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Medical Gases and Vacuum

 

Table MGV-1 Physical Properties of Oxygen

Molecular Weight

31.999

Boiling Point @ 1 atm

-297.4O F (-183.0O C)

Freezing Point @ 1 atm

-361.9O F (-218.8O C)

Critical Temperature

-181.8O F (-118.4O C)

Critical Pressure

729.1 psia (49.6 atm)

Density, Liquid @ bp, 1 atm

71.23 lb/scf

Density, Gas @ 68OF(20OC), 1atm

0.0831 lb/scf

Specific Gravity, Gas (air = 1) @ 68OF(20OC), 1atm

1.11

Specific Gravity, Liquid (Water = 1) @ 68OF(20OC), 1atm

1.14

Specific Volume @ 68OF(20OC), 1atm

12.03 scf/lb

Latent Heat of Vaporization

2.934 Btu/lb mole

Expansion Ratio, liquid to gas, bp to 68O F (20O C)

1 to 860

Solubility in water @ 77OF, 1 atm

3.16% by volume

 Table MGV-2 Physical Properties of Nitrous Oxide 

Molecular Weight

44.013

Boiling Point @ 1 atm

-127.3O F (-88.5O C)

Freezing Point @ 1 atm

-132O F (-91O C)

Critical Temperature

97.5O F (36.4O C)

Critical Pressure

1051 psia (71.5 atm)

Density, Liquid @ bp, 1 atm

71.23 lb/scf

Density, Gas @ 68OF(20OC), 1atm

0.1143 lb/scf

Specific Gravity, Gas (air = 1) @ 68OF(20OC), 1atm

1.53

Specific Gravity, Liquid (Water = 1) @ 68OF(20OC), 1atm

1.22

Specific Volume @ 68OF(20OC), 1atm

8.75 scf/lb

Latent Heat of Vaporization

3.68 Btu/lb mole

Expansion Ratio, liquid to gas, bp to 68O F (20O C)

1 to 662

Solubility in water @ 41OF, 1 atm

114% by volume

 Table MGV-3 Oxygen USP (United States Pharmacopeia) 

Purity

99%

Odor

None


*   All medical gas suppliers are required to apply FDA’s current Good Manufacturing Practices (cGMPs) to healthcare liquid oxygen USP installations.

Table MGV-4 Nitrogen NF (National Formulary) 

Purity

99%

Oxygen

< 1,0%

Carbon Monoxide

<0.001%

Odor

None


DEFINITION OF MEDICAL GASES 

A medical gas is defined as one that is manufactured, packaged, and intended for administration to a patient in anesthesia, therapy, or diagnosis. Medical gases are considered prescription drugs because their use is unsafe without the supervision of a licensed practitioner or properly instructed personnel.

REGULATING AGENCIES AND PUBLICATIONS

 United States

 Title 21 of the Code of Federal Regulations (CFR) designates medical gases as drugs, and mandates the Secretary of the Treasury and the Secretary of Health and Human Services to promulgate regulations for the efficient enforcement of the Federal Food, Drug, and Cosmetic Act (FDA) (drug portion of 21 CFR).

 Such other regulatory bodies as the Department of Transportation (DOT) and national organizations [e.g., the Compressed Gas Association (CGA) and the National Fire Protection Association (NFPA) write regulations and standards for compressed gases.  NFPA 99 is the de facto standards for pipelined medical gas systems in USA as well as many other countries in the world.

 Regulations regarding the purity of these substances are established by the United States Pharmacopeia/National Formulary (USP/NF). 

 United Kingdom 

Health Technical Memorandum (HTM) 2022-Medical Gas Pipeline Systems published by British Department of Health has been the most followed guidelines in the United Kingdom and many countries in Europe as well as many other regions of the world.   

The first volume of HTM 2022 covers the issues of design, installation, verification and validation of piped medical gases, medical compressed air and medical vacuum installations, and all medical gas pipeline systems (MGPS) installed in healthcare premises. The second volume of HTM 2022 addresses the operational management of MGPS. Due to different application requirements, guidelines for dental compressed air and vacuum systems are provided separately as HTM 2022 Supplement 1. 

British Department of Health reorganized its HTM documents in 2006. Under the new numbering system, the above-mentioned publications are now HTM 02-01 Part A, HTM 02-01 Part B, and HTM 02-01 Supplement 1, respectively. 

International Organization for Standardization (ISO) 

International Organization for Standardization (ISO) 7396-1 specifies the requirements for pipeline systems for compressed medical gases and vacuum, while ISO 7396-2 covers anesthetic gas scavenging disposal systems. 

 Japan 

The following are Japanese equivalents of ISO 7396-1 and -2 released by Japanese Standard Association (JSA):

 Japanese Industrial Standards (JIS) T 7101 Terminal units for medical gas pipeline systems (医療ガス配管設備用の端末装置):

  • Part 1: Terminal units for use with compressed medical gases and vacuum  (圧縮医療ガス及び真空と併用するための端末装置)

  • Part 2: Terminal units for anesthetic gas scavenging systems Terminal units for medical gas pipeline ( 麻酔ガス掃気系統用の端).

  •  

    KSY2007 Copyright 2006-8 by Gentec Systems Co., All Rights Reserved.

     

    Figure MGV-1 Color Coding of Medical Gases

    CYLINDER MARKINGS AND LABELING
  •    A medical gas cylinder must have designated markings permanently affixed to its neck to identify the regulatory body governing the use of the cylinder; the service pressure; the serial number; the date of manufacture; the last test date; a stick-on label identifying its contents; its hazard class and color code.

  •    The cylinder is equipped with a valve threaded into it. The valve is designed specifically for the medical gas the cylinder is designated to contain.

     


  • Canada

    Canadian Standards Association (CSA) have recently replaced its CAN/CSA-Z350-1 and -2 with ISO 7396-based the following new ones:

    • CAN/CSA-Z7396.1-06 Medical gas pipeline systems
      Part 1: Pipelines for medical gases and vacuum, and

    • CAN/CSA-Z7396.2-02 (R2007) Medical gas pipeline systems
      Part 2: Anesthetic Gas Scavenging Disposal Systems.

    The transportation of high pressure cylinders is regulated Transport Canada (TC).

    USAGES OF MEDICAL GASES AND VACUUM

    • Oxygen, used in respiratory and inhalation therapy, used in conjunction with anesthesia machines. Normal working main line pressure: 50 to 55 psig (345 to 380 kPa)


    • Nitrous oxide, used as an anesthetic agent in surgery, dental procedures and cryosurgery. Normal working main line pressure: 50 to 55 psig (345 to 380 kPa)


    • Medical air, used in breathing treatments and as a mixing component for other respiratory gases. Normal working main line pressure: 50 to 55 psig (345 to 380 kPa)


    • Carbon dioxide, used to stimulate respiration, in insufflation ("keyhole" surgery), in cryosurgery, or in dentistry for testing tooth sensitivity. Normal working main line pressure: 160 to 185 psig (1100 to 1275 kPa)


    • Helium, used in breathing mixtures for patients with impaired lungs.


    • Nitrogen, used to drive pneumatic tools; to prevent combustion and other chemical reactions; and as a component of many gas mixtures. Only nitrogen NF can be used to prepare breathing mixtures. Normal working main line pressure: 160 to 185 psig (1100 to 1275 kPa)


    • Instrument Air: to power pneumatic tools. Normal working main line pressure: 160 to 185 psig (1100 to 1275 kPa)


    • Medical/Surgical Vacuum: used to drain fluids and tissue from patients. Standard gauge pressure: 15" to 30" Hg (380 to 760 mm Hg)—with 30" Hg (760 mm Hg) as the perfect vacuum.

    MEDICAL GAS PIPELINE SYSTEM (MGPS) 

    The provision of a MGPS avoids using a large number of cylinders to be located in clinical areas (except for a few emergency and back-up cylinders), as well as portable suction devices, thus freeing space for medical use. The provision of a MGPS is also widely held to be more cost effective because centralized plant can be provided, and, particularly in the case of oxygen, liquid sources of supply can be used.

     

     

    KSY2007 Copyright 2006-8 by Gentec Systems Co., All Rights Reserved.


    Table MGV-5 Sizes of High-pressure Gas cylinders

    Cylinder Size

    Nominal Size Diameter X Height (inches) Includes 5.5 inches for valve and cap.

    Nominal Tare Weight (lbs) Includes 4.5 lbs. for valve and cap.

    Water Capacity (lbs.)

    Internal Volume @ 70° F (21° C), 1 ATM (liters/cubic feet)

    US DOT Specs

    10S

    4 X 31

    21

    8.3

    3.8/0.13

    3A1800

    A

    9 X 56

    115

    96

    43.8 / 1.55

    3AA2015

    AL

    8 X 53

    52

    64.8

    29.5 / 1.04

    3AL2015

    B

    8.5 X 31

    60

    37.9

    17.2 / 0.61

    3AA2015

    BL

    7.25 X 39

    33

    34.6

    15.7 / 0.55

    3AL2216

    C

    6 X 24

    27

    15.2

    6.88 / 0.24

    3AA2015

    CL

    6.9 X 21

    19

    13

    5.9 / 0.21

    3AL2216

    D

    4 X 18

    12

    4.9

    2.24 / 0.08

    3AA2015

    K

    9.25 X 60

    135

    110

    49.9 / 1.76

    3AA2400

    LB

    2 X 15

    4

    1

    0.44 / 0.016

    3E1800

    LP5

    12.25 X 18.25

    18.5

    47.7

    21.68 / 0.76

    4BW240

    Medical E

    4 x 26 excludes valve and cap

    14 excludes valve and cap

     

    4.5 / 0.16

    3AA2015

    QT

    3 X 14 includes 4.5 inches for valve

    2.5 includes 1.5 lbs for valve

    2.0

    0.900 /0.0318

    4B-240ET

    SSB

    8 X 37

    95

    41.6

    18.9 / 0.67

    3A1800

    XF

    12 X 46

    180

     

    60.9 / 2.15

    8AL

    XG

    15 X 56

    149

    278

    126.3 / 4.46

    4AA480

    XL

    14.5 X 50

    75

    238

    108 / 3.83

    4BA240

    XM

    10 X 49

    90

    120

    54.3 / 1.92

    3A480

    XP

    10 X 55

    55

    124

    55.7 / 1.98

    4BA300

    XM

    10 X 49

    90

    120

    54.3 / 1.92

    3A480

    XL

    14.5 X 50

    75

    238

    108 / 3.83

    4BA240

    XG

    15 X 56

    149

    278

    126.3 / 4.46

    4AA480

    XF

    12 X 46

    180

     

    60.9 / 2.15

    8AL

    SSB

    8 X 37

    95

    41.6

    18.9 / 0.67

    3A1800

     


    • O2: 2-5

    • N2O: 3-5

    • Air: 1-5

    • CO2: 1-6

    • Heliox (mixture of helium and oxygen): 2-4 

    Figure MGV-1 Pin Index Dimensions
    Units are in millimeters)

     

     

    PIN INDEX SAFETY SYSTEM (PISS)

    • The pin index safety system is used to prevent a cylinder from being filled with wrong gases and being connected to a wrong yoke on an anesthesia machine or a pipeline.

    • The system consists of three holes drilled in the valve of the gas cylinder that mate with matching pins on the yoke of the pipeline or anesthesia machine. The central opening is the actual gas outlet. The other two holes are drilled to comply with the specifications for the gas the cylinder is designed to contain.

    STORAGE AND TRANSPORTATION OF COMPRESSED AIR

    • Medical compressed air may be supplied by two types of system: (1) a high-pressure cylinder manifold system; and (2) a medical air compressor system.

    • The manifold systems for compressed air are similar in configuration to those for oxygen and nitrous oxide.

    HOSPITAL ROOMS 

    • Non-interchangeable outlets, placed on the ceilings or walls, must be color-coded and labeled with the names (ex. Oxygen) or chemical symbols (ex. O2) of the medical gases they delivered.

    • Automatic closing mechanisms in the outlet prevent gas leakage when the mating end of the transfer hose is absent. The end of each hose used to connect the pipelines to a piece of health equipment must be color-coded and provided with a gas-specific non-interchangeable adaptor.

    STORAGE AND TRANSPORTATION OF OXYGEN

    • Oxygen supply sources are divided into two categories: (1) bulk oxygen systems and (2) cylinder-manifold-supply systems.

    • In a bulk oxygen system, double-walled stainless steel containers built to withstand a pressure of 250 psig is used by most health care facilities to store liquid oxygen at a temperature between -230– -283°F (-150°– -175°C). Hose connections must be non-interchangeable to avoid misfillings.

    • The bulk oxygen container must be located away from the institution for safety reasons. An underground pipeline, fitted with protective casings in areas of high surface loads, is used to transport the oxygen to the facility's main distribution system.

    • In a cylinder-manifold-supply system, a bank of high-pressure cylinders is used as the supply manifold, and an identical manifold system with an automatic switch-over valve serves as a reserve supply.

    • Alarm systems are used to monitor the condition and operation of the supply system.

    STORAGE AND TRANSPORTATION OF NITROUS OXIDE

    • Usually, cylinders of liquefied nitrous oxide connected to a gas manifold, which are located in a designated storage room, often adjacent to the loading dock, serve as the supply of this medical gas.

    • The manifold controls the release of nitrous oxide from each tank. The gas is reduced to a working pressure of 45–55 psig before entering the main pipeline.

    • A reserve bank of cylinders is used to replace the exhausted main manifold, using an automatic switch-over valve.

    • To prevent cross-filling of tanks or rupture of the pipeline, a system of check valves, shutoff valves and pressure relief valves is employed.

    • Alarm systems are used to monitor the condition and operation of the supply system. 


     

     

     

     

     

     

     

     

     

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    Last Updated: 2008-12-18