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Ludlum Measurements 334A Operation Manual

Alpha air monitor
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LUDLUM MODEL 334A
ALPHA AIR MONITOR
April 2023

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Summary of Contents for Ludlum Measurements 334A

  • Page 1 LUDLUM MODEL 334A ALPHA AIR MONITOR April 2023...
  • Page 3 Model 334A Operations Manual...
  • Page 4 Ludlum Measurements, Inc. 501 Oak Street, Sweetwater, Texas 79556 Trademarks Ludlum, the Ludlum logo, and Model 334A are trademarks of Ludlum Measurements, Inc. Microsoft, Windows CE, ActiveSync, Excel and the Windows logo are registered trademarks of Microsoft Corporation.
  • Page 6 RETURN OF GOODS TO MANUFACTURER If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to the address below. All shipments should include documentation containing return shipping address, customer name, telephone number, description of service requested, and all other necessary information.

  • Page 8: Table Of Contents

    Table of Contents GETTING STARTED ...................... 1 ....................1 ENERAL ESCRIPTION ................... 1 NPACKING AND EPACKING 334A ..................... 2 ARTS OF THE ODEL ................3 NDERSTANDING THE ETECTOR ..................... 4 URNING THE Charging the Batteries....................4 Power Button Functions ....................5 ....................
  • Page 9 Running the Response Check ..................33 ................34 ORMAL EASUREMENT PERATION Minimum-Detectable Levels & Window Times ............34 Display: Meter/Spectrum/Log ..................34 Operational Duration ....................35 MEASUREMENT CALCULATIONS ................. 36 & C ................. 36 CUTE HRONIC OVING INDOWS ................. 36 LPHA EASUREMENT ALCULATIONS...

  • Page 10: Getting Started

    Getting Started General Description The Model 334A is a portable alpha air monitor designed to function both as a workplace monitor and a Continuous Air Monitor (CAM). Spectral analysis is conducted via a 1024-channel analyzer that feeds data to the embedded processor. Factory configuration provides alpha particulate measurements, special nuclear materials (SNM) measurements or radon progeny measurements of potential alpha energy concentration (PAEC).

  • Page 11: Parts Of The Model 334A

    A light stack containing an audible alarm and red light is mounted to the side of the case. On the front, the Model 334A contains a 5.5-inch touch-screen display. The display is most easily operated using a stylus. There are three buttons located below the touch-screen display, which allow the user to toggle displayed units and channel, as well as an alarm acknowledge to silence and clear an alarm.

  • Page 12: Understanding The Detector Head

    In addition to the Model 334A itself, the package it comes in contains an AC Adapter for charging the Model 334A, a USB sync cable for exchanging data with a PC, a flow calibration aid, and a CD with software, certificates, and training videos.

  • Page 13: Turning The Unit On

    Also the Model 334A application will be stored on non-volatile memory and will be restored once power is returned to the unit. So after the battery is fully discharged, all that is needed is to reconnect the unit to AC power and allow the battery to charge again.

  • Page 14: Power Button Functions

    Model 334A program. The Response Check function will be covered later in this manual. For now and until the Model 334A is fully calibrated, tap the Skip button to bypass the Response Check or wait for 60 seconds for it to time out and then automatically continue.

  • Page 15: Understanding The Display

    Understanding the Display The basic display for the Model 334A includes a Menu bar across the top, a Meter in the upper half of the screen and a Log entry in the lower half that toggles to view the current Spectrum.

  • Page 16: How To Change The Filter

    (optional) channels only has one unit each. How to Change the Filter After a Model 334A has been monitoring for some time, the filter will become laden with dust and need to be replaced. Do this regularly; either by a specific schedule or when the flow rate declines and indicates Lo Flow (see section 3 on configurations).

  • Page 17: Password Security

    Setting the Clock The Model 334A is configured with a real-time clock, which can be manually set or set automatically when connected via the USB port to a PC. The unit is factory calibrated to the correct customer time-zone before shipment. Whenever the battery and external power are disconnected from the main processor board during maintenance or repair, the clock will be reset to a default date.
  • Page 18 Model 334A Operations Manual Ludlum Measurements, Inc. April 2023...

  • Page 19: Calibration

    (POOR FIT status), and the unit will fail to alarm properly. Flow calibration is important, as it determines if the Model 334A is converting the pump current into the measured flow rate correctly. The calibration functions are accessed from the Calibration item on the main menu. The three calibration functions are Flow, Alpha Energy, and Alpha Efficiency.

  • Page 20: Calibration Overview

    Calibration source holders may be ordered which fit the Model 334A detector head and hold a 32 mm source in the proper position for repeatable calibration geometry. It is also very important that the alpha calibration source matches the first isotope-of-interest (IoI 1).

  • Page 21: Alpha Energy Calibration

    Several vertical red lines are scattered along the alpha spectrum. The number of lines depends on the operating configuration of the Model 334A. These lines indicate the position of the alpha peaks and can be adjusted by dragging to match up with the peak location. The numbers at the top of each red line correspond to the channel number of the peak location.

  • Page 22: Performing The Calibration

    Observe the following steps for more detail. Consideration for Radon Mode The Model 334A can be operated in “Radon Mode” by selecting PAEC as the primary IoI (Iso 1) where the radon/thoron progeny are used to determine the PAEC (potential alpha energy concentration) exposure to the worker in milli-working levels (mWL).
  • Page 23 Alpha Energy Calibration window open on the screen before leaving the Model 334A to collect the radon spectrum. Leave the Model 334A operating in a high radon area for 8-24 hours so that a well-defined radon spectrum can be accumulated.
  • Page 24 Model 334A Operations Manual the center of the peak. Another number will appear while the line is being dragged that indicates the number of counts per channel. Release the line on the channel with the highest counts. Calibrating the Isotope-of-Interest The isotope(s)-of-interest also needs to be energy calibrated at this point.

  • Page 25: Alpha Efficiency Calibration

    This efficiency is used to produce accurate exposure and concentrations in units of measure meaningful to the user (e.g. DAC-h and mWL). It also makes sure that the Model 334A is counting at an acceptable rate. To begin the Alpha Efficiency Calibration, select Calibrate—Alpha Efficiency… from the menu.

  • Page 26: Response Check

    Flow Calibration The Model 334A sample flow rate is estimated by monitoring the pump’s electrical current. Flow calibration is necessary to ensure that the Model 334A program is correctly monitoring and converting the pump current into a flow. This relationship is not linear. As a result, a three-point flow calibration is used, with validation at a fourth flow rate.

  • Page 27: Performing The Calibration

    Model 334A Operations Manual NOTE: Ensure that the variable flow restriction does not completely cut off the airflow to the pump. The pump is not designed to pull a high vacuum, and flow rates can damage the pump diaphragm. Do not allow the pump to run below 5 LPM for 7 LPM pumps (or more 4 LPM for 6 LPM pumps) for more than a few minutes.
  • Page 28 Model 334A Operations Manual The first step in the flow calibration is to reduce the flow rate by adjusting the flow restriction device to a low flow rate, at about 2 LPM below the unrestricted rate. Enter the actual value from the flowmeter in the dialogue under Measured Flow, and then hit Start Calibration.
  • Page 29 Model 334A Operations Manual The flow calibration is now completed and this example shows 0.4% error, which is acceptable. Tap Close, and when prompted, “Do you want to save the changes?” click YES. Remove the flow calibration aid from the detector head, which may be difficult because of the suction created.

  • Page 30: Configuration

    Model 334A Operations Manual SECTION Configuration The Model 334A program provides several dialogs to allow configuration of the instrument operation. These dialogs are accessed through the File and Monitor menus. Each dialog and its settings are described below. Instrument Properties This dialog controls the operation of the of the user interface aspects of the program.

  • Page 31: Instrument Options

    Alarm Ack button on the face of the Model 334A. When paired with the Use Password Security option, the user must have at least a config-level password in order to acknowledge and silence the alarm.

  • Page 32: General Tab

    Calibration Expiration Settings Calibration expires—This non-editable item displays the latest date on which the Model 334A calibration will expire. The expiration could occur sooner if the maximum runtime hours are exceeded. End of Month—this checkbox allows expirations to be posted on the last day of the month following the actual expiration date.

  • Page 33: Logging Tab

    The Logging Interval settings control the data logging behavior of the Model 334A. Several types of log files are created on the Model 334A during operation. See Section 6: Retrieving and Analyzing the Data, for more information on the log files.

  • Page 34: Isotope Tabs

    Model 334A Operations Manual Isotope Tabs The Iso 1 and 2 tabs define the parameters concerning the primary and secondary isotope- of-interest measurements. By default, the first isotope of interest is Pu-239, however, this isotope may be changed to support the measurement of other alpha-emitting isotopes.
  • Page 35 Model 334A Operations Manual Iso 1, you will find the entry ROI_1. Likewise, under the Iso 2 tab Isotope drop-down list, you will find ROI_2. Selecting a Region of Interest from the drop-down list will enable the energy region fields to be displayed and edited.

  • Page 36: Alarm Settings

    Default is 10 false alarms per year. Option: Sigma Alarming The Model 334A Alert may be ordered with sigma alarming options. A drop-down allows the user to select between standard Fixed alarming, Sigma alarming, or both Sigma AND Fixed Alarming.

  • Page 37: Flow Tab

    It also offers a Fixed Flow setting for externally plumbed units. Low Limit—This setting defines the limit in liters per minute below which the Model 334A will indicate a LO FLOW status. A low flow status can indicate a loaded or wet filter. Default is 6.0 LPM Ludlum Measurements, Inc.

  • Page 38: Radnet Tab (With Wifi Or Ethernet Option)

    Low Fail Limit—This setting defines the limit in liters per minute below which the Model 334A will indicate a FLOW FAIL status, go out of service, and will not alarm. A flow fail status can indicate a kinked or clogged vacuum line. Default is 4.5 LPM.

  • Page 39: Ascii Tab (With Rs-232, Ethernet, Or Wifi Option)

    This page contains the settings for ASCII Communications Protocol broadcasts for Model 334A units with an RS-232, Ethernet, or WiFi Option installed. The RS-232 and Ethernet options offer a RJ-9 or RJ-45 connector on the side panel respectively, while the WiFi option provides an internal antenna or broadcasting.
  • Page 40 Model 334A Operations Manual Baud—This field specifies the bits per second with which ASCII packets are broadcast. Default is 19200. WiFi Enabled—When checked, this setting transmits measurement packets wirelessly using the ASCII Protocol. Default is checked if ordered TCP/UDP Settings Ethernet Enabled—When checked, this setting transmits measurement packets...

  • Page 41: Starting A Dose Measurement

    The overall diameter of the source can be no larger than 32 mm (1.26 in.). The sources also need to match the isotope-of-interest the Model 334A is configured to measure. It is suggested that the DPM activity be calculated from 2X the surface emission rate in CPM.

  • Page 42: Running The Response Check

    Model 334A Operations Manual Running the Response Check After starting the Model 334A program, the Response Check dialog is automatically initiated. It may also be initiated from the menu by tapping Monitor – Response Check…. There are four edit fields in the upper portion of the screen: Source—This list box displays the alpha source that can be used for the response check.

  • Page 43: Normal Measurement Operation

    Chronic Dose reading for IoI 1. The Dose, Concentration, activity, and net count rate for the other isotope-of-interest—as well as the radon daughters, Po-212, Po-214, Po-218—will be displayed as well through the use of the buttons on the front panel of the Model 334A. Ludlum Measurements, Inc.

  • Page 44: Operational Duration

    Return to the log entry view by tapping View—Log. In the event that a dose or concentration reading exceeds alarm limits, the Model 334A will alarm visually and audibly, automatically display the channel of the chronic or acute reading that caused the alarm, and the status will be changed to High Alarm.

  • Page 45: Measurement Calculations

    Model 334A Operations Manual SECTION Measurement Calculations Acute & Chronic Moving-Windows In order to calculate a concentration, the counts for each counting channel are saved—along with the flow rate and volume—in a history array, so that the increase in counts over time can be used to determine the net count rate.

  • Page 46: Alpha Concentration Calculation

    Model 334A Operations Manual the two intervals is proportional to the concentration. Once the change in net count rate is known, the calibration constant and flow volume are used to derive the concentration in the specified measurement units. An additional term is included in the concentration calculation to account for the expected count rate losses due to activity that has decayed off during the last interval.

  • Page 47: Alpha Dose Calculation

    In the Model 334A, the minimum detectible concentration (MDC) is not directly related to the spectrum counts, but to the uncertainty in the peak fit.

  • Page 48: Radon Mode Considerations

    = Peak area variance for most recent Radon Mode Considerations The Model 334A may be used as a radon progeny monitor, measuring and alarming on PAEC (potential alpha energy concentration) levels of milli-Working Levels (mWL), and dose estimates in mWL-h. Alternatively, if configured for SI units, the instrument will display radon concentration in µJ/m³...
  • Page 49 Bi-212 before the ultimate energy yield of 13.69 MeV of Po-218 are summed. While its contribution is not included in the PAEC result, the Model 334A does monitor for and report the concentration and dose estimate from Po-210.

  • Page 50: Retrieving & Analyzing The Data

    SECTION Retrieving & Analyzing the Data The log files stored on the Model 334A DS Card or in the My Documents folder may be retrieved and analyzed on a PC, laptop, or workstation, either over the USB connection, or over the Ethernet/WiFi network connection.

  • Page 51: Connecting To Apc

    To connect to your Model 334A, plug the USB sync cable from the computer to the mini- USB connection on the side of the unit. If the unit is turned on, the Model 334A should automatically connect with the computer.

  • Page 52: Connecting To Apc Over Network

    Connecting to a PC Over Network To connect to your Model 334A over a WiFi or Ethernet network, you will need to know the network IP Address of the instrument from your IT staff who set up the instrument on the network.
  • Page 53 Pu239_Acute_YYYYMMDD.txt—This text file contains the log of acute readings archived during the Model 334A dose measurement period. Note: the file name may be different if Pu-239 is not defined as the isotope-of-interest. New acute log files are started daily at midnight.

  • Page 54: Transferring Data Directly To Usb Storage Media

    (°C) readings. It is deleted and a new log started when the Model 334A application starts. Once the Model 334A log data has been retrieved, you may disconnect the USB cable from the computer to the unit. Disconnecting the USB cable will not affect the operation of the unit nor the files copied or synced.

  • Page 55: Graphing Data In Excel - With Templates

    Model 334A Operations Manual  Proceed through the Text Import Wizard with these selections: Delimited – Comma (not Tab) – Date MDY – Finish – OK (=$A$1)  The data can now be graphed as desired  Save the spreadsheet to preserve the link to the imported data, for refresh later Graphing Data in Excel –...

  • Page 56: Chronic & Acute Charts

    Model 334A Operations Manual  Navigate to the folder where you synced or copied the log files to earlier. Find the spectrum file labeled Spectrum_YYYYMMDD and import it.  Click back to the Spectrum Chart tab and press the Animate button again to view the new spectrum time-lapse.
  • Page 57 Model 334A Operations Manual Alpha Chronic Chart Alpha Acute Chart Ludlum Measurements, Inc. April 2023...

  • Page 58: Radnet Operation

    RadNet Operation General Model 334A units ordered with the wireless RadNet Output option come equipped with an RJ-45 connector for connection to a local network, 802.11b-compatible wireless module and internal antenna, and are configured to allow broadcasting of RadNet measurement and spectrum UDP-packets to the local Class-C Subnet.
  • Page 59 RadNet Client Workstation Configuration In order to communicate with the Model 334A, the client workstation must be configured with a compatible IP Address in the Class-C range. Choose an address that does not conflict with each other.

  • Page 60: Ascii Operation

    ASCII log data. A wireless access point (WAP) is required to receive the transmissions from the Model 334A and relay those transmissions either via an Ethernet cable to a network workstation, or via a second wireless link to the workstation.
  • Page 61 Model 334A Operations Manual Configuration of Wireless Connections The Model 334A with the Wireless ASCII Output option includes an 802.11b/g WiFi module and antenna. Configuration of this is covered in Section 7. Standard Log Data Format The log data is reported in comma-delimited format. Each channel is transmitted in a string of data, with multiple strings each minute depending on the unit configuration.

  • Page 62: Status Conditions

    Model 334A Operations Manual Appendix Status Conditions Status Description INITIALIZING Model 334A program initialization (momentary status) NORMAL Operating normally, alarm levels below limit HIGH Dose or Concentration set point has been exceeded LO FLOW Flow rate is below Low Limit...

  • Page 63: Network File Access

    Appendix Network File Access NOTE: The following information is valid for both the 334A and 334AB. When enabled at the factory, the Model 334A/Alert Ethernet and WiFi communications provide remote access of log files without using the USB Windows Mobile Device Center connection.
  • Page 64 Model 334A Operations Manual In order to enable the access, the security policy for NTLMv2 needs to be changed: 1. Start -> Run secpol.msc 2. Go to Local Policies -> Security Options 3. Edit the properties of the Policy Network security: LAN Manager authentication level 4.
  • Page 65 The RemoteAdmin client allows the changing of the password, the addition of users and setting file sharing permissions. Technical References There is a web interface on a PC connected to the Model 334A to help set up shared folders and file sharing: https://developer.toradex.com/knowledge-base/webinterface On the Model 334AB/Alert you can enable authentication.

  • Page 66: Editing The Alpha Isotopes Database

    The alpha isotopes that appear in the drop down lists for selection as the Iso 1 and Iso 2 isotopes-of-interest are taken from a comma-delimited text file on the FlashDisk/User folder on the Model 334A. This file Isotopes.csv is user-editable from a text editor like the Windows Notepad, or from Microsoft Excel.
  • Page 67 Alarms—these four columns define the alarms in DAC and DAC-h. Typical default alarm levels are 200 DAC-h and 1000 DAC for the Acute and 20 DAC-h and 100 DAC for the Chronic. These values are updated from the Model 334A application when changed under the Alarm Settings dialog.

  • Page 68: Specifications

    Model 334A Operations Manual Appendix Specifications Sampling Head and Flow  37 mm Filter holder, masked to 25 mm collection diameter  Detector: Solid-state silicon 300-µm-depleted (450 mm² active area)  Pump: diaphragm-type, 7.0 LPM with no load Alpha Data Analysis ...

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