DIFFERENTIAL PRESSURE

Differential Pressure Transducers — Filter, Flow & Level Monitoring

A differential pressure transducer compares pressure at two points and outputs the difference as a 4–20 mA signal — the direct way to detect clogged filters, measure flow through an orifice, and read tank level. Factory-configured to your span, with 316L wetted parts.

How It Works

HOW IT WORKS

Two Ports, One Difference — ΔP = P_high − P_low

The transducer body carries two pressure ports. The high (+) port connects upstream — before the filter, before the orifice, at the bottom of the tank. The low (–) port connects downstream — after the filter, after the orifice, or to the atmosphere / vapor space.

The diaphragm deflects by the difference between the two pressures, and the piezoresistive cell converts that deflection into a proportional 4–20 mA signal. Because both ports see the same line pressure, common-mode shifts cancel out — you measure the difference, not the absolute value.

No moving parts — a welded 316L diaphragm is the only interface with the media
Common-mode rejection: line pressure changes do not shift the reading
4–20 mA two-wire output with 0–10 V or RS485 optional
Custom spans from 0–100 Pa to 0–1 MPa, factory-calibrated to your window

APPLICATIONS

Three Jobs One ΔP Transducer Does Every Day

Filter & Strainer Monitoring

Mount the high port upstream and the low port downstream of a filter. As the element loads, ΔP rises — you get a precise, repeatable "replace me" signal instead of guessing by pressure gauges, and you never starve the pump or burst the element.

Water treatment applications

Flow Measurement

Across an orifice plate, venturi or pitot tube, flow is proportional to the square root of ΔP. One differential pressure transducer plus a primary element gives you a low-cost, reliable flow reading on water, air and gas lines without moving parts in the flow.

HVAC applications

Tank Level Measurement

With one port at the tank bottom and the other open to the atmosphere (or to the vapor space of a closed tank), ΔP equals the hydrostatic head — ρ × g × h. It is the standard method for open and closed tanks, including slurries and aggressive media.

Hydraulic applications

Typical Specifications

Every differential pressure transducer is built to your span — the table below is a typical configuration, not a fixed catalog item.

Item	Typical Configuration
Measurement	Differential pressure between high (+) and low (–) ports
Pressure Range	0–100 Pa to 0–1 MPa typical (custom spans)
Output Signal	4–20 mA two-wire (0–10 V / RS485 optional)
Accuracy	±0.5% FS typical
Overpressure	2× FS without damage (static pressure per spec)
Wetted Material	316L stainless steel
Process Connection	G1/4 or M20×1.5 (other threads on request)
Enclosure	IP65 / IP67
Temperature	–20 to +85 °C

* Typical values — final span, output, thread and static pressure rating are configured per order. Send us your process data for the exact specification.

Deep Dive Guides

Pressure Transducer Working Principle →What Is a Pressure Transducer? Working Principle & Types →Pressure Sensor Types: A Complete Classification →

FAQ

Questions Buyers Ask

What is differential pressure?

Differential pressure (ΔP) is the difference between two pressures measured simultaneously — one applied to the high (+) port, one to the low (–) port. Unlike a gauge transducer, a differential pressure transducer reads the difference directly, so common-mode pressure changes cancel out and you measure only what changed between the two points.

How do I measure flow with a differential pressure transducer?

Install a primary element — an orifice plate, venturi or pitot tube — in the line. The element creates a ΔP proportional to flow squared; the transducer measures that ΔP and your controller computes flow. It is a mature, maintenance-friendly method for water, air and gas lines.

How does differential pressure detect a clogged filter?

A clean filter has a small, known ΔP across it. As the element loads, ΔP rises toward a setpoint you define. Mounted permanently, a differential pressure transducer turns "check the filter" into an automatic alarm or control action — protecting pumps and preventing element rupture.

How is tank level measured with differential pressure?

The hydrostatic pressure at the bottom of a tank equals ρ × g × h. With the high port at the bottom and the low port vented to atmosphere (open tank) or to the vapor space (closed tank), the transducer reads the level directly. It works with slurries and aggressive media where other methods fail.

What ranges and outputs are available?

Typical spans run from 0–100 Pa to 0–1 MPa, with 4–20 mA two-wire output as standard and 0–10 V or RS485 optional. Every unit is factory-configured to your span — send us the expected ΔP window and static pressure and we will set the range and proof margins.

Can I use it for static pressure too?

Every differential pressure transducer is specified with a maximum static (line) pressure it can withstand on both ports. Tell us your line pressure as well as your ΔP range — we will match the instrument so the static rating is never exceeded.

Tell Us Your ΔP Window — We Will Configure the Rest

Send your expected differential pressure range, static line pressure, media and output — factory-configured and quoted within 24 hours.