Thin humidity probe - for material moisture

Order-Nr.  0636 2135

  • Measurement of the material moisture via the equilibrium moisture content

  • Slim design (Ø 4 mm) with remote electronics – ideal for tight measuring points

Thin humidity probe with built-in electronics, incl. 4 attachable Teflon protection caps for material moisture equilibrium measurement


Product Description

Materials which take in and retain or release water are described as hygroscopic materials. Hygroscopic materials always try to form a moisture equilibrium with the surrounding air. This principle is used to measure the moisture in material by measuring moisture equilibrium.
Ideally, moisture equilibrium is measured in a bore hole in the material. To keep the bore hole as small as possible, a thin .16 in. humidity probe is used. It should be protected from dirt by a Teflon cap during measurement. The bore hole is then simply sealed using sealing clay.
Based on the moisture equilibrium measured, testo 635 automatically shows material moisture in % in the display. Material moisture calculation is available for the following materials:
– Concrete
– High-insulation bricks
– Solid bricks
– Hard wood
– Soft wood
– Gas concrete
– Particle board
– Calcium sulphate floating screed
– Cement floating screed
– Lime sand brick
Materials are easy to select from the menu. Using the "Material" user profile, the material can be accessed directly at the touch at a button.
Additional material characteristics can be stored in testo 635-2 using ComSoft.

Delivery Scope

Thin humidity probe (Ø 4 mm) with PTFE protective cap and adhesive modelling clay (4 items), including fixed cable.

Technical Data

Temperature - NTC

Measuring range

32.0° to 104.0 °F / 0 to +40 °C


±0.4 °F / ±0.2 °C

*Please also take into account the device uncertainty.

Humidity - Capacitive

Measuring range

0 to +100 %rH


±2 %rH at +77 °F (+2 to +98 %rH) / ±2 %RH at +25 °C (+2 to +98 %RH)

±0.15 %rF/K (k=1)

long-term stability: ±1 %RH / year

*The sensor accuracy corresponds to the system accuracy.

General technical data

Diameter probe shaft

0.157 in. / 4 mm

Length probe shaft

2.362 in. / 60 mm