OMEGA DPF64-SQRT Modules | DPF64-SQRT 110/220VAC Rate Meter

Technical Dossier

Product Details And Specifications

OMEGA DPF64-SQRT Series: Comprehensive Module Range and Technical Overview

The OMEGA DPF64-SQRT is a panel-mount rate meter and flow computer designed for square-root extraction of differential-pressure flow signals. It has established a significant installed base across global heavy industries including petrochemical refineries, nuclear power auxiliary systems, offshore oil & gas platforms, and large-scale water treatment facilities. The unit accepts linear 4–20 mA or pulse inputs, applies a real-time square-root function, and outputs a linearized flow rate — a critical requirement wherever orifice plates, venturi tubes, or pitot tubes are used as primary flow elements. Its dual-voltage AC supply (110/220VAC selectable) makes it deployable across North American and European plant standards without hardware modification. The DPF64-SQRT occupies a standard 1/8 DIN panel cutout, integrating directly into legacy SCADA and DCS front-panel arrays without requiring enclosure redesign.

The Evolution of DPF64-SQRT Architecture

The DPF64 platform was introduced by OMEGA Engineering as part of its DPF-series panel instrumentation line, targeting process industries that required compact, dedicated signal-conditioning displays rather than full PLC-based solutions. Early DPF64 variants provided basic rate display with analog retransmission. The -SQRT suffix designates the square-root extraction firmware variant, which was added to address the nonlinear relationship between differential pressure and volumetric flow rate inherent to all DP-based flow measurement.

Over successive hardware revisions, the DPF64-SQRT incorporated improved EMI filtering to meet IEC 61000-4 immunity standards — a direct response to the electrically noisy environments of motor control centers and variable-frequency drive installations. Later production runs added dual relay outputs for high/low flow alarms, replacing the earlier single-relay architecture. The display evolved from a 4-digit LED to a high-contrast 5-digit red LED with configurable decimal point positioning.

As the broader instrumentation market transitioned toward fieldbus and Ethernet-based architectures (HART, PROFIBUS, EtherNet/IP), the DPF64-SQRT remained relevant as a standalone local indicator and totalizer, particularly in facilities where the cost of full DCS integration for individual flow loops was not justified. The series is now considered mature/end-of-active-production; OMEGA's current equivalent platforms include the DP25B-S and iSeries DP25B-E, which add RS-485 Modbus RTU communications. For plants committed to the DPF64-SQRT form factor, long-term maintenance support — not new deployment — is the primary procurement driver.

DPF64-SQRT Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified DPF64-SQRT series range. Each unit shares the core square-root extraction engine; variants differ by power supply, output configuration, and communication options.

DPF64-SQRT: Base rate meter, square-root extraction, 4–20 mA input, 5-digit LED display, no relay output.
DPF64-SQRT 110/220VAC: Dual-voltage AC-powered variant; field-selectable 110 or 220VAC supply; standard panel-mount.
DPF64-SQRT-DC: 24VDC-powered variant for battery-backed or DC-bus panel installations.
DPF64-SQRT-R: Adds single SPDT relay output (5A, 250VAC) for high-flow alarm or pump control interlock.
DPF64-SQRT-2R: Dual SPDT relay outputs; independent high and low flow setpoints with adjustable hysteresis.
DPF64-SQRT-AO: Adds isolated 4–20 mA analog retransmission output; loop-powered retransmit to DCS or chart recorder.
DPF64-SQRT-R-AO: Combined single relay + 4–20 mA retransmission output configuration.
DPF64-SQRT-2R-AO: Dual relay + 4–20 mA retransmission; most fully specified standard variant.
DPF64-SQRT-P: Pulse input variant; accepts turbine meter or positive displacement meter pulse trains; applies square-root scaling for DP-equivalent linearization.
DPF64-SQRT-T: Totalizer function enabled; accumulates flow volume in addition to rate display; non-volatile memory retains total on power loss.
DPF64-SQRT-T-R: Totalizer + single relay; relay can be configured for batch control (total-based cutoff).
DPF64-SQRT-T-2R: Totalizer + dual relay; supports both rate alarm and batch total relay simultaneously.
DPF64-SQRT-T-AO: Totalizer + 4–20 mA retransmission; retransmit signal tracks instantaneous flow rate.
DPF64-SQRT-T-2R-AO: Full-specification variant; totalizer, dual relay, and analog retransmission; maximum I/O configuration.
DPF64-SQRT-NEMA4: NEMA 4 / IP65 front-panel sealed variant for washdown or outdoor-rated enclosure installations.
DPF64-SQRT-NEMA4-R: NEMA 4 sealed + single relay output; for outdoor pump station or irrigation control applications.
DPF64-SQRT-NEMA4-2R-AO: NEMA 4 sealed, dual relay, and analog retransmission; highest-specification weatherproof variant.

Sourcing Hard-to-Find & Obsolete DPF64-SQRT Parts

The DPF64-SQRT series has entered the mature/declining phase of its product lifecycle. OMEGA Engineering no longer lists all sub-variants as active catalog items, and lead times through standard distribution channels are extended or indefinite for certain configurations. DriveKNMS maintains a dedicated inventory program for this series, sourcing units through authorized surplus channels, factory-refurbished stock, and verified third-party overhaul programs.

For facilities operating DPF64-SQRT meters in critical flow measurement loops — particularly where replacement with a modern equivalent would require recalibration of the entire DP flow loop, panel cutout modification, or DCS configuration changes — DriveKNMS provides a like-for-like replacement service. All units are verified against the original OMEGA factory specification sheets prior to shipment. Exchange programs are available for core returns. Long-term blanket purchase agreements can be arranged for utilities and EPC contractors managing multi-site DPF64-SQRT installed bases.

Quality Control for the DPF64-SQRT Range

Each DPF64-SQRT unit processed by DriveKNMS undergoes a structured verification protocol specific to the series' signal-conditioning architecture. Input linearity is verified across the full 4–20 mA range using a calibrated current source traceable to NIST standards; the square-root extraction function is validated at 0%, 25%, 50%, 75%, and 100% of span to confirm mathematical accuracy within ±0.1% of reading. For relay-equipped variants, relay pull-in and drop-out setpoints are tested against the unit's configured thresholds, and contact resistance is measured to confirm below 100 mΩ. Analog retransmission output accuracy is verified with a calibrated loop calibrator. Power supply input is tested at both 110VAC and 220VAC for dual-voltage units to confirm correct internal tap selection and stable operation. Display segment integrity is confirmed by full 8-segment test. All units are burned in at operating temperature for a minimum of 4 hours prior to final inspection.