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Tuesday, 21 July 2015 00:00

Blog: A Perpetual Dilemma: Rent or Buy?

In this article by Robert Preville (Founder & CEO, Kwipped), the author discusses the potential benefits of renting lab equipment, as opposed to buying. Did you know that Cooper Instruments & Systems offers equipment rental options? The article expands on the following advantages renting can offer:

 

  • control cash flow
  • "try before you buy"
  • bring in job-specific equipment
  • more access to new technology

 

Click here to view the white paper.

 

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Based on work out of Germany, France and Finland, and at the request of the US Weather Bureau, two researchers of the Bureau’s electrical division began an endeavor to devise a practical system of radiometeorography for the weather service. A similar request was made by the aerological division of the Navy’s Bureau of Aeronautics, this one being researched by a team from the radio laboratory. This second team’s offering seemed better suited to both requests, so the duo from the electrical division fitted the device they had developed with Geiger counters and began launching them 20+ miles up to gather cosmic ray data. Their findings would impact thinking on radiation and the effect of cosmic rays on radio communication as well as the study of atomic structure. Using data gathered from 18 launches of their device, Leon Curtiss and Allen Astin confirmed international reports proposing that the greater part of cosmic-ray phenomena was caused by secondary effects within the Earth’s atmosphere.

 

The team from the radio division, meanwhile, successfully devised a unit that transmitted continuous data on cloud height and thickness, temperature, pressure, humidity, and light intensity in the upper atmosphere. Dubbed the “radiosonde”, the device was effective at 15+ miles up and at distances up to 200 miles. By 1940, it completely changed the US weather and meteorological services with 35,000 units being built and launched each year.

 

During the 1930s and 1940s, the Bureau was party to nearly every expedition sponsored by the National Geographic Society, including visits to the polar regions and balloon flights 14 miles into the stratosphere. The Society and the Bureau co-sponsored an expedition to the USSR to observe and photograph the 1936 solar eclipse, capturing the first-ever natural color photographs of an eclipse using a 14-foot camera conceived and constructed at the Bureau. Both the camera and the Bureau would participate in several other solar eclipse expeditions around the globe over the next few years. Dr. Briggs even organized an eclipse expedition to Brazil in 1947 that comprised 76 researchers from the Bureau, armed forces and National Geographic Society.

 

Concurrent with this atmospheric research, huge breakthroughs were made across the world in the fields of physics and atomic research. The Bureau’s first studies in this vein were into atomic chemistry, not physics. The existence of isotopes (atoms of the same chemical element with different atomic weights) had been discovered, but researchers were having difficulty finding a heavy isotope of hydrogen using the existing technology. The Bureau stepped in to suggest use of its cryogenic lab to study liquid hydrogen where experiments confirmed the existence of the proposed heavy hydrogen isotope.

 

In a series of discoveries by American and European scientists, the existence of neutrons was confirmed and the first nuclear reactions were performed. Enrico Fermi experimented using uranium with an atomic weight of 238 and bombarding the atoms with neutrons to split the nucleus, but his results were inconclusive. Later experiments by others confirmed that the same isotope of uranium could be split and finally that it could be split into two nuclei of roughly equal size but producing enormous quantities of energy in the process. These findings were relayed to Albert Einstein by Niels Bohr, who also informed him that Hitler had control of the only known source uranium ore and had placed an embargo on it.

 

This news and its significance were conveyed to President Roosevelt, who immediately sought the advice of Dr. Briggs at the Bureau. Within a week, Dr. Briggs was chairman of the newly formed Advisory Committee on Uranium. The Committee’s task was to investigate uranium fission (faster than Nazi scientists could). Less than a month from Einstein’s initial letter to the President, the Committee issued a report indicating the distinct theoretical possibility of a chain reaction that would produce enough energy for an explosive weapon or to power a submarine.

 

As the Second World War began in Europe, and recognizing the potential implications of researching nuclear fission, Dr. Briggs hesitated as to what he and the Bureau should do next. Was this a line of research he and his organization would or should pursue? The Committee was absorbed, renamed and absorbed again into a series of other national defense programs created as Nazi Germany continued its European conquests, before finally becoming inactive under the umbrella of the Manhattan District division of the Army Corps of Engineers in 1942.

 

 

**The information presented here is drawn from “Measures For Progress: A History of The National Bureau of Standards” (Rexmond C. Cochrane)

 

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Thursday, 28 May 2015 00:00

Q&A: Calibration Curve

Following is the transcript from a question and answer session conducted with a Cooper Instruments technical engineer.

 

Q:            What is a calibration curve?

A:            A calibration curve is the performance curve of the transducer; that is to say, its output in relationship to the range of applied loads from a no load condition to that of a full scale load.

If you were to measure the output of a 100 LBF load cell and record the output at 0, 25, 50, 75 and 100 LBF, theoretically you would have a curve much like the one in fig 1. As this is a perfect example, the performance curve is a straight line. In real world conditions however, there will always be a slight error that will prevent a straight line, but depending on the amount of error, the performance could possibly be accepted as straight. Whether the performance is good or not, the resulting performance representation is considered a “curve”.

 

 

Q:           How is it calculated?

A:           As shown above, the calibration curve is not calculated but rather it’s measured. Some calibrations are calculated if, during a calibration, the lab is unable to apply certain data points or force points. In cases like this, the laboratory can turn to statistical tools to calculate what the performance is most likely to be at these unmeasured points. It is; however, always best to stay away from extrapolating data unless absolutely necessary.

 

 

Q:           Most indicators offer a 2-point calibration: what does that mean?

A:           An indicator is a device that allows the user to equate a desired engineering unit to the output of the transducer. Most indicators allow for what is called a 2-point calibration, meaning you can define only 2 points on the calibration curve and the meter assumes a straight (linear) curve. So, if you follow the recommendations in the manual, you will use a no load condition of your transducer and define it as your zero load point. The second point is usually your full load point, and in the case found in Fig 1, the full scale would be defined as 100. Consequently, when the meter reads exactly half the value of the full scale point, the meter will report 50.

 

 

Q:           What are the limitations of a 2-point calibration?

A:           The limitation to a 2 point calibration is that it assumes your transducer is performing at a theoretical (perfect) level. You’ve heard the saying “nature abhors a straight line”? Well, this is a very true saying, and applies to transducer performance just as much as it does to rivers and streams. Now, the effect of the lack of linearity depends on the errors due to inaccuracies and on the user’s quality requirements.

Let’s assume that the 100 LBF transducer in our example performs with a nonlinearity specification of ±1% at half scale, and the 2 point indicator has been calibrated at 0 Lbf and 100 Lbf, when 50 Lbf is applied, the display will read 50, but the actual force is in the range of 49 to 51 Lbf. So due to the 2-point calibration, the inaccuracy of the performance curve is hidden.

So in short, the limitation of a 2 point calibration is the inability to compensate for nonlinear performing load cells, yielding inaccurate readings.

**It’s important to note that a load cell will always perform within OEM specification limits when new. However, after prolonged use and age the performance will begin to degrade, and a 2 point calibration may not be able to compensate for this change.

 

 

Q:           How does using a multi-point calibration linearize a load cell's

               performance?

A:           Now that we know there can be an amount of error between 2 points of a curve, it stands to reason that if we shorten the distance between the points, the smaller the errors will be had between those same points.

So, if we calibrate our meter with more than 2 points, we will begin to reduce the measured errors and improve the performance of the load cell system. In Fig-2 below you can see the same 2 point calibration curve in the blue dotted line. Compare this curve with that of the individual data points. You can see an error grows up to the halfway point and then reduces as it gets to the highest data point.

If we were to use a 5-point calibration method on this instance, you would get a performance more on the lines that the black line represents. Fig-3 demonstrates the new calibration curve with the red dotted line, when applying the multi-point calibration for 5 points.

 

 

Q:           How does a linearized performance prolong the useful life of a load cell?

A:           As the load cell ages with use, the linear performance will decay. With the use of a 2 point calibration, there will be a point where the load cell will not maintain the performance needed and may eventually get to a point where the errors cannot be compensated for.

With the use of an indicator with multi-point calibration functionality, the errors can be compensated for and performance can be maintained.

 

 

Q:           What solutions can Cooper Instruments offer when an indicator with 2-point calibration is not sufficient for the user's application?

A:           Cooper Instruments offers several products with multi-point calibration

               options:

The DFI INFINITY B, M3, M5 and 7i all allow for multi-point calibration. We also offer the DSC USB, which has software that allows for multi-point calibration. Our sales representatives would be happy to help you select the right product for your application.

 

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing This email address is being protected from spambots. You need JavaScript enabled to view it..

 

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With much of the US in denial, a group of foreign-born scientists led by Niels Bohr foresaw the country’s eventual involvement in WWII. Bohr, for example, urged a moratorium on publication in the Allied countries of research related to nuclear fission. It was almost a year before the scientific community truly headed Bohr’s warnings. Dr. Briggs, from his position on the Advisory Committee on Uranium, began to prepare himself and his agency for the possibility of war. Briggs prepared for the Department of Commerce and list of services the Bureau was prepared to offer “in the event of war.” Among these: to test all materials to be purchased under the Strategic Materials Act, to increase its output of optical glass, to certify US materials sent abroad (especially instruments, gages, metals and cement), and more. Dr. Briggs also included with his memorandum a copy of “The War Work of the Bureau of Standards” which detailed the Bureau’s contributions during WWI.

 

The country as a whole was totally unprepared for a new war – the armed forces had outdated equipment (and that in short supply) while much of the nation was still facing the high unemployment and sluggish manufacturing of the Great Depression. The general mood of the country was against involvement in the war (as evidenced by the 1940 Democratic Party Platform) and thus mobilization to prepare for war was slow. In taking on projects related to wartime preparation, the Bureau was forced to begin classifying much of its research. As a result, the annual reports from the Bureau became restricted to only nonconfidential research. By 1942, so much of the material was classified that there was no point in printing the annual report at all. The sensitive nature of the work being done at the Bureau also led Dr. Briggs to close the laboratories to visitors, fence in the property and close Van Ness Street, which ran through the site. By the beginning of 1942, 90 percent of Bureau staff were dedicated to war research and Military Police patrolled the “prohibited zone” that was the Bureau grounds.

 

That the Bureau would be tasked with testing the strength and properties of material like metals used for weapons, airplanes and the like or with finding materials that could be substituted for those in short supply as a result of the war would seem obvious. There were also more obscure aspects of war to be considered, however. One interesting example is the Bureau’s participation in a “joint Army-Navy program to determine the characteristics of sky glow from artificial sources and the extent to which sky glow and shore lights might aid hostile ships offshore.” Among other priority Bureau projects during the early part of the war were research on petroleum conservation (because oil tankers were great targets for enemy submarines) and the production of synthetic rubber. Gas was rationed (to save the rubber in car tires more than to save gas), resulting in numerous citizen inventions intended to save gas being submitted to the Bureau for testing.

 

Thanks to the war, the Bureau’s staff would increase by more than 238 percent from 1939 to 1945, including over 200 members of the armed forces. Even more dramatic, funding increased from $3 million just prior to US entrance into the war to $13.5 million by 1944. To accommodate the huge demand for testing and the now huge staff, all of the Bureau’s conference and lecture rooms were converted to laboratories and 2nd and 3rd shifts were introduced to make maximum use of the space and equipment. The standard work week was also lengthened from 39 hours before the war to 44 hours.

 

The Bureau continued to be involved in the development of the atomic bomb by testing the purity of uranium and other elements. While many at the Bureau suspected that a weapon using uranium might be under development, the secrecy ran so deep and the security was so tight that even researchers working directly on the project sometimes failed to realize what the end-game might be, thinking instead that the uranium would be used for power plants to power planes or submarines.

 

**The information presented here is drawn from “Measures For Progress: A History of The National Bureau of Standards” (Rexmond C. Cochrane)

 

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So, the last installment of the series left off with the establishment of the Mathematical Tables Project, which, by 1943, had produced 27 book-length tables as well as many shorter ones. The thirties also gave rise to an undertaking to identify and quantify the physical constants of pure substances, especially of industrially important organic compounds. Importing a method devised by a scientist at the Polytechnic Institute of Warsaw, Bureau chemists researched a number of substances by determining their vapor pressure, boiling point and more.

 

Thus, as mentioned in a previous installment, although the Great Depression brought with it reductions in staff and funding, as well as other hardships, the reduced bureaucracy of the time allowed the Bureau staff who remained to focus their energies on some much-needed fundamental research that would serve as the building blocks for years to come.

 

In September 1933, two Bureau researchers, Burt Carroll and Donald Hubbard, were awarded medals by the Société Française de Photographie et de Cinématographie in recognition of their contributions to the world of photo-sensitive emulsions. The Bureau’s involvement in this field began in 1921 with the need for emulsions sensitive to infrared spectra for which commercially available film was unsuited. With German equipment installed in the basement of the Bureau’s chemistry building, Carroll and Hubbard set to work on creating a better film. For 7 years, their efforts were largely futile with sometimes over 400 batches of emulsion made in a single year. By 1933, however, the two were publishing their 17th report on the mechanism of photographic hypersensitivity. They were finally creating emulsions superior to commercial ones and in publishing their methods, they would threaten trade secrets of those commercial producers. Therefore, when budget cuts were made, the emulsion project was among the first to go as one of seven projects which the Visiting Committee specifically targeted (the others were heavy hydrogen research, dental cements and alloys, certain industrial concerns, internal combustion engines, production methods for levulose and the design of a telephoto astronomical objective).

 

In 1933, Congress made its biggest reduction in Bureau appropriations with a cut of 54 percent which affected over 100 projects. Particularly hard hit were the projects involving automotive engines (over 40 different projects), because of their unpopularity with the auto industry when, for example, one manufacturer’s engine was deemed by the Bureau to be superior to the others. Also due to budget concerns, the Bureau surrendered work on standardization and specifications to the American Standards Association. Amid backlash from the industrial community at the change, it was agreed that the Bureau would continue to cooperate with the ASA.

 

Around the same time, the Bureau and Dr. Briggs were embroiled in lawsuits regarding the issuance of patents to Bureau researchers. The practice under Dr. Stratton had been that patentable material would be patented in the name of the Government and would be for public use. This method was challenged in 1922 by two researchers of the radio section who developed a method by which radios could be operated by current rather than the traditional batteries. This innovation fell outside the area of their assigned field of research and as such, they filed three patents in their own names relating to the technology. In response, a formal policy regarding patents was devised and it explicitly stated that patents for inventions and discoveries of Bureau employees would be registered to the Government. The District Court of Delaware later decided in favor of Lowell and Dunmore because the invention was not part of their assigned work. An appeal to the US Circuit Court upheld the District Court’s decision as did a further appeal to the Supreme Court which was decided in 1933 in favor of the inventors.

 

While the funding cuts were bitterly made, Dr. Briggs did acknowledge that some programs had become entrenched, not because they were useful or truly merited ongoing research, but because all possible angles of research had not yet been completely exhausted. The reductions in staff and resources forced various projects, such as radio research, down to their absolute most important aspects.

 

**The information presented here is drawn from “Measures For Progress: A History of The National Bureau of Standards” (Rexmond C. Cochrane)

 

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing This email address is being protected from spambots. You need JavaScript enabled to view it..

 

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Finally, in 1935, the Bureau could document an increase in requests from industry for data. This coincided with increased building at the state and federal levels which brought an increase in government requests for tests and calibrations (as well as a modest increase in funding, sufficient to rehire former staffers). In 1938, Congress approved construction of a new electrical testing laboratory to replace the obsolete one built 25 years earlier when voltage ranges were much lower than those being produced in the late ‘30s, further evidencing the improving economy. Thanks in large part to new dam-building projects across the country, the opening of new branch laboratories also increased during the late ‘30s.

 

Efforts to stimulate the economy through low-cost housing also led to Bureau funding for research into structural and fire-resistant properties of construction materials to be used for housing. This program and its funding were cut from New Deal sponsorship as WWII approached, but the work continuing at the urging of the building industry. After a hiatus during the war, building technology became its own division within the Bureau in 1950.

 

Also during the 1930s, the Bureau completed research relating to the preservation of paper records. The work, funded by the Carnegie Foundation, tested the effects of such forces as light, heat and humidity on storage of paper and books. Sulphur dioxide was determined to be the greatest enemy of paper storage. The work led, in turn, to studies on the preservation of all types of media and to the Bureau’s involvement in the preservation of the Declaration of Independence and the Constitution at the National Archives.

 

Another interesting line of study at the time related to X-ray dosages and ultraviolet radiation. Although both technologies were becoming quite widely used by medical professionals, they did not really understand the thresholds of safe and unsafe exposure, particularly to the equipment operators as opposed to the patients. At the urging of the president of the Radiological Society of North America, Congress provided funding at the Bureau began to research the issue. Physicist Lauriston Taylor, who had been working on X-rays and electronics at Cornell was brought on to Bureau staff to lead the work.

 

Taylor’s first order of business was to construct new equipment for the testing, which he did from parts of other equipment on hand at the Bureau. In 1928, he attended the Second International Congress of Radiology and became the first Chairman of the National Committee on Radiation Protection and Measurements. Taylor published research in 1929 showing that X-ray dosages could be quantitatively measured and in 1931 he published guides for safety shielding of operating rooms, patients and operators. Similar publications for radium, at the hand of Dr. Leon Custiss, followed in 1934.

 

Paints, made from compounds including radium, were developed to have luminous properties for applications on instrument panels for the military during WWI and also on watch faces. Little was known about the effects of the radium paint at the time. It was later determined that the amount used for a watch face was fine, but the problem was the factory application of the paint to the watch during production. Being wartime, mostly girls worked in the factories and the put their paint brush tips in their mouths to draw them to a point, thereby ingesting the paint. Hundreds of these girls died of what was later diagnosed as radium poisoning. In 1932, the American Medical Association discontinued all internal administration of radium as a remedy. The Bureau’s research on the topic was found in the 1932 handbook on radium protection and in 1941 it had a handbook of its own.

 

Also during the 1930s, work advanced in spectroanalysis with new and accurate measurements of the atomic emission spectra of chemical elements, rare gases, and rare metals. An index was published by the American Society for Testing Materials that listed almost 1,000 papers on the subject written during the preceding two decades. Dr. Briggs also proposed that the Bureau sponsor a central agency for computing fundamental tables for applied mathematics. With basically no equipment provided, the project began in New York City with hundreds of workers doing calculations by hand. The first order of business? To prepare the 16-place values of natural logarithms, the 15-place values of probability functions, and the 10-place values of Bessel functions of complex arguments. Within a decade, equipment existed to compute in minutes what 400 individuals with pencils did in months, but the Mathematical Tables Project was widely and gratefully recognized at the time.

 

**The information presented here is drawn from “Measures For Progress: A History of The National Bureau of Standards” (Rexmond C. Cochrane)

 

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing This email address is being protected from spambots. You need JavaScript enabled to view it..

 

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