Every component of a bolted flange joint has a maximum allowable stress level. The mating flanges will begin to rotate or warp at a defined stress threshold. The studs or bolts of a given specification also will yield or be stressed past their elastic properties at a defined level. Non-metallic and semi-metallic gaskets will crush under excessive applied stress loads.
Pump reliability is an old topic, but it is just as relevant today as it was the first time we heard it a few decades ago. There are some very good reasons to focus on improving pump reliability. The rewards for achieving pump reliability are great and the effort, on the surface, seems fairly simple. After all, most of the elements of reliability are just common sense. But Ralph Waldo Emerson expertly put this idea into perspective when he said: “Common sense is as rare as genius.”
Last time, we pretty much ignored ladder diagrams. This time I’m giving you lots of them. We’ll look at the ins and outs of turning those pretty pictures into powerful text. You’ll gain insight into the block commands and the various structures that can be built using List. You’ll leave with full knowledge of the perils and pitfalls.
On the design of a new machine which is to be run with a hydraulic motor, a determination of required speed and horsepower must be made so a model with suitable ratings can be selected. This article describes several methods of making such a determination. Designers who are experienced only in selecting electric motor drives need to be careful in designing hydraulic drives because of important differences between these two motors.
The chart shows approximate pressure drops which may be expected at various flows rates through sharp edge orifices for petroleum type hydraulic oil. It may be used for designing limiting flow orifices in hydraulic systems. Chart values must be considered as approximate because a number of factors such as specific gravity, orifice efficiency, plumbing ahead of and behind the orifice may cause variations from the values shown.
Whether the mismatch was due to the variation in required pump output or incorrect sizing of the pump, there is no question that the ability to easily vary pump speed has been a major advance in the overall performance of a pumping system. This has increased the energy efficiency, as well as the reliability of the equipment. Problems—such as cavitation or shaft deflection—can be alleviated by running the pump at optimal system speed. But how do variable speed drives affect mechanical seals?
Bolts and screws are not something that occupies a lot of our reliability thoughts. After, the life of an appropriate bolt in a non-aggressive environment has been extrapolated to something like 11,000 years. Yet if you use the wrong fastener, it is bound to be very aggravating. It may not even survive its own virgin installation!
The 7 Basic Steps of Hydraulic Testing & Diagnostics. Testing with gauges or a hydraulic analyzer is the most effective way to pinpoint troubles in the system. However, here are some preliminary checks you can make without using a tester or prior to using one.
It is very difficult to calculate and predict the speed of an air cylinder; there are too many variables which influence speed and on which it is difficult to gather accurate data. We must rely mainly on good design practices and use the benefit of past experience. It is better to have the cylinder speed too fast to begin with because it can always be reduced with a speed control valve, but if it is too slow to begin with, it is more difficult to increase its speed later.
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Torbjorn Idhammar is the blog manager for MaintenanceWorld.com.
A maintenance and reliability management consultant, Torbjorn has spent 25+ years in the profession and provides advice to clients around the world.
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