www.label.pl | LAB-EL Elektronika Laboratoryjna
Laboratory Electronics

MATERIAL HYGROMETER LB-795


  • 3 measuring methods
  • measuring characteristics for many materials
  • output interface RS-232
LB-795

Description

A material hygrometer LB-795 is designed for wood relative humidity measurement (or after adequate programming performed by a user) also for humidity measurement of different materials. It realises three measuring methods:

  • resistance method – marked in a hygrometer as a needle Probe (SI),
  • capacity method – marked in a hygrometer as the Electrodes (EL),
  • hygrometry method – marked in a hygrometer as a RH Probe (RH).

The hygrometer LB-795 main features:

  • possibility of material humidity measurement using three of the mentioned above measuring methods
  • basic wood types,
  • stored in a memory basic wood types characteristics: pine, spruce, oak, beech, birch, fir tree, larch, mahogany, alder tree, ash tree,
  • possibility of programming 150 user materials (50 for each measuring method),
  • possibility of storing 204 measurements in the internal memory,
  • possibility of wood temperature measurement (automatic temperature influence compensation to wood humidity for a resistance method),
  • possibility of humidity and air temperature measurement,
  • battery powered clock,
  • powered from a battery or from an outside feeder 12V,
  • communication interface RS232 with a PC computer assuring among other: readings from an internal memory of the stored measurements and user material calibration points using an outside software measurement registry into a file (in probe mode LB-701 and LB-754J),
  • hygrometer automatic switch off after 5 minutes (only in case of battery powering), switch off time is counted from the last pressing of any key button on a keyboard,
  • low battery voltage signalling (feeder).
The hygrometer co-operates with the following measuring probes:
  • LB-701 - hytherograph (RH probe),
  • LB-754J - single thermometer,
  • needle probe.
The hygrometer set includes the following:
  • hygrometer LB-795,
  • needle probe,
  • probe LB-754J (optionally),
  • probe LB-701 (optionally),
  • feeder 12V,
  • battery set,
  • communication cable (for connection with a computer),
  • model resistor,
  • covering format (optionally).

Technical data

Technical data for probes: LB-754J (thermometer) and LB-701 (hytherograph) are in adequate documents. The hygrometer LB-795 serves only the basic temperature scope in those probes (-40...+85 °C).

Meteorological parameters for wood

The measurement uncertainty of wood humidity depends on many factors such as: i. e. wood flaws in place of measurement taking, uneven humidity distribution in wood, incorrect way of measurement taking. The influence of those factors (treated each one separately) is not big and should not result in significant influence on a measurement result. In case of simultaneous projection of few of them and their unfavourable accumulation they can lead to significant measurement errors. When taking the measurement one should apply to comments and hints described in adequate chapters of the meter's manual that describe an appropriate way of measurement for each method.

The hygrometer shows wood relative humidity according to a following definition:

W[%] = (mass of water contained in wood) / (mass of completely dry wood) * 100

Wood humidity can be divided in two characteristic scopes:
  • hygroscope scope of humidity 0...30%, it is a scope of humidity that can be accepted by wood in air of humidity 0...100% (wood staying in air of certain humidity absorbs water from air and from it and accepts so called equivalent humidity - measuring method using RH Probe),
  • scope of humidity above 30% - i. e. "living" wood or wood exposed to immediate water influence.

Upper hygroscope humidity scope 30% is conventional and for different wood types assumes values from 23% to 33 %.

Meteorological parameters for Electrodes

Humidity
scope 5...100 % 
resolution 0,1 %
Meteorological parameters for needle Probe
  Humidity
Temperature (LB-754J)
scope 6...100%  -40...85 °C
resolution 0,1% 0,1°C
absolute measurement uncertainty   +/- 0,5 °C
Meteorological parameters for RH Probe
  Humidity Temperature
scope 3...30 %  -40...85 °C
resolution 0,1 % 0,1°C
absolute measurement uncertainty   +/- 0,2 °C
POWER SUPPLY
battery 4 batteries R6 (AA) 
network
stabilised feeder 12V DC / 100 mA
SCOPE OF WORK TEMPERATURES
Device Scope Comments
Probe LB-701 -40..+85 °C Water outdropping is impermissibleie
Meter LB-795 0..+50 °C
GOOD CLIMATE IS FAVORABLE
See also
See also
LB-797 LB-797
Wilgotnościomierz do gleby oraz innych materiałów sypkich to precyzyjny miernik wilgotności. Producent wilgotnościomierzy ze świadectwem wzorcowania.
LB-798 LB-798
wilgotnościomierz, higrometr do pomiaru wilgotności materiałów sypkich, wilgotnościomierz do piasku,