Container identification system for chemical drums: an RFID and camera read gate that identifies tagged drums on a conveyor
Reading every drum as it passes a gate · on-metal UHF tags rated 6 to 15 m at 2 W ERP, GRAI numbers for returnable drums, and the US power limit behind a reader's range
In an automated drum store, a container is only useful if the system knows which one it is. A container identification system does that at fixed points: a gate over the conveyor with RFID antennas and camera code readers that read each drum as it passes, match it to the warehouse record and stop the drum if nothing is read. Two choices decide whether it works: what is fixed to the drum and what number is written in it.
Fixed identification gates and read points that identify chemical drums, pails and returnable containers on conveyors and at storage transfer points, using UHF RFID tags mounted on the metal container and camera or scanner reading of codes, with the numbering written to them. Print-and-apply labelling and label verification on filled drums are covered on the Print-and-apply drum labelling station page; handheld, presentation and fixed barcode scanners as a product class on the Barcode scanner page; RFID readers by frequency band and form on the RFID reader page; drum conveyors on the Drum conveyor page.
CNFX editorial research · Sources checked October 13, 2026 · 4 sources
Tags made for steel: range on metal, housing and memory
A steel drum is a metal surface, so the tag has to be one built for it. Turck's UHF hard tags in its TW860-960 range are specified for direct mounting on metal, ISO 18000-63 / EPCglobal Gen 2, and state their reading range on metal at a reader power of 2 W ERP. [1][2]
Both datasheets warn that these distances are standard values measured in the laboratory free of material influences, that attainable distances vary with component tolerances, mounting and ambient conditions and material, especially when mounted in metal, and that testing under real operating conditions is essential, especially when reading on the fly. [1][2] For a drum gate that means trialling the chosen tag at its chosen position on a full drum of the real product, moving at conveyor speed, with the gate's own antennas.
Turck lists 10⁵ write operations for the Q21L85 tag and unlimited reads, which matters if the drum's record is rewritten in the tag on every fill rather than held in the warehouse system against a fixed number. [1]
The image shows drums on a roller conveyor passing through an aluminium-profile gate with three overhead camera readers and flat panel units on the uprights. Ask for read-rate results on your drums at line speed, and what the gate does with a drum it cannot read.
02
GRAI numbers for returnable drums: asset type plus a serial of up to 16 characters
GS1's General Specifications (GRAI change notification 21-118, 2021) define the Global Returnable Asset Identifier, AI (8003), for returnable assets. It is made of the asset owner's GS1 Company Prefix, an asset type chosen by the owner and a check digit, with a leading zero to make 14 digits, followed by an optional alphanumeric serial component of up to 16 characters that identifies an individual asset within the type. The leading zero is mandatory in every GS1 barcode that can encode AI (8003). [3]
Editorial calculation: 14 digits plus a full 16-character serial gives up to 30 characters after the application identifier. Without the serial, every drum of one type carries the same GRAI, so a system that has to tell drums apart needs the serial component. [3]
The same GS1 text says the check digit must be verified in the application software, that asset identifiers must stay unique well beyond the lifetime of the records that use them, and that the owner or manager of the asset issues them; GRAI or the Global Individual Asset Identifier, AI (8004), up to 30 characters, may be chosen at the issuer's discretion. It adds that some EPC binary coding schemes cannot encode the full serial values, so the RFID encoding has to be checked against the serials planned. [3]
Decide who issues the numbers (the drum owner or the filler), whether drums carry GRAI or GIAI, and the serial length that the RFID encoding chosen can hold.
03
Reader power behind the quoted range: 2 W ERP in a datasheet, 4 W EIRP under FCC Part 15
Under 47 CFR 15.247(b), a frequency-hopping transmitter in the 902–928 MHz band may put out at most 1 W peak conducted power when it uses at least 50 hopping channels, or 0.25 W with 25 to 49 channels, and that limit assumes an antenna gain of no more than 6 dBi; above 6 dBi the power has to be reduced by the excess. [4]
Editorial calculation: 1 W into a 6 dBi antenna is about 4 W EIRP (6 dBi ≈ ×3.98). The 2 W ERP at which Turck quotes its ranges is about 3.3 W EIRP (ERP × 1.64), so a US gate at the full Part 15 limit has comparable or slightly higher radiated power than the datasheet condition; a reader set lower, or an antenna with cable losses, gives less range than the datasheet. [4][1]
Ask for the reader's conducted power, antenna gain and cable loss at each gate antenna, so the radiated power can be compared with the condition in the tag datasheet.
04
Drums, numbers and read points for an identification gate
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Containers: [steel, plastic or fibre drums; pails; sizes]
Tag: [model; position on drum; fixing method; on-metal range at stated power]
Numbering: [GRAI or GIAI; issuer; serial length; RFID encoding]
Read points: [conveyor speed; drum spacing; gate positions; camera code types]
Reader: [region; conducted power; antenna gain; cable loss]
Exceptions: [no-read action; reject or stop; link to warehouse system]
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
How far can a UHF tag on a steel drum be read?
Turck rates two on-metal hard tags at 6 m and 15 m at 2 W ERP, and states that real distances on metal vary and must be tested. [1][2]
What number should a returnable drum carry?
GS1's GRAI, AI (8003): a 14-digit asset type with check digit plus an optional serial of up to 16 characters to tell drums apart. [3]
How much power can a US UHF reader radiate?
FCC 47 CFR 15.247 allows 1 W conducted with at least 50 hopping channels into an antenna of up to 6 dBi, about 4 W EIRP (editorial calculation). [4]
Sources and what still needs a direct check
Sources checked 2026-10-13. Two Turck tag datasheets, GS1's General Specifications text on the GRAI, and the FCC rule that limits UHF reader power in the United States.
