PCI OAFE-1550, Operation & Maintenance Manual

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OAFE-1550 Operation & Maintenance Manual
Paragon Controls Incorporated 1 Revision Level 000
1. INTRODUCTION
1.1. DESCRIPTION
The
OAFE-1550
is an AMCA certified outdoor airflow measurement system with integral signal
processor that is capable of producing an overall ±0.5% accuracy through the velocity range of 200 to
1,200 fpm and ±5% accuracy at 100 fpm.
The airflow measurement station consists of multiple airflow elements, factory mounted and pre-piped
in a casing designed for flanged connection to ductwork, control dampers, louvers, etc. An optional
inlet bell is available for plenum applications. Standard materials consist of a G90 galvanized casing
and 6063-T5 anodized aluminum flow sensors, suitable for most HVAC applications. The airflow
averaging elements are head type devices, which generate a differential (velocity) pressure signal similar
to the orifice, venture, and other head producing primary elements. The airflow measurement station is
constructed so as to comply with ASHRAE Standard 111 for equal area traversing of an airflow
measurement plane. Multiple elements are manifolded together for connection to the integral airflow
signal processor.
The signal processor utilizes current state-of-the-art digital microprocessor technology capable of
producing unequaled 24-bit (16,777,216 steps) A/D and 12 bit (4,096 steps) D/A signal conversion
resolution. Having a twelve-point linearization capability, the signal processor
can be field calibrated to
accurately determine true airflow rates even when the primary airflow measurement stations do not meet
their minimum installation requirements. The ultra low operating ranges and the auto zeroing function
of the signal processor provides accurate airflow measurement down to 100 fpm. The signal processor
accepts a temperature input signal for air temperature indication, temperature signal transmission for
remote readout, and air density compensation for standard or actual airflow calculations. A password
protected configuration menu provides quick and simple field configuration by authorized personnel.
Field configuration of engineering units, process noise filtering, operating range, alarm set points, etc,
are performed via user friendly menus and a six button touch pad.
An optional temperature transmitter with 4 to 20mA output and temperature range of -30 to 130
°
F is
available to provide a temperature input signal to the signal processor for air density compensation (see
the associated installation, operation and maintenance manual for further information).
1.2. BASIC OPERATION
The airflow measuring station produces pneumatic output signals referred to as total (high) and static
(low) pressure. These two pressures are piped to the signal processor where the static pressure is
subtracted from the total and the result indicated as velocity pressure. This measured differential
pressure is equal to the average velocity of the air stream moving through the plane that the airflow
measuring station is located in. This signal can be converted to air velocity and flow using the following
equations:
a
a
T

 
460
921 . 29
325 . 1

a
V
P
V

7 . 1096

A V Q
 
Where:
a


Actual density of air, in lb/ft
3
(0.075 lb/ft
3
at sea level and 68
°
F)
a
T = Actual temperature, in
°
F (default value is 68
°
F)
P
V
= Velocity pressure, in inches H
2
O
V = Velocity, in fpm
Q = Flow, in cfm
A = Area, in ft2
This signal is scaled and linearized before being displayed and transmitted out as a 4-20ma, 0-5vdc, or
0-10vdc signal.