FREQUENTLY ASKED QUESTIONS
Steelhead Composites accumulators' diameters refer to their Inside Diameter (ID). CNG and other gas storage vessels are measured by their Outside Diameter (OD).
In context of a pressure vessel or accumulator, composites are an advanced material formed by combination of strong and stiff fibers held together by a binder or matrix. In our case, we use carbon fibers mixed with a thermoset resin to create the structural, pressure-carrying layers of a strong yet lightweight pressure vessel and accumulator. We also use a thin, sacrificial layer of glass-fiber and resin composite on the outside for damage protection.
Steelhead Composites uses standard modulus, high strength polyacrylonitrile (PAN) based carbon fibers with verifiable strength properties for all lightweight high-pressure composite accumulators.
PAN-based carbon fibers are derived from a polyacrylonitrile (PAN) plastic precursor, which is spun into fibers, then carbonized in an oxygen-free environment at temperatures upwards of 2000°F (1100°C). The surface of each fiber is then treated, and coated with a sizing material that is compatible with the resin to be used before the fibers are wound onto creels or bobbins and ready for use.
Wet winding involves running the carbon fibers through a liquid resin bath immediately before applying them to the liner. Dry winding uses carbon fibers which are pre-impregnated with resin. This results in precise control of resin content, improved fiber placement without slippage, faster winding times, virtually no volatile organic compounds (VOCs) and eliminates the need for cleanup of wet resin.
The carbon fiber used for structural layer of the vessels is highly resistant to corrosion. The resins used in the composite material may be sensitive to the salt air and UV environment and need to be protected with a UV resistant resin. Contact Steelhead Composites to discuss specific resin options for this type of application.
Currently, we have tested our bladder accumulators in excess of 500,000 cycles under rigor and stress. Cycles of a million plus are on track to be achieved with the help of advanced engineering, material treatment, and extensive testing.
That depends on the service conditions, but no sooner than bladders currently used in traditional steel accumulators. Steelhead Composites recommends that bladders and o-rings be changed every 100,000 cycles of accumulator operation. Some applications may require more frequent bladder replacement. Steelhead offers a replacement bladder kit, tools and charging accessories.
Yes. Steelhead Composites accumulators and pressure vessels are wrapped in a protective layer of glass fiber composite that can be dyed to any color (standard colors are available to meet your needs). For low pressure accumulators that do not require a protective fiberglass layer the vessels can be painted or powder coated.
A pulsation dampener smooths out pulsations, or pressure fluctuations, in a fluid system, either on the inlet or outlet side of the pump. An accumulator’s main purpose is to store/accumulate energy and to dispense that stored energy quickly. It can be purpose designed to smooth pulsations on the discharge side of the pump by storing excess fluid energy and thereby acting as a pulsation dampener.
Steelhead Composites accumulators are cost competitive in comparison to steel. They exceed the price only by a small percentage in the smaller sized vessels (10 gal.). Steel is an affordable raw material available worldwide. Steel vessels are simple to mass produce and often are made overseas for a fraction of the price but sometimes with little to no quality control. Composite pressure vessels are engineered to be lightweight, strong, reliable and safe. This, combined with high tech materials such as seamlessly formed aluminum, epoxy impregnated carbon and glass fiber, and strong but lightweight interface components add cost. In addition Steelhead Composites is committed to high quality and to manufacturing these accumulators within the USA.
Steelhead Composites accumulators are designed to meet the design specification of ISO 11119-2 and compliant with US-DOT. We expect to offer ASME certified and CE marked composite accumulators in the near future.
A hydrostatic test is a way in which pressure vessels can be tested for strength and leaks and to ensure the quality and structural integrity of our accumulators before they are put in to service. It involves filling the vessel with water and pressurizing the vessel to the specified test pressure, which is typically 1.5 times the maximum operating pressure.
Steelhead Composites conducts hydrostatic proof testing of every single vessel to ensure quality and safety for our customers. To verify design factor of safety, we also burst test one vessel for every batch of vessels produced, with batch size ranging from 30 vessels on the low end to no more than 200 on the high end.
Steelhead Composites accumulators can handle operating temperatures during continuous operation of 185° F (85° C) on the high side -20° F (-30° C) on the low side. Alternate bladders made from custom materials are available upon request for temperature of operation beyond these limits.
Standard material is Buna-Nitrile but we also offer low temp Buna-Nitrile, extreme low temp Nitrile, high temp Nitrile, Fluoro-Elastomer, Butyl and many more depending on your application needs.
No. Steelhead accumulators have an internal diameter of 10 in. (254 mm) which requires a Steelhead Composites bladder.
They are slightly thicker than standard bladders for traditional steel accumulators. This reduces permeation of Nitrogen gas over time through the bladder wall when the accumulator is in service.
Weight, cost and ability to handle a “dirtier” working fluid or environment.
No, Steelhead Composites incorporates a patented “steel head” with steel threads or a flange fitting for robust connection to any system.
The energy stored in an accumulator depends on its size and operating pressure. Please visit Steelhead Composites website to calculate energy stored for your accumulator size or to size your accumulator based on energy storage requirements.
The standard flow rate in a Steelhead Composite accumulators can vary between 160 gallons per minute (10 Liters/sec) and 240 gallons per minute (15 Liters/sec) depending on the orientation and positioning of the accumulator.
Typically the volume of fluid that moves in and out of the accumulator is at most 50 to 70% of the nominal accumulator volume. However, this is a function of the operating pressure and temperature. Please visit Steelhead’s website to accurately calculate fluid volume that flows in and out of your accumulator or to size your accumulator based on fluid volume flow requirements.
Yes. Steelhead offers a complete line of standard straps and mounts. Custom and ultra-lightweight straps and mounts are also available.
Please use our online calculators to size your accumulator today.
If an accumulator is dropped from a height, a visual inspection of the accumulator is mandatory. If no visible damage is seen, then the accumulator can be put into service.
Our accumulators may be fitted with a thermally activated pressure relief device. But we can install a different pressure relieve valve/device if your situation requires it.
The thermally activated pressure relief device will automatically purge the bladder and allow for safe escape of Nitrogen gas from the accumulator to the atmosphere.
If the bladder ruptures, Nitrogen contained within the bladder will mix with the hydraulic fluid and the mixture will leak out of the fluid end of the accumulator.
Steelhead Composites accumulators have a one year limited warranty.
A Bottom Repairable accumulator is serviced from the bottom or fluid port side only. The accumulator must be removed from the system resulting in downtime and lost productivity. A Top Repairable accumulator is a more symmetrical design and can be serviced from the top of the accumulator. The accumulator stays connected to the fluid line during servicing resulting in faster maintenance and less downtime.