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.

–