Convert the measured current to flow rate, 2 pulse output, Turning the pulse output off/on (volumetric mode) – Dwyer Series PUB User Manual
Page 30: Operating procedures
3: Operating Procedures
26
Convert the measured current to flow rate
Assume the maximum flow rate is F
max
(gal/min) and the minimum flow rate F
min
is ‘0’ (gal/min), as shown.
To calculate the flow rate (gal/min) for a measured current I(mA) then:
3.7.2 Pulse
output
The pulse output can be used in two modes, ‘volumetric’ and ‘frequency’. When operating in the ‘volumetric’
mode a pulse is produced every time a pre-selected volume of liquid passes through the pipe; and when in the
‘frequency’ mode the output is a continuous pulse-train with a frequency proportional to the flow rate (gal/min).
Using the instrument’s menu system, the operator can use the following procedures to:
• Select the pulse output function
Off/On/Frequency.
• Volumetric mode – select the output pulse width and volume per pulse.
• Frequency mode – select the maximum pulse frequency and the corresponding maximum flow rate.
Turning the pulse output OFF/ON (volumetric mode)
Generating a ‘Test’ pulse
If the
PULSE OUTPUT menu screen is accessed from the SETUP INSTRUMENT menu, you can generate a ‘test’
pulse by selecting
Flow units and pressing the Option key.
0-20 mA
0-16 mA
4-20 mA
1.
With the instrument operating in the
FLOW
READING mode, press the Pulse function key
to access the
PULSE OUTPUT screen.
2.
A
Pulse output is ON (or OFF) message
appears in the second line of the display.
3.
To change the pulse output operational status,
select the
Output menu option then select
Off/On as required.
4.
Select
Exit and press the ENTER key to return
to the
FLOW READING screen.
PULSE OUTPUT
DD-MM-YY HH:MM:SS
Pulse output is ON
Qxx.xx%
Flow units : gal
Output : On
Vol per pulse : 10.00
Pulse width (ms) : 10
Max Pulse Freq (Hz) : 10.00
Flow at Max Freq : 200.00
Calculated Pulse Value: 20.0
Exit
4
8
12
16
20
F
max
Flo
w
(g
al/m
in
)
I (mA)
F
min
[0-16 mA scale]
[0-20 mA scale]
[4-20 mA scale]
Flow rate
I
F
max
F
min
–
(
)
×
20
-------------------------------------------
F
min
+
=
Flow rate
I
F
max
F
min
–
(
)
×
16
-------------------------------------------
F
min
+
=
Flow rate
I
4
–
(
)
F
max
F
min
–
(
)
×
16
( )
---------------------------------------------------------
F
min
+
=