Published 3 July 2026 at 10:19
Room pressurization is one of the most misunderstood parameters in modern building operations. Operating rooms are pressurized to prevent contaminated air from corridors from flowing in. Cleanrooms are pressurized (or depressurized, depending on the class) to ensure that particle-free zones are not contaminated or that pathogenic particles do not spread from sealed zones. Isolation rooms in hospitals for infectious patients are depressurized to prevent particles from spreading out. In all cases, the controlled differential pressure is typically 5–25 Pa — just a few thousandths of an atmosphere, but critical for safety. Measuring this with a standard manometer is impossible: standard manometers have a resolution starting from approximately 1 mbar (100 Pa) and upwards. A specially built low-pressure manometer is required.
What a ±137.8 mbar measurement range actually means
The HD700 precision manometer is built for exactly this purpose. The measurement range of ±137.8 mbar (equivalent to ±2 psi or ±13780 Pa) covers all common building pressurization applications with margin. The resolution is 0.001 psi — approximately 7 Pa — which enables the measurement of differential pressures down to very small values.
Combining a wide measurement range with high resolution is the technical challenge. A standard manometer with a wide range has coarse resolution; a precision manometer has high resolution but only in a narrow range. The HD700 solves this with a sensor that offers high linear accuracy across its entire range — not just in the middle.
Differential pressure vs. gauge pressure — and why both can be measured
The HD700 can be used in two modes:
Gauge mode: Pressure relative to atmospheric pressure. The standard mode for most industrial and laboratory applications.
Differential mode: Pressure between two points — the typical measurement task for building pressurization. One hose is connected to the “high” port (in the pressurized room) and one to the “low” port (in the reference room or corridor); the instrument directly displays the difference.
The 11 selectable measurement units (Pa, mbar, psi, inH2O, mmH2O, kPa, atmospheres, mmHg, inHg, ozf/in², kgf/cm²) cover all conventions used in different industries. A hospital technician chooses Pa, an HVAC engineer chooses mmH2O, a process technician chooses psi — everyone gets the same measurement value expressed in their own convention.
Why the NIST certificate matters
The instrument is delivered with a traceable NIST calibration certificate (five-week lead time). For healthcare and cleanroom applications, this is often a formal requirement in local regulations — without traceable calibration, the measurement values are not legally valid for documenting that requirements are met.
Practical consequence: a hospital technician verifying the pressurization of an operating room ahead of a Socialstyrelsen inspection needs documentation that is impossible without a traceable certificate. The HD700-NIST makes that documentation possible.
Where the precision manometer makes a real difference
Hospitals and operating rooms: Verification of positive pressure in operating rooms (typically +15 to +25 Pa), negative pressure in isolation rooms for infectious patients (typically -5 to -25 Pa), and pressure balancing of corridors and adjacent areas.
Cleanrooms: Class 100 and 1000 cleanrooms have specified pressurization requirements. A cleanroom technician verifies the pressure cascade between different class zones. Standard control equipment in cleanroom management.
Pharmaceutical production: GMP requirements for pharmaceutical cleanrooms are often stricter than technical ones: documented continuous pressurization over weeks. Precision manometers with data logging are used for this control.
Biosafety labs: BSL-3 and BSL-4 laboratories have extreme pressurization requirements to prevent pathogens from spreading out of containment. Regular checks are part of the mandatory safety work.
Food production: Sterile filling facilities for dairy products, beer, wines, and other sensitive foods. Positive pressurization prevents bacteria from entering from the environment.
HVAC balancing: Adjustment of duct system pressure during installation and service. Differential pressure across filters, dampers, and cooling loops to verify system function.
Building insulation control: Blower door testing to assess the building’s tightness against air infiltration. The standard test requires controlled pressure and precise pressure measurement.
Ventilation system verification: Stack draft, damper control, and pressurization of ventilation ducts during operation.
Chemical and process industry: Pressure measurement across filters, collectors, and components in process technical systems where small pressure deviations indicate emerging problems.
Ships and offshore: Control of pressurization in sanitary areas, galley lounges, engine rooms, and other areas where ventilation balancing is safety-critical.
Practical features worth mentioning
Max/Min/Average measurement: Captures pressure variations over time. A deviation of ten seconds is otherwise impossible to catch.
Zero function: For each new measurement, the instrument must be zeroed to the current atmospheric pressure. The HD700 does this with a single button press before the measurement begins.
Data Hold: Freezes the measurement value on the display so it can be read after the instrument has been moved from the measurement point.
Automatic shutdown: Saves battery during routine use; can be disabled for longer measurements.
USB port: Data is transferred to a PC for documentation and analysis. Software included.
What you get for the money
Precision manometer with a ±137.8 mbar measurement range and 0.001 psi (~7 Pa) resolution, 11 measurement units, Max/Min/Average recording, Data Hold, USB PC interface, large backlit LCD, robust double-cast instrument housing, traceable NIST calibration certificate.
7,109 SEK is the investment for a professional low-pressure differential instrument. For hospital technicians, pharmaceutical engineers, HVAC consultants, and cleanroom managers, it is standard equipment that is often cheaper than calling in an external calibration service for each verification. The instrument’s lifespan of decades makes the cost per measurement very low.
Read more: HD700-NIST precision manometer in the shop →
