Heat: The Science and Economics of Its Control

Johns-Manville Corporation made this film with Wilding Picture Productions, Inc., probably in the 1950s. It explains heat and its transfer by radiation, conduction and convection, then the cost of lost heat and how the economic thickness of insulation is worked out. It shows the raw materials of J-M insulations, including diatomaceous silica, calcium silicate, 85% magnesia and asbestos, as well as mineral fibre, the J-M Research Center's testing, Min-K for missiles and aircraft, and the company's plants.

What it says about asbestos and health

Nothing.

About this copy

Our copy is a transfer of a print from Johns-Manville's own film archive (box 15-90013), shown in full, 25:02 long. Produced by Wilding Picture Productions, Inc.

Transcript

A machine transcript of the soundtrack, not yet checked against the film; names and technical words may be wrong.

Our sun, the original H-bomb, the original source of nuclear fusion. The origin of all energy on Earth, billions of years the only source of heat. It fostered all life, it nourished all growth. Hotter than white hot, fusing infinitesimal atoms at millions of degrees. Its nuclear explosions thrust searing tentacles 300,000 miles long into the cold wastes of space. Little wonder that early man made it his god.

If there ever were a total eclipse, one cutting off the sun's light and its heat as well, not for a few moments, but forever, there would be nothing left living on earth. But we are spared this frozen desolation, this eternal barren waste, for we have heat, man's most important single resource. History waited until man learned he could make fire, could control heat. And today's world is only possible because of heat's scientific application to practically every industrial process. But what is heat? It is energy.

It can be turned into many other forms of energy. It drives steam turbines to provide mechanical energy. converted into chemical energy it literally can move mountains as electrical energy it lights our homes powers our commerce our industry to control valuable heat through insulation we must begin by studying the ways it can escape the three methods of heat transfer first by by radiation. Radiant heat, part of the spectrum of electromagnetic energy, travels as a wave. Like light, it can move through a vacuum. Like light, it travels in a straight line at 186,000 miles a second. Put an obstruction in its way, and a hot light cannot melt ice that it doesn't hit.

Only the exposed surface melts. The part in shadow is virtually unaffected. Secondly, heat is transferred by conduction through solid materials. Allow steam to pass inside a metal pipe. The heat travels quickly through the metal to the outside. That heat conduction occurs at different rates of speed through different materials is readily apparent in this demonstration.

Identical sized bars of different metals are heated at one end by the same heat source. The difference in time it takes their wax coating to melt illustrates the wide variation in conduction. We can use shadowgraphs to illustrate the third method of heat transfer, convection, or the movement of of air from one temperature region to another. We can feel the intense heat waves well above any visible flame, just as we can feel heat rising from a radiator. By using a powerful light source to silhouette that heat onto a screen, we can see and study this rising torrent of hot air. Cold air in this shadowgraph of a piece of ice spills downward, being heavier than the air about it.

The circulation set up by these movements of heat causing upward currents and cold causing downward ones can be seen even in a so-called dead airspace. One face of this box is kept heated, the other kept cold. Air rises along the hot surface, crosses to the the cold side where it is chilled and falls. Every round trip of this circulating air means a loss of heat. It is insulation's job to prevent such loss. By using a pipe and valve setup in still another shadowgraph, we can see a dramatic example of heat lost by convection.

The shadowgraph will not show the additional heat lost by radiation, which may be even greater. Insulating Insulating both sections of pipe cuts down the amount of lost heat, but only by properly insulating pipe and valve can heat lost by radiation, conduction, and convection be kept to a minimum. The proper material and the best thickness must be determined for each specific installation. This is part of the work of the insulation engineer who realizes that whether insulation is used for people's comfort and safety for fire protection to protect equipment or for process control it is first and foremost a way to conserve heat a way to save money all man-made heat has a price on it it costs money to build the simplest furnace it costs money to supply it with fuel it costs money to hire the people who keep it running. Thus, every unit of heat energy that is released has a definite dollar value. Now, this energy reaches the boiler by radiation and by convection.

It moves through the metal boiler walls by conduction and through the water in the boiler by convection. But the furnace walls are also conductors of heat, so there is a loss of of heat by conduction through the furnace walls and by convection and radiation outside the walls. The uninsulated boiler wall transfers heat out by conduction as easily as it transfers it to the water. So there is further heat loss by radiation and convection outside the boiler. Every unit of heat that is wasted costs exactly as much money as a unit of heat that is used. The mission of Johns-Manville is to provide materials to save this heat, thus conserving fuel and concentrating the available energy on useful work.

Efficient insulating materials pay a far greater rate of return than can be expected from practically any other form of plant investment. But what insulating materials will pay the greatest return? The men who have the answer draw on a century of experience in insulation problems. They are Johns-Manville insulation engineers. What materials? Well, it depends on the job.

Obviously, no single insulating material will do everything best. Our work then at Johns-Manville is to get the right balance of properties for each application. How thick should an insulation be? Well, you could put this on a steam line, and compared to no insulation at all, you'd save a lot of money. And then, with this, you'd save additional heat, but the insulation would cost more. And if somebody insisted, well, we could insulate way out to here, but that would cost a lot more, much more than could be saved in heat costs.

So our job is to provide insulation with the best balance of properties and to calculate the most economic thickness. Many factors enter into our calculations. Operating temperature, hours of operation, type of installation, cost of heat production, and so forth. But they can all be boiled down to these two. Annual cost of insulation in place. Annual cost of remaining heat loss.

Now the sum of these two gives us a basis for determining the economic thickness of insulation for any application. The annual cost of the insulation is based on its installed cost and the rate of amortization. Now let's assume that on a steam line the annual insulation cost in place per foot comes to 12 cents for one inch thick insulation. The annual heat loss through this one inch thickness costs a dollar and 51 cents. cents. The total annual cost then is $1.63 per foot. Two inches of insulation naturally is going to cost more, 24 cents in this case, but more heat is saved, which brings the cost down to 95 cents.

Annual total, $1.19. For three inches of insulation, the cost goes up to 37 cents, but the cost of lost heat drops to 74 cents. Total annual cost, one dollar and eleven cents. Four inches of insulation costs 53 cents. The cost of the lost heat has dropped to 64 cents. However, the additional heat saved is no longer enough to justify the added thickness.

The total annual cost, instead instead of continuing to fall, has now come back up to a dollar and 17 cents. And if we put on greater thicknesses, the total cost would continue to increase. So back here, at three inches, we have the lowest annual cost or economic thickness for this job. Actually, we're a little ahead of ourselves. You may ask, three inches of what? This or this or something else?

Well, one of the first questions is, how long does it have to last? Well, that may be measured in decades in some instances and for much shorter periods in others. How long is it going to be under temperature? Part-time or constantly? How much physical abuse is it likely to get? Now, for example, the pipe insulation in this oil refinery is going to have to take it.

Men will lean ladders against it, use it for catwalks, and that calls for strength and toughness besides insulating properties. Lines operating in the same temperature range but which are protected inside the walls of a building for example can be insulated with a material of less strength. Perhaps the insulation will be out in all kinds of weather. A lot of equipment is nowadays equipment that used to be housed in expensive plant buildings. This means we We need still more qualities in our insulating material, because the insulation and the weatherproofing over it provide the only weather protection such valuable equipment is ever going to get. They used to tell us that all we needed for an ideal insulation was a substance meeting these specifications, strength infinite, weight zero, cost in place zero, life forever, conductivity zero well it's a nice idea but obviously practical insulations only approach these specifications some more closely on one property and others on different properties and insulation can be made very strong or very light or very economical very durable or a very low conductivity and since different insulation requirements call for these properties in different combinations many raw materials are used, each one adding its own strongest points to the Johns-Manville family of insulating products.

To meet the needs of high-temperature insulation, we reach millions of years back in the geological history. These white hills of silica are actually the graveyard of billions of microscopic organisms called diatoms that lived in the ocean that once covered California. This diatomaceous silica not only provides low conductivity, but retains its physical and chemical stability at temperatures up to 2,500 degrees Fahrenheit. Limestone too is an important raw material. Combined through a heat process with diatomaceous silica, it is used to make calcium silicate insulation, material of great permanence and strength, light in weight, low in thermal conductivity stable when wet and having excellent insulating qualities dolomite rock is the starting raw material for 85% magnesia insulation a product less strong than calcium silicate but also having low thermal conductivity magnesia has been the most widely used insulation for industrial applications to 600 degrees from the world's largest asbestos mine located in Canada Johns-Manville takes the magic mineral called asbestos soft silky fibers of great strength inorganic light fire resistant asbestos is the ideal reinforcing agent for thermal insulation for a strong insulation with low first cost a heat process is used to expand a volcanic rock in which molecular water has been trapped a rock this size is converted into this large mass of light cellular insulating material. The violent temperatures of a volcano made by man are needed to manufacture mineral fiber.

Streams of molten materials are made into silky strands far finer than human hair. One of the oldest natural insulating materials is clay. In special clays are found the refractory qualities needed for manufacturing a variety of insulating fire brick that defy extremely high temperatures. It takes a a wide variety of production techniques and specially designed modern equipment to turn these raw materials into the finished products used throughout the world. From the many Johns-Manville factories come products in many forms. Pipe insulations, block insulations, insulating brick, metal clad insulations, mineral fiber felts, refractories, and structural sheet sheet insulations.

In this family of products are the answers to insulation problems that range from hundreds of degrees Fahrenheit below zero to thousands of degrees above. Such home appliances as refrigerators, freezers, water heaters, and ranges can be made better to serve better with the remarkable mineral fiber insulation developed by Johns-Manville. At sea, another of the company's discoveries contributes to the safety and comfort of passengers and crew. These attractive walls and ceilings are built of lightweight and fireproof panels. And the same material, since it combines structural strength with high temperature insulating qualities, is used to build ovens, dryers, and similar high heat equipment. Johns-Manville's leadership in the science of insulation stems not only from its products, but also from its organization of experienced contractors.

Chosen for their integrity and skill, they know the right application methods for every kind of service. In plumbing and heating systems, they apply pipe insulations to to cut heat loss or to reduce condensation. With duct insulation, they add efficiency to air conditioning systems by holding down the air temperature on its way to room outlets. In this cold storage room, inorganic, moisture-resistant insulation will help maintain the extreme temperature needed to preserve perishable food and beverages. The petroleum and petrochemical industries depend on many types of thermal insulation for process control, for safety, and for economic operation. In the power industry, Johns-Manville products are part of the engineering triumphs that have made the generating of electricity more and more economical.

This family of insulating materials also plays a part in conserving atomic fuels in the nuclear reactors of power plants. In the steel industry, too, where temperatures climb past 2,000 degrees, Johns-Manville products are at work, saving fuel and improving operation. In the high- temperature world of modern industry, insulation is an important capital investment demanding exacting design and proper application. The Johns-Manville Research Center is dedicated to finding ways of making industry's insulation investment yield the greatest possible return here researchers are at work on basic studies in the economics of the control of heat here is not only the thorough testing and appraisal of newly developed materials but a constant quality control of existing products as well in the thermal conductivity laboratory, guarded hot plate apparatus is used to test block insulations. Electrically heated pipes in a room with constant temperature are used in testing pipe insulations. The heat loss through all test samples is measured by computing the electrical energy needed to make up that loss.

To assure the highest accuracy in these measurements, every test unit is fed from one master a switchboard designed to deliver a constant output of power. As a check, readings are taken every hour while the tests are underway. With such precision equipment as this, the research engineers can measure the finest variations of insulation conductivity. There are many other properties to be tested. In the spalling test, panels of insulating fire brick under intense heat are subjected to cycles of cold water sprays. This is a means of determining their resistance to thermal shock.

Insulating qualities are not the only ones tested. For certain materials structural strength and other physical qualities are every bit as important as insulating efficiency. Here a panel undergoes a rupture test and when a new product finally emerges from its experimental stage, it too must undergo the most rigorous tests science can devise before it is made available for practical use. Anticipating future needs, the Research Center is engaged in many projects. One such project resulted in a new concept of basic insulation design of direct interest to the insulation engineer in the field. What he's talking about is the mean free path theory of of gas conduction that is applied to insulation research at Johns-Manville.

Now this theory provides a scientific way of knowing how an insulation is going to perform while it's still on the drawing board. Let me give you just one example. In missile design, space and weight are at a great premium. Yet some space and weight must be allowed for insulation needed to protect sensitive instruments, controls, and structures subject to very intense heat. Now, working within these space and weight restrictions, Johns-Manville, using this mean free path theory, has designed and created a material that closely approaches our so-called ideal insulation. Its name is Min-K, which is short for minimum conductivity.

And minimum is, well, it's almost an understatement. Min-K has been designed to have an even lower conductivity than the theoretical minimum of still air. A one inch thickness of Min-K is more efficient than several times that amount of conventional insulation. Made to help man in his conquest of space. Who can say what doors this revolutionary material may open to more efficient industrial insulations? Not only in man's conquest of outer space that control of extreme temperatures is important, the jet engines of supersonic planes also develop intense heat.

To shield them, Johns-Manville has designed a unique type of insulation. This insulation is custom fabricated of high temperature refractory felts encased in stainless steel, titanium, and other high heat resistant metal foils. All progress stems from new products and new processes and in turn all these products and processes depend on heat. Heat and conservation of the fuels which make it becomes yearly more vital to us and to our civilization. New fuels, new needs of industry push operating temperatures ever upward. Scientists now talk in the millions of degrees.

Temperatures in the tens of millions can be anticipated in the field of nuclear fusion. Johns-Manville's work in insulation research is aimed today at these foreseeable goals of tomorrow. To help make useful to man heat energy originating at temperatures far greater than the heat of the raging inferno that That is our song.