EBT vs ASD: Which Alcohol Screening Devices DOT Accepts

What's the difference between an EBT and an ASD?

An evidential breath testing device (EBT) and an alcohol screening device (ASD) are both breath-alcohol instruments, but 49 CFR Part 40 restricts what each one is allowed to do. An EBT must produce a printed, sequentially numbered result and appear on NHTSA's EBT Conforming Products List (CPL) — it can run both the initial screening test and, if needed, the confirmation test. An ASD is a simpler, usually non-printing device that appears on NHTSA's separate ASD CPL; it can only be used for the initial screening test, never the confirmation test. A program that owns only an ASD and gets a screening result of 0.02 or higher has to get the employee to an EBT for confirmation — the ASD result alone can never support a violation finding.

Which device does a DOT-regulated employer actually need?

Most FMCSA, FAA, and FTA-covered employers need access to an EBT, because any screening result at or above 0.02 requires a same-visit confirmation test and DOT expects the confirmation to happen promptly using a device capable of the sequential, printed result Part 40 requires. Some larger programs run an ASD for the initial screen — cheaper per unit, faster to administer to a large workforce — and keep an EBT on hand only for confirmations. Smaller programs, or those using a third-party breath alcohol technician (BAT) service like Foster, typically standardize on one EBT that handles both steps, which avoids the two-device workflow and the paperwork gap between screen and confirmation.

Device approval and screening path at a glance

Question	EBT	ASD
Can run screening test?	Yes	Yes
Can run confirmation test?	Yes	No
Requires printed, sequential result?	Yes	No
NHTSA list	EBT Conforming Products List	ASD Conforming Products List
Typical use	Sole device, or confirmation-only	High-volume initial screening

How do you verify a device is actually DOT-approved?

NHTSA publishes both Conforming Products Lists in the Federal Register and maintains them online; a device is approved only if the exact model and, in some cases, firmware revision appears on the current list — older models get delisted when replaced by newer conforming versions, and an employer using a delisted unit is running noncompliant tests even if the device still works fine mechanically. Manufacturers occasionally issue firmware or calibration-standard updates that require re-listing, so a device purchased years ago as CPL-compliant is not guaranteed to still be compliant today. The safest practice is to confirm CPL status at purchase and again at every recalibration, rather than assuming a device that passed once stays compliant indefinitely.

What happens if a program uses a non-approved device?

A test run on a device that isn't on the current CPL doesn't satisfy Part 40, regardless of the result. That matters most after the fact — in a post-accident investigation, an FMCSA audit, or litigation, an employer who tested on a non-conforming device may find the result unusable, which functionally means the required test was never completed. This is a common gap in smaller in-house programs that bought a device years ago and never checked whether it remained listed, versus programs that use a calibration and testing vendor who tracks CPL status as part of the service.

How Foster handles device compliance

Foster's BAT technicians run EBTs that are current on NHTSA's Conforming Products List, and our calibration program checks CPL status at every service interval — not just at initial purchase. When a manufacturer updates firmware or a model gets delisted, that shows up on our next scheduled calibration visit rather than surfacing for the first time during an audit or a post-accident review. For employers running their own in-house instruments, we can verify CPL status as part of a calibration visit even outside our standard testing contracts.

Frequently asked questions

Can an ASD be used for a DOT confirmation test?

No. Part 40 requires the confirmation test to be run on an EBT that produces a printed, sequentially numbered result. An ASD can only be used for the initial screening step, never to confirm a result of 0.02 or higher.

How often does NHTSA update the Conforming Products List?

There's no fixed schedule. NHTSA updates the CPL whenever a manufacturer submits a new or revised model for evaluation, or when a model is withdrawn. Employers should check CPL status periodically rather than assuming a device stays listed indefinitely.

Does a device need to be recalibrated to stay CPL-compliant?

Calibration and CPL listing are related but separate. A device can be properly calibrated and still be off the current CPL if a newer firmware revision superseded it. Checking both at every service interval is the only way to catch that gap.

Can an employer own both an EBT and an ASD?

Yes, and larger programs often do — ASDs for fast, low-cost initial screening across a large workforce, with an EBT available on-site or on-call for any confirmation test a screening result triggers.

Where can an employer check if their device is currently approved?

NHTSA's Conforming Products Lists for both EBTs and ASDs are published in the Federal Register and available through NHTSA's website. A calibration vendor tracking Part 40 compliance should be able to confirm a specific model and firmware version's status directly.

Need your breath alcohol program checked against current DOT device requirements? Get a quote or read more about our BAT training and certification and instrument calibration services. For the testing procedure itself, see our post on DOT alcohol screening vs. confirmation tests.