Medical Gases

Production, Applications, and Safety

Hartwig Müller

• Publisher: Wiley-VCH
• Year: 2015
• Print ISBN: 9783527333905
• eBook ISBN: 9783527676033
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

Covering the entire spectrum of medical gases, this ready reference offers a comprehensive overview of production, medical gas equipment, medical gas verification, and medical gas safety standards. With a clear focus throughout on safety, the text recommends environmentally responsible manufacturing practices during each step of the process: manufacture, storage, transport, distribution, and in applications. It also discusses standards and regulations, in particular those of the European Union.
An essential guide for researchers and professionals whose work includes the manufacture, handling, or use of medical gases.

Chapter 1
Medicinal Gases – Manufacturing

1.1 Where Do the Gases Come from?

Oxygen as the most prominent (medicinal) gas often lets us think that all other gases are of the same origin, coming right from the air. However, this is not the case. In addition to the very well-known oxygen, argon, and nitrogen, it might be advantageous to use other sources owing to technical or economic reasons. In addition, quite often specific methods of manufacturing or synthesis lead to specific types of impurities. In this chapter, we take a look at different gases, their sources, and the types of impurities that are characteristic of these different sources.

1.1.1 Gases Obtained from Air: Oxygen, Nitrogen, Argon, Xenon

Ambient air is a fascinating reservoir of numerous meteorological effects and has been known since the beginning of mankind. That atmospheric air is a gas and thus just a specific form of matter, and, moreover, that it not only contains water but is a mixture of different gases, was discovered only a few centuries ago.

Until the seventeenth century, it was a general opinion that air is an element, and as such indivisible. In laboratories as shown in the cover of the book (Figure 1.1), researchers like Jan Baptist van Helmont, (1577–1644) from the (then Spanish) Netherlands (Figure 1.1) recognized that gas is not a unique element but composed from different gases.

Figure 1.1 Jan Baptist van Helmont (1577–1644) [1].

He noticed the difference between the chemical properties of hydrogen (developed by the reaction of hydrochloric acid and zinc) and carbon dioxide (developed by the fermentation of yeast) [1]. The two compounds had a physical property that was named “chaos” by van Helmont – a word that had the same pronunciation in Dutch as “gas,” – and this became the term for this state of matter.

He discovered two gases, with almost similar physical properties as air, but with different chemical properties: hydrogen readily burned when ignited, while carbon dioxide remained chemically stable under most conditions, but giving a white precipitate with barium chloride solution.

Lavoisier et al. [2] discovered that air is composed of different gases in the late eighteenth century. They showed through chemical methods that there were at least two main components in the air, one being chemically reactive and the other one chemically inert [3]. Besides chemical absorption by specific reactions, air can be separated into its constituents by fractional distillation as with the liquids, to obtain its pure constituents, depending upon the knowledge of the art of fractionation.

As can be seen in Table 1.1, the major components of air have critical temperatures far below 0 °C. Above this temperature, no liquefaction of the gas is possible, indicating that the gas has to be cooled down first to below the critical temperature, before condensation starts, if the cooling is continued. Two well-known processes had been developed toward the end of the nineteenth and in the beginning twentieth century, respectively, by German (von Linde, 1895 [6]) and French (Claude, 1902 [7]) scientists.

Table 1.1 Composition of ambient air, typical components [4].

Name of the gas	Content (approximately)	b.p. (°C)	b.p. (K)
Nitrogen	78.1 vol%	−196	77.4
Oxygen	20.8 vol%	−183	90.2	Σ 99.8 vol%
Argon	0.9 vol%	−186	87.3
Carbon dioxide	390 ppm	−78	197.7
Neon	18.2 ppm	−246	27.1
Helium	5.2 ppm	−269	4.2	Σ 26 ppm
Methane	1.5 ppm	−162	111.6
Krypton	1.14 ppm^a	−153	119.8 K
Hydrogen	0.5 ppm	−253	20.4
Carbon monoxide	0.2 ppm^a	−192	81.6
Xenon	0.089 ppm	−108	165.1	Σ 1 ppm
Nitrous oxide	0.3 ppm	−88	184.7
Sulfur dioxide	^a	−10	263.1
Sulfur hexafluoride	^a	−63.9	209.2
Carbon tetrafluoride	^a	−128	145.2

^a Under influence of human activities: depending upon localization of sampling, carbon monoxide and sulfur dioxide can be detected near industrial activities in considerable levels under specific conditions, sulfur hexafluoride and carbon tetrafluoride are gases that often escape during aluminum electrolysis, while krypton is contaminated with the radioactive isotope Kr-85, emanated during numerous nuclear processes [5].

While Linde's process works with a throttle to release the tension of the gas and to cool down the compressed gas (the Joule–Thomson effect), Claude's method uses an adiabatic expansion machine. The result is a “cryogenic” liquid with remarkabl...

Table of contents

• Cover
• Title Page
• Related Titles
• Copyright
• Table of Contents
• Preface
• General Remarks
• Chapter 1: Medicinal Gases – Manufacturing
• Chapter 2: Pressure Vessels and Their Accessories
• Chapter 3: Analytical Methods for Gases (as Described in Ph. Eur.)
• Chapter 4: Monographs for Gases in the European and National Pharmacopoeias
• Chapter 5: Production of Medical Gases — Special Handling to Comply with GMP Rulings
• Chapter 6: Requirements of the New Good Distribution Practice (GDP)
• Chapter 7: Safe Handling of Gases
• References
• Abbreviations
• Index
• End User License Agreement