Thunder Scientific Corporation 2500 Benchtop Mobile Two-Pressure Humidity Generator Instruction Manual

Thunder Scientific Corporation 2500 Benchtop Mobile Two-Pressure Humidity

Generator

Product Information

• Product Name:
  • Thunder Scientific Corporation Model 2500 Benchtop / Mobile Two-Pressure Humidity Generator
• Features:
  • A self-contained system capable of producing atmospheres of known humidities
  • Uses the fundamental, NIST-proven, two-pressure principle
  • Continuously supplies accurately known humidity values for instrument calibration, evaluation, and verification
  • Can be used for environmental testing
• Description:
  • The Model 2500 Benchtop Humidity Generator is a self-contained system that utilizes the two-pressure principle to produce atmospheres of known humidities. It is designed for instrument calibration, evaluation, verification, and environmental testing.
  • The system can continuously supply accurately known humidity values.
• Principle of Operation:
  • The Model 2500 Benchtop Humidity Generator operates using an onboard multifunction CPU in conjunction with other peripheral cards.
  • It performs calculation and control functions to generate known humidity levels. The embedded computer control system allows unattended operation, freeing the technician from system monitoring and adjustment.
  • A computer and/or printer can be connected via the bidirectional RS-232C interface ports for remote setpoint control and continuous acquisition of system data.
  • Humidity and temperature setpoint values can be input from the front panel keypad.

Product Usage Instructions

1. Powering Up:
   • Ensure the Model 2500 Benchtop Humidity Generator is connected to a power source.
   • Apply power to the generator.
2. Setting Humidity Setpoint: The humidity setpoint values can be input using the front panel keypad. The setpoint values are limited only by the range of the 2500 humidity generator.
3. Monitoring System Status: The liquid crystal display on the front panel provides real-time visual indications of system status. It displays critical control and measurement parameters necessary for the operation of the humidity generator.
4. Pressure and Flow Control: The Model 2500 Benchtop Humidity Generator utilizes computer actuation of electromechanical valve assemblies to control pressure and mass flow. Pressure and flow are continuously measured and controlled using PID algorithms similar to those employed in temperature control.
5. Air Source: An air source is required for the operation of the humidity generator. Ensure the air source is connected properly.
6. Calibration: The 2500 humidity generator employs an integral programmatic calibration scheme. The temperature and pressure transducers can be calibrated while they are electrically connected to the humidity generator. Coefficients for each transducer are calculated by the computer and stored in the system’s nonvolatile memory until the next calibration is performed.
7. Liquid Level Readout: The liquid crystal display on the front panel provides a liquid level readout feature.

FEATURES

• 0.5 %RH Uncertainty 1
• Traceable to SI 3
• Self-Contained and Mobile
• Automated Control of User Setpoints
• 2500 ControLog® Automation Software
• HumiCalc® with Uncertainty Software
• Computerized Internal Transducer Calibration
• 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:

• To generate a known humidity, the computer controls the pressure ratio Pc/Ps utilizing the enhancement factor ratio fs/fc and the effective degree of saturation es/ec.
• 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 bidirectional 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.

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/min, L/hr, 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 .

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 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: 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 95%
• Relative Humidity Uncertainty @ PCTC: 1…………………………………………….0.5%
• Chamber Fluid Temperature Range: ……………………………………………0 to 70 °C
• Chamber Fluid Temperature Range: (Optional)…………………………-10 to 70 °C
• Chamber Temperature Uniformity: 2………………………………………………….0.1 °C
• Chamber /Saturation Temperature Uncertainty: 1…………………………….0.06 °C
• Pre-Saturator/Expansion Valve Temperature Uncertainty: 1 …………… 0.20 °C
• Chamber Pressure Range: ……………………………………………………………..Ambient
• Chamber Pressure Uncertainty: 1…………………………………………………. 0.15% FS
• Display Resolution: …………………………………………………………………………….. 0.01
• Gas Flow Rate Range: …………………………………………………………….5 to 20 L/min
• Gas Flow Rate Resolution: ………………………………………………………… 0.02 L/min
• Gas Flow Rate Uncertainty: 1…………………………………………………………… 2% FS
• Gas Type: …………………………………………………………………………….Air or Nitrogen
• Gas Pressure Rating (MAWP): ………………………………………………………175 psiG
• Heating/Cooling Rate: ………………………………………..2.5 Minutes Per °C Average
• Chamber Window: …………………………………………….6″ x 6″ (152 mm x 152 mm)
• Physical Dimensions: …. 22” H x 36” W x 23” D (559 mm x 914 mm x 584 mm)
• Chamber Dimensions: .. 15” H x 15” W x 12” D (381 mm x 381 mm x 305 mm)
• Access Port: ……………………………………………………………………………………Table A

UTILITIES

• Electrical Power: ……………………………………………………… 200/240 V~, 8 A, 60 Hz
• (Optional) ………………………………………………………………… 200/240 V~, 8 A, 50 Hz
• Air Compressor: ……………………………………………….. 100/120 V~, 15 A, 50/60 Hz
• (Optional) …………………………………………………………. 200/240 V~, 10 A, 50/60 Hz
• Air Supply (External): …………………………………….. Clean Oil Free Instrument Air ……………………………………………………………………………….. @ 175 psiG & 20 L/min

ENVIRONMENTAL

• Operating Temperature: …………………………………………………………… 15 to 30 °C
• Storage Temperature: …………………………………………………………………. 0 to 50 °C
• Humidity: ………………………………………………………. 5 to 95% RH Non-condensing

Dimensions

TABLE A Access Port Dimensions

Other custom options are available

1. Represents an expanded uncertainty using a coverage factor, k=2, at an approximate level of confidence of 95%. Uncertainty for relative humidity is not specified below 0 °C.
2. When operated at temperatures within 10 °C of room ambient temperature.
3. Traceable to the International System of Units (SI) through a national metrology institute (NIST) recognized through a CIPM MRA.

For More Information or to Place an Order Contact:

• 623 Wyoming Blvd. SE
• Albuquerque, New Mexico 87123-3198
• Ordering: 800.872.7728
• Tel: 505.265.8701
• FAX: 505.266.6203
• www.thunderscientific.com.
• 1022-2500

References

• Thunder Scientific - Humidity Calibration and Generation, NIST Standards. - Thunder Scientific - Humidity Generators

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