Description

The HC2A-AW-USB, HygroLab and HygroPalm23-AW probe are designed for use with the WP-40 sample holder. The PS-40 sample containers fit into the sample holder and ensure sample is kept at a stable temperature during sampling. A removable depth reduction insert can also be used to allow the smaller PS-14 sample containers to be used in the same sample holder.

The deep PS-40 sample cups are more suitable for products in larger chunks, or just to ensure the product doesn’t touch the probe. In general, the shallow PS-14 cups, together with the depth reduction insert, can be used for liquids, pastes or powders.

The disposable sample cups serve two purposes:

1. Provide a means storing product samples prior to measurements so that they can come to the same temperature as the probe.
2. Prevent contamination across samples.

Prior to measurements, fill a number of disposable sample cup with the products to be measured. Usually, filling up to 1/3 of the cup is sufficient. To avoid soiling the probe, do not fill the cup above the fill line (see below).

Additional Guidelines

1. Measure water activity only in a temperature stable area. This is an essential requirement! Do not measure on a bench that is located near a heater, an AC vent or an open window. Avoid direct exposure of the probe and/or product samples to sun light (heating effect). For best accuracy, temperature should not change by more than 0.01°C / minute (0.0075°C / minute in the case of product with a water activity > 0.80 aw
2. Prior to measurements, place each product sample in a disposable sample cup with the cover on. Place the cups in the same general area as the probe. Allow for sufficient time for the samples to come to the temperature of the probe (usually room temperature). A frequent mistake is to measure product samples which have been kept overnight in a refrigerator without first allowing them to come to room temperature. Another mistake is to measure samples coming straight from a hot manufacturing process. To measure water activity at a temperature other than room temperature, place both the probe and the product samples in an incubator set at the desired temperature.
3. Prior to using the probe, verify the integrity and cleanliness of the sealing O-ring located under the probe.
4. Avoid warming up the probe, the sample holder or the product sample by touching or holding for too long in your hand.

Probe Calibration

The shallower PS-14 sample cups together with the depth reduction insert are suitable for calibrating the probe with the Rotronic certified humidity standards or with saturated salt solutions.