Dwyer 682-6 : Industrial Pressure Transmitter, 0 to 3,000 psi, 4,500 psi Overpressure, 4-20 mA Output, +/-0.13% FS Accuracy, NEMA 4 / IP65

The 682-6 is a gauge pressure transmitter that measures the pressure of liquids or gases (compatible with 17-4 PH stainless steel) from 0 to 3,000 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.

Very high-pressure hydraulic systems (hydraulic presses, heavy industrial machinery, hydraulic stamping), oil & gas wellhead pressure, high-pressure water cleaning, and similar heavy industrial applications. At 3,000 psi maximum range with 4,500 psi overpressure tolerance, this is industrial-grade pressure measurement — the kind of envelope where standard HVAC sensors don't survive. For pressures above the rated range, see the 682-8 or contact Dwyer for higher-pressure custom options.

The 4,500 psi overpressure rating is the maximum static pressure the sensor can tolerate without damage or permanent zero/span shift. Inside the rated range (3,000 psi maximum measured value), the sensor is in spec. Between 3,000 and 4,500 psi the sensor will not be damaged but readings will saturate at the 20 mA top end. Exceeding 4,500 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 4,500 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).