SmartTest Family

Hand held MS2123 Moisture Series

Water Activity Analyzer

Ref: HMS2123sWAIntE

Version: 2002-02-26

Recommended Measurement for Micro-biological, Chemical, Ultra fine powder and Enzymatic Materials

Typical Applications:

Food, pharmaceutical, coatings, hygroscopic powders, pills, paper, photographic film industry

Why Use Water Activity Terminology?

The active part of moisture content and, therefore, water activity, provide better information than the total moisture content regarding the micro-biological, chemical and enzymatic stability of perishable products such as foods and seeds. For similar reasons, water activity is equally relevant in the pharmaceutical industry where it provides useful information regarding the cohesion of tablets and pills, or the adherence of coatings. Water activity can be directly compared with the relative humidity of the ambient air to prevent dimensional changes in a product (paper, photographic film), to prevent hygroscopic powders (powdered sugar, salt) from caking or turning into a solid block, etc.
Water activity can be used with some products (mostly synthetic products) as a means of indirectly measuring the total moisture content. This requires developing sorption isotherms to this purpose. Sorption isotherms are graphs that provide the relationship between water activity and moisture content at constant temperature. For most natural products, repeatable sorption isotherms cannot be reliably developed and water activity should be regarded as separate from moisture content.

Series accessories, test gas, liquids to solids with the one instruments

Water Activity Definition

Water activity Aw (or equilibrium relative humidity %ERH) measures the vapor pressure generated by the moisture present in a hygroscopic product.
Aw = p / ps  and  %ERH = 100 x Aw, where:

p    : partial pressure of water vapor at the surface of the product
ps  : saturation pressure, or the partial pressure of water vapor above pure water at the product temperature
Water activity reflects the active part of moisture content or the part which, under normal circumstances, can be exchanged between the product and its environment.
Water activity is usually defined under static conditions of equilibrium. Under such conditions, the partial pressure of water vapor (p) at the surface of the product is equal to the partial pressure of water vapor in the immediate environment of the product. Any exchange of moisture between the product and its environment is driven by a difference between these two partial pressures.

Accelerated water activity measurement in typically 5 minutes

Conventional water activity measurement with automatic detection of equilibrium

Includes carrying case, sample holder, disposable sample cups, humidity calibration standards.

Optional docking station with external AC adapter for bench top use

HBD5ms2100 analyzer accepts a large choice of probes, suitable for the direct measurement of products in bulk and other applications.

Instrument Functions

l Water activity test

l Moulds Free Safe Days (MFSL) prediction

l Humidity, temperature test

l Moisture measurement for gas, liquids and solids

l pH test supported

l Conductance test supported



Aw Range: 0.03-1.000

Accuracy: 0.015Aw (<+/-0.3°C, at room temperature )

Repeatability:< 0.005 Aw (<0.1°C, at room temperature)

Temperature: -20 to 85°C; -50 to 200°C

Instrument environ: -10 to 60°C 0-99%RH

Battery supply

3 mode to test: 

Test time: ~5 min Typical at WASmart:

Testing Mode

The HBD5MS2100NC is a battery operated water activity Analyzer with a single probe input. It features three operating modes:

Smart: accelerated water activity measurement with automatic end of measurement.

Normal: conventional water activity measurement with automatic detection of equilibrium and automatic end of measurement

Standard: water activity and temperature measurement, limited to just indicating the values and the trend of the values

The HBD5ms2123NC analyzer Set consists of the following:

HBD5ms2100 Analyzer



MS2123N probe

Universal for the measurement of gas, liquid, and solid product samples


Application assembly

additional probes accessories

order separately

Special sensors

additional probes

order separately

Standard’s Kit

1 box each EA35 (35 %RH) and EA80 (80%RH) humidity calibration standards


Carrying case




The MS2123NC is compatible with all the models of MS2123 probes to permit the direct measurement of products in bulk and quality control of packaging materials.

The probes used with the HBD5MS2123 analyzer can be calibrated and adjusted at one or more points, directly from the instrument keypad. Reference humidity values are provided by using the humidity standards.
When used with an external AC adapter, this allows powering the instrument without draining the battery. Battery charging is possible with the appropriate type of battery.

Standard Probe

MS2123N Sensor

Universal sensor for gases, liquids, solids application

Size: Dia.: Ø24; Length:300mm

Weight: 300g

Working temperature: <85 ºC

Additional Probes

FixFit NPT 1”

For fixing to pipe or temporary device.

Also needed for AW2123N-Cap

Size: Dia.: Ø42; Length:30mm

Weight: 300g

Connect: NPT1”/ZG1”.

Material: SUS316


For powder samples, accessory to HMS2123N

MS2123-Clamp Kit

for measurement of powder and bulk samples

Requires use of a sample holder and disposable sample cups

MS2123-Vap Kit

for measurement of powder and bulk samples with vaporization of the crystallized water internal of the samples.

Heating Temperature: Max 100 ºC

Requires use of a sample holder and disposable sample cups, supply of 300W AC power.



Accessory for Clamp Kit and Vap Kit

pack of 100 disposable sample cups (14mm deep)


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