Welch Allyn Schiller AT-2plus Manual page 32

Calibration
Last Calibration
BTPS
Calibration Factor
Temperature
Measured Volume
Reference Volume
AT-2plus User Guide Spirometry Supplement Page 22
date of last calibration
Factor calculated BTPS (=> Body Temperature, Ambient Pressure, Saturated with water vapour)
value. This value compensates for the difference in inhaled and exhaled humidity. The unit is
set for measuring exhaled volume (100% humidity, Temp 36.8
measured this factor is applied. The SP-1 uses ambient temperature to calculate the BTPS
factor. This is sufficient for accurate FIVC calculation. The formula used is as follows:
BTPS = 0.033 +
Where: Tu is the ambient temperature in degrees centigrade
0.033 is the equivalent to 760mmHg at 22
273.15 is degrees absolute
calculated value between measured and effective calibration air volume
o
ambient temperature in C (or
air volume measured by the system from the calibration pump
entered air volume depending on the size of the calibration pump and times the air was pumped
through the sensor; e.g. pumping 2 litres 3 times amounts to 6 litres (the recommended volume
with a 2 litre pump is 4 litres and with a 3 litre pump 6 litres)
273.15 + 36.8
273.15 + Tu
o
o
F) dependent on device setting
o
), and so when inhaled volume is
C