Hydraulic lines

Before hydraulic lines or fittings are disconnected, the affected area should be cleaned with an approved dry-cleaning solvent. 

All hydraulic lines and fittings should be capped or plugged immediately after disconnection. 

Pressure surge can be controlled by the use of surge vessels connected to the pipeline with a gas space above the liquid. If a pressure surge passes along the pipeline, liquid flows into the vessel through a check valve and the gas is compressed. Another valve then lets out the liquid at a controlled rate. This type of arrangement is used in large hydraulic lines. 

As previously mentioned, the nickel—titanium alloys have been the most widely used shape memory alloys. This family of nickel—titanium alloys is known as Nitinol (Nickel Titanium Naval Ordnance Laboratory in honor of the place where this material behavior was first observed). Nitinol have been used for military, medical, safety, and robotics applications. Specific usages include hydraulic lines capable of F-14 fighter planes, medical tweezers, anchors for attaching tendons to bones, eyeglass frames, underwire brassieres, and antiscalding valves used in water faucets and shower heads (38,39). Nitinol can be used in robotics actuators and micromanipulators that simulate human muscle motion. The ability of Nitinol to exert a smooth, controlled force when activated is a mass advantage of this material family (5). 

Developments in micro-processing have made it much easier to monitor and to control conditions in the course of manufacture, and to prepare and maintain written records. Injection moulding may be supervised with the help of melt thermocouples fitted in the nozzle, pressure transducers in the hydraulic line and in the mould, and a transducer to monitor linear movement of the screw. Information from these sensors may be displayed and depicted in relation to the control limits (upper and lower) and the operator thus made aware immediately of variations that could be significant. Conditions can be corrected more rapidly and if need be any mouldings that might not be satisfactory diverted for examination. Should the number of suspect products exceed a limit set in advance, a line can be shut down automatically. 

The slide is located in the compressor casting below the rotors, allowing internal gas recirculation without compression. Slide valve is operated by a piston located in a hydraulic cylinder and actuated by high-pressure oil from both sides. When the compressor is started, the slide valve is fully open and the compressor is unloaded. To increase capacity, a solenoid valve on the hydraulic line opens, moving the piston in the direction of increasing capacity. In order to increase partload efficiency, the slide valve is designed to consist of two parts, one traditional slide valve for capacity regulation and other for built-in volume adjustment. 

Air may not immediately be thought of as a contaminant, but the presence of air in its various forms may have an impact on the ability of the lubricant to perform its design function. Almost all lubricating oil systems contain some air. Air is found in four phases free air, dissolved air, entrained air, and foam. Free air is trapped in a system, such as an air pocket in a hydraulic line, and may have minimal contact with the fluid. It can be a contributing factor to other air problems when lines are not bled properly during equipment startup and free air is drawn into circulating oils. 

Fire-resistant fluids A major application of PAGs involves their use in fire-resistant fluids. Industrial sectors such as steel production, die casting (where leaks in high-pressure hydraulic lines can create serious fire hazards) and mining (where the consequences of fire are catastrophic) have generated a large demand for these types of hydraulic fluids indeed many countries now legislate their use. Fire-resistant fluids have been classified by several international bodies ... 

Stored, transformed from one form into another, especially irreversibly into heat, or power may be distributed to other nodes. In bond graphs, the latter ones have got so-called power ports where energy may enter or leave a node. Of course, nodes may have more than one power port. They are called multiports. The edges of a bond graph are connections between the power ports of different nodes. They are called power bonds, or just bonds. They represent the transfer of power between ports and may be associated with physical links between real systems such as a shaft between a motor and a mechanical load, or a hydraulic line between hydraulic components if it is assumed that energy is neither stored nor dissipated into heat in a physical link. Otherwise, a physical model is to be developed for the physical link. 

During the late 1980s two air tragedies resulted from very similar common cause failures. In both cases (a Japan Air Lines Boeing 747 and a United Airlines DC-10), hydraulic control was lost when the redundant hydraulic systems (seven in the 747 and three in the DC-10) were disabled by loss of hydraulic fluid when the hydraulic lines in the rudder of the aircraft were severed. Only one hydraulic system in either aircraft would have been sufficient to maintain control of the aircraft. The only location on either aircraft where all the hydraulic lines were in close proximity was in the rudder. Even though the trigger event was different for each aircraft (aft pressure bulkhead failure and sudden depressurization in the 747 and an engine explosion in the DC-10), both aircraft crashed due to common cause failure of redundant hydraulic control systems. 

September 3, 1991. At about 8 15 a hydraulic line for a conveyor belt carrying chicken parts ruptured. Normally the fluid in the line is not easily combustible, but when the line broke the fluid vaporized and was quickly ignited by the flames of a nearby gas fueled fryer. The jointly burning insulation, soybean oil, and chicken parts produced a thick yellowish smoke that quickly filled the sprawling windowless building of 30,000 square feet. When the fire made the electricity go out the inside of the building was soon dark, and the situation for the chicken processing workers became chaotic (Smothers 1991, Taylor 1991). 

Parameter p3- ram-3-t9r [NL, fr. para- + Gk metron measure] (1656) n. (1) Loosely, a system factor or variable that may take on a range of values as decided by the observer or operator of the system. Example hydraulic-line pressure and cylinder temperature are parameters in injection molding. (2) A defining constant of a statistical distribution, such as the mean or standard deviation of a normal distribution, and distinct from estimates of same calculated from sample measurements. (3) An independent variable through whose functions relations between other factors may conveniently be expressed. 

Geolast (polypropylene plus nitrile rubber) has a higher resistance than Santoprene (polypropylene plus EPDM) to oils (such as IRM 903) and fiiels, plus good hot-oil/hot-air aging. Geolast applications include molded fuel filler gasket (Cadillac Seville), carburetor components, hydraulic lines, and engine parts such as moimts and tank liners. 

The viscosity of the hydraulic oil can severely affect injection pressure. While hydraulic oils are fairly Newtonian, their viscosities will decrease with increasing temperature. Decreases in oil viscosity generally affect pressure settings pressure develops more rapidly in the hydraulic lines, causing pressure control valves to open prematurely. 

Partial Redundancy In some systems there is partial redundancy. Suppose there is only one pump supplying two sets of hydraulic lines to an actuating cylinder. The pump and cylinder have no redundancy, whereas the lines do. 

The system has only partial redundancy. A failure in the pump or cylinder would produce a failure of the system. A blockage failure in one of the lines would protect the system from failure because there is a second Une. However, routing the hydraulic lines through the same locations reduces the value of the redundant lines. Damage to one is likely to occur to the second. The value of redundancy increases if there are different locations for the redundant components... 

South Dakota. The operator of a backhoe received severe injection injuries to his hand. A hydraulic line started to leak. A small, high-pressure stream of hydraulic fluid struck the operator s hand, penetrated the skin and filled a significant part of his hand with fluid. 

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