Medical GasIntroduction to Medical Gas Analysis
Medical gases are used for patient care in healthcare facilities, dental suites, and laboratories. Typical gases used are Oxygen, Nitrous Oxide, Nitrogen, Carbon Dioxide and Medical Air. This document provides some practical information about the tests needed to guarantee Medical Gas Quality as described in the CSA International publications:
Note: Please refer to the printed version of the CSA regulations for reference. This is published here for information only.
Routine analysis includes
Carbon Dioxide (CO2) Contamination:
Carbon Monoxide (CO) Contamination:
Halogenated Hydrocarbons Contamination:
Trichlorotrifluoroethane (Halon 113)
Dichlorodifluoromethane (Halon 12)
Any detectable Halogenated Hydrocarbons above 1 ppm are “abnormal” & require further investigation.
Methane (CH4) Contamination:
CAN3-Z180.1-00 standard sets a 10 ppm Methane maximum for breathing air.
Methane Values for compressed air that are greater than about 5 ppm are “abnormal” & require further investigation.
High pressure compressors are usually equipped with odour filters (i.e. activated charcoal filters) that remove many organic vapours. A high Methane value could indicate, for example, charcoal filter saturation & the presence of lubricating oil degradation. Other sources of Methane are natural gas and marsh gas.
Volatile Non-Methane Hydrocarbons Contamination:
Air compressors (including “non-lubricated” versions) utilize some type of lubricating fluid. Many compressors contain either mineral or synthetic lubricants. Even with all the filters, compressor malfunction or poor maintenance can cause VNMH to contaminate the compressed breathing air. This can cause unpleasant taste and odours, breathing discomfort, nausea, and possibly pneumonia.
An Infrared Spectrometer can be used to measure the VNMH and identify the individual VNMH.
CSA-Z180.1-00 standard lists a 5 ppm maximum for VNMH. Detectable levels above 1 ppm are abnormal & require further investigation.
Sulfur Dioxide (SO2) Contamination:
Water Vapour Content & Dew Point:
Standard CAN3-Z180.1-00 states that compressed breathing air equal to or greater than 2216 psig shall have an atmospheric dew point not exceeding -53°C or a water vapour concentration not exceeding 27 ppm. The pressure dew point should be at least 5°C below the lowest temperature to which the cylinder and piping may be exposed at any season of the year.
The measured Dew Point is the quantity of water vapour found in the air sample at ATMOSPHERIC pressure. To determine the temperature at which water vapour may condense and freeze in the pressure reducing regulator, it is necessary to compare the pressure dew point to the ambient temperature at which the SCBA is used. Conversion tables are included in CAN3-Z180.1-00.
For example: The proposed maximum (atmospheric) dew point of -53°C or 27 ppm of water, corresponds to a pressure dew point in the regulator of -12°C or 2148 ppm of water at a line pressure of 2216 psig. However the CSA standard requires that the (pressure) Dew Point not exceed 5°C below the minimum temperature to which any part of the breathing air system is exposed at any season of the year. Thus a compressed breathing air sample with a (atmospheric) Dew Point of -53°C could not be used at a line pressure of 2216 psig in any areas where the temperatures are less than -7°C.
The standard also states under no circumstances shall the Dew Point (atmospheric) exceed -53°C for systems at or above 15.3Mpa (2216 psig).
and Oil & particulate matter. Certain gases require nitrogen & oxygen detection.
Oxygen (O2) Level Control:
An oxygen deficiency can occur in a prepared synthetic air or if the compressor air intake is located in an oxygen deficient area. Under very rare conditions, air purification systems can increase the oxygen content of air.
In addition, AirChekLab can detect the presence of a variety of other chemicals and solvents (including cleaning products that could contaminate tanks or pipeline systems.)
To insure quality, Standard Z305.1-92 requires that Medical gases shall be submitted for purity analysis at least once every 12 months.
Additional analyses shall be required following major overhaul modifications or extensive repairs to the gas pipeline system.