MAXIMATOR | Safe Validation of CNG / H2 Components

Compared with liquid fuels, natural gas is a cost-efficient and more environmentally friendly propulsion option. Motor vehicles powered by natural gas or hydrogen require special fuel tanks that need to be light, but simultaneously extremely strong, because the gas they contain is subject to high pressure. In order to be able to ensure that such tanks operate safely, manufacturers need to test them in terms of pressure resistance and leak-tightness. For one such manufacturer, Maximator GmbH in Nordhausen, Germany has developed a special pressure testing system, the world’s first process-optimized end-of-line test stand for large-volume composite tanks.

 | © 2016 Maximator GmbH

Maximator’s New End-of-Line (EOL) High-Pressure System for CNG and H2 Composite Tanks

The company, one of the leading suppliers of systems and components for high-pressure technology, has equipped the system designed for series pressure testing of type IV composite tanks with a number of special features, such that it can be called the world’s first process-optimized end-of-line system for this application area. The systems point of use is at the end of a production line (EOL – end of line), its task being the 100% testing of vehicle tanks made of plastic with CFRP/GFRP casing in accordance with the specifications set out in ECE R110 for compressed natural gas (CNG)-powered vehicles. The system can accept large-volume tanks up to 1.4m in length and test them at a pressure of up to 350 bar in one work cycle. The system could also be converted with few specific modifications for the hydrogen field and hence testing in accordance with EC79/2009 for hydrogen-powered (H2) vehicles.

Optimized process, reproducible pressure curve

The test procedure is process-optimized, which is expressed in very short clock times. All the operator needs to do is place the tanks in a holding fixture, push this fixture into the test chamber, start the test program and remove the tanks again after the test. The progress of the test can be tracked through panes made of safety glass. In the test chamber, the tanks are automatically arranged for each of the cycles that follow one another – filling of the test fluid water, pressurization, and strength as well as leak-tightness test, draining and drying – such that they proceed at high speed. The pressure intensifier, equipped with a special control developed by our engineering team in-house, enables highly reproducible pressure generation. The deviation of the actual pressure value from the target value is less than 1%.

High-tech tanks

The system is intended for testing composite tanks, i.e. tanks that are composed of several materials. In the present case, the tanks are made of plastic enveloped and reinforced by several layers of carbon fibers. Components made of composites are extremely strong with a relatively low own weight and are therefore mainly used in aerospace technology, but also increasingly in motor vehicle technology; in fact, anywhere where high strength needs to be combined with low weight. This requirement can be found in virtually all modern structural lightweight applications, an example of which is provided by tanks for vehicles propelled with natural gas or hydrogen. For example, municipal transport services are increasingly replacing diesel-powered buses by those propelled with natural gas, as this drastically reduces the particulate emissions typical of diesel drives.

Since as much gas as possible should be stored, it is added to the tanks in compressed form, which means that they are subject to high internal pressure. In the first case (CNG), this pressure is up to 260 bar, while in the second case (H2) it is up to 700 bar. Compared with steel tanks, the stand-out feature of composite tanks is, as already mentioned, their relatively low weight; they are also highly resistant to environmental influences and never rust.

Tank testing as a service

Maximator also operates a state-of the-art laboratory at its head office in Nordhausen, Germany, where it not only carries out its own development activities, but also a wide range of tests as a service. The technical equipment has recently been enhanced, which means that tests on large-volume composite components (up to 500 litres capacity and 4m long) can now also be conducted. It is possible, while testing a tank, to record its expansion behaviour in longitudinal and circumferential direction to accuracies of 0.1 mm using laser-optical expansion measurement. In the case of burst tests, tank failures can be recorded with the use of high-speed cameras to help determine failure modes. In addition, the new test stand in the Nordhausen service centre enables composite tanks to be placed under mechanical load (torsion and bending) in burst or pressure load change tests. This gives rise to informative insights into the burst behaviour of test specimens, which is advantageous to component assessment and helps to reduce development times.

The test opportunities are likely to be of particular interest to companies in the automotive, general mechanical engineering and energy technology (CNG, H2) fields, as well as processors of composites and companies in the aerospace industry.



PARKER | Five Most Important Factors You Need to Consider for Hydraulic Fittings

OEMs and fitting manufacturers are constantly finding new ways to stump us with different threads and new ways to seal them. Generally, however, when making hydraulic fitting connection choices today, there are several features to research and understand for your application. We highlight connections, attachment styles and the 5 most important factors you need to consider for hydraulic fittings.

7 common end connection types

  • JIC 37⁰ Flares: The Joint Industrial Conference (JIC) fitting is the most common hydraulic connection style. It consists of parallel threads and a 37⁰ cone on the fitting end that attaches to either a flared tube or hose fitting.
  • O-Ring Face Seals: O-ring face seal fittings have flat sealing surfaces that contain an embedded seal, which mates to flanged tubing or hose fittings. Flat sealing surfaces reduce the risk of over-torqueing, and the captured seal prevents leakage.
  • O-Ring Boss: The threads of the SAE straight thread O-Ring Boss (ORB) and the straight thread 37⁰ JIC Flare are the same threads. The difference is the way each thread seals. While the JIC seals on a metal-to-metal flare, the ORB seals on an O-ring, which offers the best leak free connection.
  • Inch Compression: The inch compression fitting is a bite type fitting for hydraulic tubing and there are very limited hose connections for this style. This fitting can be assembled onto hydraulic hard tubing in the field with minimal tooling required.
  • NPT Pipe Threads: NPT pipe threads are your traditional tapered thread fittings and have been used for 100 years. They are available in low-pressure black iron and brass, and high-pressure steel and stainless steel. This connection style is used in pneumatic and process systems and hydraulic systems.
  • DIN Metric 24⁰ Bite Type: This is the most common hydraulic fitting style in Europe. As such, there is a full line of hose fittings for this style, and it can be used with metric-sized tubing. Newer versions of this fitting style incorporate a captured elastomeric seal on the mating surface, providing better sealing and reusability.
  • Four-Bolt Flange: The 4-bolt flange connections conforming to SAE J518 and ISO 6162-1 and -2 are proven, leak-free connections and are especially suited for larger sizes, higher pressures and assembly in tight quarters.

The 5 Most Important Factors for Hydraulic Fitting Selection - Parker Hose Products Division - Fitting Connections

2 differences among attachment styles

  • Crimp Fitting: Using crimp fittings requires a crimping machine or a press to attach the fitting to the hose. If you don’t have a machine of this type in your shop or facility, a local Hydraulic distributor or supplier can fabricate the hose assembly. Locate a distributor near you.
  • Field Attachable Fitting: The advantage of field attachable fittings (also referred to as reusable fittings) is that a machine isn’t required to attach the fitting to the hose. The hose assembly can be made anywhere provided that the fitting and the hose on hand is Field Attachable Fitting compatible. In most cases, a field attachable fitting consists of two pieces; a socket and a nipple.


5 Most Important Factors to Consider for Hydraulic Fittings - Parker Hose Products Division - Fitting Attachment Styles

5 factors for fitting selection

Below are the five factors you should consider when selecting the right hydraulic fitting for your application:

  1. Versatility: JIC fittings offer the best versatility of any of the aforementioned fitting systems. Additionally, there are available fittings that can connect JIC fittings to any foreign or American port, and jump sizes can expand or reduce between any sizes. A key benefit of JIC is the great variety of product that is typically stocked by vendors, including straights, elbows, long drops and male or female threads.
  2.  Availability: JIC and NPT fittings have been the field standard for decades, and they are readily available in both volume and variety. As a growing number of OEMs converts to O-ring face seals and DIN metric fitting styles, any hydraulic hose shop should be able to identify these new fittings, but the selection may be limited. Click here to find your local Parker distributor.
  3. Pressure Rating: Many OEMs are choosing O-ring face seals and DIN metric fittings, as required pressure ratings have increased. JIC fittings are not rated for these pressure ratings, especially in high vibration applications. Similarly, NPT threads are not recommended for higher pressure. These applications require specially-rated fittings.
  4. Application: The application in which a fitting will be used is a critical factor in choosing the right fitting. The STAMP acronym applies to fittings as well as it does to hose. Size, Temperature, Application, Media and Pressure all must be taken into consideration when making this choice. The STAMP process is integrated in Parker’s HoseFinder app.
  5. Reliability: NPT pipe threads have always been popular, as leaks can be fixed by simply tightening the fitting. This practice, however, has led to cracked fittings. While JIC has been the industry standard for years, it still susceptible to cracked flares from overaggressive wrenching. The mated sealing surfaces in O-ring face seal fittings and DIN metric fittings reduce the risk of over torqueing, and provide greater reliability due to the elastomeric seal that is captured in the mating surface.

At the end of the day, all hydraulic fittings are only as good as the assembler who installed them. A general rule of thumb is to connect a hose with the least amount of connections possible. There are proper assembly procedures for each of the fitting styles, and strict adherence to those steps makes the difference between a solid connection and a problem waiting to happen.



NASH | Bearing Failure, Maintenance, and Troubleshooting

Did you know most bearing failures are not caused by manufacturer’s defect? From not enough grease to too much grease, or improper repairs by an unauthorized shop – our service technicians have seen it all.

Regardless of the cause, bearing failure puts your operation at risk for unscheduled downtime and repairs.

Bearing failure can be prevented with proper maintenance and monitoring. Included below are some of the most common causes and solutions for preventing bearing failure in your liquid ring pump or compressor.

Cause of Failure: LUBRICATION

  • Incorrect seal liquid rates
  • Incorrect grease
  • Excess grease
  • Insufficient grease
  • Contamination of grease
  • Mixing grease types
  • Use only the grease recommended by Nash for your specific model and operating conditions.
  • Monitor packing leakage.
  • Do not over-grease bearings.
  • Check grease every 6 months, refill as needed.
  • DO NOT MIX GREASE – refill grease should be the same as the existing grease.
  • Refer to your manual for additional information, or contact NASH Certified Service.

Cause of Failure: PLUGGED DRIP TRAY

  • Water/seal liquid dripping from the stuffing box can backup and enter the bearing housing, contaminating the lubricant.
  • Keep the drip tray opening (drain) clean and clear of debris to allow water to exit freely.



  • Shaft alignment
  • “Soft” pump foot
  • Piping stress


  • Check coupling alignment – to spec
  • Check for soft foot – pump properly shimmed
  • Check for equal seal flow to each side of pump
  • Eliminate piping stress, when inlet is disconnected no misalignment
  • Monitor bearing temperatures and vibration weekly


Cause of Failure: IMPROPER REPAIR

  • Shafts machined in place
  • Bearing re-used after repair
  • Proper bearing installation not followed
  • Contact NASH Certified Service for evaluation.


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