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Laboratory Electronics

HYTHEROGRAPH LB-701 with a control - reading panel LB-725A

  • functions: thermometer, hygrometer (hygrometer), recorder, regulator
  • measurement: temperature, air relative humidity
  • optionally probe LB-701T for temperature measurement in the extended scope
  • control over four external devices - climate regulation
  • big, easy to read display
  • registry up to 4000 measurement points
  • interface RS232C and a digital current loop
The hytherograph LB-701 with a control - reading panel LB-725


The hytherograph LB-701 with a control - reading panel LB-725A is designed for air temperature and humidity measurement and regulation in locked places (warehouses, laboratories, climate chambers etc.). It is a stationary device, powered from 230V/50Hz network supply.

The device is composed of two major parts: a hytherograph LB-701 (made in a form of a measurement probe) and a reading - control panel LB-725A. 1m cable connects both parts. There is a possibility of extending the probe’s cable up to 14m.

The measurement probe LB-701 includes: a thin layer temperature sensor Pt-1000, thin layer capacitive relative humidity sensor, electronic processing systems and a system of programmed nonvolatile memory, where all individual probe characteristic are stored as well as identification and technical data. A replaceable casing, which type depends on what the device is used for, protects the measurement probe sensors. The device in a standard version is equipped with a sensor casing (anti pollution filter) type F1.

The reading panel receives signals already processed that include coded information concerning temperature and relative humidity values. It allows on changeable use of different reading panels with the same hytherograph LB-701 without any influence on the measurement results.

The microprocessor from the device's reading panel, basing on the information from the probe (processed measurement signals and read calibration characteristics) computes the following values: relative humidity, temperature, dew point temperature and volume water vapor content in the air. The temperature and relative humidity values are presented on an alphanumeric LCD screen at the same time (the size of numeric characters 25 mm) and can be sent out using an interface. The lack of switches only increases device's reliability at work and simplifies its use.

Panel LB-725A control functions allow on controlling four external devices responsible for: humidifying, drying, heating and cooling.  Each device can have set limits for switching on and off in the immediate control. When using and external PC computer and an additional program it is possible to cyclically control fluent climate changes (i.e. research climate chambers).

The device is equipped with two series interfaces: voltage RS232C, which allows for it to be attached to any computer system and with a digital current loop for data transmission to long distances. The interfaces allow on remote control and automatic measurement data collection as well as entering the calibration data during the original and secondary calibration.

The panel LB-725A has a real time clock and a measurement results memory (4000 measurement points) what allows on using it as a temperature and humidity recorder. The device equipment is composed of a program for a PC computer used for setting registry parameters and for memory reading.

The device does not have any mechanic calibration elements (i.e. potentiometers). The device's calibration means sending the calibration data obtained in model climate conditions through a digital interface to device's nonvolatile memory. It guarantees comfort and high calibration accuracy as well as stability of device's meteorological parameters in time.

Hytherograph LB-701 has obtained a certificate of type RP T 95 76 issued by the President of the Central Measurement Office in Warsaw.

Hytherograph LB-701 also has a positive expertise from The Central Army Meteorology Office in Zielonka (no. 71 dated 05.05.1995), performed basing on the method of legalizing hygrometers and hygrographs.

Each thermometer-hygrometer, upon a special order, can have an individual calibration certificate from the LAB-EL Calibration Laboratory.

LB-701TThe device is produced in a version for temperature measurement only (thermometer LB-701T with a panel LB-725A). Thermometer LB-701T has a measurement converter (in a cylinder case) and an outside temperature sensor Pt1000 (or Pt100) in a standard or special case, adjusted to the individual user requirements (i.e. in a form of a rod from the acid resisting steel, with a special cable). The special casing version allows on measurement of different values in an extended temperature range (-200...+550°C). Thermometer LB-701T can be also purchased separately, as additional equipment for the already had set LB-701/LB-725A. However, in such case it is required that the internal software for the older versions of panel LB-725A is updated. The thermometer LB-701T cable length amounts to: between an outside temperature sensor and a converter - 1..40 m, between a converter and a reading panel - 1..15 m (cable length is defined by a customer).

Methods used for relative humidity and air temperature measurements using hytherographs are introduced in a description


Measurement inaccuracy +/- 0.1°C +/- 1 last digit
Scope of measurement
-40..+85°C LB-701
-200..+550°C LB-701T - sensor in a special casing
Measurement inaccuracy +/- 2.0%
+/- 1 last digit
in the scope of 10...90%,

+/- 4.0%
+/- 1 last digit
outside of the scope 10...90%
Scope of measurement LB-701 10..95% for temperatures up to +40°C
10..60% for temperatures up to +70°C
10..40% for temperatures up to +80°C
Scope of measurement LB-701H 0..100% for temperatures up to +60°C
0..70% for temperatures up to +70°C
0..40% for temperatures up to +80°C
Parameter Scope of readings Resolution
Air temperature -40.0..+85.0°C 0.1°C
Relative humidity
0.0..100.0% 0.1%
MEASUREMENT READINGS (additionally through a series interface) 
Parameter Scope of readings Resolution
Dew point temperature
-40.0..+100.0°C 0.1°C
Volume water vapor content in the air
0..99999ppm 1ppm
Time months, days, hrs., min 1 min
Probe LB-701 -40..+85°C
Thermometer sensor LB-701T -60..+90°C for a standard version 
-200..+550°C for a special version
Thermometer converter LB-701T -40..+85°C  
Panel LB-725A 0..+50°C  
Scope of temperatures
Scope of humidity 20..80%
Level of environment corrosion aggressiveness accord. PN-71/H-04651
Degree of casing protection
IP 60 (limited additionally by the class of filter protection)
*) Going beyond recommended constant work conditions (i.e. when installing the device in the open space) requires using additional protection means for the device's electronic part so that water out dropping does not start inside of the device (protecting the electronic part with silicone or using an additional external case).
230V AC / 50Hz / 10VA

INTERFACE  I - voltage

Series RS232C, 3 lines (RxD, TxD, GND), transmission parameters: 9600 bps, 8 bits of information, without evenness control, 1 stop bit.
Possibility of reading the measurement results and storing of device's calibration results in its non-volatile memory.

INTERFACE II - current

Series called digital current loop, 1 line TXD (active TXD line stage complies with 25 mA current, in the rest stage 15 mA), time transmission parameters in accordance with RS232C: 300 bps, 7 bits of information, without evenness control, 1 stop bit.
Possibility sending the measurement results automatically to long distances in big measurement systems (i.e. to multi sensor climate supervision systems - see LB-731). Output with a galvanic isolation.


  • Reading panel LB-725A: in a panel casing (to be hanged on the wall) with the overall dimensions: 160 x 166 x 87 mm.
  • Hytherograph LB-701 (measurement probe): attached by 1 m cable, with dimensions: diameter 23 mm, length (with a stay wire) 190 mm (for a probe metal casing: diameter 18 mm, length 150 mm). 
  • Thermometer LB-701T in a standard version: converter in a cylinder case with diameter 18 mm and length 160 mm, sensor in a stainless steel case with diameter 5 mm and length 100 mm, ended with a blade (see photograph above).


  • cable for the interface RS232C,
  • program "User's Interface" for a PC computer.


The following effects are available upon special order: 
  • LB-701H - with extended compared to a standard, scope of constant humidity measurement to 0...100%,
  • LB-701T - thermometer (converter with a sensor) for air temperature or any value measurement (made according to a specific client requests),
  • LB-701Fn - sensor casing version (according to a description), the version is given if it is different than F1.
Other panels that collaborate with the probe LB-701: LB-702, LB-705, LB-706, LB-706B.
Ocena produktu
The hytherograph LB-701 with a control - reading panel LB-725 is designed for air temperature and humidity measurement and regulation in locked
Ocena: 5/5, liczba głosów: 14
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