Why the URS Decides the Whole Project
In a regulated plant, the URS is the first link in a chain. The vendor's functional specification answers it, the FAT and SAT test against it, IQ/OQ/PQ prove it, and a traceability matrix ties every requirement to the test that verified it. Our IQ/OQ/PQ guide covers the documents further down the chain. This page is about getting the first one right.
For a vision station in particular, a weak URS fails in three predictable ways:
- It specifies hardware, not outcomes. “Two 5 MP cameras” tells the vendor nothing about which defects must be caught on which SKU at what speed.
- It has no defect library. Without physical samples and agreed acceptance criteria, “detect label defects” can't be tested and will be argued about at FAT.
- It ignores the life of the system. Changeovers, recipe control, challenge tests, reject verification and data integrity are where audits find gaps, long after the camera has been signed off.
Five Rules for a Testable Vision URS
- One requirement, one sentence, one ID. For example, URS-4.3. This makes the traceability matrix almost write itself.
- Use “shall” for mandatory and “should” for desirable, or a Must/Should/Could column. Vendors price differently when they know what is negotiable.
- Every requirement names its verification method: document review, FAT, SAT, IQ, OQ or PQ.
- Numbers come with conditions. A speed is “at maximum rated line speed with the smallest container”. A detection target is “on the approved challenge set”.
- Describe what you need, not how to build it. Leave optics and algorithms to the vendor unless you have a site standard, such as a preferred PLC brand.
The 13 Sections, and What Goes in Each
1. Purpose, scope and references
State which line, which inspection point and which risks this station addresses. List the standards and site documents it must comply with, for example revised Schedule M, your data-integrity SOP and, if relevant, 21 CFR Part 11 or EU GMP Annex 11. Note what is out of scope, such as serialization or aggregation if those belong to another system.
2. Process description and line placement
Describe where the station sits: after the bottle unscrambler, after the capper, after the induction sealer, or after the labeller and coder. Include upstream and downstream machines, conveyor direction, height and width, and the space available. A rough layout sketch saves a site visit.
3. Product and container matrix
One row per SKU: container type and material (HDPE, PET, glass, IML cup), dimensions and tolerances, colour and transparency, closure type, label type (paper, film, shrink sleeve, metallic) and where variable data is printed. Vision performance depends on these details more than on anything else in the document.
4. Defect library and acceptance criteria
This is the heart of the URS. For each defect, give a name, a description, a classification (critical, major or minor), the smallest size or severity that must be caught, and whether physical samples exist. Agree how the challenge set will be built and stored. Set detection and false-reject targets, with the test conditions used to verify them.
| ID | Example requirement (adapt the values) | Priority | Verified at |
|---|---|---|---|
| URS-4.1 | The system shall inspect 100% of containers passing the station. No sampling mode shall be available to operators. | Must | FAT / OQ |
| URS-4.3 | The system shall reject every unit in the approved challenge set (Appendix B) at maximum rated speed in three consecutive runs. | Must | FAT / OQ / PQ |
| URS-4.5 | False rejects on approved good product shall not exceed [X]% over a run of [N] units per SKU. | Must | SAT / PQ |
| URS-6.2 | Each reject shall be confirmed by a sensor. A failed confirmation shall stop the line. | Must | FAT / OQ |
| URS-9.4 | Recipe and parameter changes shall be recorded in an audit trail with user, date/time, old value and new value. | Must | OQ |
| URS-10.2 | Expected batch and expiry strings should be received from the line PLC or recipe rather than entered manually. | Should | FAT / SAT |
[X] and [N] are placeholders for your own targets. We deliberately don't suggest numbers. They depend on your product, defect frequency and risk assessment, and they should come from your QA team.
5. Throughput and mechanical interface
Give the maximum and minimum line speed in units per minute or per hour, container pitch, any accumulation, the available conveyor length and the reject window. Ask for performance at the maximum speed with the most difficult SKU, not the easiest.
6. Rejection and fail-safe behaviour
Specify the reject method (air blast, pusher, diverter), reject confirmation, a lockable reject bin with a bin-full sensor, and what happens on camera fault, lighting failure, trigger or encoder loss, or low air pressure. Usually you want the line to stop or every unit to be rejected. Add a consecutive-reject alarm so that an upstream machine fault is caught quickly.
7. Changeover and recipes
State how many SKUs need stored recipes, the target changeover time, who may create or edit a recipe, and how a new SKU is qualified. Recipe changes are GMP changes and need change control.
8. Operator interface
Cover screen size and location, languages, live image display, recent-reject history, counters, alarms, and what an operator can and cannot do at each access level.
9. Data, records and data integrity
List unique user accounts and access levels, audit-trail content, time synchronisation, reject image retention, report formats (per batch, per shift), backup and restore, and electronic signatures if you plan to use them. Revised Schedule M clause 20 and, for US-regulated sites, 21 CFR Part 11 set the expectations. Write them as requirements, not as “shall be Part 11 compliant”.
10. Integration
Cover PLC I/O (triggers, rejects, line stop, alarms), any SCADA or MES link such as OPC-UA, and the interface to the coder or line recipe for expected print data.
11. Utilities and environment
Give the power supply and UPS, compressed-air quality and pressure, ambient temperature and humidity, cleanroom grade, washdown and enclosure rating, and materials of construction where required.
12. Documentation and qualification
List what the vendor delivers: functional or design specification, FAT and SAT protocols and reports, IQ/OQ protocols, PQ support, drawings, I/O list, software version list, manuals, spares list and training records. Ask for sample formats with the quotation.
13. Service and support
Set expectations for warranty, AMC options, response commitments, spares held in India, the remote-support method (and your IT policy on it), and how software updates are released and documented.
Download the URS Template (Word + PDF)
An editable 13-section URS for a vision inspection station. It includes a product matrix, a defect library with acceptance criteria, rejection and fail-safe requirements, data-integrity controls, a qualification document list and a traceability column. Each section has guidance notes you delete before issue.
Common URS Mistakes on Vision Projects
- “Zero false rejects.” Every real inspection system trades sensitivity against false rejects. Set a measurable target and a test method instead. Our false rejection rate guide explains the trade-off.
- No physical samples. If you can't hand over defective units, you can't prove detection. Start collecting rejects from manual inspection now.
- Only the easiest SKU tested. Clear containers, glossy or metallic labels and small codes are where performance differs between vendors.
- Reject verification left out. A camera that detects a defect but a reject that misses it gives you a record that says “rejected” for a unit that shipped.
- Data integrity added at the end. User levels and audit trails are much cheaper to specify up front than to retrofit after OQ.
- Serialization mixed into a print-verification URS. If you need serialization or aggregation, specify that system separately. See OCR/OCV vs serialization vs aggregation.
How Optomech Uses Your URS
When you send a URS with samples, our applications team in Hyderabad reviews it against the relevant product family: BIS, CIS, LIS with OCR/OCV, ISIVS or a specialised build. We come back with questions on anything we can't verify, a proposed configuration and the documentation we would supply. If you are still choosing vendors, our 15 RFQ questions pair well with this template.