Work within the design limits – Once equipment or a process is allowed to run outside it’s design limits it will fail quickly. The only way to get long-lived, well operating plant and equipment is to keep its individual components working within their service limits throughout their life. Keywords: training manual, procedures, operator manual. [Read more…]
Plant compressed air waste control
Plant compressed air waste control. Every compressed air system will eventually develop leaks from connectors and redundant pipelines. Compressed air is very expensive to make. It is necessary to institute regular inspections for air leaks and fix them immediately.
Keywords: pressure loss, energy loss, air compressor, pressure switch. [Read more…]
Metering & Dosing Pump Operations
Metering and dosing pump operation. Any positive displacement pump can be used as a metering or dosing pump. The purpose of these pumps is to inject a known volume of liquid into a process stream. The primary requirement is that over a given period of time the pump consistently delivers the same amount of liquid. Keyword: gear pump, piston pump, helical rotor pump, diaphragm pump, peristaltic (hose) pump, additive, dosing rate. [Read more…]
Is Your Wet Scrubbing Tower Working?
Is your scrubbing tower working? A wet scrubbing tower is used to clean odors, particles, mists and vapours from a gas stream. The gas is forced through the tower. As it moves from inlet to outlet it is washed and cleaned. The washing is done with suitable chemicals that remove the active components in the gas flow. The gas is cleaned to environmentally acceptable levels and discharged to atmosphere. Keywords: packed tower, packing, fill, mist eliminator. [Read more…]
Flow meters – don’t believe what they tell you
Abstract
Flow meters – don’t believe what they tell you. A flow meter is an instrument that measures the amount of fluid (liquid or gas) that passes through it. The meter in the pipe is the detecting device and increases the count when a specific quantity of fluid passes by. There are several types of flow meters in common use. They include magnetic flow meters, vortex flow meters, mass flow meters, turbine flow meters, rotor blade meters, paddle flow meters, and ultrasonic flow meters. Usual the quoted accuracy on the flow meter specification sheet is for water at 20oC. However when the meter is installed in a process application it is unlikely that the meter will meet the quoted accuracy without site-specific calibration. Keywords: calibration, certified test equipment, flow meter accuracy.
The manufacturer performs laboratory trials of its equipment to insure the flow meter meets their claims for accuracy. Since the manufacturer does not know where their meter will be used they standardise the tests by using water at known conditions. Unless the meter is used in a situation identical to the laboratory conditions the given accuracy is unlikely to be achieved. [Read more…]
Gluing Plastic Pipes so You Can Trust Them
What you will learn from this article.
- Glued plastic pipes must have the joints prepared before gluing.
- Some plastic is joined with glue while others are solvent joined.
- Glued joints do not bond with the plastic but must be ‘hooked’ to it.
- Install thrust brackets if large glued pipes change direction sharply.
Some plastics can be joined with glues or cements. One of the most common of these is PVC. PVC can be either unplasticised (uPVC) or chlorinated (cPVC). Some plastics can be dissolved and chemically bonded together. ABS plastic is such a plastic. [Read more…]
Holiday Detection in Above-ground Tank Bottom Lining Inspection
What you will learn from this article.
- There are two ways to detect holidays in tank linings.
- Explanation of the low voltage ‘wet sponge’ method of testing linings.
- The second method is high voltage spark detection.
- Importance of confirming the presence of sufficient liner thickness.
- The likely trouble spots where linings can thin.
Set-up Tank Agitator Gearboxes for a Long Life at Low Cost
What you will learn from this article.
- The types of forces developed in a turning agitator.
- Gearbox position and configuration for long-life.
- Bearing arrangements to minimise gearbox loading.
- Simple, strong agitator support arrangements.
- Vapour seals are needed to stop fumes escaping.
- Lots of low maintenance selection and design tips.
Agitated vessels and tanks are common throughout the process and chemical industries. A properly sized agitator with correct proportions to suit the tank will deliver well-mixed product. A correctly sized gearbox with well-chosen bearings and bearing arrangements will need only regular lubrication while giving years of trouble free service. [Read more…]
Control Loops — Masters of Automatic Control
What you will learn from this article.
- Control loops automatically correct unwanted changes in a process.
- A control loop consists of components to detect and adjust the process.
- Control loop complexity reflects the accuracy and speed of control.
- Explanation of ‘open loop’, ‘closed loop’, ‘feed back’, ‘feed forward’.
The sole purpose of using process control in, say, the making of beer, is to detect what is happening during manufacture and to decide if something needs to be changed to insure the beer meets the necessary specification. The key words are ‘to detect’, ‘to decide’, ‘to change’ and ‘to meet specification’. A control loop can do all these things automatically. [Read more…]
Root Cause Analysis Answers Your Problems
What you will learn from this article.
- An explanation of root causes analysis (RCA)
- An overview of how it is applied at your work place.
- See the result of a sample RCA.
Root Cause Analysis is a step by step method that leads to the discovery of a fault’s first or root cause. Every equipment failure happens for a number of reasons. There is a definite progression of actions and consequences that lead to a failure. An RCA investigation traces the cause and effect trail from the end failure back to the root cause. Much like a detective solving a crime. [Read more…]
Cyclone Separators — an overview
What you will learn from this article.
- How cyclones and hydrocyclones work.
- Where cyclones are used.
- Design features that affect cyclones.
- How to get long life from cyclones.
A tornado can lift cars from the ground and hurl them hundreds of meters away. Chickens and ducks can be hurled kilometers away. The story of fish falling from the sky is explained by the power of a tornado to lift materials kilometers into the sky. The spinning vortex of air separates and segregates heavy and light objects. The heavy objects drop out sooner and the light objects are carried further. Cyclone separators and hydrocyclones work the same way. [Read more…]
Spread Forces Throughout Equipment and Reduce Breakdowns
What you will learn from this article.
- How forces are distributed through an object.
- Force diagrams are used to represent forces on an object.
- Position and direction of a force determines the type of stress.
- How to redistribute force in a structure.
Why don’t you fall to the ground when you sit in a chair? Why doesn’t the roof fall in on top of you? We don’t expect these sorts of things to happen. But at times chairs fail and people fall to the ground and at times roofs fall on people. When structures are put under sufficient stress they will fail. [Read more…]
Electric Motor Current Protection Saves Your Plant.
What you will learn from this article.
- Electric motor power current draw reflects the motor’s working load.
- The electric current through a power cable can be measured using the strength of the magnetic field created around the cable.
- Under-current detection protects against loss of load situations.
- Over-current detection protects against over-load situations.
Reliability Centered Maintenance — What is it?
What you will learn from this article.
- Meanings of ‘loss of function’, ‘failure modes’ and ‘failure patterns’.
- RCM provides a way to select the best maintenance strategy for new plant and equipment.
- PM Optimisation, a shorter version of RCM, is used on existing plant and equipment with sufficient known failure history.
- The RCM process and procedure is introduced.
- How to put RCM outcomes into workplace practice.
Oil — How Clean Does it Have to Be?
Clean, dry oil can extend equipment life between failure up to 8 – 10 times the normal operating life. Timken, the bearing manufacturer, reports that reducing water levels from 100 ppm (parts per million) to 25 ppm increases bearing life 2 times. British hydraulics research indicates that if solids contamination with particles larger than 5 microns (0.005 mm or 0.0002”) is reduced from the range of 5,000 – 10,000 particles per milliliter of oil to 160 – 320 particles, the machine life is increased 5 times. [Read more…]
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