GD-70D - 94 -
Calibration Gas/Concentration
Warm Up Time
After Power-Up
IPA (Isopropyl alcohol) 0 - 100 %LEL Isobutane (C4H10): 50% LEL*
(SET GD-70D TO 60% LEL)
2 hours
N2H4 (Hydrazine) 0 - 5.00 ppm Nitrous oxide (NO): 10 ppm* 6 hours
O3 (Ozone) 0 - 0.60 ppm Chlorine (Cl2): 2 ppm** 3 hours
0 - 1.00 ppm Chlorine (Cl2): 2 ppm** 3 hours
Si2H6 (Disilane) 0 - 15.0 ppm Silane (SiH4): 5 ppm or 30 ppm*** 3 hours
TMA (Trimethylamine) 0 - 15.0 ppm Ammonia (NH3): 5 ppm** 6 hours
** Gas may or may not need dilution depending on the sensor’s factor. The calibration gas multiplied
by the factor should be as close to 50% of full scale as possible.
*** Use one of the two gases listed, depending on sensor’s factor. The calibration gas multiplied by the
factor should be as close to 50% of full scale as possible.
Discussion for **
Gases with a ** next to them in the table above may or may not need to be diluted before being used to
calibrate the GD-70D. In order to figure out if you need to dilute the gas, multiply the gas concentration
listed on your calibration cylinder by the factor listed on the sensor unit at the GD-70D. The result should
be something between 10% and 100% of full scale for the sensor. A value closest to 50% of full scale is
ideal but if you can get somewhere between 10% and 100% of full scale without diluting, that is also fine.
Discussion for ***
For gases with a *** next to them in the table above, different concentrations of calibration gas need to be
used depending on the factor listed on the sensor unit. The goal is to have the calibration gas multiplied by
the factor be as close to 50% of full scale as possible. It is not necessary to dilute these gases to achieve
that goal. The concentration listed on the calibration cylinder multiplied by the factor listed on the sensor
should be as close to 50% of full scale as possible but any value between 10% and 100% of full scale can
be used to calibrate.
Calibration Equipment for Gases Needing Dilution
• 0.5 LPM fixed flow regulator (RKI Instruments, Inc. recommends that you dedicate one regulator
each for Cl2 and that you not use that regulator for any other gas)
• Tedlar gas collection bag with hose and hose clamp
• Calibration cylinder
• 100% nitrogen (N2) cylinder
• Stopwatch or other timing device
Calibration Equipment for Gases Not Needing Dilution
• Demand flow regulator
• Calibration tubing
• Calibration cylinder of appropriate concentration
Preparing for Calibration – Gases Needing Dilution
Determining Needed Calibration Gas Concentration
Before performing a calibration, you must mix your calibration gas in a gas bag. You need to first
determine what final concentration of calibration gas you need.
(1 2)
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The final concentration multiplied by the sensor’s factor must be between 10% and 100% of full scale.
Ideally, the final concentration multiplied by the sensor’s factor should be as close to 50% of full scale as
possible, but something different is acceptable as long as it’s higher than 10% of full scale and less than
100% of full scale. For example, a gas bag full of 0.1 ppm PH3 multiplied by a factor of 1.7 is 0.17 ppm
which is below the full scale value of 0.20 ppm for AsH3 or H2Se.
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