Johnson Controls DPT 264 Series Installation Guide

Setra Systems
DPT 264 Series Low Pressure Transducers and Transmitters
Installation Guide
1.0 GENERAL INFORMATION
Every Model DPT264 has been tested and calibrated before shipment. Specific performance specifications are shown on page 3 of this Guide.
Setra Systems DPT264 pressure transducers sense differential or gage (static) pressure and convert this pressure difference to a proportional high level analog output for both unidirectional and bi-directional pressure ranges. Two standard output versions are offered: A voltage output of 0 to 5 VDC or a current output of 4 to 20 mA.
2.0 MECHANICAL INSTALLATION
2.1Media Compatibility Model DPT264 transducers are designed to be used with air or non-conducting gases. Use with liquids or corrosive gases will dame the unit.
2.2 Environment
The operating temperature limits of the DPT264 are 0°F to +175°F (-18°C to +79°C) The compensated temperature range is 0°F to +150°F (-18°C to +65°C).
2.3 Mounting
The DPT264 series is designed for mounting in either 2.75: snap-track or by using the four (4) slots (suitable for #6 screws) that are provided on the plate. Optimum performance is obtained by isolating the instrument from vibration and providing relatively clean, dry ambient air to the pressure ports.
Even though there is no flow through the DPT264, a filter is located in both the high and low-pressure ports for use in extreme dust or moisture conditions.
In most cases, preferred installation is with the baseplate mounted vertically and located on a relatively flat surface in a junction box or attached to a nearby beam. Easy field replacement is possible by removing the single case screw that holds the black sensor/circuit housing to the baseplate and lifting the black housing free. The baseplate remains mounted and can be used with the replacement unit’s black sensor/circuit housing.
The axis most sensitive to vibration is the one perpendicular to the baseplate. Avoid mounting with maximum vibration along this axis.
2.4 Pressure Fittings
The Model DPT264 is designed to be used with 3/16” I.D. push-on tubing. Both the positive (high) pressure port and the reference (low) pressure port are located on the front of the unit, labeled “HIGH” and “LOW” respectively. For best results (shortest response time), 3/16” I.D. tubing is suggested for tubing lengths up to 100 feet long, 1/4” I.D. for tubing lengths up to 300 feet, and 3/8” I.D. for tubing lengths up to 900 feet.
3.0 ELECTRICAL INSTALLATION
If the Model DPT264 is supplied with the optional Conduit Enclosure, access the electrical terminations by removing the cover.
3.1 Voltage Output Units The Model DPT264 voltage output is a 3-wire circuit, with three terminals available for wiring. These terminals have the designation COM, EXC, and OUT (see Diagram 1). The power supply and signal references are commoned on the circuit (see Diagram 2). The DPT264 voltage output can operate from 9­30 VDC excitation. The DPT264 has a 0-5 VDC output.
Voltage Circuit Diagram
Readout
or
DAS
Power
Supply
Diagram 1 Diagram 2
+EXC Connect to positive terminal of 9-30 VDC Power Supply +OUT Connect to positive terminal of Control or Pressure Monitor COM Connect as the reference for power supply and output signal
3.2 Current Output Units
The Model DPT264 is a two-wire loop-powered 4 to 20 mA current output unit and delivers rated current into any external load of 0 to 800 ohms. These terminals have the designation of + and – (see Diagram 3). The current flows into the + terminal and returns back to the power supply through the – terminal (see Diagram 4). The power supply must be a DC voltage source with a voltage range between 9 and 30 measured between the + and – terminals. The unit is calibrated at the factory with a 24 VDC loop supply voltage and a 250ohm load.
OUT
Model
DPT264
EXC
COM
Current Circuit Diagram
+
DPT264
9 to 20 VDC
Current
Monitoring
Device
Diagram 3 Diagram 4
4.0 CALIBRATION
The DPT264 transducer is factory calibrated and should require no field adjustment. Generally, the mounting position will have a zero effect on ranges below 1” WC. Whenever possible, any zero and/or span offsets should be corrected by software adjustment in the user’s control system. However, both the zero and span adjustments are accessible either on the front of the unit or by removing the optional conduit enclosure. The DPT264 transducer is calibrated in the vertical position at the factory.
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