Pressure Measurement

Differential Pressure Transducer for HVAC – Model 267/267MR


Systems Model 267 and 267MR pressure transducers sense gauge (static) or differential pressure and convert this pressure difference to a proportional electrical output. The 267 series is offered with a high level voltage output or 4-20 mA current output. The 267MR offers multi-range capability and field configurable 0-5 VDC or 0-10 VDC output, as well as a 4-20 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.

  • Model 267MR Offers Multi-Range Capability, 6 Field Selectable Ranges via Dip Switches, and Field Selectable 0-5 or 0-10 VDC Output
  • Model 267 Offers an Optional 3 1/2 Digit LCD Display with a 0.5% FS Standard Accuracy
  • NEMA 4/IP65 Rated Housing
  • Optional Accuracies as High as 0.25% FS
  • 24 VAC or 24 VDC Excitation
  • PG-9, PG13.5 or Conduit Electrical Termination
  • Integral Static Pressure Probe
  • Ranges as low as 0.1 in. W.C. (25 Pa)
  • Meets CE Conformance Standards
  • Heating, Ventilating and Air-Conditioning (HVAC)
  • Energy Management Systems
  • Static Duct Pressure
  • Clean Room Pressure
  • Oven Pressurization and Furnace Draft Controls

Technical Details

Accuracy* RSS (At Constant Temp.)±1.0% FS±0.4% FS ±0.25% FS
Non-Linearity, BFSL±0.98% FS±0.38% FS ±0.22% FS
Hysteresis0.10% FS0.10% FS 0.10% FS
Non-Repeatability0.05% FS0.05% FS 0.05% FS
Thermal Effects**
Compensated Range °F(°C)+40 to +150 (+5 to +65)
Zero/Span Shift %FS/°F(°C)±0.033 (±0.06)
Maximum Line Pressure10 PSI
Overpressure10 PSI in Positive or Negative Direction
Warm-up Shift±0.1% FS Total
Position Effect**
RangeTo 0.5 in. / To 1.0 in. / To 2.5 in. / To 5.0 in.
*RSS of Non-Linearity, Non-Repeatability and Hysteresis.
**Units calibrated at nominal 70°F. Maximum thermal error computed from this datum.
***Unit is factory calibrated at 0g effect in the vertical position.

Physical Description

CaseFire-Retardant Glass Filled
Polyester (UL 94 V-0 Approved)
MoutingFour screw holes on removable
zinc plated steel base (designed
for 2.75” snap track)
Electrical ConnectionScrew Terminal Strip
Electrical TerminationPG-9/PG13.5 Strain Relief, 1/2″
Conduit Opening, or 9 Pin D-Sub
Zero and Span AdjustmentsAccessible on top of case
Display (Optional on 267 only)3 1/2 Digit LCD Integral
Display(1.74″W x 0.78″H)
Pressure Fittings3/16″ O.D. Barbed Brass for 1/4″
Push-On Tubing (Standard)
Static Pressure Probe (Optional)
1/4″ NPTF Brass (Optional)
Mounting2 Mounting Tabs with 0.18″ Holes
Pressure Probe Assembly is Supplied
with a 7.8″ 6061 Aluminum Alloy
Probe and a Gasket to Seal Against
the Duct
Weight (Approx.)9.0 ounces (255 grams)
9.5 ounces (Duct Probe Assembly)
*9 pin D-sub Connector is not suitable for NEMA4/IP-65 environments.

Electrical Data (Voltage)

Circuit3-Wire (Exc, Gnd, Sig)
Protected from Miswiring
Excitation (for 0-5 VDC Output)9 to 30 VAC/12 to 40 VDC
Excitation (for 0-10 VDC Output)11 to 30 VAC/13 to 40 VDC
Model 267
Output*0 to 5 VDC**
0 to 10 VDC**
Model 267MR
Output* (Field Selectable)0 to 5 VDC**
0 to 10 VDC**
Bidirectional Output at ZeroMid-Range of Specified Output
Output Impedance100 Ohms
Re-Ranging (267MR only)5 Position Dip Switches
(Located Inside Case)
*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)

Protected from Miswiring
Output*4 to 20 mA**
Bidirectional Output at Zero12 mA
External Load0 to 800 Ohms
Minimum loop supply voltage (VDC) = 9 + 0.02 x (Resistance of receiver plus line).
Maximum loop supply voltage (VDC) = 30 + 0.004 x (Resistance of receiver plus line).
Re-Ranging (267MR only) 4 Position Dip Switches (located inside case)
*Calibrated 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)

Pressure Media

Typically Air or Similar Non-Conducting Gases

Environmental Data

Operating* °F (°C)0 to +150 (-18 to +65)
Storage °F (°C)-65 to +180 (-54 to +82)
*Operating temperature limits of the electronics only.
Pressure media temperature may be considerably higher or lower.

Note: Specification are Subject to change without notice