Plant Maintenance

Changing out dust bags in reverse pulse dust collectors. The dust bags in pulse jet dust collectors require replacement if damaged and leaking or if blinded by the product. This work procedure indicates the process and methods to use to change-out and replace dust bags and cages in a dust collector. Keywords: tube plate, bag collar, air manifold, air plenum.

• Clean out product in the plenum.
• Mark-up a tube plate map showing the location of all blocked-off bags or leaking bags and hand-in with the work order on completion.
• Lift cages out square to tube plate without damaging the cage collar. Use tee-handle hook tool that fits down the bag and hooks onto the cage wire ring two down from the top.
• Remove the bags if they don’t come out with the cage.
• Clean top AND underside of tube plate back to clean metal.

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By Richard Lang of Abonnel Precision Engineering

This quarter we would talk a little about bronzes, their properties and applications. One of our readers said they occasionally hear people refer to a brass bush when in fact they want a bronze bush and could we write something on this. Lets also look at the range of materials one may come across:

• Leaded Gun Metal (LG2)
• Aluminium Bronze
• High tensile brass
• Phosphor Bronze (PB1)
• Manganese bronze
• Brass

[Read more…]

A Brief Introduction to Temperature Sensing Elements

The temperature of a process is an important measure to know as it indicates whether or not the process is in control.

The selection of the temperature sensing method depends on

• the required temperature range
• the measuring accuracy required
• the speed of response needed from the control system
• the process chemicals and conditions

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Equipment Operators as Watch Keepers

The watch keeper of old guarded their people and possessions. They were found walking about looking, listening, and watching for changes that signaled danger. Their job was to look for hazards and quickly raise the alarm before all of them were invaded and killed or captured into slavery. With sufficient warning the home group could rally to the defence and counter-attack the enemy.

Times haven’t changed that much. Instead of being invaded by the enemy we now get consumed by plant and equipment problems. If only there was an effective way to spot problems coming our way and mount a counter-attack before being overrun.  [Read more…]

7 Consideration for Equipment and Plant Layout for Improved Maintenance

Equipment reliability studies show that the likelihood of failure increases the more often machinery is disturbed. The chance of something being done wrong rises every time an item of plant is worked on. Nothing may go wrong the first time or the second time but with each additional disruption there is an increasing possibility that an error will be made.

Simple, fast and uncomplicated access to individual items of plant and equipment means higher plant availability and longer time between failures.  [Read more…]

The Basics on How Fluid Flows in Pipes

A fluid is either a liquid or a gas. In industry, they are piped from storage to the point of use. Correct design and installation of the piping system minimises pressure loss and improves the behaviour of equipment and processes.

This article briefly explains what happens to fluids flowing through pipes. [Read more…]

Capacitance level probes consist of a long rod or cable that protrude into a vessel and its contents. The instrument sets up an electric field between the probe and the tank wall using the contents of the tank as a dielectric (a nonconductor that allows an electric field to exist within itself). If the tank is non-metal, such as plastic or brick lined, two parallel rods are mounted in the level probe or a metal strip can be run on the outside of the tank. The electric field is set-up between the two probes or the probe and the metal strip. Figure 1 shows a simplified layout for a capacitance level probe. [Read more…]

What readers will learn from this article.

• The purpose of pressure relief valves.
• How pressure relief valves work.
• The correct way to install relief valves.
• Selection and testing issues for pressure relief valves.

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What readers will learn in this article.

• How pressure and temperature changes cause cavitation.
• How cavitation causes damage to equipment.
• Gas entrainment compounds the problem.
• Methods to reduce the occurrence of cavitation.

What is Cavitation?

Cavitation is the occurrence of vapour bubbles in a liquid. A vapour bubble will form when the pressure in a liquid falls so low it boils or the temperature rises so high it boils.  [Read more…]

What readers will learn in this article.

• Explanation of stress and strain.
• How metals yield and deform under stress.
• What happens at the molecular level in metals under stress.
• Methods to minimise stress concentrations.

Too much stress in metal will cause it to fail. Failure can occur by putting the metal under a once-only load greater than it can take or by continually loading the metal cyclically with a high load less than the breaking load (metal fatigue). [Read more…]

Written instructions make it clear.

Written directions given to maintenance tradesmen to reduce the chance of making an error and to reduce time spent looking for information are called job procedures or job instructions.  [Read more…]