Specifications

GB
OPERATION MSA
24 ALTAIR PRO - Operating Manual
3.5. Displaying the Instrument Data - excluding the Steel Mill Version
A single, quick press on the button turn ON the backlight for 10 seconds. The
Information page can be accessed by pushing the button for about one second.
 The instrument beeps twice.
There are following modes:
1) Test gas mode
2) Minimum Oxygen concentration ("
LO") - for oxygen only
3) Peak Reading
 Toxic ("HI")
 Oxygen ("HI")
 The Peak/Hi and Min/Low values can be cleared.
When this page is displayed, press the button to clear.
 "
CLR" is displayed
 Value is deleted
4) Short Term Exposure Limit ("
STL")
The STL reading displays that the instrument calculated since power-ON.
When this page is displayed, press the button to clear.
 "
CLR" is displayed
 Value is deleted
STL value is automatically reset to zero when the instrument is turned ON.
STEL value is calculated over a 15-minute exposure.
The following formula is used to calculate the STEL value:
((Minute #1 PPM value) + (Minute #2 PPM value) +...
+ (Minute #15 PPM value)) / (15 minutes) = PPM STEL value
If the instrument is ON for less than 15 minutes:
 the balance of the minute PPM values is set to zero and
 the total is divided by 15 minutes
5) Time Weighted Average ("TWA")
The TWA reading displays what the instrument has calculated since power-
ON. When this page is displayed, press the button to clear.
 "
CLR" is displayed
 Value is deleted
TWA value is automatically reset to zero when the instrument is turned ON.
TWA value is calculated over an eight-our exposure.
The following formula is used to calculate the TWA value:
Sum of 1-minute gas readings/480 minutes = PPM TWA value
If the instrument is ON for less than 8 ours (480 minutes), the balance of the
minute ppm values is set to zero.