Dwyer Series 626/628 Industrial Pressure Transmitter

Overview

The Dwyer Series 626 is an industrial pressure transmitter from Dwyer Instruments built around a piezoresistive sensor in a compact, rugged NEMA 4X (IP66) housing. It is offered with a stainless steel general purpose housing or a cast aluminium conduit housing, and measures gauge or absolute pressure of compatible gases and liquids. The 626 delivers 0.25% of full scale accuracy, while its companion Series 628 shares the same construction at 1.0% FS for applications where cost matters more than precision.

Seven Star LLC supplies the Dwyer Series 626 and 628 to pump packagers, water utilities, irrigation contractors and plant maintenance teams in Oman and the GCC, with engineering support in Muscat. Dwyer designed the series to address the common failure points that challenge pressure transmitters in harsh outdoor service, which makes it relevant to exposed pumping stations and skid-mounted equipment in the Gulf climate.

Measurement Principle

Inside the transmitter, process pressure acts on a 316L stainless steel isolating diaphragm. Behind it, a fill oil transmits the pressure to a silicon piezoresistive element, a bridge of resistors whose values change as the silicon is strained. The on-board electronics excite the bridge, compensate the signal over a 0 to 175 degree F range and convert it to a standard analog output such as 4-20 mA or 0-10 VDC. Response time is specified at 300 ms, and the stated accuracy figure includes linearity, hysteresis and repeatability.

Because the sensing element is sealed behind a welded stainless steel diaphragm, the Dwyer Series 626 can be mounted in any position and is suitable for both liquids and gases. Optional configurations add overpressure and vacuum protection to guard the sensor against pressure surges and pump cavitation, along with freeze-thaw protection and vibration resistance for outdoor equipment.

Engineering Design of the Dwyer Series 626

The Dwyer Series 626 is ordered by building a product code from series, range, housing, output, electrical connection and process connection. The general purpose (-GH) housing is a slim stainless steel body that weighs about 283 g, and the conduit box (-CB) housing is a cast aluminium enclosure with a liquid-tight fitting that can take the optional field-upgradeable LCD display. Both carry the NEMA 4X (IP66) rating.

Supply voltage is 10-30 VDC for 4-20 mA and lower voltage outputs, 13-30 VDC for 0-10 V and 2-10 V outputs, and 5 VDC for the 0.5-4.5 V ratiometric version. For a 4-20 mA loop the maximum loop resistance follows R max = 50 (Vps – 10) ohms. Electrical termination choices include a cable gland with 3 ft or 9 ft of prewired cable, a DIN EN 175801-803-C connector, UL or non-UL M12 4-pin connectors, a Packard connector and a 1/2 inch female NPT conduit opening.

Key Features

The Dwyer Series 626 offers the following features for industrial pressure measurement:

• A robust 316L stainless steel oil-filled sensor measures both liquids and gases in any mounting orientation.
• Series 626 accuracy is 0.25% FS (0.20% RSS), and Series 628 is 1.0% FS for general monitoring.
• The NEMA 4X (IP66) general purpose or conduit box housing withstands washdown and outdoor exposure.
• Gauge ranges run from 0-5 psi to 0-8000 psi, with absolute ranges from 0-15 psia to 0-300 psia and selected bar ranges.
• Output options cover 4-20 mA and several voltage signals, including a selectable voltage output on the -CB housing.
• Optional C-276 wetted parts extend chemical compatibility to more aggressive media.
• Options for overpressure, vacuum, freeze-thaw and vibration protection address common outdoor failure modes.
• Agency options include NSF/ANSI 61/372, ANSI/UL 218, ANSI/UL 508 and NFPA 20, alongside standard CE compliance.

Industrial Applications

Dwyer lists booster stations, pumping systems, irrigation equipment, PTO systems and submersible pump control as typical uses, as well as chemical dosing and injection systems. In Oman the Dwyer Series 626 fits water network booster stations, borehole and submersible pump controllers, landscape irrigation for municipalities and resorts, and pressure monitoring on chemical injection skids at oil and gas wellsites. The high pressure ranges up to 8000 psi also suit hydraulic power units and test benches.

Fire pump installations that call for UL or NFPA 20 compliant transmitters, and potable water projects that require NSF/ANSI 61 certification, can be served from the same series with the right option codes. Seven Star LLC supplies the Dwyer Series 626 and 628 with accessories such as M12 and Packard cables and the field-upgradeable LCD, so pump skid builders and EPC contractors in Muscat, Sohar, Duqm and across the GCC can source complete measurement points from one supplier.

Technical Specifications

The main Dwyer Series 626 and 628 specifications from the Dwyer datasheet are summarised below.

Other general purpose transmitters in our range include the Danfoss MBS 3000 pressure transmitter, the WIKA A-10 pressure transmitter and the ifm PN7093 pressure sensor with display.

How to Order

To order the Dwyer Series 626 or 628, send Seven Star LLC a formal RFQ with the complete product code, or the range, output and connection details, and our instrumentation division will confirm the configuration. Engineering support in Muscat serves customers across Oman and the GCC. Download the Dwyer Series 626 datasheet from this page, and contact our team for cables, displays and NIST traceable calibration certificates.