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Simulator Basics

Learn about the history and functionality of simulators in alcohol breath test instruments. Understand how simulators provide precise calibration standards and ensure accurate readings. Presented by Guth Laboratories, Inc.

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Simulator Basics

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  1. Simulator Basics IACT Newport Beach California April 10, 2014 Presented by Guth Laboratories, INC

  2. Contact Information Ted L. Pauley TLPAULEY@GUTHLABS.COM GUTH LABORATORIES, INC 590 N. 67TH ST. HARRISBURG, PA 17111 800-233-2338 FAX: 717-564-2555 WWW.GUTHLABS.COM

  3. What is a Simulator ?? An electronically temperature controlled instrument that when used with Alcohol Reference Solution, will provide precise and accurate calibration standards for use with alcohol breath test instruments.

  4. History of the Simulator Alcohol Equilibrator aka “Baby Bottle”: 1950’s Solution placed in baby bottle and operator would record temperature of the solution and use a conversion chart to look up value of solution based on the temperature of the solution.

  5. History of the Simulator Thermostatically controlled Simulators 1960’s Heat solution to 34°C (+/-0.2°C limit of thermostat and basis for NHTSA guidelines for simulators and still used today.)

  6. History of the Simulator Electronically controlled Simulators : 1980’s Elimination of Hg thermostats Electronically controlled for better precision of temperature. Ability to maintain Temperature at 34°C +/-0.05°C. (NHTSA spec: 34°C +/-0.2°C.)

  7. History of the Simulator Digital Readout Display of Temperature: 1990’s to present Eliminate need for Mercury Thermometers to verify temperature of solution. Addition of cap heaters and other improvements for better precision and accuracy readings. Ability of simulator to communicate (RS232) with Alcohol Breath Test Instrument to ensure Temperature of simulator is within tolerance before test can be conducted on Alcohol Breath test Instrument.

  8. Why We Use Simulators Provide a sample that closely resembles that of a human breath sample. Ensure that the Breath Alcohol instrument you are using is working/calibrated correctly. Early days of breath testing it was quite controversial to have people (law enforcement personnel) perform a “scientific test” with little or no training. Community of Legal Defense issues… The argument of “How do I know that a particular instrument was working properly at the time my client was tested.” Need for regulations, SOPs, guidelines etc. etc.. To ensure operators were performing tests correctly, clients or subjects were being tested on instruments that are accurate in reporting subject BACs.

  9. Anatomy of a Simulator

  10. Science of a Simulator The theory of operation of any reference sample device is based upon the scientific law first proposed by William Henry in 1803. P=KC  P=pressure of the gas (atm)  K=Henry's Law Constant (atm/M)  C=Concentration of the Gas  (M) According to Henry's Law, at a given temperature, the amount of alcohol in the air (reference sample) is proportional to the amount of alcohol in the water (reference solution). If the solution temperature is low, the reference results will be low. If the solution temperature is high, the reference results will be high.

  11. Human Breath Sample Simulator Sample 34.0 C How is a Simulator Like a Human Breath Sample?? ETHANOL

  12. Why we use 34°C • Average temperature of an exhaled breath sample 34°C = 93.2°F. • DOT specifications for simulators: Maintain 34°C +/- 0.2°C (still listed in DOT Specs) Mainly due to technology at the time in that was the best that Hg thermostats could deliver. Advancements in technology have led to electronically controlled simulators. National Highway Traffic Safety Administration DOT / NHTSA set specifications for breath test instruments; i.e Interlocks, Simulators, PBTs, EPBTs etc. Instruments approved appear on NHTSA Conforming Products list (CPL). Most agencies require instruments be on CPL and or require further testing for approval. • Guth model simulator specifications: 34°C +/- 0.05°C

  13. How the Simulator knows what 34°C is • The Simulator can’t measure Temperature (34°C). It can recognize an analog signal (i.e. electrical output from the temperature circuit). • We need to translate the voltage output of the temperature circuit to a digital output that the CPU (brain of the simulator) can recognize to regulate the heater control and display the temperature. • Use a digital multimeter and digital thermometer to calibrate the simulator.

  14. Digital Thermometer Must read out to hundredths place

  15. How does Temperature Effect Simulator Readings • For every 0.10°C change in temperature in a properly calibrated simulator with a 0.10% Alcohol Reference Solution, the value will increase/decrease 0.0007%. TEMPERATUREBAC .2°c 34.2°c .1014 .1°c 34.1°c .1007 34.0°c.1000 .1°c 33.9°c 0.0993 .2°c 33.8°c 0.0986

  16. Mercury Thermometers Expansion chamber Temp Scale 33.5°C – 34.5°C Silicon O-Ring Immersion Mark Contraction chamber Hg Bulb

  17. Mercury Thermometers Specifications • Hg thermometers are checked with a NIST traceable thermometer. Range is 34°C +/- 0.10°C. If when checked with NIST thermometer, and not in this range, replace Hg thermometer. • New Hg thermometers come with certificate that it was checked with NIST thermometer. Keep for your records. • YOU CAN’T CALIBRATE HG THERMOMETERS ONLY CHECK CALIBRATION!!!

  18. Trouble Shooting Simulators Follow manufacturer guidelines as specified in the operators manual. Failure to follow or modify the manufacturer operators manual may be viewed as “tampering” in order to achieve the desired results. The four main causes for improper results from simulators are: • TEMPERATURE OF THE SOLUTION • IS THE SIMULATOR AIR TIGHT? • ALCOHOL REFERENCE SOLUTION • TRAINING OF OPERATOR

  19. Trouble Shooting Simulators Preventative Maintenance Proper cleaning to prevent growth of algae in simulator. If Algae is present the inside of container and simulator components will have a slimy feel or if really bad will be pink to light red/ black in color. Build up of algae on the temperature sensor can cause erratic or improper control of the temperature of the solution. Build up of algae can also clog the outlets of the dispersion tube (blow pipe) resulting in inadequate flow through the simulator. Use mild bleach solution (tablespoon bleach/1gallon of H2O) allow to soak in simulator for 3-6 hours and rinse with cold or room temperature water. DO NOT USE HOT WATER!!! DAMAGE COULD OCCUR TO THE TEMPERATURE SENSOR AND COULD BREAK THE MERCURY THERMOMETER IF ONE IS PRESENT.

  20. Simulator Algae Build Up ?

  21. Trouble Shooting Simulators Temperature issues: • Agitator spinning Failure of the agitator to spin will not allow for uniform heating of the simulator solution. Solution will overheat and will result in high readings. Typically requires motor to be replaced in the simulator. • Blown fuse. Check fuse for operation and try to find cause for why fuse failed. • Heater not working or overheating. • Temperature sensor failed Check for Algae growth on temperature sensor. • Ambient conditions where simulator is located.

  22. Trouble Shooting Simulators Is Simulator Air Tight? If the simulator is not air tight, you will experience low readings depending on the severity of the leak. Small leaks may not be as evident in terms of low readings from the simulator but will result in the solution needing to be replaced more frequently than in normal operating conditions. Perform test to check if simulator is air tight. With solution in the container, reattach the top housing to the glass container. Block off the port labeled “To Breath Tester”. Connect some configuration of tubing and or mouthpiece to the return port (typically dispersion tube). Blow into the tubing or mouthpiece. You should see air being forced through the dispersion tube as is evident by the air bubbles in the solution. As you continue to blow for a few seconds, you should encounter resistance as it will become harder to blow which will be evident by fewer and fewer bubbles as it gets harder to blow. If this occurs, the simulator is airtight. If you do not experience resistance, the simulator has a leak somewhere in the system.

  23. Trouble Shooting Simulators Sources of Air leaks: • Inspect glass container for chips, breaks on threads and replace if found. • Inspect flat gasket in top housing and periodically replace to ensure tight seal between container and top housing (use silicone grease on gasket for better seal). • Ensure that all external fittings (i.e. sure lock quick connects) are tight. • Poor connection of simulator to Alcohol Breath test instrument. • Ensure that all internal fittings and connectors are tightened to factory specifications.

  24. Trouble Shooting Simulators Connecting Simulator to Alcohol Breath Test Instrument • Tubing length will effect readings on the Alcohol Breath Test Instrument (keep tubing as short as possible). Build up of condensation (i.e. water vapor) will collect in tubing as warm ethanol vapor passes from the simulator through the tubing With each passing sample, Ethanol will be absorbed by the water and not pass into the Alcohol Breath Test Instrument. • Tubing length will also effect how fast the sample cools as it passes from the simulator into the breath tester. • Flow Rate/Sample Time Proper flow rate from simulator into breath tester to ensure accurate and precise simulator readings.

  25. Alcohol Reference Solution Solution should be replaced every 30 days or every 25-30 tests which ever comes first (if not using recirculation) at a minimum. Follow your department, agency or company guidelines for changing alcohol reference solution. Changing the solution may be more frequent depending on instruments being checked and or calibrated and depletion rate of the solution. • Ensure you are using at least 500mls of solution in the simulator container to ensure proper results and to prevent damage to components of the simulator. • It is recommended that you use a certified alcohol reference solution. Certified solutions are NIST traceable. • Store solution in a cool location out of direct sunlight. Do not place solution in freezer.

  26. Simulator Calibration Simulators should be checked at least once a year and or follow department or company guidelines to verify the temperature is 34°C +/- 0.05°C using a NIST traceable thermometer. If temperature is not within specifications, the simulator needs to be recalibrated and or repaired by factory trained personnel or sent to the manufacturer. • Ensure that thermometer used to check calibration is as accurate or more accurate than listed specifications. Follow manufacturer guidelines for all equipment used to check calibration or repair of simulators to ensure it is NIST traceable.

  27. Questions??? Contact Information: Ted L. Pauley Guth Laboratories, INC 590 N. 67th. St. Harrisburg, PA 17111 tlpauley@guthlabs.com 800-233-2338 or 717-564-5470 717-564-2555 (fax) www.guthlabs.com

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