Overview - ISO 21191:2021 (Closed transfer systems for crop protection)
ISO 21191:2021 defines performance and safety requirements for Closed Transfer Systems (CTS) used to transfer liquid formulations of plant protection products (PPP) from 1 L to 20 L containers into application or mixing equipment. The standard focuses on reducing operator and environmental exposure during a single transfer operation and specifies verification methods, allowable contamination limits, and the information a manufacturer must provide (operator manual, residual risk warnings, safe working practices).
Key topics and technical requirements
- Scope: CTS for liquid PPP in 1–20 L containers; covers design, construction and verification of operator- and environment-related safety.
- Essential CTS functions:
- Interface with containers and application equipment (Annex A provides an example interface).
- Product control and measurement during transfer.
- Container rinsing and system flushing where required.
- Performance tests and requirements:
- Leakage: No observable leaks during connection, opening, emptying, measuring and rinsing. Leakage testing uses a 0.1% surfactant solution with fluorescent dye and UV inspection (see Annex C).
- Container and interface rinsing: Procedures to ensure effective drainage and rinsing after partial or full transfers.
- Transfer system residues: Limits and measurement methods for residual product remaining in the CTS after transfer.
- Speed of operation & measurement device accuracy: Functional timing and metering accuracy requirements and test procedures.
- Pressure limits and containment:
- Concentrated product in CTS shall not operate above 100 kPa unless components are pressure-tested at 2× the maximum or a secondary containment is used.
- CTS must not reduce container pressure by more than −4 kPa from ambient.
- Operator requirements:
- Manufacturers must supply an operator manual meeting ISO requirements, label controls using ISO 3767 symbols, and describe PPE and residual risks.
- CTS operation must be possible while wearing recommended PPE (including gloves).
Applications - who uses ISO 21191:2021
- CTS manufacturers and designers - to develop compliant, safe transfer devices.
- Agricultural machinery and applicator manufacturers - to ensure interfaces and systems integrate safely.
- Regulatory and certification bodies - for conformity assessment, testing and approval.
- Farm managers and applicators - as guidance for safe equipment selection, operation and training.
- Safety officers and procurement teams - to set purchase specifications and reduce operator/environmental exposure to PPP.
Related standards
Keywords: ISO 21191:2021, closed transfer systems, CTS, crop protection, plant protection products, PPP, leakage test, operator manual, equipment safety.
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