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Extremely cold environments with conditions such as snow, ice and high wind speeds are a challenge for all rubber hydraulic hoses.
Frequently, hoses must withstand temperature ranges below -57 °C which influences the rubber compounds used on the inner tube and the hose cover. What does this mean for your equipment?
When rubber is permanently cooled, the material characteristics and the bending behaviour will change even if the product has been developed for such temperature limits. Elastomers are used at the inner tube and the hose cover. When cooled to permanent low temperatures, hoses may no longer behave with their normal characteristics and become hard, stiff and inelastic. They can even decompose or work at reduced performance under continuous thermal loads. The material parameters change under the influence of heat and cold. If you cool down to lower temperatures, rubber becomes hard, tough and leathery.
Engineers describe this process with thermal changes that affect the molecular behaviour and the microstructure becomes crystalline. The result is that the rubber compounds become brittle, but in principle they remain deformable. The heat builds up in heat or mechanical energy. At -40 ° C (depending on rubber compound and hardness) the so-called glass point is reached; the rubber is hard. Crystallization of the elastomer at low temperatures may cause cracking. However, this depends strongly on the type of load in the low temperature range, more critical here are shock loads. We strongly recommend a regular visual inspection of the rubber for cracks, which can reduce its service life under unfavourable conditions and failure and leakage can occur when the temperature exceeds the rubber compounds acceptable range.
Hose manufacturers, such as Parker, are continuously putting their designs to the test. With the latest in technology, our state-of-the-art materials development and performance test labs are capable of determining baseline engineering and design properties to ensure that hoses meet application requirements. The cold-flexibility test is one of those tests required to meet specific specifications such as ISO 10619-2. An advantage to Parker's manufacturing process is the use of in-house compounds. This advantage opens new opportunities for the ideal compounds mixture of hoses such as Parker's SX35LT and SX42LT, which are multispiral hoses with four or six spiral high tensile steel wires for high pressure applications of 35,0 Mpa (5000 psi) and 42,0 Mpa (6000 psi) for extreme cold environments. These hoses are developed for extreme cold and demanding low temperature applications.
Parker also offers braided hoses with a synthetic rubber inner tube and as well a No-Skive thin synthetic rubber cover construction for mobile applications in low temperature environments such as forestry machines or refrigerated warehouses (461LT) or a 3-wire braid low-temperature compact hose with 4SP working pressures (371LT). These two hose types are not only cold resistance up to -50 °C but also characterized for an excellent ozone resistance. General typical applications are heavy construction equipment, side booms, mining and/or mobile equipment, arctic oil fields, materials handling in low temperature conditions, snow grooming equipment and any cold storage applications.
If your equipment relies on hydraulic systems, you know, it is not “IF” but “WHEN” a hydraulic hose fails, the race against downtime begins. The longer your equipment is down, the greater the loss and cost. Hydraulic system failures cause 35 to 65 percent of all mobile equipment downtimes – a great part due to relatively simple and cheap hydraulic hoses.
Ask yourself the following questions:
If YES is the answer to your questions, then the Parker Parkrimp No-Skive Self-Assembly system might be a problem solver for you.
Learn more about how to make your own assemblies using Parkrimp® No-Skive hose crimpers.
International companies with substantial expertise, such as Parker, have a global presence for the leading companies of the mobile market and can offer the right hose for each mobile application and on top, you can choose the way of product supply which best answers your individual manufacturing philosophy. The delivery options include complete hose assemblies, hose/tube assemblies, single hose and fittings and hose crimpers and tooling for the Parkimp No-Skive self- assembling.
Learn more about Hose Products.
This blog was contributed to by Conny Stöhr, marketing services manager, Hose Products Division Europe.
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Selecting the proper hose for a hydraulic assembly is critical to ensure that it meets the requirements for that specific application. One of the first steps in selecting the proper hose is to identify the type of reinforcement that is needed. The reinforcement is the strength of all hydraulic hoses; it determines the working pressure of the hose. Within the hydraulic hose industry, you will commonly see three types of reinforcement:
Download our HoseFinder app to make it easier to select your next hydraulic hose.
It is important to note that there are hoses that have a reinforcement that is a combination of fiber and wire, or multiple layers of wire braids or spiral layers but typically there are one or the other. Watch this video to see the differences.
Hose reinforcement has a direct correlation to the working pressure rating of a hydraulic hose. Pressure capacity is the defining criteria for hydraulic hose and pressure dictates how it is constructed. The type of reinforcement as well as the number of layers; 1-wire hose, 2-wire, 4-wire, etc., generally indicates pressure capacity. As you increase the number of layers, the pressure rating increases.
Hose reinforcement also impacts the flexibility of a hydraulic hose. Although hydraulic hoses are usually fairly stationary and don’t move around very much, hoses used on a piece of equipment that has a flexible joint, like a backhoe, must be flexible. Furthermore, the flexibility of hose enables components to be positioned in the most efficient or convenient places due to its ability to bend around corners, through tight spaces, or across long distances. Braided and spiral hoses definitely differ in terms of flexibility along with other differentiating factors.
Braided construction has a crisscross wire arrangement. This ends up looking like a braid when it’s all done. Braided constructions allow for increased flexibility of the hydraulic hose. Several layers of wire braid can make the hose stronger while keeping the reinforcement material untangled and maintaining a constant pitch (i.e. the inclination and the thread count per unit length). "Medium-pressure hoses" typically feature one- and two-wire braided construction. These hoses are frequently found on construction equipment, heavy-duty trucks, and fleet vehicle applications. In general, braided hose is selected for its flexibility, however, this type of hose is also more susceptible to failure under high-impulse applications.
The majority of "low-pressure braided hoses" have a textile reinforcement. In applications with typical operating pressures below 300 psi, the use of fiber braid allows for maximum flexibility. Hoses with textile reinforcement are commonly used to transmit petroleum-based fluids, diesel fuel, hot lubricating oil, air, ethylene glycol anti-freeze and water.
Below is an image of one of Parker Hose Product’s braiding machines.
At one time in the industry, two-wire braided hose was most commonly used in many applications. But the advent of larger, off-road specialty equipment drove the creation of spiral hose, which is very well suited for applications where extremely high impulse pressure is encountered.
Spiral hose construction consists of either textile or wire reinforcement. Each ply is laid at a specified angle for maximum dimensional stability. Instead of crisscrossing, wires remain parallel as they wrap around the circumference of the hose. Even though spiral reinforcement results in a stronger hose; there is an increased minimum bend radius and less flexibility due to the stiffness of the wire reinforcement in most cases. Spiral wire construction was designed to handle the high impulse applications such as construction equipment, heavy-duty trucks and fleet vehicle applications.
Below is an image of one of Parker Hose Product’s spiral hose machines.
Usually the more layers of wire, the stronger the hose, which means higher pressures can be achieved. Multi-layer spiral hoses, such as four- or six-wire construction, are used in a wide variety of applications from lawn tractors to earth movers. The demand for durable, high-performance spiral hydraulic hoses is continually growing, especially in applications where service life is critical.
Helical wire construction is used in addition to layers of fiber spiral or fiber braid hose reinforcements. Helical reinforced hoses are designed with maximum flexibility and vacuum handling in mind. The use of a helical reinforcement construction prevents collapse under vacuum. Helical wire reinforcement can be found in low pressure suction and return line hoses.
If you are in need of a hydraulic hose but don’t know which is best for your application, contact a local hose distributor. Provide them with all the details of your application in order for them to fully understand what you need. You can also download Parker’s HoseFinder to go through the STAMP process, which enables you to identify hoses based on your specific application.
From one- and two-wire braided, and up to six-wire spiral hose construction, and with a variety of cover options to protect from abrasive situations, Parker’s hydraulic hoses cover the pressure and media requirements for most hydraulic applications.
Article contributed by Kyri McDonough, marketing services manager at Hose Products Division, Parker Hannifin.
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When it’s time to provide your customer's preventive maintenance don’t forget to pay particular attention to system components that are out of sight within the system cabinet or air handler enclosure. The unit’s evaporator coils are among the more important of these hidden components. Problems can develop with dirty evaporator coils as it can effect the system's performance and efficiency. This can also lead to damage and/or breakdowns. Here is some basic information on effectively cleaning evaporator coils.
Evaporator coils are probably the most difficult to clean. They are usually packed tightly inside a blower compartment that are usually difficult to service. They may be located over bathtubs, in tight dark closets, on rooftops in commercial applications, in a hot attic or a myriad of other places that are usually cramped, dark and uncomfortable. Due to these inconveniences, evaporator coils are often left alone and not cleaned until a system problem emerges. An evaporator coil should be inspected every six months and may need to be cleaned every six months to four years, depending on environment and filtration.
Make sure to disconnect the power to the unit while cleaning the coil. This will prevent a potential electrical hazard. Disassemble the unit to the extent that both sides of the coil can be accessed. For applications that have matted hair and dirt on the intake side of the coil, it is important that they be carefully brushed clean. Failure to do so will severely limit the penetration of the coil cleaner and dramatically reduce its effectiveness. There are several disposable types of coil brushes available from different manufacturers that do a very good job of cleaning the surface dirt off while keeping your hands away from the filth and fins. One note of warning - the fins on a/c coils are very sharp and can cause severe cuts to skin. Be sure to avoid contact with the coil with your hands, arms, etc. It’s advisable to wear gloves, face mask and apron during this procedure since potential organisms growing on the coil and contact with lungs, skin, eyes or clothing may transmit disease. Once the surface dirt has been removed, a good evaporator coil cleaner, such as Acti-Klean should be mixed in a low pressure sprayer with water in a dilution ration of between 3:1 to 1:1, depending on the condition of the coil and the type of dirt encountered. Acti-Klean is a concentrated set of soaps and surfactants (wetting agents that help the cleaner penetrate the coil fully). The coil should then be sprayed liberally from both sides of the coil with the coil cleaner solution. This coil cleaner will not create the foam that condenser coil cleaners do, so don’t be shy applying the coil cleaner. Make sure that the liquid does not fall onto electrical components in the system. The cleaner will cut through grease and oils, as well as dislodge any dirt, dust and hair that may be trapped in the coil and rinses them down the condensate drain. An alternative option would be Virginia Coil Klean aerosol coil cleaner. This product will foam out dirt and dust and is certainly more convenient in the aerosol container, although it is more costly than cleaners like Acti-Klean. When the coil is clean, it is recommended that where possible the coil be rinsed off. This will aid in removing any remaining dirt from the coil. If this is not possible, then the condensate created by running the a/c system will rinse off any remaining cleaner. Depending on temperature and humidity conditions, the unit should run for between 15 minutes to 1 hour to ensure all cleaner is rinsed off the coil.
In recent years, indoor air quality receives a lot of attention. Often a case of “black mold” in some air conditioning system is reported in the news and the entire building must be evacuated and sanitized. It is a good idea after cleaning the coil that an EPA registered bacteriostat be used on the coil and surrounding ductwork and insulation to ensure that any minor growths and odors are eliminated. Doing so provides your customer a valuable service by ensuring that mold and other growths do not develop throughout the system. It is important the technician pays close attention to the volume of dirt and other growths coming off the coil. It is not uncommon for release dirt to block the opening of the condensate drain line and restrict the draining of water. If this is observed, the blockage should be removed before the drain pan overflows.
While cleaning the coil, it is a good time to clean the drain pan as well. Simply clean out any rust and deposits that may be sitting in the bottom of the pan with a towel, rag or other means. Once again, be careful not to rub your hand across the coil as the edges are quite sharp. Protective gloves are recommended.
For more information see Catalog G-1.
Article contributed by Chris Reeves, product manager, Contaminant Control Products, Sporlan Division of Parker Hannifin
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Challenged by the industry to advance the fire protection of hoses used in aircraft engine applications, engineers at the Parker Aerospace Stratoflex Products Division have used standard, low-cost materials to create a high-temperature flexible hose (HTFH) that redefines hose life expectancy. HTFH replaces traditional solutions, including both standard flexible hose and rigid pipe, to provide more durable fire protection, vibration damping, and thermal expansion flexibility to the feeder lines that supply the nozzles spraying fuel into the combustion chamber of jet engines.
Vibration is a growing challenge for today’s engine manufacturers. While new lean-burn engines deliver a more complete combustion of fuel that results in lower NOx and particulate emissions, they can cause more vibration or rumble in the engine. Additionally, lighter and thinner components used to reduce engine weight are more susceptible to vibration.
Traditional technologies used to connect fuel manifolds to nozzles are problematic, even potentially dangerous:
Our high-temperature flexible hose is a win-win for engine manufacturers. With a temperature rating of 800°F for ambient conditions with minimal fuel flow of 0.07 gpm, the kink-resistant innovation has inherent damping capability, reducing vibration sensitivity. Plus, it is easier to install, less sensitive to tolerance stack up, offers equal fire-resistance performance to integral fire sleeve hose, and eliminates the problem of thermal aging of fire protection material.
Constructed with a robust, stainless steel outer braid that is superior to a silicone fire sleeve for abrasion and chafing, HTFH has an insulating layer that acts as a fire sleeve. This insulating layer:
The end result of this advanced engineering is a product that is much less costly to maintain due to ease of replacement and significantly longer service intervals, projected to be minimum of 15 years.
Qualified in -4 and -5 sizes (1/4 inch and 5/16 inch diameters respectively) and adaptable to a wide variety of fitting styles and configurations, HTFH is redefining the market.
For additional information on Parker Aerospace systems and capabilities, please visit our website.
This post was contributed by Tracy Rice, strategic chief engineer – engines for Parker Aerospace Stratoflex Products Division.
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11 Jul 2018
As global air traffic continues to grow, the need for cleaner, more efficient airplanes is rising right along with it. In an effort to reduce the global impact of pollution attributable to aviation, the International Civil Aviation Organization (ICAO) adopted new CO2 emissions standards in 2017 for commercial aircraft, requiring new aircraft type designs to meet these standards before delivery. These regulatory requirements, coupled with airlines’ desire to reduce fuel expenses and other costs, drive engine makers to seek every possible advantage in producing more efficient aircraft engines.
One way to reduce an aircraft engine’s emissions and improve engine performance is through active clearance control (ACC). This is achieved by managing the clearance between the gas turbine casing and the tips of the rotating blades, referred to as turbine tip clearance. An engine’s turbine clearance control system (TCCS) relies on turbine clearance control valves (TCCVs) to control this tip clearance by managing the thermal expansion of the turbine case that surrounds the turbine stages of the engine.
The Fluid Systems Division of Parker Aerospace developed its line of TCCVs with a goal of exceeding customer requirements for reliability, safety, and performance. The product offers engine manufacturers a proven control mechanism that has not only undergone extensive testing but demonstrated improvements in engine fuel burn, which translate into measurable savings for its engine and airline customers.
Turbine tip clearance between the turbine blades and the turbine case is a key parameter that influences turbine efficiency and the propulsive efficiency. The tip clearance should be kept to a minimum value, considering the turbine blade and the case expansion resulting from temperature excursions during the entire operating envelope of the engine. These temperature excursions are a result of the extremely hot combusted gases that enter the turbine stage of the engine, downstream of the combustion chamber and provide the thrust required to power the engine.
The combusted air temperatures can be in excess of 2,000°F, resulting in the expansion of the turbine blades and the case, thereby increasing the tip clearance and loss of turbine efficiency. The net effect is that more fuel needs to be combusted to compensate for this loss of efficiency, in order to generate the required thrust, resulting in increased fuel burn and increase in specific fuel consumption.
By controlling the thermal expansion and contraction of the engine’s turbine casing over its operating envelope, engine manufacturers can better optimize the turbine tip clearances in the engine. A proven method of controlling this clearance is to either direct cooler air around the turbine case to cool and contract the casing ‒ or ‒ to restrict the cooler air, allowing the casing to expand when required to compensate for the turbine blade expansion. thereby maintaining the tip clearance.
This delicate balance is realized through temperature sensors in the engine that measure turbine air temperatures during the entire flight cycle. This information is relayed in real time to the engine’s full authority digital engine control (FADEC), an autonomous, system that monitors and controls all aspects of an engine’s operation, including its turbine tip clearance control system.
Depending on the flight status, the FADEC sends electrical commands to the engine’s turbine clearance control valves, signaling them to incrementally open or close (modulate the flow through the valve), to control the case thermal expansion. The opening and closing of these valves ultimately controls the amount cooling air taken from the engine’s bypass flow to manage engine casing temperatures, thereby facilitating optimum blade tip clearance control.
Parker’s TCCV consists of a butterfly valve actuated using an integral fuel-actuated actuator. The fuel actuator consists of a Parker electro-hydraulic servo valve (EHSV) integrated as part of the actuator. The EHSV receives an electrical command from the FADEC and directs the fuel flow appropriately for the actuator to either extend or retract the actuator rod. Actuator retraction or extension results in modulating the valve position to either fully open or fully closed or anywhere in between, depending on the stage of flight.
The actuator and the valve position are monitored by a linear variable displacement transducer (LVDT), which is integrated within the actuator rod. The LVDT provides the position feedback to the FADEC, which through its built-in software deduces the position of the valve (hence, the TCCV flow). Therefore, the TCCV valve system forms a closed loop sub-system with the FADEC; it receives a command, executes, and relays back the result of its action back to the FADEC for further instructions.
Turbine clearance control valves operate in a hostile environment, being exposed to aircraft engine surrounding air temperatures that can range from -65° to 350° Fahrenheit. The valves also handle the contaminated air flowing through them, as well as engine-induced vibration, and continue to function throughout the engine life.
To survive and perform in this environment, Parker’s butterfly-type valve incorporates several design features to enhance valve life, reliability, and performance. Features such as specially designed dynamic seals have been validated for long-term performance under extreme conditions, enabling superior sealing capability, low friction, and high wear resistance.
These seal designs are critical in ensuring that air flowing through the valve does not leak externally. This type of leakage is wasteful; not only does it rob the thrust-producing bypass air, it also results in less-than-optimum functionality of TCCV sub-system. Together the valve and actuator designs have a proven track record of meeting strict fire requirements during flight certification. The mechanical linkages between the actuator and the butterfly valve shaft are designed to withstand the vibration and endurance cycles required to ensure accurate position feedback and control of the TCCV system.
Parker’s Jet-Pipe® electrohydraulic servo valve (EHSV), designed and manufactured by the Parker Aerospace Control Systems Division. The EHSV is a proven, robust two-stage design that is contamination-resistant, providing the accuracy needed to precisely move the actuator to its commanded position, while providing the durability needed for long, trouble-free service life.
Parker Aerospace’s Fluid Systems Division in Irvine, California, has been providing TCCVs to engine manufacturers for nearly 40 years, continually improving the design and performance of its valves, making them extremely accurate and durable. Our longstanding engine customers include Rolls-Royce, GE Aviation, and Pratt & Whitney, among others.
Parker’s Fluid Systems Division offers its customer the benefit of extensive in-house testing capabilities for its TCCVs as well as its full line of products and systems. Parker TCCVs are designed and tested to meet and exceed vibration and endurance life requirements.
Complete endurance testing of the valves to multiple life cycles, which includes applying a full flight profile to simulate flight conditions and mimic valve performance in flight, helps ensure a TCCV design that has achieved maturity at entry into service. Our endurance test routines also include the introduction of contaminants to further prove the valves’ integrity. Additionally, we provide complete control system simulation models of the TCCV control system, utilizing either SIMULINK or Amesym for our engine customers, who in turn use this model within their larger engine control system model.
By working with our engine customers and aircraft operators, Parker FSD engineers have turned lessons learned into bankable savings for our end-use customers. The valves are designed for maintainability with the goal of lower removal and installation times on wing while achieving optimum repair and overhaul times. Put very simply, Parker valves offer lower total-lifecycle cost proposition for our customers.
The extensively tested and proven technology of Parker’s turbine clearance control valves allows aircraft engine manufacturers to achieve their desired engine performance, including extended service life while reducing fuel consumption (lower specific fuel consumption) and fuel emissions. By helping airlines meet more stringent international standards for CO2 emissions, Parker and its engine manufacturing partners become part of a global commitment to ensure an environmentally responsible future for aviation.
This post was contributed by Sanjay Bhat, new business development manager for Parker Aerospace’s Fluid Systems Division.
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Evolution of Fuel Tank Inerting for the Aerospace Industry
Parker Aerospace’s Fluid Systems Division has developed critical fuel-vent and line static dissipating tubes in collaboration with OEM customers to safeguard today’s modern composite aircraft from the risk of fuel-tank ignition and serious safety incidents.
Once used only for light structural pieces or cabin components, carbon composites are now being utilized for wing and fuselage skins, engine components, and landing gear. Lightweight and strong, composites reduce weight and increase fuel efficiency while being easy to handle, design, shape, and repair. They also offer improved reliability and durability while reducing the number of heavy fasteners and joints in an aircraft, which are potential failure points.1
Aircraft manufacturers have been attracted by the advantages of composites. New aircraft using composite wings provide lower fuel use per passenger than comparable aircraft.2 Carbon composites have been portrayed as the perfect aircraft material – except for in the way that they handle lightning strikes.
According to an article in Scientific American, “What happens when lightning strikes an airplane,” each U.S. commercial aircraft is struck by lightning more than once every year, usually attaching first to an extremity like nose or wing tip3.
Aircraft with an aluminum fuselage and wings can readily conduct the charge from a lightning strike, allowing the current to move along the skin and pass back into the atmosphere. However, composites are significantly less conductive than aluminum.
On composite structures, the current from a lightning strike does not have a highly conductive pathway that allows the electricity to transfer back into the atmosphere. Without dissipation, the lightning currents could ignite the fuel in the fuel tanks, fuel lines, and fuel vents. That’s why our fuel vent and line static isolating tubes are so valuable.
Composite wings need isolating and dissipating tubes to slowly dispel the static charge from a lightning strike, thereby preventing arcing in the system. Installed in-line with the fuel lines and fuel vents, the tubes resist electrical energy and eliminate its transfer across the tube. This protects the fuel lines and the rest of the fuel system from possible combustion.
Our fuel and vent line static isolating tubes are tested and proven. The components are currently installed on all HondaJet business aircraft as well as Northrop Grumman Global Hawk unmanned aerial vehicles. Available in multiple diameters, including 1/2-, 3/4-, 1.0-, 1.25-, 1.5-, 1.75-, 2.0-, 2.5-, 3.0-, 3.5-, and 4.0-inch inner diameter, the tubes are available with ferrules on each end and tubes with a flange mid span to meet most installation requirements.
The growing use of composites in aircraft manufacturing will increase the need for technologies that maximize the advantages of composites while minimizing their limitations. Our fuel-vent and line static isolating tubes will continue to play a critical role in keeping more-composite aircraft safe from ever-present lightning strikes.
This post was contributed by Glen Kukla, engineering team leader, Parker Aerospace, Fluid Systems Division
Quiet Aircraft Initiative is Turning Down the Cabin Volume
Aircraft Lightning Protection Rises to New Heights
10 Jul 2018