Pressure differencesfrom ±20 Pa.Stable for years — no readjustment required.
The ring balance measures tiny pressure differences purely mechanically — via the gravitational force on a calibration weight. No spring, no diaphragm, no drift.
02 · Industries
Deployed where precision matters.
Cleanroom pressure cascade
ISO 14644 mandates continuous monitoring of pressure differential between cleanroom zones — typically 5 to 20 Pa. With a ring balance, you measure these differentials purely mechanically, consistently accurate. The restoring force is based on weight and geometry — no ageing components, no drift. This supports a risk-based extension of calibration intervals once the calibration history demonstrates stability.
HVAC
Filters age, dampers drift, volume flows shift. A ring balance delivers the current differential pressure over weeks, months, and years — no drift, no readjustment required, directly usable for replacement intervals, volume flow control, and filter diagnostics.
Draft measurement and furnace pressure control
Industrial furnaces, combustion chambers, and thermal process plants depend on stable draft — typically −20 to −300 Pa negative pressure. Aggressive flue gases, high temperatures at the connection, and continuous load are the challenge. A ring balance measures here without electronic sensors in the medium and on request delivers the control signal for damper actuation directly.
Differential pressure in hazardous areas
Where flammable gases, vapours, dusts, or mists can occur, ATEX directives apply. Rixen's RW65_EX_II is intrinsically safe for Zones 0/1/2 and 20/21/22 — a mechanical differential pressure gauge with built-in 2-wire transmitter, from 40 Pa span.
GMP Annex 1
The revision of EU GMP Annex 1 (2022) tightened requirements for the continuous pressure cascade in aseptic areas. Gapless documentation, clear differential values, displays readable at any time. We deliver mechanical instruments that have met these requirements for over 30 years at Bayer, Novartis, and Vetter — without ever needing a software patch.
Differential pressure measurement in biogas plants
Biogas is wet, corrosive, and combustible. Hydrogen sulphide (H₂S), ammonia (NH₃), and saturated humidity attack electronic sensors within months. A ring balance separates the measuring element from the medium and stays stable over years — including in fermenter atmosphere, gas storage, and treatment.
Fig. · Cross-section ring balance · Rixen Messtechnik
03 · Measuring principle
Mechanical. Permanently precise.
The ring balance is a standalone measuring principle — no spring, no diaphragm. Its restoring force comes solely from a calibration weight, an element that does not age. The result: no drift, no readjustment. Where standards mandate calibration intervals, these can be extended — the measuring principle is directly traceable to physical quantities.
Pressure application
Differential pressure acts on the partition in the ring tube, generating a torque.
Calibration weight
The calibration weight counteracts the torque — like a balance scale.
Equilibrium
At equilibrium the pointer directly indicates the differential pressure.
No drift
The measuring principle contains no ageing component — calibration remains stable for decades.
04 · Areas of application
Where ring balances have been working for decades.
From cleanroom pressure hold to ATEX — wherever very small pressure differentials must be measured reliably and permanently.
Cleanrooms & operating theatres
Pressure hold against the corridor (typ. 5–30 Pa). No drift = no false alarms = no unwanted shutdowns.
Filter monitoring
Contamination indication in HEPA and submicron filters. Contact output or 4–20 mA signals replacement need.
Industrial furnaces & boilers
Draft measurement in flue duct. Insensitive to aggressive gases — ideal for corrosive atmospheres.
Volume flow measurement
Square-root scale + differential pressure transmitter = direct volume flow. No additional electronics required.
Hazardous areas (ATEX)
RW65-Ex-II: ATEX II 1 GD, intrinsically safe 4–20 mA loop, stainless steel housing on request.
Building automation
Ventilation, smoke-control stairwells, climate regulation — everywhere small pressure differentials need to be permanently documented.
Most ordered
Which ranges do customers order most?
04 · Products
Product overview.
RW65
AvailableDifferential Pressure Indicator
View details
MU-Analog-65
AvailableDifferential Pressure Transmitter (analog)
View details
MU-Digital
AvailableDifferential Pressure Transmitter with LCD Display
View details
RW65_EX_II
AvailableATEX Differential Pressure Gauge (intrinsically safe)
View details
MU-Analog-65-2L
Available2-Wire Transmitter (passive, loop-powered)
View details
Rixotact 4
AvailableDifferential Pressure Controller with Three-Point Step Output
View details
RDS
AvailableRoom Pressure Probe
View details
DKL01
AvailableIntrinsically Safe 3-Color LED Beacon
View details05 · References
Trusted by industry for decades.
Pharma & GMP
- Bayer
- Novartis
- Vetter Pharma
- EBEWE
Energy & Chemicals
- Siemens
- Evonik
- Wacker Chemie
- EnBW
Furnace & Thermal Process
- Saint-Gobain
- Honeywell
- Wienerberger
- Keller HCW
Automotive
- Volkswagen
- Porsche
- Bosch
- Daimler
Selected users · Excerpt
Ring bodies — the core of the measuring principle
MU-Digital — calibrated and ready for final assembly
MU-Analog-65 before final assembly — scale hand-painted after calibration
06 · Next step
Have an application?
Whether cleanroom, ATEX zone, or furnace control — tell us your measuring range and medium, and we will recommend the right instrument.
Call us directly · +49 234 86790