Factory acceptance testing, or FAT, gives a buyer documented evidence that a finished cylinder matches its approved drawing and performs as agreed before shipment. The test plan should be written before production. Without agreed pressure, duration, leakage limits and records, a statement such as “tested before delivery” is difficult to compare across suppliers.
Start with drawing and traceability checks
Confirm the bore, rod diameter, stroke, closed and open lengths, pin or flange interfaces, port orientation and mounting dimensions against the approved drawing. Record the cylinder serial number or another traceable identifier alongside the drawing revision. Check accessible rod finish, coating condition, protective caps and nameplate details. Where material certificates, weld records or coating reports are required, name those deliverables in the purchase specification rather than assuming they are included.
Separate the test stages
- Functional cycling: move through the full stroke in both directions, at agreed flow and load conditions, and watch for binding, unusual vibration or irregular motion.
- Pressure integrity: apply the agreed test pressure and hold time in the specified positions, inspecting for external leakage or visible deformation.
- Internal bypass: on a double-acting cylinder, measure leakage across the piston seal using a documented method and agreed acceptance limit.
- Final inspection: confirm port plugs, cleanliness, preservation, packaging and the final as-built record.
Parker’s published test procedure separates function, proof-pressure and internal-bypass tests. Its particular pressure and leakage figures belong to the products covered by that catalog; they should not be copied into an unrelated custom-cylinder contract. The correct values come from the approved design, applicable standard and project specification.
Put acceptance criteria in writing
An FAT sheet should state the test fluid, fluid temperature range, instrument identification and calibration status, test pressure, hold duration, cylinder position, permissible external and internal leakage, and whether a customer witness is required. It should record actual readings and pass/fail decisions. A pressure hold alone cannot prove the absence of internal bypass, and a no-load cycle does not prove performance under the final machine load.
Questions to settle before the test
- Which drawing revision and operating pressure govern the test?
- Are both chambers and the full stroke included?
- What leakage measurement method and threshold are acceptable?
- Which certificates, photographs and signed reports must ship with the cylinder?
For applications with additional corrosion or interface requirements, review the offshore lifting cylinder and press cylinder examples, then send the project-specific inspection plan with your inquiry. Testing must be performed by qualified personnel using a guarded, rated test setup.
Technical reference: Parker Mobile Cylinder Products and Application Guide, standard test procedure. The cover is a concept illustration, not a photograph of our test facility.