Emerson Rosemount 8600 Series, Reference Manual, Page: 44 / 130

Reference Manual
00809-0100-4860, Rev BF
Installation
May 2019
36 Rosemount 8600 Vortex Flow Meter
The flowmeter provides an isolated transistor switch-closure frequency output signal
proportional to flow, as shown in
Figure 3 - 12 . The frequency limits are as follows:

Maximum Frequency = 10000 Hz

Minimum Frequency = 0.0000035 Hz (1 pulse/79 hours)

Duty Cycle = 50%

External Supply Voltage (V
s
): 5 to 30 Vdc

Load Resistance (R
L
): 100

to 100 k


Max Switching Current = 75 mA >= V
S
/R
L

Switch Closure: Transistor, open collector
Open contact < 50

A leakage
Close contact < 20

The output may drive an externally powered electromechanical or electronic totalizer, or
may serve as a direct input to a control element.
To connect the wires, remove the FIELD TERMINALS side cover of the electronics housing.
Connect the wires as shown in
Figure 3 - 15 on page 38 .
Note
When using pulse output, be sure to follow these precautions:

Shielded twisted pair is required when the pulse output and 4–20 mA output are
run in the same conduit or cable trays. Shielded wire will also reduce false
triggering caused by noise pickup. Wiring should be 24 AWG or larger and not
exceed 5,000 ft. (1500 m).

Do not connect the powered signal wiring to the test terminals. Power could
damage the test diode in the test connection.

Do not run signal wiring in conduit or open trays with power wiring or near heavy
electrical equipment. If needed, ground signal wiring at any one point on the signal
loop, such as the negative terminal of the power supply. The electronics housing is
grounded to the meter body.
Figure 3 - 12. Example: Pulse Output Will Maintain a 50 Percent Duty Cycle for All
Frequencies
50% Duty Cycle