Senva PW31-X-100C : Wet-Wet Differential Pressure Transducer, 0-100 PSID, 4-20mA Output, 7-Year Warranty

The PW31-X-100C is a wet-to-wet differential pressure transducer that measures liquid pressure difference between two ports across the 0–100 PSID range and outputs a 2-wire 4–20 mA loop-powered current signal proportional to that differential. It delivers ±0.25% FS accuracy (±0.25 PSID at full scale) and is designed for direct connection to BAS analog inputs.

The 0–100 PSID range is the right choice when your working differential falls in the upper portion of that range — large high-head pump applications, big boiler plant differentials, district energy systems. For lower-DP applications (chiller evaporator, balance valves, small-loop pumps), the 0–5, 0–10, or 0–25 PSID variants give substantially better effective resolution. Match the sensor range to the working DP, not to the worst-case static line pressure (which is handled separately by the 500% FS maximum static rating).

500 PSIG maximum static pressure on both ports to maintain rated accuracy. The line pressure effect is ≤0.0035% FS per PSIG of static pressure (zero shift), so at the full 500 PSIG static line condition you would see a maximum zero offset of about 1.7500 PSID — well inside normal calibration drift. If your system runs at higher static pressures, you need a higher-range PW31 (max static scales with DP range at 5×).

Yes. The wetted parts are 316L stainless steel with Fluororubber (Viton) O-rings — compatible with water, water-glycol mixtures (propylene and ethylene), and any liquid or gas compatible with both 316L SS and Viton. For unusual chemistries, verify compatibility against both materials before specifying.

No. Every PW31 ships from Senva factory-calibrated with a calibration certificate documenting the unit-specific calibration data. Field calibration is neither necessary nor recommended — if a sensor reads incorrectly, the most common cause is trapped air in the pressure lines (see the bleed procedure in the installation instructions), not sensor drift.

A single-diaphragm differential sensor measures the pressure difference directly — the line pressure cancels out at the diaphragm. A pair of single-port gauge-pressure sensors computing the difference electronically inherits the full-scale error of both sensors AND is affected by line-pressure-effect drift on each side. For low-DP applications at moderate-to-high line pressures, the single-diaphragm approach delivers an order of magnitude better effective accuracy.

It means the sensor's zero and span calibration may drift by up to ±0.5% of full scale (±0.5 PSID on this 0–100 range) per year of continuous service under normal conditions. In practice, with stable wetted media and within compensated temperature range, most PW31 sensors show drift well inside this spec. For most BAS applications the drift over a 5–7 year service life remains within the original accuracy envelope.

The -X- suffix means “no bypass manifold” — the transducer ships as a standalone unit. A bypass manifold (3-valve or 5-valve) lets you isolate and equalize the sensor without depressurizing the system, which is required by many institutional specs for service and commissioning. If your spec calls for a manifold, order the PW31-3V-100C (3-valve) or PW31-5V-100C (5-valve) variant instead.

Yes. The PW31 LED display is loop-powered and connects in series with the 4–20 mA output via a Hirschmann-style connector. You can order the display separately as a retrofit, or order the PW31-X-100C-D variant up front with the display pre-fitted. The display only works with 4–20 mA loop-powered output — not available for the 0–5V or 0–10V variants.