Available Products

Air Probes
Alumina Tubes
Carbon Dioxide
CO2 Transmitters
CO2 Handhelds
Calibration Dry Wells Calibration Baths
Cement 0n Thermocouple
Ceramic Tubes
Chart Recorders
Connectors
Controllers
Data Loggers
Digital Thermometers
Extension Wire
Field Metrology Wells
Flowmeters
Flow Calibrators
Heaters
Humidity Handhelds
Humidity Sensors
Humidity Transmitters
Indicators
Infrared Pyrometers
Mulite Tubes
Multipoint Thermocouples
Panel Jacks
Partlow Recorders
Pressure Calibrators
Pressure Transducers
Pressure Transmitters
Protection Heads
Protection Tubes
Probes
%RH Probes
RTDs
RTD Probes
Solid State Relay
SSR
Surface Probes
Temperature Baths
Temperature Calibrators
Temperature Transmitters
Thermometers
Thermocouples
Thermocouple Probes Thermocouple Scanner
Thermocouple Strip Panel
Thermocouple Wire
Thermistors
Thermistor Probes
Thermowells
Wire and Cable
WIKA Pressure Transmitters
Validation Thermocouples

Hart Scientific 5121
Model 2500 Benchtop/Mobile

"Two-Pressure" Humidity Generator

FEATURES

• Accuracy ± 0.5 %RH
• Traceable to NIST
• Self Contained and Mobile
• Automated Control of User Setpoints
• ControLog TM Automation Software
• HumiCalc ® Humidity Conversion Software
• Computerized Internal Transducer Calibration
• Low Noise Air Compressor with Air Dryer
• RS-232C Serial Interface

DESCRIPTION

The Model 2500 Benchtop Humidity Generator is a self contained system capable of producing atmospheres of known humidities using the fundamental, NIST proven, "two-pressure" principle. This system is capable of continuously supplying accurately known humidity values for instrument calibration, evaluation, and verification, as well as for environmental testing. Simply apply power and the 2500 will power-up ready to generate. Humidity setpoint values are input by the operator from the front panel keypad and are limited only by the range of the 2500 humidity generator. Relative humidities are calculated from the measurements of pressure and temperature with the formula:

%RH= f_s/ f_c · e_s/ e_c · P_c/ P_s · 100

To generate a known humidity, the computer controls the pressure ratio P_c /P_s utilizing the enhancement factor ratio f_s/f_c and the effective degree of saturation e_s/e_c. Humidity produced is solely dependent on the measurement of pressures and temperatures and does not rely on any other device (such as a dew point hygrometer, psychrometer, or humidity sensor) for the measurement of water vapor content. Precision humidity generation is determined by the accuracy of the pressure measurements and on the accuracy and uniformity of temperature throughout the generating system.

PRINCIPLE OF OPERATION
The Model 2500 Benchtop Humidity Generator operates using an on board multifunction CPU in conjunction with other peripheral cards to perform calculation and control functions. The embedded computer control system allows the 2500 to generate known humidity levels unattended, freeing the operating technician from the task of system monitoring and adjustment. A computer and/or printer may be connected via the bi-directional RS-232C interface ports allowing remote setpoint control and continuous acquisition of system data. Humidity and temperature setpoint values are input by the operator from the front panel keypad while visual indications of system status are displayed in real time on the liquid crystal display.

Control / Display Screen

All control and measurement parameters critical to the operation of the humidity generator are displayed on this screen. Each parameter in the left most column is identified with a brief title and corresponding units. The generator operates in a variety of user selectable pressure, temperature, and flow units. Some of these are °C, °F, psi, "Hg, Tor, mbar, kPa, l/m, l/h, cfm and cfh. Humidity is calculated and displayed in percent relative humidity (%RH). The asterisk in the left most column indicates the active humidity control parameter. The "SetPnt" column lists control setpoints and the "Actual" column lists all of the measured data and calculated parameters of the generator.

Temperature Control: The system utilizes a fluid jacketed test chamber for extremely stable temperature control. Temperature setpoint control is attained by controlling the temperature of the circulating fluid medium that jackets the test chamber and associated humidity generation components. Chamber and saturation temperatures are governed by this medium and are digitally controlled by the computer at any value between 0 °C and 70 °C using PID (proportional-integral-derivative) algorithms.

Pressure And Flow Control: Pressure control and mass flow control are accomplished through computer actuation of electromechanical valve assemblies. Pressure and flow are measured continuously and controlled using PID algorithms similar to those employed in temperature control.

Calibration: The 2500 humidity generator employs an integral programmatic calibration scheme allowing the temperature and pressure transducers to be calibrated while they are electrically connected to the humidity generator.

Elemental Schematic of the 2500 generator.
Pressure And Flow Control: Pressure control and mass flow control are accomplished through computer actuation of electromechanical valve assemblies. Pressure and flow are measured continuously and controlled using PID algorithms similar to those employed in temperature control.

Calibration:
The 2500 humidity generator employs an integral programmatic calibration scheme allowing the temperature and pressure transducers to be calibrated while they are electrically connected to the humidity generator.

Calibration / Display Screen

2500 Test Chamber
Coefficients for each transducer are calculated by the computer and stored in the system’s nonvolatile memory until the next calibration is performed.

APPLICATIONS
The fluid jacketed test chamber can accommodate humidity sensors, hygrothermographs, chilled mirror hygrometers, and various material samples for environmental testing. Virtually any humidity and temperature point may be generated, for any length of time, within the operational limits of the generator. The output of the device under test may then be compared with the generator's printed data for analysis.

Humidity Sensors And Chart Recorders: Insert humidity probes through the two inch port in the side of the chamber or place hygrothermographs into the chamber and you can: determine humidity calibration accuracy and characterize humidity sensitivity by subjecting the sensing system to a variety of humidity levels; perform operational checks such as the sensing systems capability to correctly calculate and display other humidity parameters; determine the repeatability, stability, hysteresis, and drift characteristics of various humidity sensing systems.

Chilled Mirror Hygrometers: Install the actual chilled mirror head into the chamber or insert a sample tube through the test port and draw a sample through the chilled mirror head and you can: verify mirror temperature measurement accuracy (calibration) when the hygrometer is in thermal equilibrium with its environment; perform operational checks of the heat pump and optical components before and after mirror cleaning and balancing; determine whether the hygrometer is controlling the mirror deposit in the liquid phase or ice phase when operating at dew and frost points below 0 °C; determine if the hygrometer is correctly calculating other humidity parameters; determine the hygrometer's repeatability, stability, and drift characteristics.

Environmental Testing: The 2500 can serve as a test bed for evaluation and R&D of humidity sensors, humidity sensing systems, and humidity sensitive products, e.g., polymers, composites, film, magnetic medium, blood gas analysis, pharmaceuticals, soil hydrology, consumables, electronics, optics, etc. Depending on the temperature and humidity being generated, the 2500 may operate continuously from hours to months. With continuous generation of a nominal 50 %RH at 21 °C, the reservoir will last about two weeks between refills.

SPECIFICATIONS
Relative Humidity Range: ................................... 10 to 98%

Relative Humidity Resolution: ............................. 0.02%

Relative Humidity Accuracy @ Pc Tc: ................. ±0.5%

Chamber Temperature Range: .......................... 0 to 70 ºC

Chamber Temperature Range: (Optional) ......... -10 to +70 ºC

Chamber Temperature Resolution: .................... 0.02 ºC

Chamber Temperature Uniformity:* .................... ±0.1 ºC

Chamber Temperature Accuracy: ...................... ±0.06 ºC

Chamber Pressure Range: ................................ Ambient

Gas Flow Rate Range:....................................... 5 to 20 l/m

Gas Type: .......................................................... Air or Nitrogen

Gas Pressure Rating (MAWP): .......................... 175 psiG

Heating/Cooling Rate:......................................... 2.5 Minutes Per ºC Average

Chamber Window:............................................... 6" x 6" (152 mm x 152 mm)

Physical Dimensions: .......................................... SEE TABLE A

Physical Dimensions of Cart: .............................. SEE TABLE B

Physical Dimensions 2500 with Cart: .................. SEE TABLE C

Chamber Dimensions: ........................................ SEE TABLE D

Access Port: ....................................................... SEE TABLE E

* When operated at temperatures within 10 ºC of room ambient temperature.

Other custom options are available.

1 1/4" Swagelok Right Side
-MPD 6 1.1" (28 mm) In Door

UTILITIES
Electrical Power: ................................................ 100/120 V~, 15 A, 50/60 Hz

(Optional) .......................................................... 200/240 V~, 8 A, 50/60 Hz

Air Compressor: ................................................ 100/120 V~, 5 A, 50/60 Hz

(Optional)........................................................... 200/240 V~, 2.5 A, 50/60 Hz

Air Supply (External): ........................................ Clean Oil Free Instrument Air

.......................................................................... @ 175 psiG & 20 slpm

ENVIRONMENTAL
Operating Temperature:................................... 15 to 30 ºC

Storage Temperature: ...................................... 0 to 50 ºC

Humidity: ........................................................... 5 to 95% Non-condensing

OPTIONS
Thunder has various options available for the Model 2500.

Tri Port Array (TPA) 2 access ports in the right side of the chamber and 1 additional hygrometer sample port with a 1/4" fitting.

Low Temp (LT) Expanded chamber temperature range of -10 °C to +70 °C.

Multi Port Door (MPD) 6 each 1" diameter access ports through the door for multi probe calibration.

Chamber Fixture Mount (CFM) this option is used for the Door Fixture (DFX) accessory and must be ordered at the time you place the order for the 2500.

Chamber Fluid Temp Port (FTP) External temperature probe access port through the top panel for measurement of the saturation temperature.

Door without window (NWD) The No Window Door option provides the system with improved chamber temperature uniformity.

Multi Port Window Door (QPW) The Quad Port Window Door has 4 each 1" diameter access ports with a window configuration (ST Models Only).

Fluid Jacketed Shelf Divider (FCD) The Fluid Jacketed Chamber Divider improves chamber temperature uniformity for high volume sensor calibrations. Best application usage for calibrating large quantities of electronic humidity and temperature data loggers. Note: this option must be ordered at the time you place the order for the 2500. (ST Models Only)

Mobile Cart (CART-R), (CART-S), (CART-ST) Is specifically made for the Model 2500 but can be used to haul around any of your lab equipment.

Back to Top