Dwyer UFM - Manual (Page 16)

F - UFM
Issue 1.4 Page 16
If any of the parameters need to be changed from the default values, for example different
units are required, then the menu system must be activated via the password (see section 7).
5.2 Pulse output
Pulse output can be set up to operate in two modes, namely volumetric and frequency.
5.2.1 Volumetric mode
In Volumetric mode, each pulse output represents a measured volume of 10 gallons (default
value). In Volumetric mode, with the Vol per Pulse set to 1 and the pulse width set to 25 ms,
the maximum number of pulses that can be output (without storage) is 1/(0.025*2) = 20 pulses
per second. If the flow rate in the pipe is such that more than 20 pulses per second are
generated, a Pulse Overflow error may eventually occur if the stored number of pulses
exceeds 1000. To avoid this, set the Vol per Pulse to 100 gallons.
5.2.2 Frequency mode
In Frequency mode, the pulse output frequency is proportional to the flow rate within a
specified frequency range of 0
– 200 Hz.
5.3 4-20 mA Current output
The default 4-20 mA output setting will be ON, and the 4-20 mA LED on the keypad will be
illuminated. The default flow for 20 mA output will be automatically set depending on the pipe
size. The default flow for 4 mA is 0. This can be changed, see section 7.
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 4-20 mA current output is factory calibrated.