If you just received an Immediate Roadside Prohibition for blowing Fail or Warn, you may remember hearing a snap or click sound when you blew into the ASD. The sound indicates that the sample has been captured and, if the ASD is functioning properly, the analysis of the sample will then begin.
The Alco-Sensor IV DWF Screener ASD sucks a tiny sample of breath from a tube that runs from the mouthpiece and vents out the back of the device. Before the ASD can accept a sample, the operator must depress the Set button which pulls back two springs and inserts a trigger to hold a small plate in place. If the flow meter is working properly, when a certain volume has been reached and the flow has decreased, a solenoid will pull the trigger, the springs will lift the plate and a tiny pump will suck in a tiny sample of air from the tube into the sample chamber. Once the sample has been captured, the analysis takes place.
In a sense it is very much like a mouse trap. The trap is set by the operator pressing the Set button. When you hear the ominous snap sound, your time is almost up.
If you didn’t hear a snap sound, the device may have been malfunctioning. One thing we noticed in the piles of disclosure material that we have collected on the ASDs from around BC is that, if the device was dropped, one of the first problems that will appear will be the electronic connection between the board and the solenoid. If an ASD has been dropped it should be pulled from service. Of course, this is not something that the police in BC seem to do.