MA-037 - CB Watch 3 Operating Manual
v7.0 - May 2020
Page 53 of 118
•
The
“
short-term
”
alarm is raised if the short-term extrapolated gas pressure at 20
o
C
is calculated to drop below the gas threshold 2 (too low, lock-out) that has been set
➢
This means that the gas pressure/level will be below threshold 2 within the
short-term horizon that has been set
HMI: Measurements/Alarms
Figure 76
–
Extrapolated gas pressure alarms
Gas leak rates
Whenever there is a leak in the gas system, this manifests itself as a drop in the gas
pressure. The magnitude of the leak is shown by the rate of change of this drop, shown as a
leak rate.
This leak rate can be visualised in the HMI in terms of:
•
Gas pressure unit per hour (in the short term, using short term stack)
•
Gas pressure unit per year (in the long term, using long term stack)
•
Gas mass unit per year (in the short term, using long term stack)
•
Gas volume % per year (in the long term, using long term stack)
for one or three separate tanks depending on the number of sensors installed.
HMI: Measurements/Gas
Figure 77
–
Gas leak rates
Remember that If not enough data is available to fill the short term or long-term horizon
set, then the value cannot be calculated and a “
-
“ is displayed instead.
These calculations use the following principles:
•
The short-term gas pressure leak rate = change in pressure at 20
o
C calculated using
the values in the short-term stack, scaled to an hour (in pressure unit per hour)
•
The long-term gas pressure leak rate = change in pressure at 20
o
C calculated using
the values in the long-term stack, scaled to a year (in pressure unit per year)
