Archives :: Facts At Your Fingertips

Displaying 1 - 20 of 78 stories.
November 1, 2014
This letter is in reference to the article, Forces Acting on a Gasket [ Chem. Eng. October, 2014, p. 32a]. I need to clear my understanding on the seating stress required for the proper sealing. As per the article, seating stress for the proper sealing is indicated [see Equation (4) in the article]. This formula provides the total/maximum bolt loads on the gasket, which can be applied for the selected bolt...
November 1, 2014
Fabricated metal-wire mesh is one of the major categories of filter media. Woven metal cloths are often used to support a filter aid coating or a bed of granular or porous material. Proper selection of wire cloth can have a large impact on the cost and efficiency of the system. This column provides information on the options available for wire meshes in industrial filtration applications. Key questions for...
October 1, 2014
Gaskets are relatively simple pieces of equipment in principle, yet are entirely critical in many types of chemical process industries (CPI) applications, including pipes and vessels. An understanding of gasket function, and of the forces and stresses acting on gaskets provides a basis for decisions on gasket types and materials. Functions and types Acting as a retaining seal between two rigid stationary...
September 1, 2014
Collecting representative samples of heat-transfer fluid for routine quality checks falls short of the goal if safety or the environment is compromised. While users should consider their systems’ unique design features in consultation with their safety and health experts, incorporating the tips below can help to avoid common potential safety concerns associated with sampling these fluids, which may...
August 1, 2014
Sorbent materials are used commercially for bulk separation, as well as purification of both liquids and gases. This one-page reference provides manufacturing and application information on the most widely used industrial sorbent material — activated carbon. Four types of generic sorbents have dominated industrial adsorption: activated carbon, zeolites, silica gel and activated alumina. By worldwide...
July 1, 2014
Many industrial gases are transported, stored and used in liquid form, a situation that poses significant health and safety risks. This one-page reference highlights good safety practices for preventing personnel injury when working with cryogenic fluids. High-purity industrial gases, including nitrogen, oxygen, helium, argon and other noble gases, are commonly generated by air-separation units (ASUs)...
June 1, 2014
Cost estimation is a critical dimension of project planning in asset-heavy industries such as the chemical process industries (CPI). Construction cost indices are useful tools in cost estimation and are used to compare plant construction costs from one time period to another. Understanding them can improve the accuracy of the cost estimates, as well as the effectiveness with which they are applied. This...
May 1, 2014
Optimal functioning of centrifugal pumps over time depends on sound maintenance practices. The following material represents tips and guidelines for routine preventive and protective maintenance for centrifugal pumps. Monitoring A basic maintenance routine for centrifugal pumps should include monitoring of the following items: Bearing and lubricant condition. Monitor bearing temperatures, lubricant level...
April 1, 2014
When flammable or combustible atmospheres are present, uncontrolled discharges of static electricity are potentially dangerous or even catastrophic. A significant portion of industrial explosions and fires are attributable to static electricity each year. In theory, controlling static electricity by grounding potential sources is simple, but in practice, doing so effectively requires thorough knowledge of...
March 1, 2014
Effective level measurement in the chemical process industries (CPI) helps maintain material inventory at economic quantities, improves product quality and maximizes plant output by avoiding spills and process upsets. When they are incorrectly matched to their application, level-measurement devices can contribute to lower quality and poorer process consistency. No single level-measurement technology is...
February 1, 2014
Workers in the chemical process industries (CPI) can wear chemical protective clothing to protect themselves from exposure to potentially hazardous chemicals in the form of vapor, liquid and solid particles. While chemical protective clothing has not been regulated to the extent that safety glasses, hard hats and some other forms of personal protective equipment (PPE) have been, an international standard...
January 1, 2014
Dust is a critical consideration in the chemical process industries (CPI) from both a process safety standpoint — as a potential fire and explosion hazard — and from an occupational safety standpoint — as a potential worker exposure hazard. Reinforcing basic concepts about dust behavior and properties can help reduce the risks. Health hazards Airborne particles are solids suspended in the...
December 1, 2013
Testing in filtration processes is critical for determining the properties of solids being filtered and the ease or difficulty of the filtration. In addition, laboratory testing is important in specifying filter media, filter aids, filter area, cake space needed and cake discharge techniques. Experimental data gathered in the laboratory help in the design of the full filtration system needed for...
November 1, 2013
Calculating volumes of solids in piles as they are poured into various shaped containers can be important information for solids-handling applications. The following set of equations represents guidance to help determine solids volume in these cases. Solids in containers Solids fed through a nozzle into a cylindrical or rectangular silo normally form a partial cone of a complex shape when the material is...
October 1, 2013
Optimizing fan performance can help plants reach overall process efficiency goals. The cost of powering fans and ventilators in the chemical process industries (CPI) is significant. For example, ventilation and air-pollution control systems can account for over a quarter of energy a facility’s consumption. Fan performance is typically estimated by using a graph that shows the different pressures...
September 1, 2013
Chemical processing equipment made from thermoplastics can have distinct advantages for equipment corrosion, fluid contamination and flame retardancy. When purchased in the form of heavy-gauge sheets, these thermoplastics can be machined, fabricated and formed into a virtually unlimited variety of process equipment components that may address chemical processing challenges that other materials cannot. The...
August 1, 2013
The management of process plants requires understanding and applying the fundamental tenets of safe design, construction and operation of facilities. This overview summarizes best practices that have been developed to ensure the safest possible use of DP:DPO (diphenyl–diphenyl oxide) eutectic heat-transfer fluids. A review of the concepts necessary for effectively maintaining a leak-tight...
June 1, 2013
Dry, granular solids can be conveyed in a number of ways. Two common devices for transporting granular solids are the angular-pitch vibrating conveyor and the horizontal differential-motion conveyor. The variability in the design and performance between the two types stems from the differences in the kind of motion required to move the mass in one direction. The most significant difference between the two...
May 1, 2013
Minimizing process variability is an important component of a plant’s profitability. The performance of control valves within process control loops has a significant impact on maintaining consistent processes. This refresher outlines some of the important aspects of control-valve performance, including parameters of both the static response and the dynamic response. Static response A valve’s...
April 1, 2013
The detection of gases in plant environments has a critical and wide-ranging role in the chemical process industries (CPI). Among the major applications of gas detection are limiting personnel exposure to hazardous chemicals, preventing explosive atmospheres, protecting the environment and identifying leaks in process equipment. Table 1 summarizes the main reasons for gas monitoring. All CPI workers should...
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