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TELEDYNE
HASTINGS
INSTRUMENTS
INSTRUCTION MANUAL
MODEL 2002
VACUUM GAUGE
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Manual Print History The print history shown below lists the printing dates of all revisions and addenda created for this manual. The revision level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between revisions, contain important change information that the user should incorporate immediately into the manual. Addenda are numbered sequentially. When a new revision is created, all addenda associated with the previous revision of the
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Table of Contents 1. GENERAL INFORMATION......................................................................................................................................... 4 1.1. FEATURES................................................................................................................................................................. 4 1.2. MODEL 2002 SENSORS...................................................................................................................
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1. General Information The Model 2002 is a wide range vacuum measuring instrument consisting of a digital microprocessor-based display unit, a miniature, rugged, thin film based sensing element that measures from below 1x10-4 up to 100 Torr, a piezoresistive sensor that measures from 1 to 1000 Torr, EEPROM (Electrically Erasable/Programmable Read Only Memory), and an interconnecting cable. Together, these components provide accurate vacuum measurement over 7 decades of vacuum from 1x10-4
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board is also available. The Model 2002 instrument accepts an external TTL level "Remote Zero" to zero the instrument when another instrument (e.g. an ion gauge) indicates that the pressure is less than 1x10-5 Torr. The standard analog output is linear per decade directly corresponding to the control unit’s display. The Model 2002 comes calibrated for nitrogen. Conversion factors for other gases are selectable by the user (see section 3.5). This direct readout display allows for flexibi
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2. Installation This section is designed to assist in getting a new pressure gauge into operation as quickly and easily as possible. Please read the following instructions thoroughly before installing the instrument. 2.1. Receiving Inspection Carefully unpack the Hastings Model 2002 Instrument (part # HPM-2002), transducer (part #HPM-2002s) and cable (part # CB 2002). Inspect all items for any obvious signs of damage due to shipment. Immediately advise the carrier who delivered the shipmen
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2.4. Control Unit Installation • Environment: • Indoor use • Altitude up to 2000 meters • Operating temperature range from 50 to 400C • Maximum relative humidity: 80% for temperatures up to 310C decreasing linearly to 50% relative humidity at 400C • Installation category II Panel Mount Instructions: The control unit can be panel mounted. See detail on page 43. The dimensions of the hole on the panel are 3.62" x 3.62"(92.8mm x 92.8 mm). Slide the neoprene gasket that was shipped with
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3. Front Panel Operation 3.1. Overall Functional Description The front panel of the control unit is shown in Figure 3.1. The four circular blue buttons are used for the selection of display readout and the input of data. The green data field displays the data as determined by mode selection. The MODE switch toggles the control unit in a clockwise fashion among the six modes of operation: RUN Normal operation, pressure is displayed in scientific notation. The analog to digital converte
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Scientific Notation The Model 2002 measures pressure that spans more than seven decades. In order to easily display these readings, Hastings Instruments has employed scientific notation. In scientific notation, the mantissa (the fixed point part) is multiplied by some power of 10 (given by the exponent). Powers of 10 3 -1 10 = 1000 10 = 0.1 2 -2 10 = 100 10 = 0.01 1 -3 10 = 10 10 = 0.001 0 -4 10 = 1 10 = 0.0001 +2 As an example: 7.60 x 10 Torr mantissa expone
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This will not correct the calibration if the tube has become contaminated or damaged. This reset will not affect the gas selection, units or setpoints. Also see unit’s mode for default calibration restoration. 3.3. High and Low Set Point Modes The Model 2002 provides TTL outputs for process control. The I/O cable is attached via a 9-pin sub-D connector to the rear panel of the control unit. The pinout is shown in Figure 4.2. To view the high set point, place the Model 2002 in the
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An important point to be noted is the fact that after the adjustment, the new calibration coefficient is only in temporary memory. If the instrument were unplugged at this point, it would revert back to the original displayed value upon restarting. Place the Model 2002 back in the RUN mode to store all of the current calibration coefficients in permanent memory. To perform a full calibration on the Model 2002 system, first use the Zero Coefficient Adjustment Procedure. Followed by the Mi
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3. Place the instrument in the CAL mode, then simultaneously press the UP and DOWN switches to bypass the interlock. The CAL light will start to flash indicating that the calibration mode has been activated. 4. Press the ZERO switch once if below 6x10-5 Torr otherwise use the UP and DOWN switch to adjust the display of the Model 2002 to match the pressure indicated by the reference. If using the UP and DOWN switch to adjust the display, wait 20 seconds between presses at very low pressure t
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TABLE 1 Gas Mode Gas Displayed Number 0.0………………………..Nitrogen 0.1…………………...……..Argon 0.2…………………...…….Helium 0.3………………...…Water Vapor 0.4………………....……..Custom light will now flash. Use the UP and DOWN switches to individually select the desired code. Return the Model 2002 to the RUN mode. Note: Factory calibration is performed using nitrogen only. Displayed pressure measurements using other gases are based on established gas thermal conductivity data. 3.6. UNITS Mode The Mode
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4. Rear Panel Description A schematic of the rear panel of the Model 2002 control unit is shown in Figure 4.2 ( Rear Panel Figure). The transducer is connected to the control unit via an female 9-pin “D” connector on the rear panel. An I/O cable can be connected via a male 9-pin “D” connector on the rear panel. The I/O cable provides an analog output signal, a remote zero input capability, high and low alarm TTL outputs, and a + 5 VDC Power Supply Output. The I/O cable also provides an ana
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If the analog output voltage is being used in a data acquisition system, the following formulas can be used to calculate pressure. EXP=INT (*V)-6 MANT=1+18*V-9*(EXP+9) exp Pressure (Torr)=Mant x 10 Therefore, Note that the INT function simply returns to the first digit in a number. Examples: INT (2.56) = 2 INT (9.87) = 9 --------------------------------------------------------------------------------------------------------------------- Voltage to pressure conversion ex
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4.3. TTL Outputs TTL outputs are provided for process control. High and Low set points are entered on the front panel (see Section 3.4) and TTL signals are generated on the I/O cable in the following manner: 1. When the pressure as indicated by the Model 2002 is above the High set point, the High signal line (pin #3) will be set to a TTL high level (+5 VDC). When the indicated pressure is below the High set point, the High signal line (pin#3) will be set to a TTL low level (+0 VDC). 2.
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5. Theory of Operation The Model 2002 transducer is comprised of two very different sensors which provide a span of measurement extending from 1000 Torr down to less than 1x10-4 Torr. The piezoresistive device is a direct force sensor which provides pressure indication from 1000 Torr down to less than 1 Torr. The thin film Pirani device is a thermal conductivity sensor that provides pressure indication from 100 Torr down to less than 1x10-4 Torr. The two decade overlap in measurement ra
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To insure temperature invariance, dVo SdV VdS ⎛ ⎞ = P⎜ + ⎟ dT dT dT ⎝ ⎠ 1 dV 1 dS dVo ⎛ ⎞ = − + = 0 ⎜ ⎟ Therefore dT V dT S dT ⎝ ⎠ This requires for any change in sensitivity to be countered by an equal but opposite change in applied voltage. The temperature compensation is a network of temperature dependent resistive components and fixed temperature compensation current source compensation, TCR = -TCS. Sensitivity of the sensor is proportional to the sensor factor (K), the strain
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5.2. Pirani Sensor Figure 5.3a shows a thin film Pt resistive element on a one micron thick Si N continuous membrane 3 4 0 surrounded by a thin film Pt reference resistor on a Si substrate. The membrane is heated to a constant 8 C above ambient temperature that is monitored by the substrate resistor. The membrane resistor is approximately 60 Ω and a constant substrate to membrane resistance ratio is maintained at 3.86. Figure 5.3b shows the Pirani die in cross section. A parallel Si li
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Since the first two losses are essentially constant at high vacuum for a given sensor, we can measure these losses and subtract them from the input power which leaves only the rate of heat transmission through the gas (E ). g In the viscous flow regime, the Eg loss is directly dependent on the thermal conductivity of the gas (Kg), the surface area of the membrane, the differential temperature and is inversely proportional to distance between the mem
