Breathalyzer FAQ
We are often asked similar questions
about a breathalyzer - how they work, what the differences are, what the
different displays mean etc - so we've gathered together some of the more
typical phone enquires which you may find useful in deciding which device is the
best one for you!
A Personal breathalyzer vs Police
breathalyzer
A Police Breathalyzer always uses a fuel cell sensor but "consumer" or
"personal" breathalyzers often use far cheaper semi-conductor
sensors which estimate the concentration of the alcohol test based upon
one or two pre-calibrated points. At these points a breathalyzer
test may
be quite accurate, but at other values the drift can be
quite dramatic - anything up to 30-35% variance on sub-£60 models is
not unusual in practical use. It is a case of get-what-you-pay-for,
as while a personal breathalyzer maybe around £60 - £100, a typical Police Breathalyzer costs
upwards of £800. (See ""Personal
Breathalyzer vs Pro Breathalyzer" )
How does a breathalyzer work?
When you drink, alcohol is digested and
passes through the stomach into the blood stream. From there it passes through the alveoli into the lungs, and
it is this that a breathalyzer test for alcohol is designed to measure.
Alcohol testing concentrations are often very low and the
breathalyzer sensor has to be very sensitive to
detect the levels involved - hence why it is so important that a consistent sample of air is
so important and why a breathalyzer such as the "AlcoSense One" that does not
use a tube (to ensure a minimum 1.5ltr sample size) can never give
an accurate breathalyzer test result.
Breathalyzer sampling methods
A
Professional, police-grade
breathalyzer such as the UK-Approved
Dräeger 6510
breathalyzer measure an exact volume of air each time the breathalyzer
is used. A Personal breathalyzer
often just provides the user with two beeps, a fixed time apart (on more
expensive models with a pressure sensor to ensure a minimum "blow" level) but the actual
breathalyzer sample size to test for alcohol can vary considerably from person to person. If the
breathalyzer is only being used to test yourself, you are likely to get
consistent results but a breathalyzer of this type should never be used for
testing someone else. (See
"Using a breathalyzer on someone
else")
Breathalyzer calibration
Any breathalyzer can only
remain accurate for so long before it needs to be calibrated against a known
concentration level. Each method requires
specialized breathalyzer calibration equipment and trained
breathalyzer technicians; it is not a procedure
that can be conducted by untrained users or without the proper
equipment. There is no such thing as a "self
calibrating" breathalyzer - and a breathalyzer that uses a
replaceable sensor may seem to be a good answer, but as the sensor
is not tested in the breathalyzer itself there may be numerous other
factors that would influence the breathalyzer result. It's a bit
like servicing a car just by replacing the engine - just because the
engine works, it doesn't meant the whole car will perform as it
should! See
breathalyzer
calibration
UK Alcohol Limits for a Breathalyzer
-
35 microgrammes - as used by
a professional breathalyzer such as the Dräeger 6510, XT & 7410
and the AlcoDigital 3000 -
80 mg/100ml - as displayed by a
breathalyzer such as the AlcoHawk Pro & PT500 -
0.35 mg/L - non-standard but
available on the PT500 and AlcoDigital 3000
0.08% BAC - used by the majority of "consumer"
breathalyzers
Popular breathalyzer myths
A 2003 episode of MythBusters tested a number of
methods that supposedly allow a person to fool a professional breathalyzer test.
These included mints, onions, denture cream,
mouthwash, pennies and batteries; all proved
ineffective when tested against a Police Breathalyzer however
certain other substances may well affect a semi-conductor based
personal breathalyzer. (See our
breathalyzer FAQ's
for more details)
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