Paper cup air pressure dew point checks help answer whether the supplied compressed air can remain free of condensed water under the relevant line conditions. A clean-looking filter bowl or an empty drain does not measure water vapor. The measurement location and pressure must be recorded with the dew point value.
Confirm the required air quality and test method with the installed equipment suppliers. A dryness result does not establish particle, oil or microbiological quality. This guide provides a verification record, not a universal air-quality class or dryer-sizing specification.
Diagnostic decision table
| Observation | Interpretation question | Record with the result |
|---|---|---|
| Low dew point at dryer outlet | Does the machine branch agree? | Sampling location and pressure |
| Reading taken after expansion | Is it atmospheric or pressure dew point? | Pressure at the sensor |
| Dry at idle, worse under demand | Was the dryer tested under load? | Flow context and operating state |
| Liquid water despite acceptable reading | Where and when did condensation occur? | Branch temperature and event timing |
Define the question the measurement must answer
Identify whether the investigation concerns dryer performance, a distant distribution branch or the point supplying the paper cup machine. Draw the sampling locations and note any filters, regulators, receivers or long exposed sections between them. A measurement at one point cannot automatically characterize every branch in the factory.
Obtain the machine and pneumatic-component air requirements before deciding whether a result passes. Note the coldest relevant conditions in the distribution path and the pressure at which the air is used. Seasonal changes or a cold section of pipe may matter even when the machine room itself feels warm.
Preserve the pressure basis of the reading
Atlas Copco distinguishes pressure dew point at the operating pressure from atmospheric dew point after expansion. Do not compare the two numbers directly as if they were the same condition. Record whether pressure is reported as gauge or absolute and whether the instrument applies a conversion.
Use a sensor and sampling assembly rated and specified for the intended measurement. Qualified personnel should install the connection with the line safely isolated and depressurized under the approved procedure. Do not loosen a pressurized fitting to create a sample outlet or route an uncontrolled compressed-air jet toward people or product.
Follow the instrument sampling instructions
Record instrument identity, calibration status, sample-cell arrangement and the stabilization criterion required by its instructions. Keep the sampling path appropriate for humidity measurement. Contamination, leakage or moisture retained in unsuitable tubing can distort a reading, especially when comparing very dry air.
Observe the sensor response until the specified stable condition is reached rather than recording the first displayed number. Keep sample flow within the instrument arrangement requirements. If the connection was recently opened or exposed to room air, annotate that event. A changing reading may describe the sampling setup recovering, not a dryer fault.
Measure representative production conditions
Compare the relevant locations during an identified operating period, including normal machine demand and any shared consumers that affect the branch. Preserve dryer state, line pressure and known drain or bypass events. An idle test can miss a performance problem that appears only during sustained factory use.
If a poor result appears at the machine but not at the dryer outlet, review the branch history and sampling methods before concluding that the dryer is undersized. If liquid water is already present, investigate its path and timing; a later acceptable vapor reading does not erase an earlier condensation event. Keep maintenance observations separate from the measured data.
Report a bounded conclusion and next action
A useful record lists the measured dew point, pressure basis, location, operating state, instrument and observation period. State whether the evidence addresses the defined requirement. If the requirement is missing, report the measurement without inventing a pass threshold from another machine or a general dryer brochure.
Send HANNAI the branch sketch and results if pneumatic behavior remains inconsistent. Pair the moisture evidence with the existing pressure and filtration checks, while treating each as a separate requirement. Once a corrective action is authorized, repeat the relevant operating condition to verify it; replacing a filter element alone does not demonstrate that water-vapor control has improved.
Related equipment and next checks
Review the HN-M100 machine utilities and the related guide to compressed-air moisture and filtration. The Engineering Notes archive connects these checks with wider machine planning.
Technical reference
- Atlas Copco explanation of pressure and atmospheric dew point — general reference; confirm applicability to the installed equipment.
Frequently asked questions
Does an empty filter bowl prove dry air?
No. It does not measure water vapor.
Can atmospheric and pressure dew points be compared directly?
No. Preserve the pressure basis and use the appropriate validated conversion if needed.
Is a dryer-outlet reading sufficient for every machine?
Check whether the relevant distribution branch is represented.
Does dryness prove complete air quality?
No. Other contaminants require their own agreed specifications and checks.
Review the evidence with HANNAI
Send your machine model, component identification and the observations described in this guide. Include the drawing or material reference and any before-and-after measurements so the required next check can be identified.