Dew Point Measurement Testing

Service overview

Is your air as dry as it needs to be? A number, not a guess

We measure, log and report the water vapour content of your compressed air and technical gases as the pressure dew point: the temperature at which water starts to condense at the pressure in your pipe. At dryer outlets, receivers, critical points of use and the far ends of your branches, a calibrated instrument logs dew point with line pressure, ambient temperature and time, long enough to capture dryer switching and load changes.

Testing runs at line pressure, with no shutdown. A top-mounted tapping with an isolation valve is all it needs. Your report gives, for each point, the measured dew point range, its atmospheric dew point and ppm v/v equivalents, the ISO 8573-1 water class and pass or fail against your requirement, with the probable causes of any failure. It applies equally to nitrogen, argon, CO₂, breathing air and medical air.

PDPPressure dew point, logged over time
ADP and ppm v/vOn the basis your specification uses
ISO 8573-1Water class for every point tested
No shutdownMeasured at line pressure

Benefits

The problems it solves

Once air has passed a dryer, no water is visible, whether it's at −40 °C or +10 °C PDP. Here is what that hides, and how testing shows it.

Water you can't see

The problem

Dried air looks the same whatever its dew point, until condensate forms in the process.

How it solves it

Each tested point gets a measured ISO 8573-1 water class, not an assumed one.
Ratings that assume a cool day

The problem

Saturated air at 45 °C carries about 65 % more water vapour than at 35 °C, the reference condition for dryer ratings.

How it solves it

Testing under your actual conditions confirms what the dryer delivers on your hottest days and at peak load.
Slow degradation

The problem

Ageing desiccant, refrigerant loss, drifting purge and leaking seals each raise the dew point a few degrees, well before any alarm.

How it solves it

A rise of a few degrees exposes the fault before moisture reaches your process.
Is it the dryer or the network?

The problem

A dry dryer outlet can still feed a wet point of use through an open bypass or a cross-connection to undried air.

How it solves it

Readings along the air path show whether the dryer or the network is at fault, so money goes on the real cause.
Frozen lines and rust

The problem

Outdoor instrument lines freeze when the dew point is above the pipe temperature, and steel corrodes fast once surface humidity passes about 60 %.

How it solves it

Testing outdoor lines against the lowest expected ambient keeps control valves and shutdown systems working through winter.
Sensors that drift

The problem

Fixed dew point sensors drift with age and contamination and can report a compliant value while wet air reaches the process.

How it solves it

A side-by-side check with a calibrated instrument shows whether your own monitoring still tells the truth.

Where it’s used

Wherever moisture has a limit

Any line with a dew point to meet can be tested. These are some of the places it counts most.

Power generation
Instrument air for valve actuators and dry air for switchgear, tested before winter.
Food and beverage
Air in direct contact with food at Class 2 (−40 °C PDP), with results forming part of the HACCP verification record.
Pharmaceuticals
Air for tablet coating, granulation, packaging and blanketing, tested during qualification and routine monitoring.
Automotive and surface finishing
Air at spray booth drops, where moisture causes blistering and poor adhesion.
Plastics and packaging
PET blow-moulding air and resin dryer air, at the dew point hygroscopic materials require.
Oil, gas and petrochemicals
Instrument air at least 10 °C below the lowest ambient and never above +4 °C, as ISA-7.0.01 requires.