Utility Requirements
60 H157655_1_008
System Operating Pressure Recommended Average
Flow*
AVANCE + VT Unit 6-8 bar (80-120 psi) 43 l/min. (~1.52 cfm)
AVANCE + VT + Sample
Changer
6-8 bar (80-120 psi) 55 l/min. (~1.95 cfm)**
AVANCE + MAS 6-8 bar (80-120 psi) 300 l/min. (~11 cfm)
* This is the actual consumption and minimum needed at the instrument input after the
N2 supply (either a bulk tank, or a N2 separator). The sample lift to exchange a sample
needs for about 1 minute 100 l/min. For a standard NMR system we expect 3...5 sample
exchanges (which are included in recommended flow).
** A recommended flow of 100 liters/min. per sample for sample exchange (about 1
minute), average consumption will depend on the number of samples being used. Typical
number of sample exchanges is up to 12 per hour (which is included in the recommended
average flow).
For non-MAS work, if an air-compressor and N2 separator are used, the flow
requirements are 50% higher, i.e. 3 cfm. It is recommended to use a dual unit oil-less air-
compressor rated at minimum double capacity of the specified requirement. Please refer
to the next section on air compressors.
Table8.2: Pressure and Flow Requirements
8.3.3 Other Specifications
Oil Content:
Purity: ISO 8573-1 2010 [1:1:0] (oil free).
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
850-1000 ≧ 97
Table8.3: VT Nitrogen Gas Quality (500 MHz and above)
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