METER AQUALAB PAWKIT User Manual

11
PAWKIT
Thermopile
sensor
Sensor
chamber
Sensor
cover
Sensor
filter
Figure11 PAWKIT hardware
The PAWKIT uses a capacitance humidity sensor to measure the water activity of a sample.
The sensor is suspended behind the sensor filter and uses a special polymer material
sandwiched between two microporous electrodes to sense humidity changes. The sensor
measures a specific capacitance, which is translated by the software and displayed as
water activity on the instrument screen. At equilibrium, the relative humidity of the air in the
chamber is the same as the water activity of the sample.
The PAWKIT is accurate to ±0.02 a
w
. For many applications, this accuracy is more than
adequate. If a higher accuracy is required, METER recommends using the AQUALAB 4TE or
TDL Water Activity Meter. Contact Customer Support for more details.
The PAWKIT system comes with 60 disposable plastic sample cups and one stainless steel
sample cup. Additional quantities of cups can be purchased from METER.
3.3 THEORY
Water is a major component of foods, pharmaceuticals, and cosmetics. Water influences
the texture, appearance, taste and spoilage of these products. Quantifying these attributes
require two basic types of water analysis: moisture content and water activity (a
w
):
3.3.1 MOISTURE CONTENT
Moisture content implies a quantitative analysis to determine the total amount of water
present in a sample. There are two primary methods for determining moisture content: loss
on drying and Karl Fischer titration. Secondary methods, such as near infrared (NIR) and
nuclear magnetic resonance (NMR), may also be used. Moisture content determination
is essential in meeting product nutritional labeling regulations, specifying recipes, and
monitoring processes.

METER AQUALAB PAWKIT Specifications

General

Brand	METER
Model	AQUALAB PAWKIT
Category	Measuring Instruments
Language	English