CR4® - The Engineer's Place for News and Discussion®

Elasto Proxy's Sealing Solutions Blog

Elasto Proxy's Sealing Solutions Blog is the place for conversation and discussion about the design and custom fabrication of rubber and plastic components. For nearly 25 years, our family-owned company has provided high-quality, low-volume seals to a variety of industries. Doug Sharpe, Elasto Proxy's co-founder, is a former president of the International Sealing Distribution Association (ISD), a not-for-profit trade association that enhances member success through information, education, and interaction. By blogging for CR4 in this same supportive and collaborative spirit, Doug and other members of the Elasto Proxy team will share our experiences with you.

Noise Control and Acoustic Insulation: Sound Sources and Frequencies

Posted March 19, 2018 6:51 PM by Doug Sharpe

Acoustic insulation absorbs, transmits, or redirects sound – a form of energy that travels in waves. Unwanted sounds, or noise, aren’t just unpleasant to hear. They can harm human health, jeopardize worker safety, and contribute to structural fatigue. The consequences of noise can be severe, but its characteristics are sometimes misunderstood.

In Part 1 of this series, Elasto Proxy shared a surprising example of two machines running at different decibel (dB) levels in the same room. In Part 2, we’ll examine some other sources of noise in the industries we serve. Importantly, you’ll learn why acoustic insulation must account for more than just a sound’s source. Frequency, the speed of the change of the sound, is a key design consideration for noise control.

Noise Sources

Noise can be caused by mechanical vibration, solid-to-solid contact, and fluid-solid interaction. Mechanical vibration induces resonance in structures such as vehicles, machinery, and equipment. Solid-to-solid contact includes both impact and friction. Fluid-solid interaction happens when air, a type of fluid, flows around built structures.

Mobile equipment and military vehicles are susceptible to all three noise sources. Mechanical vibrations from a vehicle’s engine bay can penetrate the cabin’s interior. Solid-to-solid contact occurs whenever a vehicle’s tires or tracks roll along roadways or off-road terrain. Friction happens during vehicle braking, especially with sudden stops. Air flow around a vehicle’s exterior can also cause unwanted sounds.

Designers of aircraft, infrastructure, and equipment face similar challenges. Airplane flaps, helicopter rotors, wind turbines, and fans have turbulent air flows around their edges. HVAC systems and light fixtures can induce mechanical vibrations. Solid-to-solid contact happens when an airplane’s wheels hit the runway. In the food processing industry, pouring ingredients into a hopper can also cause noise.

Frequency and Noise Control

Frequency is an important feature of sound and, in turn, noise control. Hertz (Hz), the unit of measure that’s used for frequency, is the number of oscillations per second in a sound wave. Higher-frequency sounds have shorter distances between oscillations. Lower-frequency sounds have longer-distances. That’s nice to know from a scientific perspective, but what are the implications for acoustic insulation?

Physical barriers are less effective against lower-frequency sounds like the rumble of a diesel engine. When the source of the noise and its receiver are on different sides of a barrier, the goal is to block the sound. That’s why in mobile equipment and military vehicles, acoustic insulation is attached to the firewall that separates the engine bay from the cabin.

Sound absorption isn’t the only method of noise control. In buildings, physically separating the two sides of a wall makes it harder for sound to pass through. Known as decoupling, this soundproofing method uses acoustic insulation as the medium between two panels. Decoupling can be effective, but only at frequencies where resonance levels won’t induce mechanical vibrations – and more noise.

As noise control methods, sound absorption and decoupling are effective when the source and receiver are on different sides of a wall, screen, equipment enclosure, or other type of barrier. When the sound and receiver are on the same side, it’s important to limit the sound’s reflections instead. Since higher-frequency sounds radiate towards the ceiling, acoustic insulation may be installed overhead.

Choose Acoustic Insulation from Elasto Proxy

Acoustic radiation is complex. Product designers, engineers, and technical buyers need to know more than just the decibel level. Both the source of a sound and its frequency are important design consdierations. Acoustic insulation can also be “tuned” to permit or prevent the passage of specific frequency ranges. Design assistance, custom fabrication, and testing services can strengthen your application.

Do you need custom acoustic insulation? Then it’s time to contact Elasto Proxy.

Add a comment

Nitrile vs. Neoprene: What’s the Difference?

Posted March 12, 2018 4:55 PM by Doug Sharpe

What’s the difference between nitrile and neoprene for seals, gaskets, and insulation? Both elastomers provide good resistance to compression set and tearing. They withstand the same range of service temperatures, too. Some grades of neoprene offer excellent resistance to abrasion, but nitrile is known for its abrasion resistance at elevated temperatures.

Nitrile and neoprene rubber have many similarities, but there are some important differences between these elastomers. In this article from Elasto Proxy, you’ll learn when nitrile is recommended and when neoprene is used. You’ll also compare these common compounds across all a full list of material properties so that you can make the right choice for your application.

Nitrile vs. Neoprene: Material Properties

Nitrile offers excellent oil and solvent resistance across a wide temperature range. This synthetic elastomer has very good resistance to engine oil and gasoline, very good resistance to alkalis and acids, and superior resistance to petroleum-based hydraulic fluids. Neoprene offers moderate resistance to oils and petroleum products, but provides significantly greater resistance to sunlight, ozone, and weather.

The differences don’t end there. Nitrile rubber has poor flame resistance. By contrast, neoprene provides very good-to-excellent resistance against the spread of flame. Nitrile is attacked by sunlight, ozone, and weather, but neoprene provides reliable resistance against these environmental conditions. Yet neither rubber resists aromatics or ketones, two types of organic compounds.

As the following table shows, nitrile and neoprene are both similar and different in terms of properties.



General Information

Common NamesNitrile, Buna-N, NBRNeoprene
Chemical NamesAcrylonitrile-butadienepolychloroprene
ASTM D-2000 ClassificationBF, BG, BK, CHBC, BE

Physical Properties

Elongation400% to 600%100% to 800%
Hardness (Shore A)35 to 9015 to 95

Mechanical Properties

Compression SetGoodGood
Rebound RatingGoodFair to Very Good
Flex Cracking ResistanceGoodGood to Very Good
Abrasion ResistanceGood to ExcellentVery Good to Excellent
Tear ResistanceGoodGood
Impact ResistanceFair to GoodGood to Excellent
Flame ResistancePoorVery Good to Excellent

Thermal Properties

Minimum Service Temperature-30° F to -70° F-30° F to -70° F
Maximum Service Temperature+220° F to +280°F+220° F to +280° F

Environmental Resistance

SunlightPoorGood to Very Good
WaterGood to ExcellentExcellent
SteamFairPoor to Good
Gas PermeabilityFair to GoodFair to Good

Chemical Resistance

Generally Resistant ToGases, Aliphatic Hydrocarbon, Oils and FuelsModerate chemicals and acids, ozone, oils, fats, greases, and solvents
Generally Attacked ByKetones, Ozone, Sunlight, Aromatic Oil, Flame, WeatherEsters, ketones, and chlorinated, aromatic, and nitro hydrocarbons

Nitrile vs. Neoprene: Applications

Nitrile rubber is recommended for applications that require oil and fuel resistance, abrasion resistance, and temperature resistance up to 280° F. In mobile equipment and military vehicles, nitrile seals or gaskets are used in carburetor diaphragms, fuel systems, and hydraulic hoses. Nitrile also supports rubber-to-metal bonding, which makes it a good choice for applications in the processing industry. Yet nitrile isn’t recommended for sealing and insulation that requires resistance to fire, sunlight, ozone, or weather.

Neoprene rubber resists fire and withstands sunlight, ozone, and weather. Specific grades of neoprene can also meet flame, smoke and toxicity (FST) requirements for the mass transit industry. Applications include door seals, window seals, hose covers, vibration mounts, and shock absorbers. Neoprene is also used with HVAC units, electrical or electronic enclosures, and weather stripping for fire doors. Additional applications include expansion joints and bearing pads in built structures.

Nitrile vs. Neoprene: Make the Right Choice

Compound selection is critical because choosing the wrong rubber can cause more than just a component-level failure. Are you wondering whether nitrile or neoprene is the right elastomer for your application? Do you need custom-fabricated sealing solutions that add value and reduce risk? Then it’s time to talk to Elasto Proxy. Contact us to discuss your application.

Add a comment

Acoustic Insulation: What You Need to Know About Noise

Posted March 05, 2018 4:55 PM by Doug Sharpe

Acoustic insulation absorbs, transmits, or redirects sound – a form of energy that travels in waves. Some sounds are pleasant to hear, but others can harm human health, endanger workers, or contribute to structural fatigue. Undesirable sounds, or noise, have characteristics that designers of acoustic insulation need to understand. Without this knowledge, noise problems can cause design-related headaches.

In Part 1 of this series from Elasto Proxy, you’ll learn about the consequences of noise and discover why its characteristics might not be what you think. You’ll also consider why decibel-level differences in noise sources matter. Then, in Part 2, we’ll examine sound measurements and noise control in greater detail. Along the way, we invite you to contact us with your questions about acoustic insulation.

The Consequences of Noise

From a scientific perspective, noise is indistinguishable from sound. Both are vibrations that travel through a medium such as air or water. The difference, of course, is in what happens when these vibrations reach a listener. In terms of human health, excessive noise can cause hearing loss and induce cardiovascular stress. Not surprisingly then, noise levels are regulated by government agencies and authorities.

In the workplace, noise can make it hard for workers to hear fire alarms or safety-related announcements. Noise can also impede concentration and interfere with employee communications. Loud or disruptive sounds are problematic, but so are sound-induced vibrations that cause structural fatigue and stress concentrations in parts, assemblies, equipment, and buildings.

For engineers, acoustic insulation needs to ensure the safety and comfort of people, protect the life of engineered products, and support overall performance. There are financial incentives for noise control, too. Many customers want quieter vehicles, machinery, and equipment. Buyers also need to comply with occupational health and safety requirements to avoid fines and penalties.

The Characteristics of Noise

Solving the problem of noise requires a basic understanding of sound. Noise, or sound, is a pressure wave that travels from a source through a medium to a receiver. The human ear detects variations in pressure caused by these sound waves. The amplitude of the variation, the noise level, is measured in decibels (dB). The speed of the change of the sound, the frequency, is measured in Hertz (Hz).

Sound pressure levels (SPL) use a logarithmic scale where the reference is the threshold of hearing. To a person with normal hearing, a 1 dB increase in noise level is barely perceptible; an increase of 3 dB is clearly perceptible. If the noise level increases by 10 dB, the sound will seem twice as loud. Yet an increase of 20 dB doesn’t mean that the noise level will seem twice as loud as a 10 dB increase.

What does this mean for product designers who need to reduce noise levels? How great of a reduction in decibels do you need to achieve? The following table describes the relationship between decibel reduction and sound power.

Reducing the noise level by

Reduces the sound power by

1 dB21%
3 dB50%
10 dB90%
20 dB99%

Decibel-Level Differences Between Noise Sources

In environments such as machine rooms and manufacturing facilities, engineers must also consider decibel-level differences between noise sources. For example, let’s say that two machines are running in the same room and that each machine has a noise level of 90 dB. Machine 1 continues to run at 90 dB, but the noise level for Machine 2 increases.

The following table explains how machine room personnel will perceive these sounds. Note that A-weighted decibels (dBA) are an expression of the relative loudness of sounds in air.

Machine 1

Machine 2

Total Noise Level


90 dBA90 dBA93 dBAWhen Machines 1 and 2 produce the same noise level (90 dBA), the total noise level is 93 dBA.
90 dBA95 dBA96 dBAWhen Machine 2 is 5 dB louder than Machine 1, the total noise level is just 1 dBA louder than the loudest machine.
90 dBA100 dBA100 dBAWhen Machine 2 is 10 dB louder than Machine 1, the total noise level is the same as the loudest machine.

Ask Elasto Proxy About Acoustic Insulation

Next week, we’ll continue our series about acoustic insulation and the science of sound. In the meantime, we invite you to contact us with your questions about acoustic insulation.

Add a comment

Sponge Rubber vs. Solid Rubber: What's the Difference?

Posted February 28, 2018 6:24 AM by Doug Sharpe

What’s the difference between solid rubber and sponge rubber? Both are elastomers, natural or synthetic polymers with elastic properties. Both are also subjected to vulcanization, a process that uses heat and a chemical agent such as sulfur to improve durability. Solid rubber and sponge rubber are available in many of the same compounds, such as EPDM, silicone, and neoprene. They can be extruded into the same shapes or molded into sheets, too.

At the most basic level, the difference between solid rubber and sponge rubber is about air. Sponge rubber contains balloon-like cells or interconnected pockets that either hold air or permit its passage. Solid rubber doesn’t share this cellular structure. Both types of materials provide sealing and insulation, but sponge rubber provides better cushioning. Solid rubber provides stronger impact resistance. Each type of elastomer has its advantages then, but what else do engineers need to know?

Solid Rubber

Solid rubber can be soft, medium, or hard. Durometer, a measure of hardness, is expressed as a number on the Shore A scale. The soft rubber that’s used in pencil erasers has a durometer of 40 (Shore A). The hard rubber in hockey pucks has a durometer of 90 (Shore A). This range of durometers is important to note because the difference between solid rubber and sponge rubber isn’t just about one being harder than the other.

In addition to durometer, the physical properties of solid rubber include density, rigidity, and force distribution. Harder, denser rubbers provide greater resistance to abrasion, wear, and other stresses. These elastomers can also resist permanent indentation. Harder elastomers are stiffer and less elastic, but they can repel applied forces and sudden impacts. Rubber has desirable acoustical properties, too. Harder rubber can redirect sound waves while softer elastomers absorb and disperse sounds.

Solid rubber materials are used in shock absorbers, bumpers, and anti-vibration pads for vehicles, machinery, and equipment. These industrial rubber products reduce the risk of downtime by protecting mechanical parts. In the case of rubber bumpers, solid elastomers can absorb impacts such as when a truck strikes a loading dock. Applications for solid rubber seals and gaskets include surface protection and fluid containment.

Sponge Rubber

Like solid rubber, sponge rubber is available in different durometers. Sponge rubber is usually softer, but that’s not always the case. For example, a 40-durometer sponge rubber is harder than a 30-durometer solid rubber. Differences in material hardness are important, but so is a rubber’s ability to return to its original thickness after a compressive force (such as a closed door) is removed. Sponge rubber provides better cushioning than solid rubber but can become over-compressed so that seal failure results.

Sponge rubber is available with either open cells or closed cells. Open-cell sponge rubber contains open, interconnected pockets that permit the passage of air, water, gases, and chemicals when the material is not compressed. Closed-cell sponge rubber contains balloon-like cells that prevent the passage of these substances at low pressures. Foam rubber also has a cellular structure but is different than sponge rubber because of how it’s made.

Sponge rubber products are used for cushioning, shock absorption, vibration dampening, weather stripping, and soundproofing. Sponge rubber is also used in thermal insulation, filters, and custom gaskets that need to meet various standards and approvals. For example, silicone sponge rubber with a UL 94 flame rating is used in electrical equipment. Solid rubber materials can also meet different standards and approvals, so engineers need to select compounds with care.

Get Help with Compound Selection

Do you have questions about solid rubber and sponge rubber? Do you need help choosing the right compound, or are you trying to strike a balance between cushioning and impact resistance? Elasto Proxy can answer your questions about elastomers and fabricate the custom seals, gaskets, and insulation that you need. To get started, contact us.

Add a comment

Molded Rubber Products

Posted February 20, 2018 12:00 AM by Doug Sharpe

Did you know that Elasto Proxy supplies molded rubber products? We’re not just a distributor of stock materials, and we’re not just a custom fabricator of seals, gaskets, and insulation. Instead, Elasto Proxy is value-added supplier with a wide range of products and services. By sourcing molded parts from Elasto Proxy, major manufacturers have consolidated their vendor lists. No matter what your company’s size, you can save time and money by doing more business with Elasto Proxy.

Consolidate Your Vendor List

Carrying more vendors than you need isn’t cost-effective. Establishing credit terms, managing payment information, and calculating vendor scorecards takes time. There’s also a cost to issuing purchase orders, receiving shipments, and stocking items. By ordering more items from a single supplier, you can combine shipments and reduce processing costs. Instead of ordering custom gaskets or insulation from one supplier and molded rubber products from another, you can increase efficiency with one-stop shopping.

There are other advantages, too. Compared to smaller vendors, Elasto Proxy can warehouse your molded rubber products at our facilities near Montreal or Toronto, Canada, or in Simpsonville, South Carolina (USA). All three of these locations are situated along major transportation corridors. If you issue Elasto Proxy a blanket purchase order, we can schedule regular releases. Plus, we can combine shipments of molded rubber products with the custom-fabricated parts that you regularly need.

Types of Molded Rubber Products

Elasto Proxy supplies these and other molded rubber products

  • Grommets
  • Vibration mounts
  • Bumpers
  • Silicone connectors

We also provide molded rubber hose clamps, rubber-to-metal molding, and molded plastic products like the pedals on hospital beds. Let’s take a closer look.

Rubber Grommets

Grommets are molded rubber products through which wires or cables are fed. They are installed in holes in thin panels and are made of elastomers such as EPDM, neoprene, nitrile, or silicone. Rubber grommets are usually shaped like rings or eyelets, but can also be flanged, collared, or horseshoe-shaped. Dimensional specifications vary with grommet style, but usually include inside diameter (ID), outside diameter (OD), groove width, groove diameter, and overall thickness.

Vibration Mounts

Vibration mounts or isolation mounts prevent the transmission of noise, shock, and vibration in vehicles, equipment, and machinery. These molded rubber products attach with a threaded metal fastener and are rated for a specific load capacity. The rubber in an anti-vibration mount acts as spring and absorbs energy that can damage mechanical systems. Isolation mounts come in many different sizes and shapes, including mounting pads. Metal threads are specified in U.S. and metric thread sizes.

Rubber Bumpers

Rubber bumpers provide protection against low-speed collisions and low-speed impacts. They are installed on trucks, trailers, loading docks, and generator sets (gensets). Rubber truck bumpers are made of EPDM, SBR, and other elastomers that can withstand wind, weather, abrasion, and incidental contact with petroleum products. Typically, these molded rubber parts install with metal fasteners like screws and bolts. Bumpers with embedded washers are also available.

Silicone Connectors

Silicone connectors are molded rubber products that connect the intake pipes and tubes in diesel-powered vehicles and equipment. These engine components resist high temperatures and provide strength and flexibility. Product types include silicone elbows, silicone reducers, straight hoses, hump hoses, and wrapped hoses. To meet application-specific requirements, a silicone connector can include fabric, wire, or liner materials.

Other Molded Products

Elasto Proxy also supplies molded rubber hose clamps for joining pipes. These rubber parts have recessed nut-and-bolt holes so that there’s no exposed metal after assembly. Applications include industrial machinery, vehicles, and equipment. Metal-to-rubber bonding is used with a host of parts, including grommets, vibration mounts, and bumpers. For the medical and healthcare industry, Elasto Proxy has supplied molded plastic partslike Delrin® rollers, bed-mounted holders, and color-coded plastic pedals.

Find Molded Rubber Products (and More)

Do you need molded rubber products? Would you like to consolidate your vendor list so that you can do more business with a trusted supplier? Elasto Proxy is a distributor of stock materials, a custom fabricator, and a supplier of molded rubber products like grommets, vibration mounts, bumpers, and silicone connectors. We provide molded hose clamps, rubber-to-metal molding and molded plastic products, too.

To simplify your supply chain, contact Elasto Proxy.

Add a comment

Previous in Blog: Four Values That Define Elasto Proxy  
Show all Blog Entries in this Blog