filter manufacturer for their environmental standards compliance. Universal Air Filter products meet the most recent environmental criteria for RoHS, REACH, and WEEE.
Should air filters be cleaned or replaced?
The NEBS standard recommends replacing the air filter. It is preferred for the air filter to have a framework or support structure to prevent dust migration during air filter replacement.
How often should the air filter be replaced in a telecommunications system or device?
Telecommunications products are installed in a wide variety of environments with varying degrees of building ventilation and filtration. However, in most instances, it is recommended the air filter is inspected and replaced approximately every three to six months. Air filter replacement frequency can be adjusted to better suit the specific environment.
What is the practical difference regarding the air filter depth or thickness?
Most air filters are designed to meet the thermal management, flame safety and air filtration performance requirements. A thin air filter media may be more closed, while a thick air filter media could be more open. The combination of filter media thickness and openness affect air flow resistance and filtration performance. Each type of filter offers benefits depending upon the space available, filter media depth loading, and overall industrial design. Universal Air Filter’s engineering team can help by reviewing design considerations for your specific application.
NEBS Technical Specifications
- NEBS GR-63-CORE ISSUE 5R4-18 [138] All fan-cooled equipment occupying greater the 1U of vertical rack space (45mm [1.75in]) shall be equipped with filters. Fan filters shall be replaceable with equipment operating. Rectifiers, distribution bays, and sealed equipment with only outside fan cooling do not require filters.
- O4-19 [206] It is an objective that fan-cooled equipment occupying 1U of vertical rack space (45mm [1.75in]) or less should be equipped with filters. These air filters should be replaceable with equipment operating. Rectifiers, distribution bays, and sealed equipment with only outside fan cooling do not require filters.
- R4-20 [139] All equipment fan filters used in equipment occupying 2U of vertical rack space (90 mm or 3.5 in) or less shall have either a: Minimum dust arrestance of 80%, per ASHRAE Standard 52.1-1992 Minimum Efficiency Rating Value (MERV) of 4, per ASHRAE Standard 52.2-2017
- R4-21[176] All equipment fan filters used in equipment occupying 2U of vertical rack space (90mm [3.5in]) or less shall have either a: Minimum dust arrestance of 65%, per ASHRAE Standard 52.1-1992 Minimum Efficiency Rating Value (MERV) of 2, per ANSI/ASHRAE Standard 52.2-2017
- R4-22 [140] Construction and system fit of equipment fan filters shall prevent any air bypass. Inadvertent leakage that may result from mechanical fits or tolerances, (examples may include spaces between circuit pack face plates, connector or cable matrices, chassis screw or mounting holes, etc.), is not considered bypass.
- NOTE: Polymer filter media must also meet the fire-resistance requirements per Section 4.2.3.1, “Materials, Components, Wire, and Cable Fire-Resistance Criteria.”
- R4-23[141] Construction and system fit of equipment fan filters shall prevent any air bypass. Inadvertent leakage that may result from mechanical fits or tolerances, (examples may include spaces between circuit pack face plates, connector or cable matrices, chassis screw or mounting holes, etc.), is not considered bypass.
- R4-24 [142] Equipment shall have a provision for fan-filter replacement without particulate contaminants from the filter being introduced into equipment. If filters can be changed with fans operating, filter replacement methods that minimize touching the media and/or dislodging captured particulates shall be specified. Filter designs with rigid frames that are withdrawn from the airflow for removal satisfy the intent of this requirement.
- R4-25 [143] The equipment manufacturer shall provide a method for determining equipment fan filter replacement schedules. This guideline shall be included in the product documentation.
- O4-26 [144] If possible, active alarming should be provided to indicate the need for fan filter replacement.
- R4-27 [145] Equipment fan filters shall be single use and not the types that require cleaning.
- O4-28 [194] It is an objective that equipment fan filters utilize recyclable materials.
Learn more about how Universal Air Filter complies with the Telecordia NEBS GR-63 Core Standard