Hourly Trend; Daily Trend; Table 10-4 - Suggested Guidelines For Setting The Gas Level High Alarm - GE Hydran 201 i Instruction Manual

Chapter 10 • Alarms
Table 10-4 - Suggested Guidelines for Setting the Gas Level High Alarm Condition
Hydran 201Ti Maximum Reading
Obtained During the Monitoring Period
Below 70 ppm
From 70 to 400 ppm
Above 400 ppm
10.4.1.2

Hourly Trend

The hourly trend alarm uses the following parameters:
• HourTrAlr H and HourTrAlr HH: Hourly trend High and High-High alarm set points.
• HourTrAlr Delay: The hourly trend alarm delay determines the period of time during
which the hourly trend must exceed the corresponding High and High-High alarm set
points in order to trigger the alarm. Accordingly, the hourly trend must get below the
alarm set point for the same amount of time in order to cancel the alarm. This delay is set
in percentage of the period of the hourly trend computation.
• HourlyTr Period: The period of time (in hours) during which the hourly trend is
calculated. Increasing the period decreases the normal fluctuations of the readings, but
increases the response time.
The readings of the Hydran 201i System should be monitored over a minimum period of
two weeks before setting these parameters; follow the same rules as for the gas High alarm
(see Section 10.4.1.1 on page 10-9).
10.4.1.3

Daily Trend

The daily trend alarm uses the following parameters:
• DayTrAlr H and DayTrAlr HH: Daily trend High and High-High alarm set points.
• DayTrAlr Delay: The daily trend alarm delay determines the period of time during
which the daily trend must exceed the corresponding High and High-High alarm set
points in order to trigger the alarm. Accordingly, the daily trend must get below the alarm
set point for the same amount of time in order to cancel the alarm. This delay is set in
percentage of the period of the daily trend computation.
10-10
Minimum Suggested Alarm Set Point
to Reduce the Likelihood of Unnecessary Alarms
100 ppm
1.5 times the highest H201Ti reading
200 ppm above the highest H201Ti reading
Rev. 6, March 2011 Part 17997