A client pre-qualification questionnaire lands in the inbox of a contract logistics firm in Bhiwandi. Forty questions about insurance, training records, vehicle age. Question 23 is a single line with a yes/no box: Do you conduct alcohol screening of drivers and operators?
There is no partial credit. The contracts manager cannot write "we tell them not to drink." Somebody has to decide whether a BAC tester becomes part of how the operation runs, who administers it, and what happens when it reads above zero at six in the morning with a loaded vehicle waiting.
That decision is easier once you know what the device is actually telling you. Most confusion about alcohol screening comes from expecting a number to do work it was never designed to do.
What a BAC tester actually measures
A BAC tester estimates blood alcohol concentration from a sample of deep lung air. It does not sample blood. When alcohol is in the bloodstream, a predictable fraction crosses into the air in the alveoli, and the device measures that and converts it using a fixed ratio.
The number you see is an estimate of what a blood draw would show. It is reliable enough for screening decisions across every serious industrial and transport setting, which is why it is the default tool worldwide. It is an estimate all the same, and your policy should treat it as one.
In India, the reference point most people know is Section 185 of the Motor Vehicles Act, which sets the driving threshold at 30 mg of alcohol per 100 ml of blood. Workplaces are free to set a stricter internal standard, and most safety-critical operations set it at zero for anyone driving, operating machinery, working at height or handling energised equipment.
Units you will see on the display
Unit What it means Where you will see it
mg/100ml Milligrams of alcohol per 100 ml of blood Indian enforcement and most Indian workplace policies
%BAC Percentage by volume, e.g. 0.030% Imported devices, US-configured displays
mg/L Milligrams per litre of breath Breath-based readouts on some units
Set the device to the unit your policy is written in. A supervisor comparing 0.030% against a policy written in mg/100ml is a dispute waiting to happen. For a fuller walk through interpretation, see our guide on what a BAC tester reading actually means.
Fuel cell or semiconductor: the one specification that matters
Every other feature is secondary to the sensor.
Semiconductor sensors use a heated metal oxide film whose resistance changes in the presence of alcohol vapour. They are inexpensive and fast. They also respond to other volatile compounds, which means mouthwash, certain solvents, paint fumes, ketones from a diabetic or a fasting worker, and even some fruit-based drinks can nudge the reading. Drift over time is real and the sensor ages.
Fuel cell sensors oxidise ethanol electrochemically and generate a current proportional to the alcohol present. They are specific to ethanol, far more stable between calibrations, and hold accuracy over thousands of tests. They cost more and warm up a little slower.
For personal curiosity, a semiconductor unit is fine. For any test where a person may be sent home, marked absent, or handed a warning letter, use fuel cell. The moment a reading carries a consequence for someone's pay or record, the sensor has to be defensible. Our breath tester selection guide goes deeper into matching sensor type to test volume.
Types of BAC tester and who each one suits
Personal pocket units. Small, battery-powered, semiconductor or entry-level fuel cell. Useful for a family that wants to know whether the person holding the car keys after a wedding reception should be holding them. Not built for fifty tests a morning.
Workplace screening units. Fuel cell, replaceable mouthpieces, memory for stored results, printer or data port. Built for repeated daily use at a plant gate, a transport office, a warehouse muster point.
Passive and non-contact screeners. No mouthpiece; the subject speaks or blows near a sampling port. Fast for high-throughput queues, useful as a first pass. Any positive should be confirmed on a mouthpiece test.
Fleet and vehicle-linked devices. Interlock-style units that tie into vehicle starting, or handheld units logged against driver ID at dispatch.
A hospitality venue, a mine and a school campus need different things from the same basic technology. The blood alcohol content tester guide for venues covers the door-and-exit case specifically.
Where a sobriety tester fits into a real policy
A sobriety tester on a shelf is not a programme. What makes screening hold up is the written rule around it, and that rule needs to answer five questions before the first test is ever run.
• Who gets tested and when. Pre-shift, random, post-incident, for-cause on visible signs, or return-to-duty. Name the categories.
• What the threshold is. Zero, or the Section 185 figure, or something in between. State it in one unit.
• Who administers. Named, trained people. Not whoever is standing nearest.
• What happens on a positive. A waiting period and a confirmatory test, then a defined consequence. Never immediate dismissal on a single reading.
• How results are recorded and who can see them. Alcohol test results are sensitive personal data. Access should be restricted and storage deliberate.
The confirmatory retest matters more than people expect. Residual alcohol in the mouth from a recent drink, a mouth spray, or certain medicines can inflate a reading for roughly fifteen to twenty minutes. Waiting that interval and retesting removes the most common source of a false positive and the most common basis for a challenge.
Where drugs are in scope alongside alcohol, the operational model changes, because oral fluid and urine screening involve chain of custody and laboratory confirmation. Our note on combined drug and alcohol testing sets out what to keep in-house and what to outsource.
The part nobody budgets for: calibration
Every alcohol sensor drifts. Fuel cells drift slowly, semiconductors faster, but both drift. A BAC tester that has not been calibrated in eighteen months produces numbers, not evidence.
Manufacturers typically specify calibration either at a fixed interval, often six or twelve months, or after a set number of tests, whichever comes first. A high-volume gate device hits the test count long before the calendar date.
Budget for three recurring items:
• Calibration, with a dated certificate retained for audit
• Mouthpieces, which are single-use and consumed at the rate of your headcount
• Sensor replacement, once the cell reaches end of life
An auditor or an insurer reviewing an incident will ask for the calibration certificate covering the date of the test. If it does not exist, the reading effectively does not exist either. The ownership guide on drift, calibration and sensor life explains how to plan the cycle, and the real cost of owning a blood alcohol tester puts numbers around the recurring side.
Mistakes that undo good intentions
Testing too soon after arrival. Let the person settle, rinse with water, and wait. A test taken while someone is still catching their breath from a climb up the stairs gives a poor sample.
One device for five hundred people. Throughput determines how many units you need. A single handheld at a gate with a shift change of two hundred creates a queue that will be abandoned within a fortnight.
Untrained administrators. The person holding the device decides how the result is received. Training covers the procedure and the conversation.
No second device. When the only unit goes for calibration, screening stops. A spare is not a luxury; it is what keeps the programme continuous.
Treating the number as a verdict. A BAC tester tells you alcohol is present at a certain level. It does not tell you why, and it does not decide the consequence. Your policy does. That distinction is covered in BAC testing at work and who signs off on it.
Making the decision
If you are answering a client questionnaire, satisfying an insurer, or closing an audit finding, work backwards from the consequence. If a positive result can affect someone's employment, buy a fuel cell device, calibrate it on schedule, train named administrators and write the policy before the device arrives.
If it is a family car and a late night out, a simple personal unit does its job: it turns an argument into a number.
When you are ready to specify quantity, sensor type and calibration support, the questions worth settling first are laid out in what to decide before you raise the PO. AlcoBreath supplies fuel cell and semiconductor units across both cases, with calibration support for workplace deployments.