MAN0923_Issue 3_04/15 Touchpoint Pro
Operating Instructions
195
15. Appendix 2 - Congurable
Parameter Reference Guide
15.1.10 Threshold Alarm Hysteresis
Access Level: Engineer
Parameter Name Default Setting Value Range Comment
Threshold Alarm
Hysteresis
2 %FSD 0.0 to 10.0 %FSD The hysteresis value will be applied to a channel coming out
of an alarm condition, e.g. if the alarm level is 20 %FSD, and
hysteresis is set to 2 %, the alarm will not be cancelled until
the reading has dropped below 18 %FSD.
15.1.11 Short Term Exposure Limit (STEL) Alarm Settings
Caution: In some countries, the use of STEL and LTEL alarms with xed gas detection equipment is
not recommended. Refer to local and national regulations.
Note: The Short Term Exposure Limit (STEL) calculation is a moving time-weighted average (TWA) gas
reading over a given time interval (STEL Time Interval). The STEL alarm is set if the result exceeds the
congured STEL Alarm Level. The STEL sample rate is 4 Hz, and the STEL reading is updated every 30 s.
STEL =(HM_TWA1+HM_TWA2+HM_TWA3……….+HM_TWAN)/STELN
where
STEL = Short Term Exposure Limit TWA
HM_TWA1=1stHalfMinuteTWA
HM_TWA2=2ndHalfMinuteTWA
HM_TWAN=NthHalfMinuteTWA
STELN = Number of Half Minute TWA Samples received in STEL interval
Access Level: Engineer
Parameter Name Default Setting Value Range
STEL Alarm Enable Disabled Enabled / Disabled
STEL Alarm Level 20 %FSD According to sensor range
STEL Alarm Latch Latching Latching / Non-Latching
STEL Time Interval 10 min. 5, 10, 15, 20, 30, 40 and 60 min.
15.1.12 Long Term Exposure Limit (LTEL) Alarm Settings
Caution: The Touchpoint Pro LTEL calculation assumes an 8 hour working period. In some countries,
the use of STEL and LTEL alarms with xed gas detection equipment is not recommended. Refer to
local and national regulations.
Note: The Long Term Exposure Limit (LTEL) calculation is a moving time-weighted average (TWA) over an 8
hour time interval. The sample interval is 30 s, and the LTEL reading is updated every 10 minutes.
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