Connecticut will soon be deploying new breath testing machines, having entered into an agreement with the Draeger company to replace the Intoxilyzer 500 machine. The new machine has some similarities to the old machine, and I have set forth them below. Much of this work is credited to Bruce Kapsack of Kapsack & Bair in Oakland CA who has presented multiple times on this topic. The following data is from my notes of his presentations, as well as my own review of the Draeger information which was submitted to the state of Connecticut in the proposal.
1. Mouthpiece – same as Intox, with a spit trap
2. Breath Tube – As with any other breath device, the 9250 starts with a breath tube. This tube is kept coiled around a heating unit on the top of the machine. It is much more flexible than the old Intox hoses. It contains a heating unit and most importantly the optional breath temperature thermometer. Heated tube 2 tubes, 1 inside the outer tube. Inside one is kink proof.
3. Differential pressure sensors. These measure the flow that is going into the breath machine. It determines the volume of air exhaled into the machine (for saving and printing on the results) and to determine that the sample given is of sufficient size to generate an actual result.
4. Infrared source. Similar to the mechanism In the Intox, but we haven’t had one that we can open up to determine the filament. Intox uses a tungsten filament, which degrades over time
5. IR bounces 7 times through the sample chamber which is coated in polished platinum. The chamber is removeable and the parabolic mirrors can be moved slightly. It is critical to see if the machine had been serviced because even a minor change in the length of the path of the ir beam will impact the results.
6. IR Detector – the Draeger uses a single 9.5 micro filter, which is different than the 3.39, 3.6. 3.9 filters of the intox 5000. Intox had a 5 filter wheel, but only 3 were for ethanol, the other 2 were for methanol and isoproprynol. This is MORE specific for alcohol, but it is not ONLY specific for alcohol. Toluene also absorbs 9.5 micro ir light for about 10% of the sample. But since Toluene has a different partition ratio, and if it exists it is from long term exposure, it will give a higher reading. More importantly, other alcohols, methyl and isopropyl, will also absorb the 9.5 light; To the tune of 80% and 20% respectively. This is a significant problem since the Draeger does not use any other subtracting frequencies. This would be worse then the INTOX because the intox uses 3.39 and 3.6 to establish the baseline for ethanol.
7. Amplifier. This is the computer chip for the conversion of the IR sample to the BrAC level.
8. In order to combat this problem and to make an allegedly better machine, the Draeger 7110 employs a second system for analysis, EC. After all the parameters for a valid IR test have been met, a small port opens in the sample chamber and a portion of the same air, 1cc, is diverted in to a separate EC chamber for analysis.
The volume, 1cc, is critical since the result is multiplied to get the BrAC for 210 liters. However, no system exists to verify the taking of 1cc. This is a problem. The piston is dependant on rubber rings. Alcohol is a good solvent. Slowly the rings will be eaten away and the 1cc may not be 1cc anymore.
The EC is a wafer of acid between two porous discs. As breath passes over the disc some of the breath passes through the top and settles on the wafer. A chemical reaction occurs and a small amount of current is generated.
This current is then measured by the machine and assigned a Breath Alcohol equivalent. The resulting number is either printed out or checked with the IR result. Depending on the software results for each can be printed or stored. The software can also be set up to print an “ok” message for the EC reading so long as it is within the design parameters of the IR reading.
Like the IR, the EC is not ethyl alcohol specific. It is virtually unaffected by other volatiles, but is fully subject to error caused by other alcohols. In order to combat this, Draeger has designed a timing protocol to determine if the reaction is ethyl, methyl or isopropyl.
It works like this; all three alcohols will cause the chemical reaction. All three will give a result. The difference is in the speed with which the breakdown occurs. Each one will cause the chemical reaction in a unique time. It will do so at that speed every time taking in to consideration the degradation of the underlying cell.
9. PUMP to clear the chamber
Unlike its competitors, the Draeger does NOT have an RFI detector built in. It is an after market option. This is because the machine is allegedly fully shielded. The Draeger is able to do so, be fully shielded, based on temperature issues. Other breath machines used moving parts which create large amounts of heat. Additionally, those older machines used much more electricity in the workings. The Draeger is low electric due to no moving parts (it is all solid state) and low power usage. This in turn makes it low heat and so can be fully enclosed without the fear of melt down.
As for day to day maintenance, the Draeger is tamper proof via a color coded key system. Depending on the level of the technician, they are given a color coded key and password which will allow them to access various parts of the internal workings and software. In order to do more, a different access level is necessary. I am still working on getting the key level.
Calibration can be done with either dry or wet bath solutions and if dry is used, barometric compensation is built in (good bye Boyle’s Law). Of course Henry and his law is still around for wet bath simulators.
Finally, airblank is NOT through the IR. Instead a sample from the IR chamber is piped in to the EC chamber and checked for any alcohol. Rather than the old air blank reset, only if the chamber is truly alcohol free can the machine be used.