The Dwyer 682-3 is a gauge pressure transmitter from the SERIES 682 family, engineered for harsh industrial environments. Designed to withstand environmental effects such as shock, vibration, temperature, and EMI/RFI, the 682 series packages a capacitive sensing element and signal-conditioning electronics inside a welded 17-4 PH stainless steel housing rated NEMA 4 / IP65 — making it suitable for hydraulic systems, compressor discharge monitoring, industrial engine oil pressure, fuel systems, off-road and mobile equipment, and any liquid or gas pressure measurement in the 0–250 psi range.
The 682-3 measures gauge pressure from 0 to 250 psi with a maximum overpressure tolerance of 500 psi (2× the working range) and delivers a 2-wire 4–20 mA current loop output proportional to the measured pressure. Accuracy is ±0.13% of full scale (±0.325 psi at full scale on this range), inclusive of non-linearity, hysteresis, and non-repeatability. The 9–30 VDC operating voltage range and 800 Ω loop resistance make the 682 a drop-in replacement for most industrial transmitters, with a 5 ms response time fast enough for closed-loop pressure control.
Hydraulic system pressure monitoring, compressor discharge, industrial engine oil and fuel pressure, off-road equipment, refrigeration high-side, and process applications requiring rugged pressure measurement up to 250 psi with NEMA 4 weatherproof protection.
Key Features
Combined accuracy spec (RSS of non-linearity, hysteresis, and non-repeatability) of ±0.13% of full scale — ±0.325 psi at full scale on this 0–250 psi range. Better than most industrial transmitters in its class.
Solid-state capacitive pressure sensor with no moving parts — immune to mechanical wear and inherently more shock-resistant than diaphragm-strain-gauge designs. Long-term stability of 0.5% FS per year keeps the sensor inside spec without periodic recalibration.
Precipitation-hardened 17-4 PH stainless steel pressure port and wetted components — harder and more corrosion-resistant than standard 304 SS, suitable for industrial fluids including hydraulic oil, fuel, refrigerants, and high-pressure water.
Fully welded stainless steel housing rated NEMA 4 / IP65 — weatherproof for outdoor installation, washdown environments, and harsh industrial conditions. Not affected by EMI/RFI interference common to industrial sites.
Industry-standard 4–20 mA current loop on a 2-wire cable — loop-powered, noise-immune over long cable runs, and compatible with virtually any industrial controller or PLC analog input. 800 Ω max loop resistance, 9–30 VDC supply.
Rated for 200 g shock and 20 g vibration across 50–2000 Hz — survives the kind of mounting environments (engine compartments, compressor skids, off-road equipment) where lab-grade sensors fail within months. 5 ms response time.
Technical Specifications
| Specification | Value |
|---|---|
| Series | 682 |
| Manufacturer Part Number | 682-3 |
| Sensor Type | Capacitive, solid-state |
| Service | Compatible liquids and gases (17-4 PH SS-compatible) |
| Wetted Parts | 17-4 PH stainless steel |
| Pressure Range | 0 to 250 psi (gauge) |
| Overpressure Limit | 500 psi (2× range) |
| Accuracy | ±0.13% FS (±0.325 psi at full scale) — RSS of non-linearity, hysteresis, non-repeatability |
| Long-Term Stability | 0.5% FS / year |
| Output Signal | 4–20 mA, 2-wire current loop |
| Power Requirements | 9 to 30 VDC |
| Loop Resistance | 800 Ω max |
| Response Time | 5 ms |
| Zero / Span Adjustment | External potentiometers, ±0.5 mA non-interactive |
| Operating Temperature | −40 to 260°F (−40 to 125°C) |
| Compensated Temperature Range | −4 to 176°F (−20 to 80°C) |
| Thermal Effect (Zero Shift) | 1.0% FS / 100°F |
| Thermal Effect (Span Shift) | ±1.5% FS / 100°F |
| Humidity | 10 to 90% RH, non-condensing |
| Process Connection | 1/4" male NPT |
| Electrical Connection | 2 ft (51 cm) multiconductor cable, vented to atmosphere |
| Enclosure | Welded 17-4 PH stainless steel |
| Protection Rating | NEMA 4 / IP65 |
| Shock | 200 g operating |
| Vibration | 20 g, 50–2000 Hz |
| Weight | 8 oz (227 g) |
| Agency Approval | CE |
| Warranty | 1-year manufacturer warranty |
What’s In the Box
- Dwyer Series 682 industrial pressure transmitter (682-3, 0–250 psi gauge, 4–20 mA output)
- 2 ft (51 cm) integral multiconductor cable
- Factory calibration (no field calibration required)
- Installation instructions (also available below as PDF)
Documentation
Frequently Asked Questions
The 682-3 is a gauge pressure transmitter that measures the pressure of liquids or gases (compatible with 17-4 PH stainless steel) from 0 to 250 psi relative to atmosphere, and outputs a 2-wire 4–20 mA current loop signal proportional to the measured pressure. The output is loop-powered (the sensor draws its operating current from the same 2-wire loop), compatible with virtually any industrial controller or PLC analog input.
This range fits the heart of industrial pressure applications: hydraulic system working pressures (commonly 500–3000 psi), compressor discharge, engine oil and fuel pressures, and refrigeration high-side. The accuracy spec of ±0.325 psi at full scale gives you usable resolution at the typical operating pressures, and the 500 psi overpressure rating handles transient spikes and pump pulsations without damage.
The 500 psi overpressure rating is the maximum static pressure the sensor can tolerate without damage or permanent zero/span shift. Inside the rated range (250 psi maximum measured value), the sensor is in spec. Between 250 and 500 psi the sensor will not be damaged but readings will saturate at the 20 mA top end. Exceeding 500 psi can permanently damage the capacitive sensing element. For applications with potential transient spikes (water hammer, pump start-up, valve closure), size the sensor so peak transients stay inside the overpressure rating, not just inside the working range.
The 682 wetted parts are 17-4 PH (precipitation-hardened) stainless steel — corrosion-resistant and harder than standard 304 SS. Compatible with hydraulic oils, fuels, refrigerants, water (including high-pressure water service), compressed air, nitrogen, and most industrial gases and liquids. For unusual chemistries, aggressive acids, or chloride-rich environments, verify 17-4 PH SS compatibility against your specific fluid before specifying.
Every Series 682 ships factory-calibrated and typically requires no field adjustment. If field calibration is needed, external zero and span potentiometers are accessible by removing the pan head screws on the housing — each adjustment has a non-interactive ±0.5 mA (approximately ±1.0 mA total) range. Dwyer recommends correcting any small offsets via software in the user's control system rather than touching the potentiometers, and to replace the pan head screws after any adjustment to maintain the NEMA 4 / IP65 enclosure rating.
Because the 682 measures gauge pressure (pressure relative to atmosphere), the reference side of the sensor needs a path to atmospheric pressure that compensates for barometric and altitude changes. Dwyer routes that reference vent through the integral cable rather than drilling a separate vent port in the housing — preserving the NEMA 4 rating. The installation requirement: the end of the cable must terminate in a vented junction box (or similar enclosure with a controlled atmospheric vent). Do not seal or cap the cable end. The installation manual PDF below shows a recommended vented junction box configuration.
Yes — the welded stainless steel housing and NEMA 4 / IP65 rating are specifically designed for outdoor and harsh-environment use. The 682 is rated for 500 psi overpressure, 200 g shock, 20 g vibration across 50–2000 Hz, an operating temperature of −40 to 260°F, and is unaffected by EMI/RFI interference. Common deployments include compressor skids, engine compartments, off-road equipment, outdoor refrigeration systems, and industrial process plants. The cable end junction box should be rated for the local environment as well.
HVAC sensors (Belimo 22WP, Senva PW31, BAPI ZPM, etc.) are typically rated to lower static pressures, lower temperatures, lower shock/vibration, and use strain-gauge or piezoresistive sensing elements. They're designed for mechanical room and clean-environment service. The Dwyer 682 is industrial-grade: capacitive sensing element (no moving diaphragm), 17-4 PH SS construction, 200 g shock rating, and pressure ranges extending to 10,000 psi. Pick the 682 when the install environment is rough (engine bays, off-road, outdoor industrial) or when the pressure range exceeds typical HVAC envelope (above ~250 psi).
