Data Center Vibration, Acoustic & Interior Lining
H-O Products die-cuts and converts fan-tray and blower isolation pads, rack anti-vibration footing pads, acoustic absorber linings for enclosures, seismic-bracing interface pads, drive-array damping layers, and the interface gaskets behind generator-room acoustic panels, the quiet side of the data center, built to your drawing.
Built for: 19-inch and OCP rack platforms, fan-wall and in-row cooling hardware, storage arrays whose drives feel every blade-pass tone, edge and telecom equipment commonly framed by Telcordia GR-63-CORE (NEBS) at the platform level, and the enclosure interiors where airborne fan noise gets absorbed instead of reflected.
To treat data-center vibration and noise, name the job first: isolation, damping, or absorption. Fan trays & blowers: isolate on PORON® 4701-series microcellular urethane pads (methods per ASTM D3574; the 4701-40V0 grade lists UL 94 V-0 on its TDS), sized so blade-pass and running-speed tones land above the √2 crossover. Rack footing: 25#/27# rebonded neoprene sized by static bearing stress (ASTM D1056).
Enclosure lining: open-cell polyurethane hybrid foam, with BISCO® silicone where a flame class is named and the BISCO® A2 barrier for transmission loss.
The remaining duties are mapped in the When-to-spec list. Values are per the TDS on file; see the material reference below for ordering details.
Platform-level, by designation (the evaluation belongs to the tested platform or facility design): Telcordia GR-63-CORE (NEBS physical protection, including its earthquake and acoustic criteria). Treatment-level, on the tested assembly: ASTM E756 (damping loss factor) · ASTM C423 (sound absorption / NRC) · ASTM E90 / E413 (transmission loss / STC) · ISO 10846 (resilient-element transfer properties).
Material-level, per the vendor TDS: ASTM D1056 (cellular rubber classes) · ASTM D3574 (flexible cellular polyurethane methods) · ASTM D395 (compression set) · UL 94 (flammability classes on the rated grades).
- Fan-tray & blower pads: PORON® 4701 series (40V0 for V-0 duty)
- Higher-energy blower cushions: HyPUR-cel® I0906
- Rack footing pads: 25# / 27# rebonded neoprene
- Seismic interface pads: natural rubber / Atlas bearing elastomer
- Low-creep leveling shims: cork-rubber BC351-207 / SP52
- Panel damping layers: SBE41VN / ENSOLITE® IG1 vinyl nitrile
- Absorber linings: PU hybrid foam / F-26 felt
- Flame-class & barrier duty: BISCO® HT-870 / A2 sound barrier
Where are you in the spec process?
This page serves engineers who already know the pad, lining, or damping layer they want and engineers still working out whether the problem is isolation, damping, or absorption. Pick the path that matches where you are; you don't have to read the rest.
Send a drawing, get a quote
A fan-tray isolation pad, a rack footing pad set, an absorber lining die-cut, a seismic interface pad, a drive-bay damping layer, or a complete kiss-cut treatment kit on your drawing.
Skip to the quote form →Walk the six jobs, source to receiver
Six numbered jobs (fan tray, rack footing, enclosure lining, seismic brace, drive array, generator room), a treatment checklist builder, and seven material families with TDS-cited methods and by-designation standards language.
Start with job 1 →
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1Send drawingUpload a DXF, STEP, or PDF, or describe the fan tray, rack, enclosure, or brace detail. A sample part works too.
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2Material reviewEngineering reviews static loads, disturbance frequencies, gap budgets, and any flame-class requirement against the vendor TDSs, and frames the standards language correctly: material classes (UL 94) per TDS, platform frameworks (GR-63-CORE) by designation, acoustic ratings with the tested treatment.
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3PrototypeSamples typically ship in 3–5 business days for common configurations on materials we keep on hand. Made-to-order; MOQ varies by material and part.
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4ProductionStandard production runs ship about 2 weeks after drawing approval, on flatbed die-cutting, CNC knife cutting for kiss-cut pad sets, waterjet cutting for thick elastomer sections, slitting for strip stock, and kitting for per-rack and per-enclosure treatment kits. Ongoing parts run with material traceability and lot-code TDS records.
Which vibration or noise path are you treating?
The six vibration and acoustic jobs, zone by zone
Pick a zone to see the job, the materials that lead it, and what to put on the drawing.
Fan-tray & blower isolation pads
Almost every steady tone in a data hall starts at a fan: running-speed once-per-rev from imbalance, blade-pass at blade count times speed, and the broadband rush of moving air. A fan tray bolted hard to its chassis hands all of that to the sheet metal, which re-radiates it as noise and walks it into everything the chassis touches.
The fix at the source is a resilient layer between fan frame and tray, and between tray and chassis: a pad soft enough to put the mounted natural frequency well below the disturbance tones, so the assembly sits in the isolation region above the √2 crossover instead of the amplification region below it.
What H-O converts. Die-cut and kiss-cut isolation pads, grommet-style mounting washers, and perimeter strips from PORON® 4701-series microcellular urethane, soft grades such as 4701-30 very soft for light fan frames, firmer grades where the tray carries mass, with compression behavior per ASTM D3574 on the grade TDSs and the family's low compression set keeping the deflection (and the natural frequency) where the design put it. PORON® 4701-40V0 serves locations where a UL 94 V-0 class is named on the pad itself, per its TDS.
For higher-energy blower cushions and thicker sections, HyPUR-cel® I0906 microcellular polyurethane and vinyl nitrile foam step in. Parts ship kiss-cut on liner in per-tray counts through CNC knife cutting and kitting.
Material guidance. The pad is a spring specified by its compression-force-deflection curve, not its thickness: get the supported mass per pad and the lowest disturbance frequency onto the drawing, and the firmness grade and gauge fall out of those two numbers. An over-stiff pad is the classic miss; it amplifies the very tone it was meant to cut. Final material selection should be validated in the application; performance depends on grade, geometry, compression, and environment.
Fan or blower mass and mounting pattern, tray drawing or footprint, lowest disturbance frequency (running speed and blade count if known), available gap, any flame-class requirement on the pad, and per-tray quantities.
Rack anti-vibration footing pads
The rack base is a two-way street. Floor-borne vibration, from cooling plants, adjacent construction, rooftop equipment, or a generator under load, climbs into the cabinet from below; and a cabinet full of fans and drives pushes its own energy back into the slab and the raised floor. An elastomer footing pad between base (or caster plate, or leveling foot) and floor blunts both directions at once, and unlike a bolted isolator it adds no hardware to the seismic and grounding story the cabinet already carries.
What H-O converts. Footing pads, plinth strips, and full base-frame pads from 25# and 27# rebonded neoprene, the classic machinery base-pad construction, dense enough to carry a loaded cabinet while still deflecting into its working range, with per-grade data per ASTM D1056 on the TDSs. Lighter equipment, wall-mount cabinets, and shelf-mounted gear take SBE41VN/SBE42VN vinyl nitrile pads at gentler bearing stresses.
Where a footing pad must hold a precise height over years, server rows are leveled to millimeters, cork-rubber BC351-207 and technical cork SP52 give a stiff, very-low-creep shim that tolerates oils and cleaners. Thick sections cut clean on waterjet; production pads run on flatbed dies.
Material guidance. Footing pads are a static-stress calculation: cabinet mass over total pad area must land inside the grade's working range. Too much stress and the pad bottoms out (transmitting vibration straight through); too little and it does not deflect enough to isolate. Send masses and bearing areas, both come straight off the rack layout, and the density grade follows. May be suitable as a retrofit across an operating row; final selection should be validated in the application.
Loaded cabinet mass (or range across the row), base or foot bearing areas, floor type (slab, raised floor, plinth), height budget, leveling tolerance, and quantities per row and per site.
Acoustic absorber linings for enclosures
A bare metal enclosure is an echo chamber: fan noise reflects off every interior face, builds, and pours out of each vent and seam louder than it needs to be. An absorber lining changes the room the noise lives in. Die-cut panels of open-cell material on the interior faces convert acoustic energy to heat instead of reflecting it, which is why a lined cabinet, an edge-compute pod, or an acoustic hood reads quieter at the grille with no other change.
The lining is a converted-materials job: cut to the panel geometry, relieved around fasteners and cable paths, and mounted with an adhesive system that survives the interior.
What H-O converts. Die-cut absorber panels and lining sets from open-cell polyurethane hybrid foam, porous F-26/F-10 SAE pressed felt for thin absorptive layers, and 20 PPI reticulated foam where the lining must also pass airflow (its grade lists a UL 94 HF-1 class per the vendor TDS).
Where the design brief names a flame class on the lining or the cavity runs warm for years, BISCO® cellular silicone grades such as HT-870 Soft and the flame-rated RS-800 Medium sponge carry per-grade UL 94 listings on their TDSs. Where the treatment needs a barrier layer as well as an absorber, mass that blocks transmission rather than soaking reflection, the BISCO® A2 sound barrier and its fiberglass-reinforced version laminate into the stack.
Material guidance. Absorption is rated on the tested treatment, not the raw sheet: NRC and absorption coefficients follow ASTM C423 on the assembled panel, and transmission-loss numbers (STC per ASTM E413, from E90 data) belong to the tested construction. Specify the faces to be lined, the thickness budget, and the frequency character of the noise (small fans put their energy high, where thinner linings work hardest).
Most linings mount with a pressure-sensitive adhesive; adhesive performance depends on the substrate, its surface energy and preparation, temperature, exposure, dwell time, applied pressure, joint geometry, and assembly method, so the adhesive system should be validated on the actual painted or coated interior panel before the lining kit is released.
Panel drawings or interior dimensions, thickness budget per face, cutouts for vents, fasteners, and cable paths, any flame-class requirement on the lining material, the PSA requirement, and per-enclosure quantities.
Seismic-bracing interface pads
Seismic bracing ties cabinets, frames, and overhead infrastructure to the structure, and every tie is also a vibration short-circuit and a fretting interface: steel brace against painted cabinet steel, clamp against strut, anchor plate against slab. The interface pad is the small part that makes the bracing livable, distributing clamp load, stopping metal-to-metal rattle and fretting corrosion at the joint, and taking the hard edge off the vibration path the brace would otherwise open.
In telecom and data-center platforms the bracing design itself is commonly framed by Telcordia GR-63-CORE (NEBS) earthquake criteria at the system level; the pad supports that design and claims none of it.
What H-O converts. Die-cut interface pads, clamp liners, and anchor-plate pads from natural rubber (the BLAST 139 class) for resilience under sustained clamp load, Atlas bearing-grade elastomer (the 258/268/278 designations) where the joint carries structural bearing stress, and cork-rubber or technical cork DC100-312 where the pad must hold torque without creeping, a clamped joint that thins out is a loose joint.
Thin pressed felt liners serve sliding and thermal-movement joints. Thick bearing sections cut on waterjet to the bracket outline, holes and slots to print.
Material guidance. The controlling properties are bearing stress and creep, not softness: pick the stiffest material that still conforms to the joint, and confirm compression set per ASTM D395 (elastomers) or the cellular procedures in ASTM D1056 on the grade TDS for anything cellular. The bracing system's seismic qualification belongs to the tested platform and the engineer of record; the pads are converter-side components inside that design. Final material selection should be validated in the application.
Brace and clamp drawings, joint bearing areas and clamp loads or torque specs, pad thickness budget, environment at the joint (slab, overhead, plenum), and counts per cabinet and per site.
HDD & storage-array damping
Rotating disks are the most vibration-sensitive components left in the data center: a drive's heads follow tracks measured in nanometers, and rotational vibration from neighboring drives, chassis fans, and even loud acoustic events is a commonly reported cause of degraded drive throughput in dense arrays. The materials job sits in the millimeters around each drive and tray: decouple the drive from the carrier, damp the carrier and chassis panels that ring at fan tones, and keep the array's own seek energy from cross-talking drive to drive.
What H-O converts. Thin and kiss-cut damping parts on liner: drive-carrier gaskets and corner pads from soft PORON® microcellular urethane (the 4790-92 extra-soft slow-rebound grade where the duty wants a lossy, energy-soaking touch, and ShockSeal® 4790-79 where the pad doubles as a dust seal); free-layer panel damping from lossy SBE41VN vinyl nitrile and ENSOLITE® MLC cut to the panel profile; and anti-rattle strips of F-10 pressed felt at sliding carrier interfaces where stick-slip squeak starts.
Multi-layer constructions, foam, adhesive, film, laminate to a target gauge and ship as per-chassis kits.
Material guidance. Damping is the job here, not isolation: the layer drains panel resonance as heat, and its effectiveness is characterized as a loss factor per ASTM E756 on the tested treatment, the rated number belongs to the treated panel, not the raw foam. Keep the parts thin and the coverage honest: a damping layer works where the panel actually bends. In dense arrays, treat the chassis and carrier first; the drive maker's own mounting spec governs what touches the drive. Final selection should be validated in the application.
Carrier and chassis drawings, drive count and layout, the fan tones or vibration data if measured, gauge budget per part, PSA and liner requirements, and per-chassis quantities for kitting.
Generator-room acoustic-panel interfaces
The loudest room on the campus gets engineered panel systems: absorptive wall and ceiling panels, acoustic doors, and silencer hardware, designed and rated by the panel-system maker on tested assemblies.
What the panel system still needs from a converter is everything at its edges: the perimeter gaskets that stop flanking leaks around each panel, the isolation strips between panel frames and the structure they would otherwise re-radiate through, the spacer and bearing pads behind standoff-mounted panels, and the pads under ancillary equipment that shares the room.
A panel system that is sealed and decoupled at its boundaries performs the way its test report says; one that leaks at the edges gives back its rating at every gap.
What H-O converts. Panel-perimeter gaskets and frame isolation strips from vinyl nitrile foam and neoprene foam, oil- and weather-tolerant closed-cell chemistries suited to a room with a permanent haze of fuel and oil mist (classes per ASTM D1056 on the grade TDSs); barrier-layer from the BISCO® A2 sound-barrier line where the design laminates mass into a panel or lagging detail; standoff and bearing pads from 27# rebonded neoprene and Atlas bearing-grade elastomer; and slit strip stock for long panel runs through slitting.
The room's deeper safety-side treatment, sound-barrier walls, fire barriers, and the generator's own base isolation, lives on the data-center safety & generator sibling page; this section carries the panel-interface layer.
Material guidance. The room's acoustic rating belongs to the tested panel assembly and the acoustic engineer's design; the converter-side parts are chosen for closure force, fluid tolerance, and longevity at the boundary. Name the fuel and oil exposure when specifying anything in this room, it overrides softer-material preferences, and confirm fluid resistance per the grade TDS. Final material selection should be validated in the application.
Panel-system drawings or the maker's interface details, gasket cross-sections and run lengths, frame standoff loads, the fluid environment (diesel, oil mist, washdown), and quantities per room.
Where vibration and noise travel: the six treatment points
A representative cross-section of an equipment row. Numbered callouts mark the six treatment points this page serves; the numbers match the job sections above. Representative line-art diagram, not a product photo or an engineering drawing.
Representative cross-section for orientation only. Geometry, equipment mix, and room layout vary by facility; the vibration and noise paths do not.
The decisions that drive a data-center vibration & acoustic spec
Noise and vibration parts are chosen by the path first — structure-borne or airborne — then tuned to the frequency that matters.
Identify the path, then size the part to the disturbing frequency and the static load. Isolators and dampers carry their own deflection and damping data per grade TDS.
Show all 5 selection factors tap to expand
Vibration & acoustic failures you can prevent at spec
Vibration and noise problems in equipment platforms rarely arrive as failures; they arrive as a hum that wasn't in the prototype, a drive array that benchmarks slower in the bottom of the rack, a brace joint that starts to rattle in year two. Five patterns cover most of what goes wrong, and each one is a specification decision made before the first part is cut.
The job decides the material, and naming the wrong job is the root failure. A soft isolator is not a damper; a damping layer is not a sound barrier; an absorber lining adds no transmission loss. Each of the five patterns below starts with one of those substitutions.
Show all 5 failure modes tap to expand
1. The fan pad that amplified the tone it was meant to cut
A fan tray got isolation pads picked by gap fill: the right thickness, far too stiff. The mounted natural frequency landed just under the blade-pass tone, inside the amplification region below the √2 crossover, and the lined-up chassis hummed louder than the unpadded prototype. The fix: treat the pad as a spring.
State the supported mass per pad and the lowest disturbance frequency, and pick the PORON® firmness grade whose compression-force-deflection data (per ASTM D3574 on the TDS) puts the natural frequency well below the disturbance, then let thickness follow.
Softer-than-instinct is usually right at fan masses. [4]
2. The footing pad that bottomed out under a loaded rack
A footing pad sized on the empty cabinet's mass met the commissioned cabinet, twice the weight in servers, cabling, and batteries, and compressed past its working range into a solid block: vibration walked straight through, and the leveling height drifted. The fix: size by static bearing stress at the loaded mass, including the heaviest configuration the platform ships.
Dense rebonded neoprene (25#/27#) carries loaded-cabinet stresses inside its working range with per-grade data per ASTM D1056 on the TDSs; lighter gear belongs on vinyl nitrile at gentler stresses.
Bearing areas and masses come off the rack layout; send both. [5]
3. The lining that absorbed nothing (or fed a fire-review finding)
Two versions of one failure. In the first, a closed-cell gasket foam was specified as an "acoustic lining": closed cells reflect, open cells absorb, and the enclosure measured as loud as bare metal.
In the second, an effective open-cell absorber went in with no flame-class documentation, and the materials review stalled on an undocumented lining. The fix: use genuinely open-cell absorber materials for absorption duty, and decide the flame-class requirement before the material, not after: flame-rated lining options carry per-grade UL 94 listings on their vendor TDSs, and absorption ratings (ASTM C423) belong to the tested treatment.
Both decisions go on the drawing. [2]
4. The brace joint that rattled in year two
A seismic brace was clamped steel-on-steel to save a part number.
Thermal cycling and micro-motion loosened the joint, fretting opened the clamp load, and the row developed a rattle that audits flagged, in the one joint whose whole purpose is staying tight. The fix: put an interface pad in every brace-to-cabinet and clamp-to-strut joint, chosen for bearing stress and creep rather than softness: bearing-grade elastomer or natural rubber where the joint carries load, cork-rubber where torque retention over years governs (compression set per ASTM D395 / D1056 per the grade TDS).
The bracing design's seismic qualification stays with the platform and the engineer of record; the pad keeps the joint quiet inside it. [7]
5. The drive array that benchmarked slower next to the fan wall
A dense storage chassis met a high-static-pressure fan upgrade, and throughput dropped on the drives nearest the fans: rotational vibration from fan tones, passed through an undamped chassis, kept the heads off track often enough to measure. The fix: treat the transmission path.
Thin lossy layers on the chassis and carrier panels that actually bend (loss factor characterized per ASTM E756 on the tested treatment), soft decoupling pads at carrier interfaces, and felt at sliding contacts, while respecting the drive maker's mounting spec at the drive itself.
Measure before and after; the rated improvement belongs to the treated assembly. [1]
Specification Tools
Two tools to take you from "the platform hums" to here's the treatment-part checklist for the drawing set: a treatment checklist builder that assembles the part list with its material families, and a side-by-side comparison of every isolation, damping, and acoustic family on this page.
1. Vibration & acoustic treatment checklist builder
Check the vibration and noise paths your platform carries. The builder assembles the corresponding treatment parts into a checklist with the material family and what to send with the drawing. The default selection below is pre-built for a typical dense compute-and-storage rack; every part is also printed in the material reference section, so nothing here exists only behind a script.
Treatment-part checklist: 3 parts selected
Each checked path adds its part below. The list is the starting bill of materials for the engineering review, not a performance claim: material classes (UL 94) come from the grade TDS, platform frameworks (GR-63-CORE) are cited by designation, acoustic and damping ratings belong to the tested treatment, and final material selection should be validated in the application.
- Fan-tray isolation pads: PORON® 4701 series (4701-40V0 for V-0 duty)Send: fan mass per pad, lowest disturbance frequency, gap budget. Cite: ASTM D3574 methods; UL 94 V-0 per the 40V0 TDS.
- Rack footing pads: 25# / 27# rebonded neopreneSend: loaded cabinet mass, bearing areas, height budget. Cite: ASTM D1056 classes per the grade TDS.
- Drive-array damping: vinyl nitrile / soft PORON® layers + felt anti-rattleSend: carrier and chassis drawings, gauge budget, fan tones if measured. Cite: loss factor per ASTM E756 on the tested treatment.
2. Side-by-side: vibration & acoustic family comparison matrix
Every family called out on this page, with construction, the property that drives its selection, the standards its TDS cites, and the job it serves. Click a column header to sort. Click any material name to jump to its accordion entry.
| Material | Construction | Selection property | Standards on the TDS / by designation | Job on this page | |
|---|---|---|---|---|---|
| Isolation & cushioning families | |||||
| PORON® 4701 Series (4701-40V0, ShockSeal® 4790-79, 4790-92)Microcellular urethane | Microcellular PU foam | CFD curve + low compression set | ASTM D3574, D395; UL 94 V-0 (40V0 TDS) | Fan-tray pads; drive-carrier pads | |
| HyPUR-cel® I0906 PolyurethaneMicrocellular PU | Microcellular PU foam | Progressive energy absorption | ASTM D3574 (per grade TDS) | Blower cushions; thicker pads | |
| Rebonded Neoprene (25# / 27#)Dense rebonded foam | Rebonded neoprene | Static bearing stress | ASTM D1056 (per grade TDS) | Rack footing; standoff pads | |
| Natural Rubber (BLAST 139) + Atlas Bearing Elastomer (168/258/268/278)Solid elastomer | Solid / bearing elastomer | Resilience under clamp load | ASTM D395; values per vendor TDS | Seismic-brace interfaces | |
| Cork-Rubber (BC351-207, DC100-312, SP52)Rubberized cork | Cork-elastomer composite | Very low creep; torque retention | Values per vendor TDS | Leveling shims; clamped joints | |
| Damping, absorption & barrier families | |||||
| Vinyl Nitrile Foam (SBE41VN/SBE42VN, ENSOLITE® IG1 / MLC)Closed-cell VN | Closed-cell VN foam | Lossy character; oil tolerance | ASTM D1056 (per grade TDS) | Panel damping; genset-room gaskets | |
| Open-Cell Absorber Set (PU hybrid foam, 20 PPI reticulated, pressed felt)Open-cell / porous | Open-cell PU / felt | Absorption (tested treatment) | ASTM C423 (treatment); D3574; HF-1 class on the rated reticulated grade TDS | Enclosure linings | |
| BISCO® Silicone (HT-870 Soft, RS-800 Medium) + A2 Sound BarrierCellular silicone / barrier | Silicone foam; loaded barrier sheet | Flame class; barrier mass | UL 94 listings per grade TDS; STC per tested assembly (E90/E413) | Flame-class linings; barrier layers | |
| SAE Pressed Felt (F-10, F-26)Compressed wool felt | Pressed wool felt | Stable low friction; porous absorption | SAE felt class designations (per vendor TDS) | Anti-rattle; thin absorptive layers | |
1. SDOF vibration-isolation calculator & transmissibility curve
Estimate how much of a fan, blower, or floor disturbance a resilient pad actually keeps out of the chassis. Enter the disturbance frequency and the mounted natural frequency directly, or enter the isolated mass and the pad’s static deflection and the tool derives the natural frequency for you.
The curve plots the idealized single-degree-of-freedom transmissibility for your damping ratio and marks your operating point against the √2 crossover, the frequency above which a mount isolates instead of amplifies. This is a first-order design estimate, not a prediction of installed performance.
The lowest steady tone you must isolate — fan running speed, blade-pass (blade count × rev/s), or a floor-borne source.
The frequency the mounted assembly bounces at on its pad. Softer pad and heavier mass → lower fₙ → isolation starts earlier.
Supported mass carried by each pad (total isolated mass ÷ number of mounts).
How far the pad compresses under the static load. Natural frequency follows from deflection: fₙ ≈ 15.76 / √δmm.
Fraction of critical damping. Elastomeric/foam pads commonly fall near 0.02–0.10; higher damping tames resonance but slightly reduces deep isolation. Use the grade’s measured value when known.
(1 − Tᵣ) × 100, reported only when r > √2. This is a textbook single-degree-of-freedom (SDOF) estimate: it assumes one rigid mass on a linear, viscously-damped spring with a rigid base, and ignores multiple modes, mount wave effects, structural compliance, and non-linear foam behavior. It is a starting point for the conversation, not a substitute for a rig test or a structural-dynamics analysis. The mount’s measured transfer properties follow ISO 10846; material classes (UL 94) come from the grade TDS; platform frameworks (Telcordia GR-63-CORE) are cited by designation only; and final material selection should be validated in the application. H-O supplies the pads, the vendor TDSs, and lot-code traceability behind them.
Skip ahead and request your engineering review now
If your drawing set already calls out a foam grade, a pad footprint, a lining thickness, or a damping-layer construction, send it over for engineering review against the vendor TDSs and the standards language.
Material reference
Detailed specs for the seven vibration and acoustic families referenced on this page: the isolation set (PORON® microcellular urethane with HyPUR-cel®, rebonded neoprene, natural rubber and bearing elastomer, cork-rubber), the damping set (vinyl nitrile and ENSOLITE® foams), and the acoustic set (open-cell absorbers and felt, BISCO® silicone with the A2 sound-barrier line).
Values are per the vendor TDS on file for each grade with the method named; platform frameworks are cited by designation only, and treatment-level ratings belong to the tested assembly. H-O die-cuts, kiss-cuts, slits, laminates, and kits every family to drawing.
PORON® Microcellular Urethane (4701 Series, 4701-40V0, ShockSeal® 4790-79, 4790-92) + HyPUR-cel® I0906Fan-tray isolation & drive-carrier pads · ASTM D3574 methods · V-0 class on the 40V0 TDS
Specify the supported mass per pad and the lowest disturbance frequency, not just thickness. The grade firmness and gauge fall out of those two numbers; an over-stiff pad amplifies instead of isolating.
Rebonded Neoprene (25# / 27# Densities)Rack footing & standoff pads · static bearing stress · ASTM D1056 data per grade TDS
Send loaded masses and bearing areas; both come straight off the rack layout, and the density grade follows. A bottomed-out pad transmits everything.
Natural Rubber (BLAST 139, 4130 Open-Cell) + Atlas Bearing-Grade Elastomer (168/258/268/278)Seismic-brace interface & bearing pads · resilience under clamp load · values per vendor TDS
The bracing system's seismic qualification belongs to the tested platform and the engineer of record. The pad is a converter-side component inside that design, and this page cites the framework by designation only.
Vinyl Nitrile Foam (SBE41VN / SBE42VN, ENSOLITE® IG1 / MLC)Panel damping layers & generator-room gaskets · lossy closed-cell · ASTM D1056 classes per grade TDS
Damping layers work where the panel actually bends; coverage and placement matter as much as material. The rated loss factor belongs to the tested treatment.
BISCO® Cellular Silicone (HT-870 Soft, RS-800 Medium) + A2 Sound-Barrier LineFlame-class linings & barrier layers · UL 94 listings per grade TDS · STC per tested assembly
Decide the flame-class requirement before the material: it picks between the urethane and silicone tracks before cost does, and the class belongs to the grade per its TDS.
Cork-Rubber (BC351-207, DC100-312, SP52)Low-creep leveling shims & clamped-joint pads · torque retention · values per vendor TDS
Choose cork-rubber for stiffness and creep resistance, not isolation: it is the support-and-shim material in this set, and it pairs with (rather than replaces) the resilient families.
Open-Cell Absorber & Felt Set (PU Hybrid Foam, 20 PPI Reticulated, SAE Pressed Felt F-10 / F-26)Enclosure absorber linings & anti-rattle layers · absorption rated on the tested treatment (ASTM C423)
Closed-cell foams do not absorb; specify open-cell for absorption duty, and remember the NRC belongs to the tested panel, thickness and mounting included.
Data-center vibration & acoustic materials: engineer-grade FAQ
Ten of the questions we hear most from rack, cooling, storage, and facility teams. If your question isn't here, send a drawing or call, engineering picks up.
Do these materials carry NEBS or seismic listings?
No material does: Telcordia GR-63-CORE (NEBS physical protection, including its earthquake and acoustic criteria) evaluates platforms and systems, so the result belongs to the tested system and the engineer of record. What a pad or lining carries is its own documentation: UL 94 flammability classes on the rated grades per the vendor TDS, ASTM D1056 or D3574 method data behind its properties, and lot-code traceability.
The materials on this page support designs commonly framed by GR-63-CORE, cited by designation only. H-O's own certification is ISO 9001:2015, covering the quality system the parts are made under. [7]
What goes under a fan tray to stop it humming through the chassis?
Commonly a microcellular urethane pad set at the mounting points: PORON® 4701-series grades chosen by compression-force-deflection (per ASTM D3574 on the TDS) against the fan mass, sized so the mounted natural frequency sits well below the running-speed and blade-pass tones, putting the assembly in the isolation region above the √2 crossover. The 4701-40V0 grade carries a UL 94 V-0 class per its TDS where the location demands one.
Send the fan mass, the mounting pattern, and the lowest disturbance frequency; firmness and gauge fall out of those numbers. [6]
How do I size rack anti-vibration footing pads?
By static bearing stress: loaded cabinet mass over total pad area, placed so each pad's stress sits inside its grade's working range per the ASTM D1056 data on the TDS. Dense rebonded neoprene (25# and 27#) carries loaded-cabinet stresses; lighter wall-mount and shelf gear belongs on vinyl nitrile at gentler stresses; and cork-rubber serves where the pad is really a low-creep leveling shim. Size to the heaviest configuration the platform ships, including batteries and cabling, not the empty cabinet. [5]
What lines an enclosure to quiet fan noise, and does it need a flame rating?
A genuinely open-cell absorber: open-cell polyurethane hybrid foam for general lining, thin pressed felt where the budget is millimeters, and reticulated foam where the lining shares a panel with airflow. Closed-cell gasket foams reflect rather than absorb.
The flame-rating decision belongs to the platform's materials rules; when one is named, flame-rated options carry per-grade UL 94 listings on their vendor TDSs (the 20 PPI reticulated grade lists an HF-1 class; BISCO® silicone grades carry their own listings). Absorption is rated per ASTM C423 on the tested treatment, thickness and mounting included. [2]
Loss factor, NRC, STC: which number do I actually spec?
They rate three different jobs. Loss factor (ASTM E756) rates damping: how fast a treated panel drains its resonance. NRC and absorption coefficients (ASTM C423) rate absorption: how much sound a lining soaks up instead of reflecting. STC (ASTM E413, from E90 data) rates transmission loss: how much sound a barrier blocks. All three belong to the tested treatment or construction, not the raw material, which is why this page specifies materials by family and method and leaves the rated number with the assembly that earned it. [1]
Can foam parts really protect hard drives from fan vibration?
They treat the transmission path, which is where most of the problem lives. Rotational vibration from fans and neighboring drives reaches a disk through the carrier and chassis; thin lossy damping layers on the panels that bend, soft decoupling pads at carrier interfaces, and felt at sliding contacts each take a bite out of that path. The drive maker's mounting spec governs what touches the drive itself, and the improvement is measured on the treated assembly, before and after.
It is an incremental, additive treatment, commonly reported to matter most in dense arrays near high-static-pressure fans.
What sits between a seismic brace and the cabinet?
An interface pad chosen for bearing stress and creep rather than softness: natural rubber or Atlas bearing-grade elastomer where the joint carries load, cork-rubber where torque retention over years governs, thin felt at sliding and thermal-movement joints.
The pad distributes clamp load, stops fretting and rattle, and closes the vibration short-circuit the brace opens, without changing the bracing design, whose seismic qualification stays with the tested platform and the engineer of record (GR-63-CORE cited by designation). Confirm compression set per ASTM D395 / D1056 on the grade TDS. [7]
What does H-O supply for generator-room acoustic panels?
The interface layer the panel system needs at its boundaries: perimeter gaskets that stop flanking leaks around each panel, isolation strips between frames and structure, standoff and bearing pads, and barrier-layer from the BISCO® A2 sound-barrier line where the design laminates mass into a detail.
The panel system's acoustic rating belongs to its maker's tested assembly; the converter-side parts are chosen for closure force, fluid tolerance (name the diesel and oil-mist exposure), and longevity. The room's deeper treatment lives on the data-center safety & generator sibling page.
Will adhesive-backed damping layers and linings stick to powder-coated panels?
Only if the adhesive system is chosen for the finish: powder coatings are commonly low-surface-energy substrates, and a PSA that grips bare metal may release from textured paint, especially on a warm interior panel. Adhesive performance depends on the substrate, its surface energy and preparation, temperature, exposure, dwell time, applied pressure, joint geometry, and assembly method, so the adhesive system should be validated on the actual painted or coated panel before the kit is released.
Send a sample panel with the RFQ; H-O laminates the PSA grade your validation selects and documents it per the adhesive vendor's TDS.
Can H-O kit the whole treatment set per rack or per enclosure?
Yes: fan-tray pads, footing pads, lining panels, brace-interface pads, and drive-bay damping parts can ship as kitted, sequenced sets, one kit per rack, enclosure, or chassis, parts kiss-cut on liner in assembly order, with lot-code TDS records per material. H-O and converts sheet, roll, and slab stock to drawing in Winsted, Connecticut under an ISO 9001:2015 certified quality management system; we do not mold or extrude in-house, and molded isolator hardware is coordinated through a partner network.
Glossary: terms used on this page
Quick reference for the vibration, damping, and acoustic terminology used throughout. Each entry links to the relevant standard or test method where applicable.
Transmissibility
The ratio of force or motion transmitted through a resilient mount to the force or motion put into it, plotted against the frequency ratio f/fn. Below √2 the mount amplifies; above √2 it isolates. Lab measurement of a mount's transfer properties follows ISO 10846 [4].
Natural frequency & the √2 crossover
The frequency a mounted mass bounces at on its resilient pad. Isolation only begins once the disturbance frequency exceeds about 1.4× (√2×) the natural frequency; the softer the pad and the heavier the mass, the lower the natural frequency and the earlier isolation starts.
Damping loss factor (η)
The measure of how fast a damping treatment converts panel vibration to heat, characterized per ASTM E756 [1] by the cantilever-beam method. The rated value belongs to the tested treatment (material, thickness, and panel together), not the raw sheet.
Free-layer vs constrained-layer damping
A free-layer treatment bonds a lossy layer to one face of a panel and damps it through extension; a constrained-layer treatment sandwiches the lossy layer under a stiff skin and damps it through shear, usually achieving more with less thickness. H-O laminates and both constructions to panel profile.
Compression force deflection (CFD)
The pressure a cellular material exerts at a given compression, the curve that turns a foam pad into a specifiable spring. Reported per ASTM D3574 [6] on the PORON® TDSs; isolation pads are specified by their CFD window against the supported mass, not by thickness.
Compression set
Permanent deformation after sustained compression, measured per ASTM D395 (elastomers) and the cellular procedures in ASTM D1056 [5]. A pad that sets drifts off its design natural frequency; a clamped joint that sets goes loose. The property that decides whether a spec is still valid in year five.
Sound absorption & NRC
How much incident sound a porous treatment dissipates instead of reflecting, measured per ASTM C423 [2] and summarized as the Noise Reduction Coefficient. Open-cell structure is the prerequisite; the rating belongs to the tested panel at its tested thickness and mounting.
Transmission loss & STC
How much airborne sound a barrier blocks, measured per ASTM E90 and rated as the single-number Sound Transmission Class per ASTM E413 [3]. Barrier performance comes from mass and decoupling, which is the A2 sound-barrier line's job in a lining stack; the STC belongs to the tested construction.
Rotational vibration (RV)
Angular vibration about a hard drive's spindle axis, the component drive heads are most sensitive to. Fan tones and neighboring-drive seeks deliver it through the carrier and chassis; damping the transmission path is the converter-side contribution to keeping heads on track.
Telcordia GR-63-CORE (by designation)
The NEBS physical-protection requirements document, including earthquake (zone) and acoustic criteria for network equipment, per [7]. It evaluates platforms and systems; on this page it is cited by designation, and the materials support designs commonly framed by it.
Static bearing stress
Supported load divided by pad bearing area: the number that sizes footing and bearing pads. Each grade has a working range per its TDS; above it the pad bottoms out and transmits, below it the pad barely deflects and does little.
Rebonded neoprene
Dense slab made of granulated neoprene re-bonded under pressure, the classic machinery base-pad construction, specified by static bearing stress with per-grade data per ASTM D1056 on the TDSs. The 25# and 27# density designations carry this page's rack-footing duty.
BSR (buzz, squeak & rattle)
The noise an assembly makes against itself: stick-slip squeak at sliding contacts, loose-part rattle, panel buzz at resonance. The fixes are thin, precisely placed felt and soft-foam parts at the contact lines, drive carriers and brace clamps included.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, and vendor technical data sheets cited throughout this page. Platform frameworks are cited by designation: they evaluate systems and platforms, and the result belongs to the tested assembly. Treatment-level acoustic and damping ratings belong to the tested treatment or construction. Standards editions current as of June 2026; verify against the publishing body before final spec.
H-O converts materials tested to the material-level methods on the source vendor's TDS; H-O does not certify systems or independently certify materials unless explicitly stated on the quote.
[1] ASTM E756
Standard Test Method for Measuring Vibration-Damping Properties of Materials (ASTM International). The cantilever-beam loss-factor method behind every damping claim on this page; the rated value belongs to the tested treatment.
[2] ASTM C423
Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method (ASTM International). The method behind NRC ratings for absorber linings, measured on the tested panel at its tested thickness and mounting.
[3] ASTM E90 / E413
Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss (E90) and Classification for Rating Sound Insulation (E413, the STC rating) (ASTM International). Barrier and panel-system ratings follow these methods on the tested construction.
[4] ISO 10846
Acoustics and vibration — Laboratory measurement of vibro-acoustic transfer properties of resilient elements (International Organization for Standardization). The measurement framework for resilient-mount transfer properties referenced by the isolation discussion.
[5] ASTM D1056
Standard Specification for Flexible Cellular Materials — Sponge or Expanded Rubber (ASTM International). The classification system behind the rebonded neoprene, vinyl nitrile, and neoprene foam grades on this page, per the vendor TDSs.
[6] ASTM D3574 / D395
Standard Test Methods for Flexible Cellular Materials — Slab, Bonded, and Molded Urethane Foams (D3574, including the compression-force-deflection procedures) and Standard Test Methods for Rubber Property — Compression Set (D395) (ASTM International). The methods behind the PORON® and HyPUR-cel® data cited per grade TDS.
[7] Telcordia GR-63-CORE (by designation)
NEBS Requirements: Physical Protection (Telcordia/Ericsson), including earthquake-zone and acoustic criteria for network equipment platforms. Cited by designation as platform-level design context; the evaluation belongs to the tested system, and the materials on this page support designs commonly framed by it.
[8] UL 94 (by designation, classes per grade TDS)
Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (UL). Flammability classes (V-0, HF-1, and others) belong to the individual listed material grades per their vendor TDSs; this page names the class only where a grade's TDS lists it.
Updated . Standards editions current at publication; verify against the publishing body before final spec. H-O converts materials tested to the methods cited; H-O does not certify systems. Lot-specific documentation available on request.
Get a vibration & acoustic materials engineering quote
Send a drawing set, a chassis sample, or the treatment checklist from the builder above. We typically respond within one business day with a material recommendation, prototype lead time, and TDS verification against your bearing stresses, gauge budgets, and any flame-class callouts.
See also: related H-O application pages
Engineering content for the parent NVH application, the adjacent data-center sub-applications, the die-cutting capability behind the parts, and the owning industry hub. Each page covers material selection, failure modes, and converter-side process detail for its application family.
Parent application
NVH, shock & vibration control
The cross-industry isolation and damping overview: natural-frequency logic, CFD selection, and the elastomer and foam catalog this page's parts draw from.
Read the page
Sibling sub-application
Data center indoor sealing & airflow management
The same white space, different physics: aisle-containment strips, rack blanking gaskets, raised-floor grommets, and CRAC/CRAH unit gasketing.
Read the page
Sibling sub-application
Telecom equipment protection & packaging
Edge protection, wear pads, and dunnage that guard telecom gear through shipping and field handling.
Read the page
Sibling sub-application
Telecom rack bonding & assembly
The adhesive side of the same racks: gasket-attach systems, bonding tapes, and the substrate-validation discipline this page's PSA-backed parts inherit.
Read the page
Capability
Flatbed die-cutting
The process behind the pads, layers, and linings on this page: thick-section elastomer and foam die-cutting to drawing, with tooling guidance and tolerances.
Read the page
Industry hub
Telecom & data centers
The full telecom and data-center application family: thermal, EMI, power insulation, outdoor sealing, white-space airflow, and this page's vibration set.
Read the page
Material data & standards. All compression, bearing, and flame-class values on this page are taken from the source vendor's technical data sheets with the method named (ASTM D1056, D3574, D395; UL 94 classes per the listed grade TDSs). Treatment-level ratings (loss factor per ASTM E756, absorption per C423, transmission loss per E90/E413) belong to the tested treatment or construction, not the raw material.
Platform frameworks (Telcordia GR-63-CORE and seismic/building requirements) are cited by designation only: the evaluation belongs to the tested platform and the engineer of record, and the materials on this page support designs commonly framed by them. H-O converts materials; H-O does not model structures, run acoustic or seismic testing, or certify systems, and does not independently certify materials against the standards cited.
Performance depends on grade, geometry, compression, adhesive system, and environment; final material selection should be validated in the application against the vendor TDS.
Conversion scope. H-O and converts sheet, roll, and slab stock to drawing in Winsted, Connecticut: die-cut and kiss-cut pads, layers, and linings, slit strip stock, waterjet-cut thick sections, laminated barrier constructions, and kitted per-rack and per-enclosure sets, with material traceability and lot-code TDS records. H-O does not mold or extrude in-house; molded isolator and bushing hardware is coordinated through a partner network. Lead-time and MOQ details are in the process strip and the quote form above.