Pressure Measurement
Differential Pressure Transducer
Model 264 (HVAC Application)
Setra Model 264 Pressure Transducer 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, Model 264 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 (Setracerama™). 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.
- 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 | 10 PSI | |
| 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 temperature may be considerably higher or lower. | ||
Physical Description
| Case | Fire-Retardant Glass Filled Polyester (UL 94 V-0 Approved) | |
| Mounting | 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 20 mA** | |
| Bidirectional Output at Zero | 12 mA** | |
| 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
