Differential Pressure Transducer for HVAC – Model 264

 

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Systems 264 pressure transducers sense differential or gauge (static) pressure and convert this pressure difference to a proportional electrical output for either unidirectional or bidirectional pressure ranges. The 264 Series is offered with a high level analog 0 to 5 VDC or 4 to 20 mA output.

In a typical Setra configuration, a compact housing contains two closely-spaced, parallel, electrically-isolated metallic surfaces, one of which is essentially a diaphragm capable of slight flexing under applied pressure. The diaphragm is constructed of low-hysteresis material such as 17-4 PH SS or a proprietary compound of fused glass and ceramic (Setraceramâ„¢). These firmly secured surfaces (or plates) are mounted so that a slight mechanical flexing of the assembly, caused by a minute change in applied pressure, alters the gap between them (creating, in effect, a variable capacitor). The resulting change in capacitance is detected by a sensitive linear comparator circuit (employing proprietary, custom-designed ASICs), which amplifies and outputs a proportional, high-level signal.

 

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  • Up to 10 PSI overpressure on all ranges
  • Installation time minimized with snap track mounting and easy - to - access pressure ports and eectrical connections
  • 0 to 5 VDC or 2-wire 4 to 20 mA analog outputs are compatible with energy management systems
  • Reverse wiring protection
  • Internal regulation permits use with unregulated DC uower uupplies
  • Fire retardent case (UL 94 V-0 Approved)
  • Meets CE conformance standards
  • Heating, Ventilating and Air Conditioning (HVAC)
  • Energy Management Systems
  • Variable Air Volume and Fan Control (VAV)
  • Environmental Pollution Control
  • Lab and Fume Hood Control
  • Oven Pressurization and Furnace Draft Controls
Technical Details
Performance
Standard Optional
Accuracy* RSS(at constant temp) ±1.0% FS ±0.4% FS ±0.25% FS
Non-Linearity, BFSL ±0.96% FS ±0.38% FS ±0.22% FS
Hysteresis 0.10% FS 0.10% FS 0.10% FS
Non-Repeatability 0.05% FS 0.05% FS 0.05%FS
Thermal Effects**
Compensated Range °F(°C) 0 to +150 (-18 to +65)
Zero/Span Shift %FS/°F(°C) 0.033 (0.06)
Maximum Line Pressure 10psi
Overpressure Up to 10 psi in Positive or
Negative Direction
Long Term Stability 0.5% FS/1 YR
Position Effect Range Zero Offset (%FS/G)
(Unit is factory calibrated at 0g
effect in the vertical position.)
To 0.5 in. / To 1.0 in. / To 2.5 in. /
To 5 in.
0.60 / 0.50 / 0.22 / 0.14
* RSS of Non-Linearity, Hysteresis, and Non-Repeatability.
**Units calibrated at nominal 70°F. Maximum thermal error computed from
this datum.
Environmental Data
Temperature
Operating* °F (°C) 0 to +175 (-18 to +79)
Storage °F (°C) -65 to +250 (-54 to +121)
*Operating temperature limits of the electronics only. Pressure media
temperatures may be considerably higher
Physical Description
Case Fire-Retardant Glass Filled
Polyester (UL 94 V-0 Approved)
Mouting Four screw holes on removable
zinc plated steel base (designed
for 2.75” snap track)
Electrical Connection Screw Terminal Strip
Pressure Fittings 3/16” O.D. barbed brass
pressure fitting for 1/4” push-on
tubing
Zero and Span Adjustments Accessible on top of case
Weight (Approx.) 10 ounces
Pressure Media
Typically air or similar non-conducting gases
Electrical Data (Voltage)
Circuit 3-Wire (Com, Exc, Out)
Excitation 9 to 30 VDC
Output* 0 to 5 VDC**
Bidirectional Output at Zero Pressure 2.5 VDC**
Output Impedance 100 ohms
*Calibrated into a 50K ohm load, operable into a 5000 ohm load or greater.
**Zero output factory set to within ±50mV (±25 mV for optional accuracies).
**Span (Full Scale) output factory set to within ±50mV. (±25 mV for optional accuracies).
Electrical Data (Current)
Circuit 2-Wire
Output* 4 to 20mA**
Bidirectional Output at Zero Pressure 12mA**
External Load 0 to 800 ohms
Minimum supply voltage (VDC) = 9+ 0.02 x (Resistance of receiver plus line).
Maximum supply voltage (VDC) = 30+ 0.004 x (Resistance of receiver plus line).
*Calibrated at factory with a 24 VDC loop supply voltage and a 250 ohm load.
**Zero output factory set to within ±0.16mA (±0.08 mA for optional accuracies).
**Span (Full Scale) output factory set to wtihin ±0.16mA (±0.08 mA for
optional accuracies).
Note: Specification are subject to change without notice.


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