Lower Explosive Limit (LEL)
The minimum concentration of a flammable gas in air capable of igniting is called the Lower Explosive Limit, or LEL. This limit varies with the type of gas and with…
Bathtub Curve
Failure rate tends to be constant during a component’s useful lifespan where the major cause of failure is random events (“Acts of God”). However, lambda does not remain constant over…
Flow Meter Calibration
We have different Types of Flow Meter Calibration Techniques available. Flow meter calibration by volumetric method and by weighing method.
Control Valve Failure Rate Calculation
Suppose a control valve manufacturer produces a large number of valves, which are then sold to customers and used in comparable process applications. After a period of 5 years, data…
Transistor Failure Rate Calculation
Suppose a semiconductor manufacturer creates a microprocessor “chip” containing 2500000 transistors, each of which is virtually identical to the next in terms of ruggedness and exposure to degrading factors such…
Failure rate and MTBF of Safety Instrumented Systems
In reliability engineering, it is important to be able to quantity the reliability (or conversely, the probability of failure) for common components, and for systems comprised of those components. As…
Applying Probability Laws to a Safety Instrumented System
The relatively simple concepts of AND and OR Boolean functions become surprisingly complicated when applying them to real-life measures of component reliability, mainly because reliability is measured in multiple ways.…
Safety Instrumented System Probability
While the term “probability” may evoke images of imprecision, probability is in fact an exact mathematical concept: the ratio a specific outcome to total possible outcomes where 1 (100%) represents…
Control Valve Noise Problems
A troublesome phenomenon in severe services is the audible noise produced by turbulence as the fluid moves through a control valve. Noise output is worse for gas services experiencing sonic…
Control Valve Erosion Problems
A problem common to control valves used in slurry service (where the process fluid is a liquid containing a substantial quantity of hard, solid particles) is erosion, where the valve…
