UFM2/UBT User Manual
Issue 1.1b July 20 Page 29
4.1.2 Frequency Mode
In Frequency mode, the output frequency is proportional to the flow rate within a specified frequency
range of 1 – 200Hz.
4.1.3 Energy Pulse (UBT only)
When the Pulse Output is set to Energy, the kWh LED will be permanently illuminated. Choose
from 1,10,100kWh or 1MWh when in metric mode and 1,10,100kBTU or 1MBTU in imperial mode.
Each pulse represents an amount of energy e.g. 1BTU. The same limitation on maximum pulse rate
applies as detailed in the Volumetric Mode. Again a larger unit of energy per pulse or a smaller
pulse width may be required.
4.1.4 Flow Alarm - Low Flow
For the Low Alarm the user can set a range between 0 and 9999 (no decimal places), in the same
units being used to measure flow. The default setting is normally open, but the user can select
between N/O and N/C. There is a 2.5% hysteresis on the switching of the output. Once the low flow
alarm is activated, the flow rate must rise by 2.5% more than the set value to deactivate the alarm
again.
4.1.5 Flow Alarm – Signal Loss
If the flow reading (signal) is lost, as indicated by the flow rate being displayed as “-----“, the alarm
will be triggered. The default setting is normally open, but the user can select between N/O and N/C.
4.2 4-20 mA Current Output (UFM2 only)
The default 4-20 mA output setting is OFF, and the 4-20 mA LED on the keypad will not be
illuminated. The default flow for 4 mA is 0. This can be changed, see page 22.
If the flow reading is greater than that set as the 20 mA value, or there is negative flow, or no flow
signal can be detected, then an alarm current of 3.5 mA will generated.
NOTE: THE 4-20MA CURRENT OUTPUT IS FACTORY CALIBRATED.
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