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Thunder Scientific series 3900 Operation And Maintenance Manual

Low humidity generator
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OPERATION AND MAINTENANCE MANUAL
LOW HUMIDITY GENERATOR
SERIES 3900
®

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February 28, 2025

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May 14, 2025

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Summary of Contents for Thunder Scientific series 3900

  • Page 1 OPERATION AND MAINTENANCE MANUAL LOW HUMIDITY GENERATOR SERIES 3900 ®...
  • Page 2 MADE IN USA THUNDER SCIENTIFIC® is the registered trademark of Thunder Scientific Corporation. All the information provided in this document is correct and true at the time of publication. Thunder Scientific Corporation reserves the right to change any technical data without notice.
  • Page 3 Model 3900 Low Humidity Generator...

  • Page 4: Table Of Contents

    TABLE OF CONTENTS Section 1 - GENERAL INFORMATION List of Reference Drawings - iv Warranty INTRODUCTION ---------------------------------------------------------------- 1-1 PRINCIPLE OF OPERATION ------------------------------------------------- 1-1 1.2.1 General Description --------------------------------------------------------- 1-1 1.2.2 Humidity Formulas --------------------------------------------------------- 1-1 1.2.2.1 Saturation Vapor Pressure, e ----------------------------------------- 1-2 1.2.2.2 Enhancement Factor, ƒ...
  • Page 5 1.5.5.3 Saturator Vent/Purge Solenoid Valve ----------------------------- 1-13 1.5.5.4 Pressure Select Solenoid Valve ------------------------------------ 1-13 1.5.5.5 Saturator Refrigerant Solenoid Valve ----------------------------- 1-14 1.5.5.6 Saturator Inlet/Outlet Heater --------------------------------------- 1-14 1.5.5.7 Saturator Fluid Heater ----------------------------------------------- 1-14 1.5.5.8 Saturator Fluid Circulation Pump --------------------------------- 1-14 1.5.5.9 Saturator Refrigeration Compressors ----------------------------- 1-14 1.5.5.10...
  • Page 6 3.2.5.1 Purging Procedure ---------------------------------------------------- 3-11 3.2.6 Saturator Clear -------------------------------------------------------------- 3-12 3.2.6.1 Saturator Clear Procedure ------------------------------------------- 3-12 3.2.7 Generating ------------------------------------------------------------------- 3-13 3.2.7.1 Generating Procedure ------------------------------------------------ 3-14 3.2.7.2 Example Instrument Set-up ----------------------------------------- 3-15 3.2.8 Saturator Fill ---------------------------------------------------------------- 3-16 3.2.8.1 Saturator Fill Procedure --------------------------------------------- 3-16 3.2.9 Stopping --------------------------------------------------------------------- 3-18 3.2.10...

  • Page 7: List Of Reference Drawings

    4.4.2 Refrigerant Charge -------------------------------------------------------- 4-25 4.4.3 Saturator Fluid System ---------------------------------------------------- 4-25 4.4.4 Methanol System Drain/Fill Procedure --------------------------------- 4-25 ERROR CODES AND TROUBLESHOOTING --------------------------- 4-27 Section 5 - PARTS LIST 3900 PARTS LIST ---------------------------------------------------------------- 5-1 LIST OF REFERENCE DRAWINGS DRAWING # DRAWING TITLE 94D39901 -------------------------Mechanical/ Utility 95D39902 -------------------------Component Locations...
  • Page 8 WARRANTY Thunder Scientific Corporation (TSC) warrants, to the Buyer, the Product manufactured by TSC to be free of defects in material and workmanship under normal use and service and to be free from inadequate mechanical design when operated within the specified design limitations for a period of one year from date of acceptance.
  • Page 9 10. Computer IO Control Cable 11. Pure Water Fill Funnel 12. 1/4” 30 Micron Muffler 13. Pressure Transducer 0 – 50 Psi 14. 1/4” Swage x 9/16” – 18 STD Thunder Scientific Corporation Web: www.thunderscientific.com 623 Wyoming Blvd. SE E-mail: support@thunderscientific.com Albuquerque, NM 87123...
  • Page 10 Suomi English Tämä tuote noudattaa WEEE-direktiivin (2002/96/EY) This product complies with the WEEE Directive (2002/96/EC) marking merkintävaatimuksia. Kiinnitetty etiketti osoittaa, että tätä requirements. The affixed label indicates that you must not discard sähkö-/elektroniikkalaitetta ei saa hävittää kotitalousjätteissä. this electrical/electronic product in domestic household waste. Tuoteluokka: Viitaten WEEE-direktiivin liitteessä...
  • Page 11 Deutsch Nederlands Dieses Produkt stimmt mit den Kennzeichnungsanforderungen Dit product voldoet aan de merktekenvereisten van de AEEA- der WEEE-Richtlinie (2002/96/EC) überein. Das angebrachte richtlijn (2002/96/EG). Het aangebrachte merkteken duidt erop dat Etikett weist darauf hin, dass dieses elektrische/elektronische dit elektrische/elektronische product niet met het huishoudelijk Produkt nicht in Hausmüll entsorgt werden darf.

  • Page 12: Introduction

    Section 1 GENERAL INFORMATION INTRODUCTION The Model 3900 low humidity generating system is a facility capable of producing known humidity values using the combined fundamental principles of the "two temperature" and "two pressure" generators developed by NIST. This system is capable of continuously supplying accurately known humidity values for instrument calibration and evaluation.

  • Page 13: Saturation Vapor Pressure, E

    1.2.2.1 Saturation Vapor Pressure, e Saturation Vapor Pressure (SVP) is the pressure exerted by water vapor alone when in equilibrium with pure ice or water, and is expressed as a function of temperature only. Since SVP can be established with respect to either ice or water, two separate formulas are used. Wexler's formula for SVP over water is expressed as ...

  • Page 14: Enhancement Factor, Ƒ

    1.2.2.2 Enhancement Factor, ƒ The enhancement factor, ƒ, corrects for the non-ideal behavior of air when it is used as the carrier gas. The enhancement factor is a function of two independent variables; pressure, P, and temperature, T. A formula for calculation of the enhancement factor at any given pressure and temperature above freezing is given by Greenspan ...

  • Page 15: Frost Point

    Again the variables, α and β, are given as ∑ α i = 0 ∑ and β i = 0 where A 3.6449 x 10 2.93631 x 10 4.88635 x 10 4.36543 x 10 = -1.07271 x 10 7.61989 x 10 = -1.74771 x 10 2.46721 x 10 , and...

  • Page 16: Dew Point

    1.2.2.4 Dew Point Dew point temperature, T d , is the temperature to which a gas must be cooled in order to just begin condensing water vapor in the form of dew. Unlike frost point, dew point can exist both above and below freezing. In relation to the two-temperature two-pressure generator, dew point vapor pressure is derived from the formula ƒ(T ∗...

  • Page 17: Parts Per Million By Weight, Ppmw

    1.2.2.6 Parts Per Million by Weight, PPM PPM w is a relationship between the weight of the molecules of water vapor to those of the dry gas carrier. PPM w is related to PPM v by the relationship (10) ∗ where MW molecular weight of water (≈...

  • Page 18: Specifications

    1.3 SPECIFICATIONS Frost / Dew Point Range: ----------------------------------------------------------- -95 to +10 °C Frost / Dew Point Uncertainty: * ----------------------------------------- (-95 to -90 °C) 0.9 °C --------------------------------------------------------------------------------- (-90 to -80 °C) 0.5 °C --------------------------------------------------------------------------------- (-80 to -70 °C) 0.2 °C ---------------------------------------------------------------------------------- (-70 to 10 °C) 0.1 °C Parts Per Million Range: --------------------------------------------------- 0.05 to 12000 PPMv Relative Humidity Range: -------------------------------------------------------- 0.0002 to ~50% Saturation Pressure Range: ------------------------------------------------- Ambient to 300 psiA...

  • Page 19: Computer/Control System

    COMPUTER / CONTROL SYSTEM 1.4.1 General Description The Computer Control System is embedded in the humidity generator. The computer controls all aspects of the humidity generation process (i.e. controlling temperatures, pressures, etc.) as well as performing all human interface functions of keypad input and information display.

  • Page 20: Liquid Crystal Display (Lcd)

    1.4.2.2 Liquid Crystal Display (LCD) Reference Drawing 95S39913 The display incorporated into the 3900 low humidity generator is a backlit, 256 x 128, dot matrix Liquid Crystal Display (LCD). It is used for the purpose of displaying system information such as setpoints, measurements and any other information pertinent to the operation of the 3900 humidity generator.

  • Page 21: Electrical System

    ELECTRICAL SYSTEM 1.5.1 AC Power Distribution Reference Drawings 95D39904, 95S39906 through 95S39909 The 3900 requires a single phase AC power source. From the primary power switch CBS1, primary power is distributed to the refrigeration compressors, C1 and C2, through SSR8 and SSR9, the saturator fluid heater H1 through SSR10;...

  • Page 22: Analog Inputs

    1.5.4 Analog Inputs The temperature, flow and pressure transducers are measured by the Analog to Digital Converter. Each of these is discussed further in the following sections. 1.5.4.1 Temperature Measurement Reference Drawing 95S39912, 95S39915 & 916 Two thermistors are used by the system for continuous real time temperature monitoring. A 1KΩ...

  • Page 23: Low Range Saturation Pressure Transducer

    1.5.4.3 Low Range Saturation Pressure Transducer Reference Drawings 95S39912, 95S39915 & 916 The Low Range Saturation Pressure Transducer TR3 is powered by the ±15 VDC power supply PS1, and has a measurement range of 0 to 50 psiA. This pressure transducer is pneumatically connected to the saturator via a computer controlled solenoid valve SOL4 that is only activated below 50 psiA to monitor saturation pressure.

  • Page 24: Control Logic

    1.5.5 Control Logic All control is performed digitally at a logic level of 5 VDC. Activation of most devices is accomplished by applying a logic low to the control input of the associated solid state relay or other coupling device. 1.5.5.1 Gas Supply Solenoid Valve Reference Drawings 95S39908, 95S39915 &...

  • Page 25: Saturator Refrigerant Solenoid Valve

    1.5.5.5 Saturator Refrigerant Solenoid Valve Reference Drawings 95S39908, 95S39917 The Saturator Refrigerant Solenoid Valve SOL5, when activated, allows refrigerant to be injected into the refrigeration evaporator EX1 to cool and control the temperature of the saturator. Activation of this solenoid valve is accomplished by applying a low from the CPU (monitored at TIB terminal C0) to the optical input (-) side of SSR0 on the Solid State Relay Board.

  • Page 26: Flow Control Valve

    1.5.5.10 Flow Control Valve Reference Drawing 95S39910, 95S39915 & 916 The Flow Control Valve V1 is a bi-directional ball valve actuated by a gear reduced stepper motor. The valve is driven indirectly via pulses from the CPU to TIB terminals B0 & B2, which triggers stepper motor driver SMD-1.

  • Page 27: Pneumatic System

    PNEUMATIC SYSTEM The pneumatic system of the Model 3900 is an open loop "two pressure" system. Dry, high pressure, high purity gas is saturated with water vapor as it passes through the saturator assembly, then reduced to test pressure. Once reduced to the test pressure the gas is sent to the device under test and ultimately vented to the atmosphere.

  • Page 28: Refrigeration

    REFRIGERATION The Model 3900 utilizes a cascade refrigeration system to cool the fluid circulating in the saturator assembly. 1.8.1 Saturator Refrigeration Reference Drawing 95S39917 The saturator fluid system is cooled by two hermetic refrigeration systems in cascade. The high stage refrigeration utilizes Refrigerant 134A. This refrigerant is compressed from a low- pressure vapor into a high-pressure vapor by compressor C1.

  • Page 29: Section 2 - Installation

    Section 2 INSTALLATION GENERAL Preparations should be made to have adequate floor space, proper power source, and a dry gas supply available at the location of installation. FACILITIES REQUIRED Reference Drawing 94D39901 2.2.1 Floor Space A minimum 9 ft (0.84 m ) of floor space is recommended for the 3900.

  • Page 30: Methanol Filling Procedure

    2.3.1 Methanol Filling Procedure Reference Drawing 08D39922 Equipment Required: 1. 1.5 gallons (5.675 Liters) of anhydrous methanol 2. 7/8" (23 mm) socket with 6" (0.15 m) extension 3. 3/16" (4.5 mm) ball/hex driver (to remove counter top bolts) 4. 3/8" (9.5 mm) ball/hex driver (to remove Methanol Expansion Tank Fill Port Plug) 5.

  • Page 31: Vent Muffler

    2.3.2 Vent Muffler Install vent muffler into gas vent port at rear of system. POSITIONING & LEVELING 1) Position the system so as to have access to all sides of the console. 2) Lower leveling legs and raise the wheels off the floor to hold system stationary. Level the console using counter top as a reference.

  • Page 32: Section 3 - Operation

    Section 3 OPERATION 3.1 GENERAL At this point, all preparation and positioning of the Model 3900 humidity generator should have been performed. Refer to section 2. 3.2 STANDARD OPERATING PROCEDURES 3.2.1 Power-Up 1) Verify that the gas supply connection has been made and the gas supply is pressurized. Open any On/Off valve in the supply line if applicable.
  • Page 33 The Date and Time are displayed at the bottom of the screen, updating continuously every few seconds. To the right of the Date and Time is a number enclosed in square brackets [ ]. This is a measurement of the regulated input supply pressure. column lists the user entered (and system calculated) control setpoints.

  • Page 34: Changing The Display Contrast

    The test pressure, P , in pounds per square inch absolute, measured whenever TEST psi the test pressure transducer is plugged in. (Pressure units may be set to psi, bar, or hPa. See section 3.3) Since test pressure is used in the determination of Frost Point, Dew Point, and %RH, the test pressure transducer should be placed as close as possible to, but downstream of, the device under test in order to measure device pressure.

  • Page 35: Changing Setpoints

    3.2.3 Changing Setpoints After the initial power-up sequence of section 3.2.1, the Control/Display screen appears. On the display are four rectangular function key labels. These labels correspond to the four blank keys on their right. Function Key Labels Keys SetPnt Actual CHNG *FRST PT...

  • Page 36: Example Setpoint Change

    3.2.3.1 Example Setpoint Change Change the setpoints to -20 °C Frost Point at a flow rate of 0.50 L/min. 1) Press [CHNG SETP]. The key labels change to arrows, and the cursor begins flashing. SetPnt Actual *FRST PT -1_ 0 .00 DEW PT -11.23 PPMv...
  • Page 37 5) Using the arrows and numeric keys as necessary, make the setpoint value FLOW appear as 0.500 SetPnt Actual *FRST PT -20.00 DEW PT -11.23 PPMv 2581. PPMw 1605. 10.37 SATUR 70.92 SATUR 10.00 TEST 14 70 TEST 21 11 FLOW 0_ .

  • Page 38: Control Modes

    3.2.4 Control Modes The generator has the ability to control the humidity in one of six possible modes. Mode 0 is controlled at a constant value by varying the saturation *FRST PT pressure, P , to compensate for changes in either saturation temperature, Power-up , or test pressure, P .

  • Page 39: Changing Control Mode

    3.2.4.1 Changing Control Mode 1) Get into the setpoint editing mode by pressing [CHNG SETP]. The key labels change to arrows. SetPnt Actual *FRST PT -1_ 0 .00 DEW PT -11.23 PPMv 2581. PPMw 1605. 10.37 SATUR 70.92 SATUR 10.00 TEST 14 70 TEST...
  • Page 40 4) With the cursor still on that parameter, press <ENTER>. The asterisk will then appear next to this selected control mode parameter. SetPnt Actual FRST PT -10.00 DEW PT -11.23 *PPMv 2000. PPMw 1244. 8.051 SATUR 91.08 SATUR 10.00 TEST 14 70 TEST 21 11...

  • Page 41: Purging

    3.2.5 Purging The Purge mode is generally used to prevent icing within the saturator and dry the saturator outlet after movement (transportation), storage (power off, no gas flow, etc.), after performing the saturator fill procedure (section 3.2.8), or while transitioning the saturator from higher to lower temperatures.
  • Page 42 3.2.5.1 Purge Procedure 1) From the idle Control/Display screen press [PRG]. The pump and compressors start and purge gas begins flowing within several seconds. Or, if the system is currently running in the Generate mode, press [PRG GEN*] to switch to Purge mode. Within a few seconds, the following screen appears.

  • Page 43: Saturator Clear

    3.2.6 Saturator Clear This procedure is used to clear the saturator of any excess water that may have occurred as a result of filling (see section 3.2.8), as a result of movement (such as transportation), or as a result of freezing and thawing a full saturator. Any time that water is observed at the gas vent whether after filling, movement, or thawing, the saturator should be cleared several times until no further indication of excess water exists.

  • Page 44: Generating

    3.2.7 Generating The Generate mode is used to generate a gas stream of desired humidity. In the Generate mode, the gas flows through the saturator where it is saturated with water vapor at the indicated saturation temperature and saturation pressure conditions, then flows to the device under test at test pressure and test temperature conditions.

  • Page 45: Generating Procedure

    3.2.7.1 Generating Procedure Note - Before attempting to Generate after periods of inactivity, the Purge procedure (section 3.2.5) must be performed and allowed to purge for 24 to 48 hours. To operate the system in the Generate mode: 1) Enter the desired setpoints (section 3.2.3) and set the control mode (section 3.2.4). 2) From an idle mode press [GEN].

  • Page 46: Example Instrument Set-Up

    3.2.7.2 Example Instrument Set-Up A chilled mirror hygrometer is to receive dew/frost point calibration at ambient temperature and pressure conditions. 1) Connect the gas inlet side of the chilled mirror to the generator outlet fitting with polished ® ID stainless steel tubing. The generator outlet is the Swagelok fitting located on the counter top farthest from the front of the generator.

  • Page 47: Saturator Fill

    3.2.8 Saturator Fill The saturator filling procedure should be performed upon initial use after installation, and approximately every 500 hours or more of operation thereafter, depending upon the humidities and flow rates generated. Generating high flow rates and high humidity values requires more frequent filling.
  • Page 48 2) View the Saturation Temperature ( ). If the Saturation Temperature Setpoint SATUR is below 0 °C, then (1) adjust the dew point to 2 °C or warmer, and (2) adjust the saturation temperature to 5 °C or warmer. Allow the Saturation Temperature to warm above 0 °C and stabilize before proceeding to allow all ice in the saturator to completely melt.

  • Page 49: Stopping

    3.2.9 Stopping The system may be stopped while either Generating or Purging. When stopped, all system functions shutdown, pressure is vented, the printer is disabled (if attached), and the idle Control/Display screen is shown. The system must be stopped in order to access the Edit and Cal modes.

  • Page 50: Shutdown

    3.2.10 Shutdown A shutdown should be performed when servicing the 3900, or when use is not frequent enough (such as day to day) to justify leaving the instrument in the Generate or Purge mode. When these conditions apply, follow the complete shutdown procedure: 1) Press the [STOP] key.

  • Page 51: Editing System Coefficients And Parameters

    3.3 EDITING SYSTEM COEFFICIENTS AND PARAMETERS All of the calibration coefficients and system parameters may be viewed and/or edited by the operator. The following is a summary of these items. Category Editable Parameters Temperature Coefficients Coefficients and Averaging Pressure Coefficients Coefficients and Averaging Flow Coefficients Coefficients and Averaging...
  • Page 52 An incorrect code prevents access and returns to step 3. A correct code results in the display of calibration coefficients. EDIT NEXT SATURATION TEMP, Ts Zero [-.877401 PREV Span [ 9.78206E-03] [-6.07702E-09] [ 10 DONE Last Cal Date 03/17/10 4) Using the [NEXT] and [PREV] keys, view any or all of the remaining coefficient and parameter screens.

  • Page 53: Coefficients And Parameters

    3.3.2 Coefficients and Parameters Each of the values on the various coefficient and parameter screens will be discussed in detail in the following sections. 3.3.2.1 Temperature Coefficients EDIT NEXT SATURATION TEMP, Ts Zero [-.877401 Span [ 9.98206E-03] PREV [-6.07702E-09] [ 10 DONE Last Cal Date 03/17/10 The ZERO, SPAN, and LIN values are coefficients to the formula...

  • Page 54: Reference Resistor Coefficients

    3.3.2.2 Reference Resistor Coefficients These coefficients are factory set and similar to the temperature coefficients of section 3.3.2.1. The reference resistor is approximately 10KΩ with coefficients chosen to provide a reference value of approximately 0 °C. An AVG amount of approximately 50 is typical. Any change made to either the reference resistor or the coefficients (with the exception of AVG) requires that the temperature calibration of section 4.2.2 be performed on both temperature probes.

  • Page 55: Flow Coefficients

    3.3.2.4 Flow Coefficients EDIT NEXT MASS FLOW RATE Zero PREV Span [ 4E-04 [ 10 DONE Last Cal Date 03/14/10 The ZERO, SPAN, and LIN values are coefficients to the formula Flow = A + Bx + Cx where A = zero coefficient B = span coefficient C = linearity coefficient x = output of the A/D converter card.

  • Page 56: Console Port Parameters

    3.3.2.5 Console Port Parameters These parameters affect the manner in which the bi-directional RS-232C Console Port behaves. EDIT NEXT CONSOLE PORT PARAMETERS Baud [ 2400 PREV Data Stop Parity [ 13 DONE Cancel Baud: 300, 600, 1200, 2400, 4800, 9600, 19200 or 38400 bits per second Data: 7 or 8 bit word size.

  • Page 57: Printer Port Parameters

    3.3.2.6 Printer Port Parameters These parameters affect the manner in which the unidirectional RS-232 Printer Port behaves. It not only affects communication parameters, but time interval between printouts of system data, and the number of lines to print per page. EDIT NEXT PRINTER PORT PARAMETERS...

  • Page 58: Miscellaneous User Parameters

    3.3.2.8 Miscellaneous User Parameters This screen is used to change the Miscellaneous User Parameters. EDIT MISC USER PARAMETERS P Units [ 0 NEXT T Units [ 0 F Units [ 0 DateFmt [ 0 PREV [ 28.9645 Tt Type [ 0 Pt Type [ 50 Pg Warn [ 50 DONE...
  • Page 59 Pg Stop: If the supply pressure drops below this pressure while generating or purging, the system will shutdown. Note - If the Flow Rate setpoint is set to zero (0), the system does not shutdown on low supply pressure. This allows gas supply bottles to be changed while generating and purging without requiring that the system be shutdown.

  • Page 60: Section 4 - Calibration And Maintenance

    Section 4 CALIBRATION AND MAINTENANCE 4.1 GENERAL The Model 3900 low humidity generation system requires little periodic maintenance. Following the proper operating procedures as given in this manual will help assure trouble- free operation of this system. 4.2 CALIBRATION Proper calibration of the temperature and pressure transducers is critical to the accuracy of the generated humidity.

  • Page 61: A/D Card

    Calibration of all transducers is to be performed "in the system, as a system". There are no provisions for, nor is it recommended that calibration of any of the transducers (temperature, pressure, or flow) be performed while electrically disconnected from the generator. Since all calibration is performed mathematically by the computer, there are no manual adjustments to make.

  • Page 62: Test Temperature Calibration Procedure

    4.2.2.1 Test Temperature Calibration Procedure Reference Drawing 95D39902 Equipment Required: 1. Temperature Bath (per section 4.2). 2. Standard or Reference thermometer (per section 4.2) Calibration Procedure: 1) Bring a precision temperature bath with reference thermometer to the system, and install the Test Temperature thermistor into temperature bath. If using water as the fluid medium, do not submerse the probe completely or water may get into the probe and damage the thermistor element.
  • Page 63 4) Press the [TEMP CAL] key. The probe selection screen appears. MARK /CLR Count Satur Tmp *Test EXIT QUIT 5) Using [MARK/CLR] and the down arrow key as necessary, mark the Test Tmp probe. A marked probe is indicated with an asterisk on the left. Since the two temperature probes require different calibration ranges, the computer will only allow you to mark one probe at a time.
  • Page 64 Then press <ENTER>. The LOW temperature value just entered, and the values of the marked probe are automatically saved to memory for later computation of calibration coefficients. Note - If a mistake was made during the temperature entry mode, use [OOPS] rather than <ENTER>.
  • Page 65 13) Check the accuracy of the calibration if desired, by repeating steps 4 through 6, however, don't "mark" any of the probes for calibration. Adjust the temperature bath to any values between 0 and 50 °C and visually compare readings. When done, press [EXIT QUIT].

  • Page 66: Saturation Temperature Calibration

    4.2.2.2 Saturation Temperature Calibration Reference Drawings 95D39902 Equipment Required: Standard or Reference Thermometer (per section 4.2) 3/16" (4.5 mm) ball/hex driver 9/16" (15 mm) wrench 9/16" (15 mm) socket with 6" (15 cm) extension Calibration Procedure: The saturation temperature probe may be calibrated using the 3900's temperature controlled saturator as the fluid bath.
  • Page 67 9) Press the [CAL] key. The calibration menu appears. TEMP PRES FLOW DONE 10) Press the [TEMP CAL] key. The probe selection screen appears. MARK /CLR Count *Satur Tmp Test EXIT QUIT 11) Using [MARK/CLR] and the down arrow key as necessary, mark the Satur Tmp probe.
  • Page 68 To obtain access to the setpoint control, press the <ENTER> key on the numeric keypad. SetPoint -4 _ 0 .0 Control Count *Satur Tmp 2464 24.89 Test 2135 21.35 High *OFF At this time, the cursor will begin flashing on the control setpoint in the saturator temperature control section.
  • Page 69 Note - Using the [LOW TEMP], [MID TEMP], or [HIGH TEMP] key more than once allows the previous point of the thermistor to be over-written with the most current measured value. reference thermometer value will also be over-written with the new value entered.

  • Page 70: Pressure Transducer Calibration

    4.2.3 Pressure Transducer Calibration Pressure Transducer Calibration is typically performed in a calibration laboratory and requires that the transducers be removed from the pneumatic system of the 3900, but must remain electrically connected. The pressure readings must be precise in order to retain accurate relative humidity calculations.

  • Page 71: Saturator And Test Pressure Calibration Procedure

    4.2.3.1 Saturator and Test Pressure Calibration Procedure Reference Drawing 95D39902 1) For safety purposes, switch console power OFF and remove the line cord. 2) For safety purposes, turn OFF or disconnect air supply. CAUTION! ALL SYSTEM PRESSURE MUST BE VENTED BEFORE PROCEEDING. 3) Bring the pressure source to the generator or take the generator to the pressure calibration lab.
  • Page 72 8) Press the [EDIT/CAL] key, then the [CAL] key. The calibration menu appears. TEMP PRES FLOW DONE 9) Press the [PRES CAL] key. 10) Using [MARK /CLR] and the down arrow key as necessary, mark the transducer to be calibrated. A marked transducer is indicated with an asterisk in the left most display column.
  • Page 73 Note - For all transducers, ambient pressure may be used for the low pressure calibration point. Note - If a mistake is made during reference pressure entry, pressing the [OOPS] key cancels the data entry mode, leaving all values for that point unchanged. 13) Apply the mid range pressure and watch the displayed value.
  • Page 74 16) If a printer is attached, a calibration record of the pressure points and calculated coefficients is printed. Press the [PRNT COEF] key if additional printouts are desired. This is the only opportunity to print this report. Upon leaving this screen, the data used for report generation is lost (with the exception of the calculated coefficients being displayed.) 17) To save the coefficients, press [SAVE QUIT].

  • Page 75: Supply Pressure Transducer Calibration

    4.2.3.2 Supply Pressure Transducer Calibration The supply pressure measurement, while indicated on the screen, is not critical to the accuracy of the 3900 and is not used in the humidity calculations. Reference Drawing 95D39902 Equipment Required: 1. Gas Supply of at least 300 psi, 21 bar, or 21000 hPa gauge. Calibration Procedure: 1) For safety purposes, switch the console power OFF and then remove front console panel.
  • Page 76 7) Apply the lower recommended calibration pressure by adjusting the internal pressure regulator REG fully counter clockwise and watch the displayed value. Once stable, press the [LOW PRES] key and enter the reference pressure as read from the regulator's pressure gauge (zero in this case). Since the regulator is a non-relieving type, pressure is vented through the pump purge solenoid.

  • Page 77: Flow Meter Calibration

    4.2.4 Flow Meter Calibration The flow measurement, while indicated on the screen, is not critical to the accuracy of the generated humidity and is not used in the humidity calculations. Flow calibration accuracy depends upon the requirements of the user. Equipment Required: 1.
  • Page 78 5) Press [CAL]. The calibration menu appears. TEMP PRES FLOW DONE 6) Press [FLOW CAL]. 7) Press [MARK/CLR] to mark the flow meter (indicated by an asterisk to its left). MARK /CLR Count l/min _ M ass Flow EXIT QUIT 8) Press [OK].
  • Page 79 9) Allow a few moments for stability of the flow indication. This "no flow" condition will be used for a LOW flow reference. Press [LOW FLOW] to store this point. Then press <ENTER>. Count l/min OOPS *Mass Flow .0144 High 10) Using the 1.0 liter data obtained in step 2, calculate the following: 1.0 + (Reference Indication) - (3900 Indication) Press [MID FLOW] and enter this calculated value.
  • Page 80 12) Press [CALC COEF] to calculate the new flow meter coefficients. These new coefficients appear on the display. PRNT COEF MASS FLOW RATE Zero [-1.56852E-03] EXIT Span [ 3.92120E-04] QUIT [ 2.62802E-09] SAVE QUIT 13) If a printer is attached, a calibration record of the flow points and calculated coefficients is printed.

  • Page 81: Printing Condensed Coefficient Report

    4.2.5 Printing Condensed Coefficient Report If a printer is connected to the Printer Port, a Coefficient Report for the temperature, pressure and flow transducers may be printed. This condensed report lists the current system calibration coefficients and calibration date for all of the system transducers. This report is printed from the Edit/Cal menu.

  • Page 82: Routine Maintenance

    4.3 ROUTINE MAINTENANCE 4.3.1 Console Intake: Monthly Reference Drawing 94D39901 Equipment Required: (None) Cleaning Procedure: 1) Locate console intake on left side of console. 2) Remove any obstruction and dust from console panel. 3) Remove left console panel and dust finned aluminum condenser. 4) Replace left console panel 4.3.2 7 Micron Gas Input Filter: Yearly Reference Drawing (pneumatic)

  • Page 83: Servicing Refrigeration And Fluid Systems

    4.4 SERVICING REFRIGERATION AND FLUID SYSTEMS Reference Drawing 95S39917 Before starting repairs on either refrigeration system, the serviceman should be familiar with the location of all components of the stages. Especially important is the identification of the high and low stages of the refrigeration system. The high stage compressor always connects directly to the air-cooled condenser.

  • Page 84: Oil In Low Stage Evaporator

    4.4.1.2 Oil In Low Stage Evaporator The migration of compressor oil to the low stage capillary tube will create symptoms similar to those of moisture. Solidification does occur as the oil reaches the capillary tube. This can reduce flow resulting in lower suction pressure. If the cabinet is warmed to a temperature of - 18 °C or higher and then restarted, the oil will be flushed out of the capillary tube and will not build up again for a week or more.
  • Page 85 To drain saturator fluid system, proceed as follows: 1) Disconnect power source from console. 2) Remove right side console panel. 3) Locate saturator drain valve (located below pump on right side of console). Remove insulation on drain valve outlet. Remove Drain Valve Cap and connect 1/4" hose to drain valve.
  • Page 86 4.5 ERROR CODES and TROUBLESHOOTING Prior to system start-up, and during humidity generation, the system monitors itself for errors and sources of possible malfunction. When a catastrophic error occurs, the system automatically shuts down, then alerts the operator with a visual flashing message and an audible tone.
  • Page 87 Error 4 - Low Supply Pressure This indicates that there is insufficient gas supply pressure to continue or that icing has occurred (section 3.2.5.1 Note 2). Check the gas supply. A malfunction of solenoid valve SOL1 or solid state relay SSR5 may also cause this problem. Error 8 - Cabinet Temperature Overrange The measured cabinet temperature is too high.
  • Page 88 Error 768 - Test Pressure Overrange The test pressure transducer indicates a pressure more than 10% above its full scale reading. The most likely cause is a pressure transducer malfunction or calibration error. Error 1024 - Low Range Saturation Pressure Underrange The low range saturation pressure transducer indicates a pressure less than 10 psiA.
  • Page 89 Section 5 3900 PARTS LISTS Find # Qty. Description Part Number Analog A/D Card MCM7418 Analog Terminal Board ADP7409TB Compressor, R-134A COMPR-220V/50HZ Compressor, R-23 COMPR-220V/50HZ CBS1 Power Switch PWRSW-2P Fan, Console MR77B3 Fan, Console FN624N CON1 Condenser, R-134A BT-COND CON2 Condenser, R-13 D95A00186 CP1,2...
  • Page 90 3900 PARTS LIST (continued) Find # Qty. Description Part Number SSR0-5 DC SSR Module G4DC5 SSR6,7 AC SSR Module G4AC5 SSR8-10 10 Amp SSR R24D10 SSRB SSR Module Board OP2512 Transducer, Pressure ST2500G1 Transducer, Flow BK5860E Transducer, Pressure PTE50 Transducer, Pressure DCT300A Transducer, Pressure PTE50...
  • Page 91 PRODUCTION THIRD ANGLE PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-1 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION Mechanical / Utility TOLERANCES 07/28/1994 FISCHER DRAWN 3900 .X ±.25...
  • Page 92 Thunder Scientific Corporation PRODUCTION THIRD ANGLE PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-2 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION Component Locations TOLERANCES FISCHER 4/4/1995 DRAWN 3900 .X ±.25...
  • Page 93 Thunder Scientific Corporation PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-3 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION Cards & Card Cage TOLERANCES 3/31/1995 FISCHER DRAWN 3900 ±.25...
  • Page 94 THIRD ANGLE Thunder Scientific Corporation PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-4 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION 3900 Bus Diagram TOLERANCES FISCHER 3/29/1995 DRAWN 3900 .X ±.25...
  • Page 95 Thunder Scientific Corporation PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-5 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION Electrical Sub Panel Layout TOLERANCES FISCHER 3/29/1995 DRAWN 3900 .X ±.25...

  • Page 96: Terminal Layout

    THIRD ANGLE Thunder Scientific Corporation PROJECTION DESIGNATION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY 39-Z-6 623 Wyoming S.E. Albuquerque, NM 87123 TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT WRITTEN PERMISSION Terminal Layout TOLERANCES FISCHER 3/29/1995 DRAWN 3900 .X ±.25...
  • Page 97 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC 623 Wyoming S.E. Albuquerque, NM 87123 AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION AC - DC Power Schematic...
  • Page 98 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Solid State Relay Module Schematic TOLERANCES FISCHER...
  • Page 99 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Compressor, Heater, Alarm Schematic TOLERANCES FISCHER...
  • Page 100 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Flow Valve Driver Schematic TOLERANCES FISCHER...
  • Page 101 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Expansion Valve Driver Schematic TOLERANCES FISCHER...
  • Page 102 PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED TEMPERATURE 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC REFERENCE AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Temp Probe / Transducer Schematic TOLERANCES...
  • Page 103 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Display Block Diagram TOLERANCES FISCHER...
  • Page 104 HAND CORNER OF THE PROJECTION THIS DRAWING AND INFORMATION CONTAINED LEFT SIDE PANEL 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION RS-232C / Printer Console TOLERANCES...
  • Page 105 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Pneumatic System - Generate Mode TOLERANCES FISCHER...
  • Page 106 Thunder Scientific Corporation PROPRIETARY NOTICE THIRD ANGLE PROJECTION THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION Pneumatic System - Purge Mode TOLERANCES FISCHER...
  • Page 107 CON1 RECR PROPRIETARY NOTICE: PROPRIETARY NOTICE: PROPRIETARY NOTICE: PROPRIETARY NOTICE: This Drawing and Information Contained Within is Proprietary to Thunder Scientific and cannot be Copied or Reproduced without Written Permission TOLERANCES TOLERANCES THIRD ANGLE PROJECTION THIRD ANGLE PROJECTION PRODUCTION Thunder Scientific Corporation DESIGNATION ±...
  • Page 108 (HP OPTION) CN25 DETECT DETECT PS1 (5V COM) PROPRIETARY NOTICE: This Drawing and Information Contained Within is Proprietary to Thunder Scientific and cannot be Copied or Reproduced without Written Permission TOLERANCES TOLERANCES THIRD ANGLE PROJECTION THIRD ANGLE PROJECTION PRODUCTION Thunder Scientific Corporation DESIGNATION ±...
  • Page 109 PROBE PARTS LIST PROPRIETARY NOTICE: PROPRIETARY NOTICE: PROPRIETARY NOTICE: PROPRIETARY NOTICE: This Drawing and Information Contained Within is Proprietary to Thunder Scientific and cannot be Copied or Reproduced without Written Permission TOLERANCES TOLERANCES THIRD ANGLE PROJECTION THIRD ANGLE PROJECTION PRODUCTION...
  • Page 110 IS AT ROOM TEMPERATURE SLOWLY ADD METHANOL TO METHANOL EXPANSION TANK UNTIL METHANOL IS OBSERVED IN THE SATURATOR METHANOL ACCESS PORT REFER TO SECTION 2.3.1 IN THE SERIES 3900 OPERATION AND MAINTENANCE MANUAL SERIES 3900 LOW HUMIDITY SP SD@U6S`ÃIPUD8@) uv†Ã9…hvtÃhqÃDs‚…€h‡v‚Ã8‚‡hvrqÃXv‡uvÃv†ÃQ…‚ƒ…vr‡h…’Ç‚à uˆqr…ÃTpvr‡vsvpÃhqÃph‚‡ÃirÃ8‚ƒvrqÂ…ÃSrƒ…‚qˆprqÐv‡u‚ˆ‡ÃX…v‡‡rÃQr…€v††v‚...
  • Page 111 PROJECTION Insert tubing with pre-swaged THIS DRAWING AND INFORMATION CONTAINED 623 Wyoming S.E. Albuquerque, NM 87123 WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC ferrules into fitting body. AND CANNOT BE COPIED OR REPRODUCED WITHOUT SPECIFIC WRITTEN PERMISSION 4 Port Sample Cell Assembly 2.
  • Page 112 Command Summary The following is a comprehensive list of commands, grouped by type, which are available over the RS-232 interface. Each of the commands is organized in alphabetical order on the following pages. Each command contains examples of its usage and proper syntax. Setpoint / Data Retrieval Commands Returns current system actual/generated values Returns current value of generated Dew Point...
  • Page 113 Utility/Status Commands Returns number of Saturator Clear cycles remaining CL= Sets number of Saturator Clear cycles Returns the system date Returns Date Format type Sets Date Format type Returns Error code ?MW Returns Molecular Weight MW= Sets Molecular Weight Returns Print Interval Sets Print Interval Returns Print On/Off status Sets Print On/Off status...
  • Page 114 Read Actual Values Description Returns the current generated system values. Prerequisites None Syntax Parameters None Remarks Data Returned returns a list of 11 comma separated values indicating the current data and status of the system. These values are returned in the same order as they appear on the 3900 screen.
  • Page 115 The data returned indicates that the system is currently running (last item in the list=1), and the generated values are: Frost Point = -10 °C Dew Point = -11.23 °C PPMv = 2581 PPMw = 1606 %RH = 10.39 Sat Pressure = 34.73 psiA Sat Temperature = -0.01 °C Test Pressure = 14.7 psiA Test Temperature = 21.1 °C...
  • Page 116 Read Saturator Clear Cycles Description Returns an integer value that corresponds to the number of Saturator Clear cycles left to complete. Prerequisites Firmware Ver 2.0 or newer Syntax ?CLEAR Parameters None Remarks Data Returned returns the number of saturator clear cycles left to complete. Examples command is used to request the number of saturator clears left to complete:...
  • Page 117 Set Saturator Clear Cycles Description Changes the number of Saturator Clear Cycles to a given value. Prerequisites Firmware Ver 2.0 or newer Syntax CL=value Parameters value The value is the number of clear cycles the generator should complete before returning to a purge mode. Remarks Data Returned None.
  • Page 118 Read System Date Description Returns the current system date. Prerequisites Firmware Ver 2.0 or newer Syntax ?DATE Parameters None Remarks Data Returned returns the system date in the current date format. Examples command is used to request the current date, assuming the system is using the default US date format: computer sends <CR>...
  • Page 119 Read Date Format Description Returns an integer value that corresponds to a date format type. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned returns one of two values to indicate the current date format. The two possible returned values are as follows: VALUE DESCRIPTION US date format, mm/dd/yy...
  • Page 120 Change Date Format Description Changes the system date format to one of two possible date format types. Prerequisites Firmware Ver 2.0 or newer Syntax DF=value Parameters value The value corresponds to a date format type. The date format types are as follows: VALUE DESCRIPTION US date format, mm/dd/yy...
  • Page 121 Read Generated Dew Point Description Returns the current value of the Dew Point being generated. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the Dew Point value, in °C, calculated from the current generator values for Ts, Ps, Tt, and Pt.
  • Page 122 Change Dew Point Setpoint Description Changes the Dew Point setpoint to a given value. Prerequisites None Syntax DP=setpoint Parameters setpoint The setpoint value is the Dew Point, in °C, that the system should generate. Remarks Control Mode Changed Sending setpoint also changes the control mode to Dew Point (mode 1).
  • Page 123 Read Error Number Description Returns the current error number relating to system shutdown. Prerequisites None Syntax Parameters None Remarks Data Returned returns one of several values indicating the reason(s) that the system shut down. The value returned can be any one, or an algebraic combination, of several, of the following: VALUE DESCRIPTION...
  • Page 124 Read Flow Rate Description Returns the current value of the Flow Rate. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Flow Rate in liters/minute. Examples command is used to request the current Flow Rate: computer sends <CR>...
  • Page 125 Change Flow Rate Setpoint Description Changes the Flow Rate setpoint to a given value. Prerequisites Firmware Ver 2.0 or newer Syntax FL=setpoint Parameters setpoint The setpoint value is the Flow rate, in l/m, that the system should control at. Remarks Data Returned None.
  • Page 126 Read Generated Frost Point Description Returns the current value of the Frost Point being generated. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the Frost Point value, in °C, calculated from the current generator values for Ts, Ps, Tt, and Pt.
  • Page 127 Change Frost Point Setpoint Description Changes the Frost Point setpoint to a given value. Prerequisites None Syntax FP=setpoint Parameters setpoint The setpoint value is the Frost Point, in °C, that the system should generate. Remarks Control Mode Changed Sending setpoint also changes the control mode to Frost Point (mode 0).
  • Page 128 Start the System Description Starts the system just as if the front panel "GEN" key had been pressed. Prerequisites Firmware Ver 2.0 or newer Syntax GENERATE Parameters None Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Examples command is used to start the system.
  • Page 129 Read Molecular Weight Description Returns the molecular weight of the carrier gas in g/mol. Prerequisites None Syntax Parameters None Remarks Data Returned returns the value currently being used as the molecular weight of the carrier gas in g/mol. The molecular weight of the carrier gas is used by the system when calculating PPMw from the fundamental measurements of Ts, Ps, Tt and Pt.
  • Page 130 Change Molecular Weight Description Changes the value used as the Molecular Weight of the carrier gas to a given value. Prerequisites None Syntax MW=value Parameters value The value is the molecular weight of the carrier/supply gas in grams/mole. If zero is input for the molecular weight the system will revert to a default value of 28.9645, the molecular weight of Air.
  • Page 131 Read Gas Supply Pressure Description Returns the current value of the Gas Supply Pressure. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Gas Supply Pressure in current system units. Examples command is used to request the current Gas Supply Pressure value, assuming the system units are in psi:...
  • Page 132 Read Print Interval Description Returns the print interval in seconds. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned returns the value currently being used as the print interval in seconds. Examples command is used to request the current print interval: computer sends <CR>...
  • Page 133 Change Print Interval Description Changes the printer interval to a given value and executes a Print Now command (PRI). Prerequisites Firmware Ver 2.0 or newer Syntax PI=value Parameters value The value is the time interval (in whole seconds) that the system will use as the lapse time between printed data points.
  • Page 134 Read Print ON/OFF Status Description Returns an integer value that is associated with the Print On/Off status. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned returns an integer value indicating the print function is on or off. The printer status values are as follows: VALUE DESCRIPTION...
  • Page 135 Change Print ON/OFF Status Description Changes the current print on/off status. Prerequisites Firmware Ver 2.0 or newer Syntax PU=value Parameters value The value corresponds to the following: VALUE DESCRIPTION Print off Print on Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Examples value command is used to turn on the generators print...
  • Page 136 Print System Data Description Sends one line of data to a printer if connected to the 3900's printer port just as if the front panel Enter or Decimal Point key had been pressed in a non-setpoint entering mode. Prerequisites The system must be running, and the serial port parameters must match between the 3900 and the printer used.
  • Page 137 Read Saturation Pressure Description Returns the current value of the Saturation Pressure. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Saturation Pressure in current system units. Examples command is used to request the current Saturation Pressure value, assuming the system units are in psi: computer sends...
  • Page 138 Change Saturation Pressure Setpoint Description Changes the Saturation Pressure setpoint to a given value. Prerequisites None Syntax PS=setpoint Parameters setpoint The setpoint value is the Saturation Pressure, in current system units, that the system should control at. Remarks Control Mode Changed setpoint also changes the control mode to Saturation Sending Pressure (mode 5).
  • Page 139 Read Test Pressure Description Returns the current Test Pressure value. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Test Pressure in current system units. If the external pressure transducer is not connected then this value is the test pressure setpoint value.
  • Page 140 Change Test Pressure Setpoint Description Changes the Test Pressure setpoint to a given value. Prerequisites None Syntax PT=setpoint Parameters setpoint The setpoint value is the Test Pressure, in current system units, that the system should use for calculations when the external pressure transducer is not connected.
  • Page 141 Read Pressure Units Description Returns an integer value that is associated with the Pressure unit’s type. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned returns an integer value indicating which of the 3 possible pressure unit types the system is using. The Pressure unit types are as follows: VALUE DESCRIPTION...
  • Page 142 Change Pressure Units Description Changes the current pressure units type. Prerequisites Firmware Ver 2.0 or newer Syntax PU=value Parameters value The value corresponds to one of the three following pressure unit types: VALUE DESCRIPTION psi, pounds per square inch hPa, hectoPascals Remarks Data Returned None.
  • Page 143 Purge the System Description Starts the system in the purge mode, just as though the Purge mode had been activated from the front panel. Prerequisites Firmware Ver 2.0 or newer Syntax PURGE Parameters None Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Examples command is used to start the system in the purge mode.
  • Page 144 Read Generated PPMv Description Returns the current value of the PPMv, Parts Per Million by Volume, being generated. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the PPMv value calculated from the current generator values for Ts, Ps, Tt, and Pt.
  • Page 145 Change PPMv Setpoint Description Changes the PPMv setpoint to a given value. Prerequisites None Syntax PV=setpoint Parameters setpoint The setpoint value is the PPMv that the system should generate. Remarks Control Mode Changed Sending setpoint also changes the control mode to PPMv (mode 2).
  • Page 146 Read Generated PPMw Description Returns the current value of the PPMw, Parts Per Million by Weight, being generated. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the PPMw value calculated from the current generator values for Ts, Ps, Tt, Pt and the molecular weight of the gas type being used.
  • Page 147 Change PPMw Setpoint Description Changes the PPMw setpoint to a given value. Prerequisites None Syntax PW=setpoint Parameters setpoint The setpoint value is the PPMw that the system should generate. Remarks Control Mode Changed Sending setpoint also changes the control mode to PPMw (mode 3).
  • Page 148 Read Generated %RH Description Returns the current value of the %RH being generated. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the %RH value calculated from the current generator values for Ts, Ps, Tt, and Pt as defined by the RH calculation method.
  • Page 149 Change RH Setpoint Description Changes the RH setpoint to a given value. Prerequisites None Syntax RH=setpoint Parameters setpoint The setpoint value is the %RH that the system should generate. Remarks Control Mode Changed Sending setpoint also changes the control mode to %RH (mode 4). In this mode Frost Point, Dew Point, PPMv, PPMw and Saturation Pressure setpoints vary as system temperatures and pressures change.
  • Page 150 Read Run Status Description Returns the current system operating status. Prerequisites None Syntax ?RUN Parameters None Remarks Data Returned returns one of three values to indicate whether or not the system is currently generating, purging or idle. The three possible returned values are as follows: VALUE DESCRIPTION...
  • Page 151 Save System Parameters Description Saves the current system parameters (i.e. Date Format, Molecular Weight, Pressure Units, Print Interval, and RH calculation method) to non-volatile memory for use as system defaults. Prerequisites None Syntax SAVE Parameters None Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Examples command is used to save all changes previously made to the SAVE...
  • Page 152 Read Setpoints Description Returns the current system Setpoints and operating mode. Prerequisites None Syntax Parameters None Remarks Data Returned returns a list of 11 comma separated values indicating the current setpoints and control mode of the system. These values are returned in the same order as they appear on the 3900 screen.
  • Page 153 The data returned indicates that the setpoints are: Frost Point = 8.894 °C Dew Point = -10 °C (also the control mode) PPMv = 2846 PPMw = 1771 %RH = 11.44 Sat Pressure = 131.5 psiA Sat Temperature = 10 °C Test Pressure = 14.7 psiA Test Temperature = 21.1 °C Flow Rate = 0.2 l/m...
  • Page 154 Stop the System Description Stops the system just as if the front panel "STOP" key had been pressed. Prerequisites None Syntax STOP Parameters None Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Examples command is used to stop a running or purging system. STOP STOP computer sends...
  • Page 155 Cabinet Fan Temperature Description Returns the cabinet fan temperature in °C. Prerequisites None Syntax Parameters None Remarks Data Returned returns the value (in whole degrees only) of the cabinet fan temperature. Examples command is used to read the current cabinet temperature. computer sends <CR>...
  • Page 156 Read System Date Description Returns the current system time. Prerequisites Firmware Ver 2.0 or newer Syntax ?TIME Parameters None Remarks Data Returned returns the system time in hh:mm:ss. Examples command is used to request the current time: computer sends <CR> 13:59:32 3900 responds <CR><LF>...
  • Page 157 Read Saturation Temperature Description Returns the current value of the Saturation Temperature. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Saturation Temperature in degrees Celsius. Examples command is used to request the current Saturation Temperature: computer sends <CR>...
  • Page 158 Change Saturation Temp Setpoint Description Changes the Saturation Temperature setpoint to a given value. Prerequisites None Syntax TS=setpoint Parameters setpoint The setpoint value is the Saturation Temperature, in °C, that the system should control at. Remarks Data Returned None. The only response is a carriage return/linefeed terminator. Control Modes and Saturation Temperature An inherent characteristic of the 3900 is its ability to adjust the Saturation Temperature setpoint to allow the generator to achieve a...
  • Page 159 Read Test Temperature Description Returns the current Test Temperature value. Prerequisites Firmware Ver 2.0 or newer Syntax Parameters None Remarks Data Returned The value returned is the current value of the Test Temperature in degrees Celsius. If the external temperature probe is not connected then this value is the test temperature setpoint value.
  • Page 160 Change Test Temperature Setpoint Description Changes the Test Temperature setpoint to a given value. Prerequisites None Syntax TT=setpoint Parameters setpoint The setpoint value is the Test Temperature, in °C that the system should use in calculations when the external temperature probe is not connected.
  • Page 161 Read WMO Status Description Returns an integer value that corresponds to the RH calculation method. Prerequisites None Syntax Parameters None Remarks Data Returned returns one of two values to indicate the current RH calculation method. The two possible returned values are as follows: VALUE DESCRIPTION Normal...
  • Page 162 Change WMO Status Description Changes the system RH calculation method. Prerequisites None Syntax WM=status Parameters status The status corresponds to an RH calculation type. The RH calculation types are as follows: VALUE DESCRIPTION Normal WMO, World Meteorological Organization A value other than 0 or 1 will cause the system to default to the Normal method.
  • Page 163 System Authorization Code: 3900 This code was designed to prevent unauthorized personnel access to the calibration coefficients.
  • Page 164 THUNDER SCIENTIFIC CORPORATION ® 623 Wyoming Blvd. SE ~ Albuquerque NM 87123-3198 www.thunderscientific.com...

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