PD4-6624 & PD4-6628 Loop-Powered Flow Rate/Totalizers
Instruction Manual
8
Predefined and Custom Units
The PD4-6624/28 flow rate/totalizers have the most
common predefined rate and volume units. If the
desired unit is not available, the user can program a
custom unit.
•
If the total is disabled in the
System
– Total
menu, the meter has six available
preprogrammed unit classes: volume, height,
temperature, pressure, weight, and rate. When
the desired unit class or unit of measure within a
class is not available, a custom unit may be
programmed.
Password Protection
A password can be set up for programming security to
prevent unauthorized changes to the programmed
parameter settings.
Remote Contacts
Remote Contacts are standard on the PD4 and the
meter can be operated via a remote control station
(PDA2364-MRUE). The PDA2364-MRUE mimics the
PD4 meter’s four programming buttons: Menu, Right
Arrow, Up Arrow, and Enter.
Multiple Outputs
•
Two open collector outputs (standard)
•
Two solid-state relays (optional)
•
One 4-20 mA output (optional)
The open collector outputs and relays generally
operate in the same manner, with the major exception
being the open collectors are not available for pump
alternation and the relays are not available with pulse
features. The open collectors and relays can be
controlled either automatically or manually.
The isolated analog output signal can be configured
to represent the process variable (rate, total, or
retransmit). It can also be reverse scaled such that
the meter’s high calibration value outputs 4 mA and
the meter’s low calibration outputs 20 mA.
Input Signal Conditioning
Functions (
FUNCTION
)
The
Function
menu is used to select the input signal
conditioner applied to the input: linear, square root,
programmable exponent, or round horizontal tank
volume calculation. Multi-point linearization is part of
the linear function selection.
Meters are set up at the factory for linear function with
2-point linearization. The linear function provides a
display that is linear with respect to the input signal.
Square Root Linearization (
SQROOT
)
The square root function can be used to linearize the
signal from a differential pressure transmitter and
display flow rate in engineering units.
PD4-6624 Displaying Flow Rate by Applying the Square
Root Function to the Output of a DP Transmitter.
Programmable Exponent
Linearization (
EXPONENT
)
The programmable exponent can be used to linearize
the signal from level transmitters in open-channel flow
applications using weirs and flumes.
The PD4-6624, in combination with an ultrasonic level
transmitter, makes for an economical way to measure
and display open channel flow rate in most weirs and
flumes. A guide such as the ISCO Open Channel
Flow Measurement Handbook can provide the user
with all the information needed: the exponent used in
the flow equation for the desired flow units and the
flow rate for any given head height. For example, to
display the open channel flow rate from a 3" Parshall
flume, the ISCO handbook advises the exponent is
1.547 and at the maximum head height of 3.0 feet,
the flow rate is 3.508 MGD.
