Concentration and formulation
A trade name or broad chemical family is not enough. Water content, stabilisers, solvents, oxidisers, impurities and proprietary additives can change the response of metals, plastics and elastomers.
Product-contact selection guide
Chemical compatibility and wetted parts for filling machines.
Approve the complete product path—tank, pump, hose, valves, seals, meter, manifold, nozzle and cleaning route—against the exact formulation and operating conditions rather than selecting from one generic material name.
Scope and compatibility boundary
This guide supports early machinery specification. It is not a universal chemical-resistance chart or approval of any material for a named product. The user should provide the current SDS and formulation evidence, while material suppliers and competent project specialists confirm suitability for the actual concentration, temperature, exposure, cleaning and service life.
How do you select wetted parts for a chemical filling machine?
Select wetted parts by tracing every product-contact component and checking it against the exact formulation, concentration, temperature, pressure, exposure time, movement and cleaning regime. A tank material alone does not approve seals, hoses, valve seats, diaphragms, pump components or nozzle internals, and a short filling trial does not prove long-term resistance.
Material compatibility and explosion protection are separate decisions. A machine may need corrosion-resistant product-contact parts, ATEX-related ignition-source controls, or both. The project brief should make those evidence routes visible rather than hiding them inside the word “chemical”.
Map the complete wetted path before choosing the dosing method
| Product-path item | Evidence to obtain | Failure or quality concern | Acceptance question |
|---|---|---|---|
| Source vessel and feed pump | Construction, lining, pump principle, pressure, temperature and cleaning duty. | Corrosion, swelling, contamination, pulsation, heat or incompatible seals. | Does the supply remain stable and compatible throughout the batch and cleaning cycle? |
| Hoses, pipework and fittings | Inner material, reinforcement, conductive or dissipative properties where relevant, end connections and replacement specification. | Permeation, softening, embrittlement, leakage, trapped product or loss of intended static path. | Is every replacement controlled to the same approved specification? |
| Valves, seals and diaphragms | Exact elastomer or polymer grade, movement, pressure differential, contact time and expected cycle count. | Swelling, shrinkage, sticking, cracking, loss of shut-off or extractables. | Has the dynamic service been checked, not only static immersion? |
| Metering element | Piston, flow path, pump chamber, load-cell discharge arrangement or other dosing contact parts. | Wear, friction, viscosity sensitivity, product retention and inconsistent cut-off. | Does the selected measuring principle remain suitable after temperature and viscosity changes? |
| Manifold and filling nozzle | Internal geometry, dead spaces, shut-off surfaces, anti-drip parts and cleaning access. | Drips, stringing, crystallisation, cross-contamination or incomplete drainage. | Can the actual product and cleaning fluid leave the path in a controlled, inspectable way? |
Which conditions can change a chemical compatibility decision?
Temperature and duration
Compatibility at ambient temperature for a brief contact may not represent warm product, overnight retention, soak cleaning or repeated exposure over the expected service interval.
Movement and mechanical duty
A seal that appears acceptable in a static chart may behave differently when flexed, compressed, abraded or exposed to pressure cycles. Dynamic service should be part of the approval basis.
Use material names as a starting point, not a final approval
Projects may consider stainless steels, PP, PVC, PTFE and selected elastomers or other materials, but the family name does not define the exact grade, filler, reinforcement, processing method or component construction. Record the material at the level needed to control procurement and replacement, and ask the responsible supplier to state the conditions and limits supporting the recommendation.
Cleaning chemistry belongs in the same review.
The product may be compatible with a component while the rinse, solvent, detergent or sanitising chemical is not. Include cleaning concentration, temperature, contact time, flow direction, drainage and whether the machine is left wet or dry between campaigns.
A practical compatibility approval sequence
- Define the exact products. Include normal formulations, concentrations, variants and any product heated or cooled during processing.
- Draw the complete contact path. Include temporary hoses, filters, recovery vessels, drains, sample points and cleaning connections.
- Build a component-level schedule. Record body material, seals, seats, liners, adhesives, coatings and internal parts rather than one headline material.
- Obtain supplier evidence. State temperature, exposure, movement, pressure and cleaning conditions when requesting a compatibility recommendation.
- Use representative trials for process behaviour. Test fill, foam, drip, drainage and cleaning observations, while keeping long-term material approval as a separate evidence task.
- Control changes. Reassess after formulation, concentration, supplier, temperature, cleaning chemical or replacement-part changes.
What a representative product trial can and cannot prove
A product trial can reveal viscosity, foam, wetting, stringing, nozzle cut-off, container stability, residual product and immediate cleaning behaviour. It may identify obvious incompatibility, but a short trial cannot establish long-term corrosion rate, permeation, elastomer life or the effect of repeated temperature and cleaning cycles. Define the trial objective and retain the material-approval boundary in the FAT record.
Authoritative UK context
HSE explains that a Safety Data Sheet helps the user make a risk assessment but is not itself the assessment. Use that information with the DSEAR control hierarchy, which includes keeping incompatible substances apart and controlling releases, while obtaining product-specific material evidence from the responsible suppliers.
Compatibility questions
Questions buyers ask before approving the product path.
Is the SDS enough to select filling-machine materials?
No. The SDS is essential hazard and handling evidence, but it may not contain the detailed formulation or component-specific resistance data needed to approve every wetted part. Provide the SDS, concentration, temperature, cleaning chemistry and any supplier compatibility information available.
Can one material be used for the entire product path?
Not as a generic assumption. Tanks, hoses, valves, seals, pumps and nozzles perform different mechanical duties and may use different grades or constructions. Approve the complete schedule and the interfaces between components.
Does a successful sample trial prove long-term compatibility?
No. A short trial is valuable for process behaviour and immediate observations, but it does not normally reproduce months of exposure, repeated cleaning, pressure cycles or ageing. Keep process acceptance and long-term material approval as linked but separate evidence.
Should cleaning fluid be included in the material review?
Yes. Cleaning chemicals, concentration, temperature and soak time can be as demanding as the filled product. Include every planned rinse, solvent, detergent and recovery step, plus any mixed or residual condition that can occur during changeover.
What happens when a seal or hose is replaced?
The replacement should match the controlled approved specification, not merely the size or colour of the original part. Record manufacturer, grade, construction and any conductive or dissipative requirement so maintenance does not unintentionally change chemical or static behaviour.
When is a corrosion-resistant filler preferable?
A corrosion-resistant route is considered when the product or cleaning regime is incompatible with the standard wetted path or surrounding machine construction. The final configuration depends on the exact chemistry, exposure, pack, dosing method and site controls rather than a broad label such as acid or bleach.
Your machine recommendation
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