The American Society ofMechanical Engineers

PEERLESSType "M" Odorizer

National Historic Mechanical Engineering LandmarkDesignated September 10, 1992

PEERLESS MFG. CO.

NATIONAL HISTORICMECHANICAL ENGINEERING LANDMARK

PEERLESS MANUFACTURING

METERING–TYPE GAS ODORIZER1937

THIS EARLY TYPE-M GAS ODORIZER SERVED FROM 1942 TO 1992.IT WAS DEVELOPED A FEW MONTHS AFTER 294 SCHOOL CHILDRENAND ADULTS DIED IN A NATURAL GAS EXPLOSION ON MARCH 18,1937, IN NEW LONDON, TEXAS. THE TEXAS LEGISLATURE RESPONDEDBY REQUIRING NATURAL GAS TO BE ODORIZED SO THAT LEAKSW O U L D B E A P P A R E N T . T H E W I D E L Y U S E D T Y P E - M O D O R I Z E RINJECTS A PRECISE AMOUNT OF PUNGENT LIQUID INTO THE GASFLOW. ITS CREATORS WERE DON A. SILLERS, FOUNDER OF PEERLESSMANUFACTURING, AND ALEXANDER CLARKE.

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS - 1992

Throughout history, engineers and designers have incorporated many safety devices intodesigns or machines for the benefit of mankind. The natural gas odorizers are, however, truesafety devices. They approach the problem of handling an odorless, colorless, highlyexplosive fuel by adding an easily recognizable, offensive odor. Anyone who has entered aroom and smelled gas has benefitted from this or some similar device. If an explosion wasprevented because of someone’s ability to recognize the presence of natural gas, it is becauseof effective gas odorization.

On March 18, 1937, an explosion at the public school at New London, Texas, and the resultingdeaths of 294 children and adults focused world-wide attention on the dangers of utilizingnatural gas as a fuel. After this tragic accident, consumer demand for natural gas suffered asetback. The Peerless Type "M" Gas Odorizer was introduced in mid 1937 and patented in1941. By the end of World War II, natural gas was established as a safe, dependable fuel.

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BACKGROUND

Natural gas, principally methane (CH4), occurs as a suitable combustion fuel without aninherent odor or color. Odoriferous gases that do occur naturally contain high levels of sulfuror other corrosive constituents that make them unusable as a fuel without further refinement.Due to the lack of any method of human detection, natural gas was initially considered a veryhazardous fuel source. Leaks in piping and appliances could go undetected until enough gasescaped and accumulated to form an explosive atmosphere.

Efforts to add an odor to odorless vapors initially began in Germany around 1880. R. vonQuaglio used nitrobenzene and ethyl mercaptan to impart a detectable odor to blue water gasin order to indicate the presence of carbon-monoxide. In 1911, German iron and steelproducers odorized blast-furnace gas by passing the gas through beds of calcium carbide inorder to incorporate acetylene. They then were able to use this odorized gas to heat domesticresidences.

During and after World War I, several studies in the United States were made into theintroduction of odorants into fuel gases for underground leak detection and warnings wherefuel gases were used for industrial purposes in mines and other confined installations. Workcontinued in Germany during this time, with at least one patent being issued in 1924 to usesolids to odorize manufactured gas.

In 1926 - 1927 studies were being made in both Europe and the United States to develop acommercially suitable odorant for fuel gas. During this time, emphasis in the United Stateschanged from manufactured gas to natural gas. Calodorant #3, a successful odorant, becameavailable as a by-product of gasoline sweetening. Also, Sharples Chemical Companydeveloped amyl mercaptan in the late 1920s and early 1930s.

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EARLY ODORIZING EQUIPMENT

Early equipment for introducing odorant into natural gas was often crude and normallydesigned on site by the user. Most common were drip or evaporative methods that did notadequately compensate for variations in gas flow and pressure. When pumps were used, theywere usually the reciprocating types subject to packing leaks. Tightening the packing toprevent the malodorous leaks often caused the pump to cease operation.

Odorization was initially performed on a voluntary basis and no government regulations wereestablished. Most natural-gas service companies used some form of odorization if the gasdistributed lacked a natural odor. However, in some areas of the country there was anothersource (other than the service companies) for natural gas. In many areas where gasoline orbutane were refined, untreated and unodorized residue gases were gathered and returned tothe leases in residue lines either to be used as a boiler fuel or flared off. Many public facilitiessuch as churches, schools, and government buildings in these particular areas obtained theirgas directly from residue lines. Often, such users were allowed to tap into the lines and usethe fuel free of charge.

NEW LONDON SCHOOL DISASTER

On March 18, 1937, in the small East Texas Community of New London, a tragic event tookplace. In a public school building heated by non-odorized residue gas, an explosion occurredin which 294 school children and faculty perished. Later analysis theorized that leaking gashad collected in the crawl space under the floor and was ignited by an electric switch in anearby shop class. The emotional shock of this tragedy was experienced throughout thenation. World leaders, including Adolph Hitler, expressed concern and sent condolences.

As it often happens, this tragedy and its associated awareness of present potential dangerspurred much activity to resolve this problem. Within two months, the State of Texasestablished regulations for gas odorization, enforcing them under the authority of the TexasRailroad Commission. These new regulations required the odorization of all gas used inpublic buildings. They also contained strict specifications for the odorant and provided forapproval of all plans and specifications for the equipment used to introduce the odorant.

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PEERLESSTYPE “M” ODORIZER

(METER TYPE)

T h e P e e r l e s s R O B O T t h at

M E T E R S t h e o d o r a n t f r om

your s to rage tank to your

gas line. . .

PEERLESS TYPE "M" ODORIZER

Two months later, in July, 1937, Peerless Manufacturing shipped its first Type “M” Odorizer,an invention of Donald A. Sillers of Dallas, Texas and Alexander Clarke of Coleman, Texas.During this same month, the inventors applied for a patent, which was later granted (U.S.Patent, 2,240,808, dated May 6, 1941). The Peerless Type “M” Odorizer worked byintroducing a measured amount of liquid odorant into the gas stream. This amount wasproportional to the volumetric gas flow regardless of pressure. This was especially importantsince the actual volume of vapor changes significantly with changes in operating pressure.Also, variations in viscosity, temperature or pressure of the odorant did not substantially affectthe measured amount of odorant.

Features unique to the Peerless Type “M” Odorizer were due to the basic operating principleand pump-drive design. The Type “M” utilized a dipper-type pump, driven by a modifieddiaphragm-type gas-flow meter. The complete pump, drive mechanism, and odorant reser-voir were enclosed within a containment vessel at main line pressure. The meter provided areliable and accurate drive mechanism. The pump had no seals or packing to leak or wearout. The containment device virtually eliminated odorant exposure to the atmosphere andwell protected the mechanism from tampering and airborne contaminants or corrosion.

M O R E A C C U R A T E LY

M O R E D E P E N D A B LY

M O R E E C O N O M I C A L LY

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PRINCIPLE of OPERATION for PEERLESS Type “M” ODORIZER

OPERATION

A small side-stream flow, bypassed from the main gas line, drove the diaphragm meter in theType “M” Odorizer. This side stream was produced by a pressure reduction caused by anorifice or partially closed valve located in the main line. The flow through this side streamwas regulated by an adjustable flow-control valve and served as the driving force to carry theodorant back to the main line. Since the main line and side stream were parallel flows, thepressure loss across the side stream was always equal to the pressure in the main line. Underuniform operating pressure, the flows would thus be proportional. When changes in thepressures occurred, the flow control valve was adjusted to predetermined settings to compen-sate for the associated change in actual flow. In instances where frequent pressure changesoccurred, an automatic adjustment valve was available. However, when changes were rareor seasonal, a manual adjustment valve was practical.

A pump composed of a curved hollow tube introduced liquid odorant to the gas side stream.As this tube rotated around the drive axle, it dispensed a measured amount of odorant. Thepreset level in the internal reservior governed the quantity of odorant dispensed. A floatactuated valve, which regulated the odorant flow from the storage tank, kept this levelconstant. Adjusting the level in the reservoir and changing the drive sprockets allowedinfinite adjustments to be made to the odorant dispensing rate. Once the initial dispensingrate was set, it would remain proportional to the main gas line flow throughout the setoperating range.

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PEERLESS TYPE "M" ODORIZER

CONTAINMENTVESSEL

CHAINDRIVE

GASMETER

ODORANTSTORAGETANK

PUMP

CHAINDRIVE

MAIN LINE GASMETER

METERSHAFT

ORIFICE

PUMPROTATINGCURVEDTUBE

FLOATODORANT

RESERVIOR

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PEERLESS TYPE "M" ODORIZER - SERIAL NUMBER 2105

Morton Thiokol installed Peerless Type “M” Odorizer - Serial Number 2105 on May 15,1942 at the U.S. Army Ammunition Plant in Karnack, Texas. According to site personnel,it operated twenty-five years without maintenance. Morton Thiokol removed it from serviceon February 20, 1992 and replaced it with a new unit. For nearly fifty years, this smallmechanism did its job. Simple and innovative when built, it proved to be effective andreliable.

DESIGNERS AND INVENTORS

Donald A. Sillers, Sr., (1895-1947) was the designer-inventor of several gas processing andhandling devices, including liquid-vapor separators, solid-vapor separators, a gas meter, andthe gravity balance (a device used to determine specific gravity of gas). Mr. Sillers graduatedfrom Carnegie Tech (Mellon) with a BSME degree and was employed by Lone Star Gas asSuperintendent of Gas Measurement. Founder and president of Peerless ManufacturingCompany of Dallas, he was an industry leader in gas separation and odorization, and was aregistered professional engineer in Texas.

Alexander Clarke, Sr., (1878-1958), invented several electrical, mechanical, and pneumaticdevices. After working for General Electric in Schenectady, New York, he helped to establishColeman Oil and Gas Company of Coleman, Texas, and served as its president. Mr. Clarkelater worked in several capacities for Lone Star Gas, and was a registered professionalengineer in Texas.

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BIBLIOGRAPHY

Blow, Steve. “A Lost Generation: ’37 New London School Blast Survivors Recall Deathsof 300.” Dallas Morning News 1 Mar. 1987: 1A, 26A

“Gas Utilities Docket No. 122.” Railroad Commission of Texas, Austin.

Gill, Charles E., “History and Purpose of Gas Odorization.” Institute of Gas Technology,Gas Symposium, Chicago, 1965.

“New London (Tex.) Disaster.” Accident Report in the Railroad Commission of TexasHistorical Files, Austin.

Robertson, Seth T., “History of Gas Odorization.” Proc. of Gas Symposium, Institute of GasTechnology, Chicago, August, 1980.

Tussing, Arlon R. and Connie C. Barlow. The Natural Gas Industry: Evolution, Structure,and Economics. Cambridge: Ballinger Publishing Co., 1984.

ACKNOWLEDGEMENTS

The North Texas Section and the Petroleum Division of the American Society of MechanicalEngineers (ASME) gratefully acknowledge the efforts of all who contributed to the designa-tion of the Peerless Type “M” Odorizer as a National Historic Mechanical EngineeringLandmark. Special thanks are extended to the staff of Peerless Manufacturing Company; thestaff of Lone Star Gas; the Institute of Gas Technology; the members of the ASME RegionX History and Heritage Committee for their advice and guidance; the local PetroleumTechnical Chapter; the employees of Morton Thiokol Longhorn Munitions Plant; those whohelped develop the Peerless Type “M” Odorizer; and finally, the many persons who offeredtheir encouragement, support and participation in the designation ceremony.

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The American Society of Mechanical EngineersJoseph A. Falcon, P.E., PresidentReid P. McNally, Jr., Vice President, Region XJeffrey W. Schroeter, P.E., Chairman, Region X Commission on Public AffairsGeorge T. Butler III, P.E., Chairman, Region X History and Heritage CommitteeIbrahim Konuk, Chairman, Petroleum DivisionThomas D. Pestorius, Senior Vice President, Council on Public AffairsLorraine A. Kincaid, P.E., Vice President, Board of Public InformationDavid L. Belden, P.E. Executive DirectorDavid R. Cook, P.E., Director, Southern Regional Office

The ASME History & Heritage CommitteeEuan F.C. Somerscales, ChairmanRobert M. Vogel, SecretaryRobert B. GaitherR. Michael Hunt, P.E.J.L. Lee, P.E.John H. LienhardJoseph P. van Overveen, P.E.Richard S. Hartenberg, P.E., Member EmeritusCarron Garvin-Donohue, Staff LiaisonDiane Kaylor, Special Projects

The ASME North Texas SectionKenneth L. Decker, P.E., ChairmanGary Henderson, P.E., Vice ChairmanLarry V. Moore, P.E., SecretaryAllan Sheppard, Treasurer

The ASME North Texas Section - Petroleum Division Technical ChapterJack Clemens, P.E., ChairmanWes Morrow, P.E., Vice ChairmanDon Hallden, Secretary-Treasurer

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THE ASME HISTORY AND HERITAGE PROGRAM

The ASME History and Heritage Recognition Program began in September 1971. Toimplement and achieve its goals, ASME formed a History and Heritage Committee, initiallycomposed of mechanical engineers, historians of technology and the Curator Emeritus ofMechanical and Civil Engineering of the Smithsonian Institution. The Committee providesa public service by examining, noting, recording, and acknowledging mechanical engineeringachievements of particular significance.

The Peerless Type "M" Odorizer is the 104th National Historic Mechanical EngineeringLandmark to be designated. Since the ASME History and Heritage recognition programbegan, 149 Historic Mechanical Engineering Landmarks, 6 Mechanical Engineering HeritageSites, and 3 Mechanical Engineering Collections have been recognized. Each reflects itsinfluence on society, in either its immediate locale, nationwide, or throughout the world.

An ASME landmark represents a progressive step in the evolution of mechanical engineering.Site designations note an event or development of clear historical importance to mechanicalengineers. Collections mark the contributions of a number of objects with special significanceto the historical development of mechanical engineering.

The ASME historic mechanical engineering recognition program illuminates our technologyheritage and serves to encourage the preservation of the physical remains of historicallyimportant works. It provides an annotated roster for engineering students, educators, histo-rians, and travelers and helps establish persistent reminders of where we have been and wherewe are going along the divergent paths of discovery.

The History and Heritage Committee is part of the ASME Council on Public Affairs andBoard on Public Information. For further information, pleas contact Public Information, theAmerican Society of Mechanical Engineers, 345 East 47th Street, New York, NY 10017-2392, (212) 705-7740; telefax 212-705-7141.

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PEERLESS MFG. CO.

H163