A regulator can show the expected pressure at idle yet fall when cylinders and vacuum ejectors demand flow. A sticky adjustment mechanism, restricted filter, undersized supply, leaking relief seat or inaccurate gauge can make the machine appear to have random pneumatic timing faults.
Diagnosis should compare upstream and downstream pressure over the real cycle. Depressurize stored air and secure actuators before removing a gauge or regulator. Use the installed component range, flow direction and relieving/non-relieving design rather than a universal setting.
Decision matrix
| Test item | Evidence | Meaning |
|---|---|---|
| Upstream supply | Pressure at idle and peak demand | Shows available source margin |
| Regulated outlet | Set pressure and minimum during cycles | Reveals droop or restriction |
| Gauge | Range, zero, damage and comparison instrument | Confirms displayed value |
| Regulator | Flow direction, adjustment lock and relief behavior | Confirms correct device function |
| Downstream | Leaks, filter drop and simultaneous demand | Separates regulator from system load |
Identify the pressure boundary
Map compressor/header, shutoff, filter, regulator, lubricator if fitted, pressure switch, gauge and downstream branches. Record where the machine pressure specification applies. A gauge after a long or restricted line can read differently from the regulator port.
Confirm flow arrow and regulator code. Relieving and non-relieving regulators respond differently when the setpoint is reduced. Do not vent a circuit through a component that was not designed to relieve stored air.
Compare idle and dynamic pressure
Fit calibrated test instruments only at approved ports and ranges. Record upstream and outlet pressure at idle, during individual station movement and during simultaneous demand. Synchronize readings with machine sequence or video so the pressure dip has a known cause.
If both upstream and downstream fall, investigate factory supply, receiver, piping or shared demand. If upstream remains stable while outlet falls, inspect regulator capacity, filter restriction and local fittings before increasing the setpoint.
Check gauge accuracy and condition
Depressurize, verify the gauge returns to zero and inspect lens, pointer, port and vibration damage. Compare it with a traceable gauge over relevant points according to the site calibration plan. A narrow-range gauge can be damaged by overpressure; an excessively wide range makes small changes hard to see.
Do not tap or bend the pointer to make readings agree. Replace or calibrate through the approved process and label status. Keep liquid-filled or special gauges matched to the environment and mounting orientation.
Inspect adjustment, leakage and filtration
Check adjustment knob, lock, thread and mounting for damage. Use an approved leak-detection method at ports and the relief opening. Record filter condition and pressure drop because a saturated or incorrect element can imitate regulator droop.
The linked moisture/filtration guide supports upstream air-quality review. Do not use sealant that can enter pneumatic passages, and never exceed component ratings to clear contamination.
Approve performance through machine cycles
Set pressure only to the documented machine requirement, lock the adjuster and run repeated startup, normal and stop/restart cycles. Confirm cylinder timing, cushioning, vacuum threshold and pressure-switch behavior while recording the minimum outlet pressure.
Send HANNAI regulator/gauge codes, test-port locations, upstream/outlet traces and the affected mechanism. A stable static reading is not enough; release requires repeatable dynamic pressure under actual demand.
Technical references
- Festo pressure regulator product principles — general component guidance; the installed machine documentation remains controlling.
Related machine and guide
Review the paper cup production line for machine context, then use the compressed air moisture and filtration guide for the adjacent check. Browse all Buyer Guides when building a wider project checklist.
Frequently asked questions
Why is pressure correct when the machine is stopped but low in production?
Flow demand can reveal supply, filter, regulator or piping restriction.
Can a gauge be checked by whether it returns to zero?
Zero is only one check; compare it with a suitable calibrated instrument.
Can the set pressure simply be increased?
Not before locating droop and confirming component and machine limits.
What readings are most useful?
Upstream and outlet pressure synchronized with individual and simultaneous machine actions.
Review your machine configuration with HANNAI
Send the machine model, project reference, component labels, drawings, photos and a description of the required result. We will clarify which details must be confirmed before a quotation or technical recommendation.