Protimeter HygroMaster L with Hygrostick
The Protimeter HygroMaster L is a handheld thermo-hygrometer for professionals. It measures relative humidity, air temperature, dew point and specific humidity, with a replaceable humidity and temperature sensor. It is the lighter-featured version of the HygroMaster 2, built for spot readings of air condition.
This version ships with the Hygrostick, the sensor built for sustained high humidity and equilibrium relative humidity in concrete. It reads from 30% to 98% RH and will not report below 30%.
What is in the box
- HygroMaster L instrument
- Hygrostick humidity sensor (POL4750)
- Soft pouch
- Instructions
- 9 V battery
Applications
- Flood and water damage restoration
- Building survey and dampness diagnosis
- Concrete and concrete floor moisture measurement, in situ
- HVAC test and measurement
HygroMaster L or HygroMaster 2?
Both instruments use the same humidity sensors, share the same accuracy figures and are the same size and weight. The L is the lighter-featured model, and the difference is what it does not do.
| HygroMaster L | HygroMaster 2 | |
|---|---|---|
| Relative humidity, air temperature, dew point, specific humidity | Yes | Yes |
| Infrared surface temperature with laser pointer | No | Yes |
| Plug-in surface temperature probe | No | Yes |
| Surface proximity to dew point | No | Yes |
| Unattended data logging and PC download | No | Yes |
Choose the L if you take spot readings of air condition and record them yourself. Choose the HygroMaster 2 if you need to leave the instrument recording, or if you report surface temperature against dew point — which is the measurement that tells you whether a surface is about to attract condensation.
Hygrostick or Quickstick
The instrument takes two interchangeable sensors and they are not equivalent.
| Hygrostick (POL4750) | Short Quickstick (POL8751) | |
|---|---|---|
| Humidity range | 30% to 98% RH | 0% to 99% RH |
| Below 30% RH | Will not read | Reads to 0% |
| Best for | Sustained high humidity, equilibrium RH in concrete, harsh environments | General ambient work, fast spot readings, drying verification |
| Response | Slower, stable under prolonged wet conditions | Fast |
If you are verifying that a structure has finished drying, ambient readings often sit below 30% RH and a Hygrostick will not report them. If you are leaving a sensor in a sleeved hole in a slab, the Hygrostick is the sensor built for it. Both are consumables: buy Hygrosticks singly or in a 5 pack, and Quickstick ST sensors singly.
Specifications
Taken from the HygroMaster L instruction manual, INS7750L/51L Rev D.
| Measures | Relative humidity, air temperature, dew point and specific humidity (mixing ratio, g/kg or GPP) |
|---|---|
| Hygrostick (POL4750) | 30–40% RH ±3% at 20°C; 41–98% RH ±2% at 20°C. Temperature −10°C to 50°C ±0.3°C |
| Short Quickstick (POL8751) | 0–10% RH ±3% at 25°C; 10–70% RH ±2%; 70–99% RH ±3%. Temperature 0°C to 50°C ±0.5°C |
| Operating conditions | 0°C to 50°C, 0–95% RH non-condensing |
| Power | 9 V alkaline battery |
| Size | 177 × 80 × 38 mm |
| Gross weight | 182 g (instrument only) |
| Regulatory compliance | CE, RoHS, ETL |
| Warranty | 24 months on the instrument. Excludes wear on accessories and consumables |
Frequently asked questions
Does it measure moisture in timber, plaster or concrete?
No. This is a hygrometer, not a moisture meter. It measures the air, not the moisture content inside a material. For material moisture you need a pin or non-invasive meter such as the MMS3.
Can I use it for ASTM F2170 concrete testing?
Yes, with a Hygrostick, an extension lead and sleeves. The hole still has to be drilled, sleeved and left to equilibrate. The instrument alone is not enough.
Can I add a surface temperature probe later?
No. Surface temperature, infrared and dew point proximity are HygroMaster 2 functions and cannot be added to the L. If you need them, buy the 2.
How often should it be calibrated?
Twelve months is a sensible starting interval, adjusted to your own work and quality procedures. Humidity sensors are replaced rather than recalibrated; conformance certification for the instrument is available in Australia.
The reading is slow to settle — is it faulty?
Usually not. A Hygrostick is deliberately slow and stable and can take considerable time to equilibrate, particularly moving from a wet environment to a dry one. Fast spot readings are what the Quickstick is for.
Care and maintenance
- Treat humidity sensors as consumables — replace rather than attempt to recalibrate
- Remove the 9 V battery before extended storage
- Retrieve a Hygrostick once its reading has stabilised rather than leaving it in a saturated hole indefinitely
- Clean with a dry cloth only; no solvents on the display or the sensor
Documents
- HygroMaster L instruction manual (INS7750L/51L Rev D, September 2024)
- HygroMaster L datasheet (AAS-920-755C, September 2024)
Not sure whether the L or the HygroMaster 2 suits the work you do, or which sensor you need? Contact Carpet Cleaners Warehouse before ordering and we will confirm the right configuration.
