Series-679

Supported Applications

The Dwyer Series 679 is a factory-calibrated gauge pressure transmitter designed for weatherproof service in NEMA 4/IP56 environments. It senses gauge pressure and converts it to a proportional analog output, specifically compatible with corrosive liquids and gases that are chemically resistant to 17-4 PH Stainless Steel wetted parts. The device functions as a true gauge transducer where the reference side of the sensing diaphragm is vented to atmosphere.

Applications include monitoring pressure in processes involving media suitable for 17-4 PH SS, with specific exclusion noted: hydrogen is not recommended. The transmitter supports standard pipe fittings and includes two 1/2" NPT female conduit ports for electrical termination via a removable terminal block connector or direct wiring.

Operating Conditions & Performance

The Series 679 delivers an accuracy of ±0.25% FS, which includes non-linearity, hysteresis, and non-repeatability. Stability is rated at less than .5% FS per year. The transmitter operates within a compensated temperature range of -4 to +176 °F (-20 to +80 °C) for ambient conditions, while the process temperature limits extend from -40 to +260 °F (-40 to +125 °C). Humidity tolerance is specified as 10 to 90% RH, non-condensing.

Electrical performance requires a DC power supply in the range of 9-30 VDC. For current output units (4-20 mA), the loop resistance must not exceed 800 ohms. The device is factory calibrated to specific zero and span settings: voltage outputs are set at 0.1 VDC (±25mV) for zero and 5.1 VDC (±50mV) for span, while current outputs are set at 4 mA (±0.08mA) for zero and 20 mA (±0.16mA) for span.

Model Selection & Overpressure Limits

The series offers nine distinct models covering pressure ranges from low to high differential, each with a defined overpressure limit:

• 679-0: 0 to 25 psi range; 100 psi overpressure.
• 679-1: 0 to 50 psi range; 150 psi overpressure.
• 679-2: 0 to 100 psi range; 300 psi overpressure.
• 679-3: 0 to 250 psi range; 500 psi overpressure.
• 679-4: 0 to 500 psi range; 1000 psi overpressure.
• 679-5: 0 to 1000 psi range; 2000 psi overpressure.
• 679-6: 0 to 3000 psi range; 4500 psi overpressure.
• 679-7: 0 to 5000 psi range; 7500 psi overpressure.
• 679-8: 0 to 10,000 psi range; 12,000 psi overpressure.

Configuration Options

The Series 679 is available with two primary output signal configurations: a voltage output of 0.1 to 5.1 VDC or a current output of 4-20 mA (2-wire). The housing material is aluminum, providing the NEMA 4/IP56 weatherproof rating required for outdoor or washdown environments.

Key configurable and fixed features include:

• Process Connection: Standard 1/4" male NPT fitting. For pressures exceeding 500 psig, the use of a sealant such as Loctite Hydraulic Sealant is suggested.
• Electrical Connections: Two 1/2" conduit ports with a removable terminal block connector featuring five terminals (+EXC, -EXC, GND, -OUT, +OUT).
• Adjustment Options: Zero and span adjustments are available via software in the user's control system or physically through potentiometer screws located under the removable screw top cover. Adjustments allow for ±15% non-interactive changes.
• Agency Approvals: CE marked.

Key Product Differences

The primary variation within the Series 679 is defined by the model number suffix (0 through 8), which dictates the specific pressure measurement range and corresponding overpressure limit. The physical dimensions of the unit are consistent across models, with an overall height of 4.00 [102] mm, width of 4.02 [102] mm, and depth of 2.55 [65] mm.

While both voltage (0.1 to 5.1 VDC) and current (4-20 mA) outputs are documented capabilities for the series family, specific stocked variants may be configured for one output type depending on the model selection table provided in technical documentation. The device is not field repairable; recalibration or service requires return to the factory.