Setra 269 Operating Manual

Installation Guide

Setra Systems Model 269 High Performance

Very Low Differential Pressure Transducer

1.0 GENERAL INFORMATION

Every Model 269 has been tested and calibrated before shipment. Specific
performance specifications are shown on page 3 of this Guide.

Setra Systems 269 pressure transducers sense differential or gauge (static)
pressure and convert this pressure difference to a proportional high level
analog output for both unidirectional and bidirectional pressure ranges. A
current output of 4 to 20 mA is offered.

2.0 MECHANICAL INSTALLATION

2.1 Media Compatibility

Model 269 transducers are designed to be used with air or nonconducting

gases. Use with liquids or corrosive gases will damage the unit.

2.2 Environment

The operating temperature limits of the 269 are -20°F to +160°F
The compensated temperature range is 20°F to +140°F

2.3 Pressure Fittings

The Model 269 is designed to be used with 3/16” I.D. push-on tubing on a
removable process head. Both the positive (high) pressure port and the
reference (low) pressure port are located on the top of the unit, labeled “+”
(HIGH) and “-” (LOW) respectively. For best results (shortest response times),
3/16” I.D. tubing is suggested for tubing lengths up to100 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
(See Diagram 1).

3.0 ELECTRICAL INSTALLATION

3.1 Current Output Units

The Model 269 is a two-wire loop-powered 4 to 20mA 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 1).

The current flows into the + terminal and returns back to the power supply
through the - terminal (See Diagram 2). The power supply must be a DC
voltage source with a voltage range between 13.5 and 30 measured between
the + and - terminals. The unit is calibrated at the factory with a 24 VDC loop
supply voltage and a 250 ohm load.

Low Pressure Port

.48”

High Pressure Port

Detachable Process
Head

Din
Rail

4.50”
Detachable

Electrical
Connector

Shield
to
Ground

- +

2.90”

3.70”

Turn-Down
Switch

3.90”

1.30”

2.35”

4.0. CALIBRATION

The 269 transducer is factory calibrated and should require no field adjustment
if mounted in a vertical position. Whenever possible, any zero and/or span
offsets should be corrected by software adjustment in the user’s control system.
However, fine zero and span adjustments can be made thru a calibration secure
access key. The Model 269 transducer zero offset is trimmed in the vertical
position (pressure ports pointing upward) prior to shipping from factory.

4.1 Zero/Span Adjustments with Security Key

To make secure zero and span adjustments, remove detachable process head by
pressing and pulling on side tabs. Install calibration security key in-place of
process head. (See Diagram 3).

4.2 Zero Adjustment (Current Output)

While applying zero differential pressure, zero may be adjusted by pressing the
cal button to tare zero. If fine adjustment is needed on analog output, depress
cal button while turning the encoder.

4.3 Span Adjustment (Current Output)

Span or full scale output adjustments should only be performed by using an
accurate pressure standard (electronic manometer, digital pressure gauge, etc.)
with at least comparable accuracy to the 269 transducer. With full range
pressure applied to the high pressure port (reference port open to atmosphere),
the span may be adjusted by pressing the cal button to set span. If fine
adjustment is needed on span, and control pressure is applied at least 75% of
full range, turn encoder until target output is achieved.

Diagram 1

4.4 Turn Down Adjustment (Option)

For units with optional turn-down gain, turn down is easily adjusted through
use of slider switch located on side of unit. (See Diagram 1)

2