Maintenance Best Practices.

preventive maintenance(PM system)

ldentify the System Operating Condition

Equipment Manufacturer’s Maintenance

Requirements

System Component Maintenance Requirements

Symptoms:

1. The carriage drive has slowed down in both directions.2. The cutting torch traverse cylinder is operating slowly when extending.3. The system is running hotter than usual.

Hydraulic machines are machinery and tools that use Heavy equipmentto do simple work. fluid powerliquid

is a common example.

A fundamental feature of hydraulic systems is the ability to apply force or torque multiplication in an easy way, independent of the distance between the input and output, without the need for mechanical gears or levers.

To obtain a good work from hydraulic circuits we should be sure from that, we have suitable safety devises in this circuits to avoid damage or failure.

:

safety valves hydraulic fuse

Legal and code requirements in industry:

In most countries, industries are legally required to protect pressure vessels and other equipment by using relief valves. Also, in most countries, equipment design codes such as those provided by the ASME, API and other organizations like ISO (ISO 4126) must be complied with and those codes include design standards for relief valves.

•ASME (American Society of Mechanical Engineers) Boiler & Pressure Vessel Code.•API (American Petroleum Institute) Recommended Practice 520 and API Standard 526, API Standard 2000 (low pressure - Storage tank)

Special functions:

To overcome nuisance Velocity fuses work by sensing flow across a control orifice when the pressure differential exceeds a predetermined amount (usually 50 psid). A spring-biased poppet closes, shutting flow to the damaged hydraulic circuit. trips, a time delay feature in a velocity fuse allows an overshoot above rated flow for up to 0.2 sec before closing. This prevents nuisance trips caused by sudden flow surges.

Elevator and lift applications may mandate a maximum deceleration. Other requirements include safety pressure rating (7to 8 times normal operating pressure), maximum speed, and performance requirements. To meet these requirements, a variable orifice incorporated into the velocity fuse limits the shock load to less than 0.3 Gs and closing time to less than 0.2 sec.

A safety control conforming to the above standards is not required only in the following press applications:

• Forging and other presses where the material cannot be manually handled.

• Machines running in automatic mode with closed working areas, although a safety control may still be required for maintenance and machine set-up.

• Closing speed of the press slower than 0.4 inches/second (10 mm/s).

• Stroke of the ram less than 0.24 inches (6 mm).

Picture 1: Standardized Rexroth Press Control Size 6