Izs Permeation Tubes (Options 53, 55 & 57) - Teledyne 100E Instruction Manual

Model 100E Instruction Manual
Span gas is created when zero air passes over a permeation tube containing liquid SO
under high pressure, which slowly permeates through a PTFE membrane into the
surrounding air. The speed at which the SO
effusion rate. The concentration of the span gas is determined by three factors:
• Size of the membrane: The larger the area of the membrane, the more permeation
occurs.
• Temperature of the NO
inside the tube and therefore increases the effusion rate.
• Flow rate of the zero air: If the previous two variables are constant, the
permeation rate of the into the zero air stream will be constant. Therefore, a lower
flow rate of zero air produces higher concentrations of SO
a constant flow rate and a constant permeation rate, hence, variations in
concentration can be achieved by changing the IZS temperature.
The permeation tube is not included in the IZS Option and must be ordered
Permeation Tube Heater
In order to keep the permeation rate constant, the IZS enclosure is heated to a constant
50° C (10° above the maximum operating temperature of the instrument). The IZS
heater is controlled by a precise PID (Proportional/Integral/Derivative) temperature
control loop. A thermistor measures the actual temperature and reports it to the CPU for
control feedback.
Gas flow must be maintained at all time for units with a permeation tube
installed. Insufficient gas flow allows gas to build up to levels that will
5.4.3. IZS Permeation Tubes (Options 53, 55 & 57)
Several replacement permeation tubes are available for the IZS option. They are identical
in size and shape but are designed to have different effusion rates.
Option
OPT 53
OPT 55
OPT 57
Each tube comes with a calibration certificate, traceable to a NIST standard, specifying
its actual effusion rate of that tube to within ±5% when immersed in a gas stream
045150102 Rev XB1
: Increasing the temperature of the increases the pressure
2
NOTE
separately. See Section 5.4.3 below.
CAUTION
contaminate the instrument.
Effusion Rate
(± 25%)
421 ng/min
842 ng/min
222 ng/min
Optional Hardware and Software
permeates the membrane is called the
2
Approximate
Concentration
300 - 500 ppb
600 - 1000 ppb
800 – 1200 ppb
. The M100E usually has
2
Specified Flow Rate
0.76 lpm
0.76 lpm
0.56 lpm
2
51