Taiwan 0809 090 375 | Intl +65 6415 5353 | Welcome to our new site - found a bug? Please report it here
Series-668
Cost-Effective HVAC Differential Pressure Transmitter, ± 1% Accuracy, Compact
- Good accuracy at low pressure ranges provides exceptional value for ensuring control and minimizing costly out of specification conditions
- High overpressure rating eliminates possible damage to unit reducing unnecessary service time
Series-668
From
TWD
9,597
Product Overview
- Accuracy ± 1 %
- Accuracy Detail ± 1% of full-scale (RSS) (includes non-linearity, hysteresis, and non-repeatability)
- Applications HVAC
- Compensated Temperature, Max 65 °C
- Compensated Temperature, Min -18 °C
- Display Type N/A
- Electrical Output 4 to 20 mA
- Loop Resistance 0 to 800 Ω
- Materials Glass Filled Polyester
- Media Compatibility Clean dry air / inert gas, HVAC / room air, Inert / non-reactive gases, Helium, Nitrogen, Non-Corrosive Dry Gases
- Number of Wires 2
- Operating Temperature, Max 65 °C
- Operating Temperature, Min -18 °C
- Output Signal Current
- Measurement Pressure Type Differential
- Process Connection Size 3/16 in
- Process Connection Type Barbed Fitting
- Proof Pressure Up to 10 psi
- Response Time < 60 ms
- Series ID Series-668
- Span Adjustment Adjustable
- Storage Temperature, Max 85 °C
- Storage Temperature, Min -40 °C
- Supply Power Type DC
- Supply Voltage 12 to 30 Vdc
- Thermal Effects 0.018% FS/°C
- Weight 85 g
- Zero Setting Adjustable Range ± 1 mA, noninteractive.
Supported Applications
The Dwyer Series 668 is a compact differential pressure transmitter designed for measuring low pressures in HVAC systems. Documented applications include building pressurization, air flow control, and variable air volume (VAV) systems within building management environments.
Operating Conditions & Performance
The Series 668 utilizes a variable capacitance sensor to achieve an accuracy of ±1% FS (RSS), which includes non-linearity, hysteresis, and non-repeatability. The transmitter operates within an ambient temperature range of 0 to 150°F (-18 to 65°C) with thermal effects specified as 0.033% FS/°F (0.18% FS/°C). It is rated for a maximum pressure limit of 10 psig (0.69 bar) and features reverse-polarity protection on the input.
Performance specifications include:
- Response Time: <60 msec
- Power Supply: 12 to 30 VDC
- Output Signal: 4 to 20 mA, 2-wire (load resistance: 0 to 800 Ω)
- Storage Temperature: -40 to 185°F (-40 to 85°C)
The device is suitable for service with air and non-conductive gases. The housing material is fire retardant glass filled polyester.
Configuration Options
The series offers a broad selection of fixed pressure ranges, categorized into standard unidirectional models and bi-directional configurations. Ranges span from 0 to 0.25 in w.c. up to 0 to 100 in w.c., with specific low-range options such as -0.05 to 0.20 in w.c.
Configuration options include:
- Housing Styles: Standard compact housing or an optional conduit cover (indicated by the 'C' suffix, e.g., 668C-1).
- Process Connection: 3/16" OD fitting for 1/4" ID tubing.
- Calibration Options: NIST traceable calibration certificate available (add '-NISTCAL-PT1' to the model number).
The transmitter features a terminal strip electrical connection and allows for non-interactive zero and span adjustment. For optimal response times, tubing recommendations suggest 3/16" I.D. for lengths up to 100 feet, 1/4" I.D. for lengths up to 300 feet, and 3/8" I.D. for lengths up to 900 feet.
Key Product Differences
The Series 668 is distinguished by its model numbering system which encodes the pressure range directly into the part number (e.g., 668-1 corresponds to a 0 to 0.25 in w.c. range). The series includes two primary housing variations: the standard compact unit and the conduit cover version.
Available accessories include:
- A-489: 4" straight static pressure tip with flange.
- A-302F-A: 303 SS static pressure tip with mounting flange, designed for 3/16" ID rubber or plastic tubing; includes a 4" insertion depth and mounting screws.
Note that these devices are not field repairable. Pressure ranges are fixed at the factory and cannot be changed in the field.
PDFs & Manuals
