Learn the Terminology - Fluid Power

Lockout/Tagout:  The placement of a tagout device (LO/TO) on a power switch, in accordance with an established procedure, to indicate that the power switch and the equipment being  controlled may not be operated until the tagout is removed.

Fluid Power - Learn the Terminology

Velocity:   The time rate (speed) of linear motion in a given direction.

Viscosity:  A measure of the internal friction or the resistance of a fluid to flow.

Viscosity Index:  A measure of how viscosity changes in relation to temperature.

Installing Hose Assemblies III

Review the Safety Precautions found in previous blog posts about “Maintaining a Safe Work Environment” as well as your equipment’s operations manual before installing hydraulic hose assemblies. Installation varies depending on coupling configurations, use of adapters, and routing.

Coupling Configurations

Male fitting to port connections can be made using four types of configurations:

§  Solid male (MP, MB, MBSPT, etc.).

§  Male swivels (MPX, MBX, MIX).

§  Flanges (FL, FLH, FLC, FLK).
 

§  Block-style adapters with Lock- nuts.

Flanges

Flanges are installed using clamp halves/flange half sets. Use the following procedural steps for proper flange fitting installation:

1. Put a small amount of oil on the O-ring and place in the groove. Oil will prevent the O-ring from falling out.

2. Place fitting over port.

3. Install clamp halves over flange head and thread in bolts by hand.

4. Use torque wrench to tighten using crossing pattern.

5. Torque to manufacturer’s specifications.

Installing Hose Assemblies II

Review the Safety Precautions found in previous blog posts about “Maintaining a Safe Work Environment” as well as your equipment’s operations manual before installing hydraulic hose assemblies. Installation varies depending on coupling configurations, use of adapters, and routing.

Coupling Configurations

Male fitting to port connections can be made using four types of configurations:

§  Solid male (MP, MB, MBSPT, etc.).

§  Male swivels (MPX, MBX, MIX).

·         Flanges (FL, FLH, FLC, FLK).

·         Block-style adapters with Lock- nuts.

Male Swivel

Male swivel installation does not require hose rotation.  Install the male thread into the port and use a wrench to torque properly.  Orient the hose curvature to assist in routing, since the hose does not rotate.  Male swivels (except MIX) have internal O-rings that must be compatible with the fluid used.

Installing Hose Assemblies I

Review the safety precautions found in previous blog posts about “Maintaining a Safe Work Environment” as well as your equipment’s operations manual before installing hydraulic hose assemblies. Installation varies depending on coupling configurations, use of adapters, and routing.

Coupling Configurations

Male fitting to port connections can be made using four types of configurations:

§  Solid male (MP, MB, MBSPT, etc.).

§  Male swivels (MPX, MBX, MIX).

      ·         Flanges (FL, FLH, FLC, FLK).

·         Block-style adapters with Lock- nuts.

Solid Male

Solid male fittings are installed by rotating the entire hose assembly when the male thread is threaded into a port. For ease of installation and improved seal, Teflon® tape can be used on tapered threads.

If an O-ring is used, lubricate it with oil before installation. A poor seal can be the result of a dry O-ring sticking and pulling away from the sealing area.

Once hand-tight, use a wrench on the hex to properly torque the fitting. Since hose rotation is necessary, never use two solid males on the same hose assembly.

 

  

Maintaining a Safe Work Environment - Electrical V

Establishing a safe working environment in and around your hydraulic equipment requires a few things you must be aware of.  These include:

·         Pressure

·         Temperature

·         Flammability

·         Mechanical

·         Electrical

Electrical

Hydraulic equipment should always be turn off before starting to do work on the equipment.   Prior to working on any plant equipment, lock the control box, and tag it with a warning sign that states “DOWN FOR MAINTENANCE. DO NOT TURN ON POWER.”   If the equipment is mobile, take the key and/or disconnect the battery cables from the battery so the equipment can’t be started.

During normal equipment operation, you may be exposed to electrical hazards such as high-voltage power lines and underground power sources. Always identify these potential hazards before running the equipment. Most hydraulic hose is wire-reinforced, making it conductive to electricity. Even non-wire reinforced hose may be conductive through the rubber compound itself or moisture that penetrates a pin-pricked hose cover. Some equipment requires the use of non-conductive hose if there’s a chance of contacting power sources.

OSHA standards require that all hydraulic tools used on or near energized power lines or equipment be supplied with non-conducting hose having adequate strength for normal operating pressures [29 CFR 1926.951(f)(3)].

Faulty wiring can also be an electrical hazard. A regular preventive maintenance program should always include a wiring check.

Maintaining a Safe Work Environment - Pressure IV

Establishing a safe working environment in and around your hydraulic equipment requires a few things you must be aware of.  These include:

·         Pressure

·         Temperature

·         Flammability

·         Mechanical

·         Electricity

Flammability

All hydraulic fluids (including fire resistant hydraulic fluids) are flammable when exposed to the proper conditions.  Exceptions are those fluids comprised primarily of water.

Systems leaking pressurized hydraulic fluids that develop a mist or fine spray that come in contact with a source of ignition can flash or explode. These very severe explosions can cause serious injury or death.

Precautions should be taken to eliminate all ignition sources from contact with escaping fluids, sprays or mists resulting from hydraulic failures.  Sources of ignition could include electrical discharges (sparks), open flames, extremely high temperatures, hot manifolds, engine blocks, and sparks caused by metal-to-metal contact.

Mechanical

Unexpected mechanical motion can be dangerous. Watch out for swinging arms, booms, rollers, or presses.  Anything that moves can be dangerous if a hose fails. For example, when a hose bursts, objects supported by fluid pressure may fall and vehicles or machines could lose their brakes because of pressure loss.

Maintaining a Safe Work Environment - Pressure III

Establishing a safe working environment in and around your hydraulic equipment requires a few things you must be aware.  These include:

·         Pressure

·         Temperature

·         Flammability

·         Mechanical

·         Electricity

Pressure

Operating pressures of hydraulic systems can be up to 10,000 psi.

The dangers that could be encountered with hydraulic fluid under pressure include:

Whipping Hose:  If the hose end or end fitting comes apart under pressure, the loose hose can whip around with great force. This has the potential to cause serious injury. Restrain or shield the hose using clamps or protective shielding if this hazard exists.

Stored Energy: Hydraulic systems sometimes use accumulators to store potential energy or absorb shock. This energy can create pressure that keeps the system’s components moving.

Temperature

Hydraulic systems typically operate at 150° to 180°F, but hydraulic systems can go as high as 300°F. Liquid at these temperatures may burn skin. Metal parts (such as fittings and adapters) are also hot and may cause burns. Hoses can also become hot.

Hose Cleanliness – Methods of measurement Part 3

There are three principal methods to measure the contamination level in a component, circuit, or system. The methods are Gravimetric Measurement (ISO 4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum Particle Size Analysis (ISO 4407).

Maximum Particle Size Analysis (ISO 4407)  

This evaluation is done using a microscope. A microscope is used to identify and measure the size of individual pieces of contaminant. Particle size is important in reference to maximum clearances of hydraulic components.

Whether hydraulic assembly cleanliness applies to you or not, it is worthwhile to understand the significant impact that contamination levels can have on the life of hydraulic system components.

Implementing a thorough cleanliness system may have a significant impact on warranty returns for hydraulically powered equipment.

Hose Cleanliness – Methods of measurement Part 1 - Gravimetric Measurement

There are three principal methods to measure the contamination level in a component, circuit, or system.

The methods are: Gravimetric Measurement (ISO 4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum Particle Size Analysis (ISO 4407).

 

This discussion will cover Gravimetric Measurement.

Gravimetric Measurement (ISO 4405) is a reporting method that references the total mass of

contaminant found in a hydraulic component. This total mass of contaminant measurement is then normalized by the total internal component surface area of a hydraulic component. A fluid is used to

dislodge contamination in a hose assembly and is then poured through a membrane catch filter.

An analytical balance is used to measure the total mass of contaminate which has been flushed out of a component. The total mass of contaminate and is referenced to the surface area or volume of the assembly.

Gates currently offers a system of four Gravimetric measurement (ISO 4405) levels of cleanliness for hydraulic assembly that can be used to meet or exceed cleanliness requirements.

Fluid Power - Learn the Terminology

Burst Pressure - The pressure that causes rupture.  Reference pressure intended for destructive testing purposes and design safety factors only.

Fluid Power - Learn the Terminology

Buffing: The partial removal of the hose cover in order to put on a coupling. A stone wheel is typically used to grind or buff the cover to remove the cover material.

Learn the Terminology

Cut-Off Length:  The length of that part of the coupling not directly in contact with or applied to the hose. Subtract the sum of the cut-off length of the two couplings from the total length of the assembly, and you will have the approximate hose-cut length to be replaced.

Dash Size:   A shorthand method of denoting the size of a particular end fitting or the inside diameter of a hose.  Measured in 1/16 of an inch (i.e., -4 = 4/16” or ¼”).

Hose Cleanliness – Methods of measurement Part 2

There are three principal methods to measure the contamination level in a component, circuit, or system:

1) Gravimetric Measurement (ISO 4405)

2) Particle Size Distribution Analysis (ISO 4406 or NAS 1638)

3) Maximum Particle Size Analysis (ISO 4407).

This post will discuss the second method (above).

Particle Size Distribution Analysis (ISO 4406 or NAS1638) 

Particle Size Distribution Analysis is a reporting method to gauge both the size and number of contaminant particles in a calculated quantity of hydraulic fluid.  A fluid sample is either taken directly out of a hydraulic system or a known quantity of fluid is used to dislodge contaminants out of a hydraulic component. This fluid is run through a particle counting instrument to size and count contaminant particles.

These particle ‘counts’ can then be normalized by comparing the total component volume and to a corresponding ISO 4406 ‘code’ level of particle contamination. Levels of five and 15 microns of contamination are reported on a logarithmic scale corresponding to and ISO 4406 ‘code’ for the number of particles greater than or equal to these respective sizes per milliliter of fluid.
 

 

Hose Cleanliness – affects Valves, Pumps, System cooling

Valves: Microscopic contamination (similar to erosion) can mill away tolerances which are used for sealing purposes. On spring centering valves, the debris may get caught between the valve and the wall surface. The contamination will cause the slowing down of the motion of the valve or causing sluggish or adverse mechanical actuation.

Abrasive particles enter the clearances between moving parts they score and hone the surfaces to greater tolerances. As these tolerances broaden, system performance is compromised by pressure losses incurred due to fluid leakage from high to lower pressures.

The worst occurrence is when particles that are greater than or equal in size to the orifice openings become wedged between the two surfaces. The contamination may cause wear to occur or it may cause the system components to seize.

Pumps & drives: Microscopic contamination can mill away material, creating leak points. These leak points rob the hydraulic system of pressure and cause poor responsiveness.

System cooling: Working fluid may not flow through to remove contaminants generated from metal to metal contact when passages become blocked. Lower flow rates mean greater heat buildup in systems and thermal breakdown of the working fluid.

 

Hose Cleanliness - Origin of Contamination

Origins of contamination may be from system components, the hydraulic working fluid, the outside environment, or be generated by the system itself. These contaminants, some large and some microscopic, can have a profound impact on the performance and longevity of the hydraulic system.

There are three principal means through which contamination can

occur in a typical hydraulic system. 

Contamination can be:

1.    Generated during system operation

2.    Built into the system during assembly

3.     Ingested by the system during operation

 The working fluid in hydraulic systems should be as homogeneous as possible and free of all visible and microscopic debris for optimum performance. The complete absence of contamination in hydraulic systems is unrealistic, but an acceptable and defined level of contamination is generally considered hydraulic system cleanliness. The best approach to cleanliness is to prevent contamination in the first place. Use clean hose and couplings and keep them clean (i.e. cap ends). Clean hose bore after cutting to length as cutting hose to length is a major contributor to contamination.

Learn the Terminology - Fluid Power

Compressibility:  The change in volume of a unit volume of a fluid when subjected to a unit change of pressure.

Contaminant:  Any material or substance that is unwanted or adversely affects the fluid power system or components or both.

Corrosion: The chemical change in the mechanical elements caused by the interaction of fluid or contaminants or both. More specifically related to chemical changes in  metals. The products of change may be introduced into the system as generated particulate contamination.

Fluid Power: Learn the Terminology - Cavitation

Cavitation: A localized gaseous condition within a liquid stream causing the rapid implosion of a gaseous bubble.

Hose Cleanliness

Hose Cleanliness

When the customer becomes more dependent on ISO standards, your

strategy needs to reflect a dedication to system cleanliness.

What is Hydraulic System Cleanliness?

 

“Cleanliness” is a term used to describe the level of solid and
liquid contamination found in hydraulic systems. “Contamination”

is defined as any substance that is not part of the hydraulic system’s

working fluid.

Why is cleanliness important to your customers?

There are several reasons:

 

   Efficient production - clean systems provide for maximum productivity.

   Improved control  -  spare parts use can be controlled through preventive maintenance and monitoring  contamination.

   Reduce equipment downtime  - through scheduled inspections

   Safety hazards minimized - through preventing contamination related

failure for increased life expectancy of components on equipment.

Reduced repair cost  - due to fewer breakdowns.

 

Several reputable sources have claimed that 70 to 80 percent of

hydraulic system failures are due to contamination. By establishing

a contamination control program, costly repairs and downtime may

be minimized. A contamination  control program can be as simple

as establishing an allowable level of contamination within a hydraulic

system, supplying cleaned components for the system, and monitoring

levels of contamination as part of a preventive maintenance

program.

 

 

Hydraulic Fluid Properties

Lubricity – the fluid must keep friction low and maintain an adequate film between moving parts to prevent wear of pumps, bearings, vanes, gears, pistons and rods. Increasing pressures and, consequently, closer tolerances, make lubricity even more important.

Viscosity – fluid “thickness” or resistance to flow. Pump manufacturers specify this according to clearances, speeds, temperatures and suction characteristics. The fluid must be thin enough to flow freely, yet heavy enough to prevent wear and leakage. Viscosity might not be so critical in selecting a hydraulic fluid except that it varies with temperature. Fluid thickens when it cools, thins as it heats up. Because some hydraulic systems must work under wide temperature extremes, viscosity range is important.

Viscosity Index – This measures the rate of viscosity change with temperature: the higher the index, the more stable the viscosity as temperature varies.