Relative micro-manometer

differentialdialglass

Overview
The Compensated Micro-manometer is a precision instrument designed for measuring very small positive pressures, negative pressures (vacuum), and differential pressures of non-corrosive gases. It can be used for calibration of other pressure instruments when used with an appropriate regulator. It features an elegant, durable housing, clear indication, and a scale plate graduated in mmH₂O (millimeters of water column).

Intended Use & Applications

• Primary function: Measurement of low positive pressure, negative pressure (vacuum), and differential pressure of non-corrosive gases.
• Secondary function: Calibration of other pressure instruments (when used with a regulator).
• Typical users:
  • University teaching and research laboratories
  • Metrology and calibration institutions
  • Coal mining enterprise laboratories
  • Industrial HVAC and ventilation testing
  • Filter resistance measurement
  • Cleanroom pressure differential monitoring

Key Features

• High accuracy for micro-pressure measurements
• Compensated design that eliminates liquid level reading errors
• Clear scale plate with mmH₂O graduations
• Smooth adjustment mechanism for precise pressure setting
• Built-in leveling system for accurate vertical alignment
• Attractive, durable housing suitable for laboratory environments

Technical Specifications (table summary)
Parameter | Specification
Measurement Range | mmH₂O (e.g., -250 ~ +250 mmH₂O, 0 ~ 1500 mmH₂O, etc.)
Basic Error | % of full scale or [ ] mmH₂O (model-dependent)
Scale Division | 200 divisions on the fine adjustment dial
Pressure Unit | mmH₂O (millimeters of water column)
Working Medium | Non-corrosive gases (air, nitrogen, etc.)
Ambient Temperature | [ ] °C (typical laboratory conditions)
Dimensions | [ ] mm
Weight | [ ] kg

Construction & Components
The instrument consists of four main sections: the fine adjustment part, the level observation part, the reflector part, and the housing part.

1. Fine Adjustment Part

• A fine adjustment dial engraved with 200 equal divisions is fixed onto a long lead screw.
• The lead screw drives the water storage cylinder up or down.
• An indicator slider is attached to the static pressure connection nozzle on the water chamber.
• The slider moves along a graduated scale, indicating the displacement height of the water storage cylinder.

2. Level Observation Part

• A level head is installed inside the observation tube.
• The operator observes the change in liquid level inside the observation tube when pressure is applied through the dynamic pressure tube.

3. Reflector Part

• A reflector mirror is fixed within the mirror housing to reflect the contact condition between the level head and the liquid surface.
• Zero adjustment ("base point") is achieved when the tip of the level head touches its reflected image, indicating the correct reference for readings.

4. Housing Part

• The housing and cross-arm support the long lead screw.
• A leveling bubble (spirit level) and leveling screws are mounted on the housing to adjust vertical alignment before use.

Operating Principle (Simplified)
The compensated micro-manometer balances an applied pressure against the hydrostatic pressure of a liquid column (typically water or a low-viscosity oil). The water cylinder height is adjusted with the fine adjustment dial until the liquid level returns to a fixed reference point observed via the reflector; the applied pressure is then read directly from the scale and dial, compensated for zero drift.

Included in Standard Delivery

• Compensated Micro-manometer main unit
• Leveling bubble (spirit level) – pre-installed
• Adjustment tools
• Operating manual (Chinese / English available upon request)

Not included (required for operation)

• Working liquid (distilled water or specified fluid)
• Connecting hoses
• Pressure regulator (if used for calibration)
• External pressure source (if required)

Operation & Safety Notes
Before use:

• Place the instrument on a stable, vibration-free horizontal table.
• Adjust the leveling screws until the leveling bubble is centered.
• Fill with the specified working liquid to the correct level (see manual).
• Perform the base point zero adjustment using the reflector and fine adjustment dial.

During use:

• Ensure the gas being measured is non-corrosive to prevent damage to internal components.
• Do not exceed the maximum rated pressure range.
• Make all connections carefully to avoid leaks.
• Allow sufficient stabilization time after each pressure change.

After use:

• Release all pressure before disconnecting.
• Clean any spilled liquid immediately.
• Cover the instrument when not in use to prevent dust contamination.

General care

• Re-calibrate periodically according to local metrology regulations.
• Handle the glass observation tube and reflector with care.
• Store in a clean, dry environment within the specified temperature range.

Ordering Information
When ordering specify:

• Required pressure range (mmH₂O)
• Required accuracy class
• Preferred working liquid (if other than water)
• Any calibration certificate requirements (standard or traceable)

Caractéristiques / Spécifications techniques

• Measurement ranges available: examples include -250 ~ +250 mmH₂O, 0 ~ 1500 mmH₂O (model dependent)
• Scale division: 200 divisions on the fine adjustment dial
• Pressure unit: mmH₂O (millimeters of water column)
• Working medium: non-corrosive gases (air, nitrogen, etc.)
• Compensated design to eliminate liquid level reading errors
• Built-in leveling system (leveling bubble and leveling screws)