For many years, Campbell Scientific has offered the HMP45C as our higher-accuracy temperature and
relative-humidity probe.With the retirement of the HMP45C (due to part obsolescence), our goal was to find an appropriate replacement that would minimize the difficulties that can surface when replacing one sensor with another—a replacement in fit, form, and function.
Our search led us to the HC2S3. The HC2S3 offers comparable accuracy to the HMP45C at a reduced price. The HC2S3 also has similar wiring and programming,and is housed in the same 41003-5 10-plate radiation shield (requires included hex plug) as the HMP45C.
The HC2S3 is offered in standard or high accuracy versions. The standard accuracy is calibrated at 23 degrees C at 10%, 35% and 80% humidity. The high accuracy is adjusted at 23 degrees C and 10, 20, 30, 40, 50, 60, 70, 80, 90% relative humidity and then calibrated at 20, 50 and 80% relative humidity giving superior accuracy suitable for such applications as Bowen Ratio.The HC2S3 uses a capacitive sensor to measure relative humidity and a 100 ohm PRT to measure temperature. It includes a polyethylene filter that protects the capacitive sensor from fine dust and particles and minimizes water absorption and retention. Alternatively, a Teflon filter is available for marine environments.
Added to this, the HC2 S3 not only measures relative humidity and temperature but calculates dew/frost point.
Although the HMP45C is no longer available, we will still re-calibrate existing probes through our standard RMA procedure.