2456-LEM Laboratory Environment Monitor

Monitor barometric pressure, ambient temperature, relative humidity and air density

Monitor barometric pressure, ambient temperature, relative humidity and air density

  • Communicates via RS-232 or RS-485
  • Includes software to display all parameters in addition to data logging and calibration
  • Precision to 0.1 °C, 0.04 inHg (1.3 mbar) and 3 % RH
  • Ideal for calibration labs, clean rooms, storage facilities or use with Ruska piston gauges
  • Replaces mechanical strip chart recorders


The Laboratory Environment Monitor (LEM) provides the ability to measure barometric pressure, ambient temperature, relative humidity and air density. The LEM transmits these measurements via an RS-232 or RS-485 interface to a PC. The supplied software can then be used to monitor and log all the above parameters for one or up to eight LEMs, simultaneously.

The supplied software allows the LEM to be used as a stand alone instrument and performs a variety of functions, including various units selection, as well as as well as data logging. The LEM is an ideal replacement to older data loggers, such as mechanical strip chart recorders. The software includes options for logging in intervals of one minute, five minutes or 15 minutes. The space delimited text file keeps file sizes small, while allowing easy insertion into spreadsheet applications for data analysis and graphing. The LEM also provides air density measurement— a critical factor for mass calibration labs to correct for air buoyancy effects.

Annual recalibration of the LEM is accomplished through the supplied software. Once calibrated, the new coefficients are downloaded to the LEM and stored in non-volatile memory.

If a barometric pressure accuracy better than 0.04 inHg (1.3 mbar) is required, a variety of digital barometers with an RS-232 interface can be directly connected to the LEM. The LEM will transmit the barometric pressure reading from the external barometer to the PC and LEM software via a single communication link.

The LEM is compatible with a Ruska Model 2456 piston gauge monitor and WinPrompt® software, which automates the operation of the extensive line of Ruska primary pressure standards. The LEM allows WinPrompt to automatically compensate for air buoyancy effects on the mass set of the piston gauge. The LEM is also compatible with the Model 2465 autofloat gas piston gauge.



General specifications

Units Temperature: °F or °C
Pressure: mmHg, cmHg, inHg, kPa, mbar, psi, bar, kg/cm2
Humidity: %RH Air Density: g/cm3, kg/m3, lb/in3
Power 10 to 36 V dc, 250 mA maximum (supplied with 115/230 ac adapter).
Optional power via RS-485.
Temperature Operating: 18 °C to 28 °C (64 °F to 82 °F)
Storage: -20 °C to 70 °C (-4 °F to 158 °F)
Humidity 5 % to 95 % RH, non-condensing
Weight 0.23 kg (0.5 lb)
Dimensions (H x W x D) 133.35 mm x 82.55 mm x 31.75 mm (5.25 in x 3.25 in x 1.25 in)
Communications RS-232 or RS-485
Warm up time 30 minutes
Data update One second
Temperature 18 °C to 28 °C (64 °F to 82 °F)
Pressure 20 inHg to 34 inHg (700 mbar to 1150 mbar)
Humidity 5 to 95 % RH
Precision Temperature: ± 0.1°C (0.18 °F)
Pressure: ± 0.04 inHg (1.3 mbar)
Humidity: ± 3 % RH Precision is defined as the combined effects of linearity, repeatability and hysteresis.
Total uncertainty Temperature: ± 0.5°C (0.9 °F) per year
Pressure: ± 0.08 inHg (2.7 mbar) per year
Humidity: ± 10 % RH per year
Expression of accuracy (uncertainty) conforms with the recommendations of the ISO Guide
to the expression of uncertainty in measurement and includes RSS of precision, stability,
temperature effects, and the calibration standard to 2 sigma (95 %).
Software Requires Microsoft® Windows® 95 or higher, 1.6 MB of available
hard disk space, 32 MB RAM, RS-232 or RS-485, interface includes
extensive help and system manual includes syntax commands.



Model Name


2456-LEM Laboratory Environment Monitor


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