Setra 267 Very Low Differential Pressure Transducer

Overview

The Setra 267 is a very low differential pressure transducer that Setra Systems describes as its most rugged high accuracy low differential product. It measures pressures from 0.1 inch of water column up to 100 inches WC, in unidirectional or bidirectional form, and converts them into a 4-20 mA or 0-5/0-10 VDC signal for building automation and process control systems. A NEMA 4 rated housing, an optional LCD display and an optional static pressure probe let one transducer cover wall mounting, duct mounting and outdoor locations.

Seven Star LLC supplies the Setra 267 to HVAC contractors, BMS integrators and cleanroom operators throughout Oman and the GCC, backed by engineering support in Muscat. The transducer is widely specified where low pressures must be held tightly, such as pharmaceutical cleanrooms, hospital isolation suites and data centre containment, all of which are growing segments in the Sultanate.

Measurement Principle

At the heart of the Setra 267 is an all stainless steel capacitive sensing element that Setra designs and manufactures itself. A thin, tensioned diaphragm and a fixed electrode form a variable capacitor; when differential pressure deflects the diaphragm, the gap and therefore the capacitance change. The welded, dead-ended construction keeps process air away from the electronics, and because the capacitive signal is relatively large it needs only minimal amplification, which supports good accuracy and long-term stability.

Setra states that its capacitive technology has been used in more than 8 million installations. For the user this means a transducer with long-term stability of 0.1% FS total, low hysteresis of plus or minus 0.10% FS and non-repeatability of plus or minus 0.05% FS, so a room pressure or duct static setpoint holds without frequent recalibration.

Engineering Design of the Setra 267

The Setra 267 is housed in an IP65/NEMA 4 case of glass-filled polycarbonate rated UL94 V-0, weighing about 255 g, or 270 g with the duct probe assembly. Pressure connections are either 3/16 inch barbed brass fittings or 1/4 inch NPTF brass fittings, and electrical entry is through a PG-9 or PG-13.5 strain relief, a 1/2 inch conduit opening or a 9-pin D-sub connector. Zero and span adjustments and the screw terminal strip sit inside the case, and the housing is offered in both wall and duct mount configurations.

The current output version is a 2-wire 4-20 mA loop, protected from miswiring, while the voltage version is a 3-wire circuit with excitation, ground and signal. Setra calibrates the current version with a 24 VDC loop supply and a 250 ohm load, and sets zero and span within plus or minus 0.16 mA, or 0.08 mA for the optional accuracy grades. Maximum line pressure is 10 psi, with overpressure protection up to 10 psi depending on range.

Key Features

Key Setra 267 features for building and process applications include:

• Ranges from 0-0.1 in WC to 0-100 in WC, plus bidirectional and pascal ranges from 25 Pa to 7000 Pa.
• Accuracy choices of 1% FS, 0.5% FS with display, and optional 0.4% FS or 0.25% FS with a calibration certificate.
• An all stainless steel capacitive sensor delivers stability of 0.1% FS total.
• The NEMA 4 (IP65) glass-filled polycarbonate housing withstands difficult environments.
• An optional 3.5 digit LCD display allows local reading during commissioning and balancing.
• The optional baffled static duct probe avoids velocity pressure errors and saves installation time.
• Outputs of 4-20 mA, 0-5 VDC or 0-10 VDC with 24 VAC or 24 VDC excitation.
• PG-9, PG-13.5, conduit or D-sub terminations, with CE and RoHS compliance.

Industrial Applications

Setra lists HVAC systems, energy management systems, static duct pressure, cleanroom pressure, and oven pressurisation and furnace draft controls as typical applications. In Oman the Setra 267 is a good fit for variable air volume systems in Muscat office towers, supply fan static pressure control in malls and hotels, and room pressure monitoring in hospitals and laboratories where negative or positive pressure must be proven continuously.

With its 0.5% FS display version and optional 0.25% FS accuracy, the Setra 267 also suits pharmaceutical and food plants in the Sohar and Salalah free zones that must document room pressure cascades, and data centres that control hot and cold aisle differentials. Seven Star LLC supplies the Setra 267 alongside other Setra pressure products, so consultants and contractors across the GCC can standardise on one sensor family. Because the same part number structure covers wall and duct versions, current and voltage outputs and every accuracy grade, a project schedule can list each monitoring point by its exact code, which simplifies submittals, spares planning and later replacements.

Technical Specifications

The Setra 267 data below is taken from the Setra datasheet (SSP267).

See also the Setra 264 low differential pressure transducer, the Setra 209 pressure transducer and the Dwyer Series MSX Magnesense transmitter.

How to Order

To order the Setra 267, send Seven Star LLC a formal RFQ with the full part number, or the range, output, fitting, termination and accuracy you need, and our instrumentation division will build the correct code. We provide engineering support in Muscat for customers in Oman and the GCC. Download the Setra 267 datasheet from this page and contact our team for delivery times and calibration documentation.