Utility Requirements
66 / 120 H157654_9_011
8.3.3 Other Specifications
Oil Content:
Purity: ISO 8573-1 2010 [1:1:0] (oil free).
ISO 8573-1:2010 specifies purity classes of compressed air with respect to particles, water
and oil independent of the location in the compressed air system at which the air is specified
or measured.
When specifying the purity of air required, the standard must always be referenced, followed
by the purity class selected for each contaminant. A purity of 1:1:0 means:
• Class 1 Particulate: In each cubic meter of compressed air, the particulate count should
not exceed 20,000 particles in the 0.1 - 0.5 micron size range, 400 particles in the 0.5 - 1
micron size range and 10 particles in the 1 - 5 micron size range.
• Class 1 Water: A pressure dewpoint (PDP) of -70°C or better is required and no liquid
water is allowed.
• Class 0 Oil: As specified by the equipment user or supplier and more stringent than Class
1.
Water Content:
For the BCU-I cooling unit the compressed gas should have a dew point of -51°C (–60°F).
For the BCU-II cooling unit, the dew point requirement is - 80°C (-112°F).
For room temperature work and higher: Dew point of < 4°C (39.2°F).
For low temperature work: The dew point must be at least 20°C (68°F) below the operating
temperature.
If a cooling unit is used, then the dew point of the compressed nitrogen should be at least
10°C (50°F) below the temperature at the heat exchanger output.
Solid Impurities:
Use 5 micron filters for high resolution NMR. For MAS probes use 1 micron filters. The filters
should retain a minimum of 99.99% of the specified particles.
VT Nitrogen Gas Quality
Proton Frequency (MHz) Purity (volume percentage)
500 ≧ 95
600-800 ≧ 96
900-1200 ≧ 97
Table8.3: VT Nitrogen Gas Quality (500 MHz and above)
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