Faqs

Summary FAQ's

How does the Dewcheck compensate for Barometric Pressure?

If the pressure has changes, the sensor always gives the correct values for the relative humidity, since we use an almost perfect sensor. Inside the RH probe is a microchip containing its calibration values and together with the air temperature probe it computes the correct values.

What is the correct name for an instrument like DewCheck?

Dewcheck has become a generic name for instruments that measure the relevant climate parameters for coating applications. Other wordings are: Dewmeter, 319, Dewpointmeter or dew point meter in short dpm.

When is the best time to measure the climate parameters with the Dewcheck dewmeter gauge and how many time should I measure during a working shift?

Always follow the paint specifications if these prescribe the frequency of measurements with a dewmeter. In case this topic is not included in the specifications the frequency of measurements should be decided using common sense. Climate parameters like the relative humidity and air-temperature and therefore also the dewpoint are changing continuously. Depending on the results of the Dewcheck dewmeter one could decide how often measurements should be taken. If the surface temperature is well above dewpoint on an early and shiny summer morning it is most likely no problems may be expected during the coming day if weather conditions remain stabile. On the contrary, if the surface temperature is just over 3°C above dewpoint at the end of the day and the air temperature is falling rapidly it is advised to increase the frequency of measurements with the dewmeter. Keep in mind that the climate conditions are also important after the work is stopped. A wet coating or bare sandblasted steel will suffer from condensation as well.

Should I check the climate parameters as well when no work is in progress?

This depends on the situation. When bare steel (open blast) is left behind at the end of a shift or working day it is critical to avoid condensation. Also when a freshly applied coating, that has not been cured properly, is left behind the climate parameters has to stay within their critical limits. Especially at night times, when ambient temperatures drop (negative) climate changes can be expected. Many clients such a certain defence departments and ship-owners now dictate climate registration throughout the entire coating process.

How can I control the climate conditions with my dewmeter/dpm after working hours or during my absence?

DewCheck dewmeters have different data-logging options. A manual log option is build in but this is only useful when the instrument is in the hand of an operator. With optional Dewcheck Dock it is possible to fix the instrument with a set of integrated magnets against a steel object, also a magnetic surface probe is included. Configureted like this the dewmeter will log all climate data autonomous. Data can be downloaded to a PC for analysis or record keeping at the end of the job.

Why does my Dewcheck dewmeter remains accurate and is guaranteed for 2 years while many electronic hygrometers need frequent recalibrations?

The performance of each hygrometer depends mainly on the quality of the RH-sensing element. The Dewcheck dew point meter is equipped with a Rotronic® C-94 sensor. Almost 10 years of experience in producing dew point meters for coating applications has lead to this choice. This sensor from Switzerland has a reputation as one of the best sensor elements in the world. The Rotronic® C-94 sensor is especially developed for high end measuring applications in harsh industrial environments and for portable equipment. It is mend to remain accurate and stabile for years during continuous operation. Many hygrometer uses sensors that are originally designed for use in static applications like air-conditioners, laundry dryers etc.. These sensors are to be used as indicators rather than for measuring applications. Although the cost price of a Rotronic® C-94 sensor is significantly higher than most other RH-sensors it has proven to be the only sensor element that could guarantee the Dewcheck dew point meter years of accurate measuring without the need for frequent recalibrations.

Is it necessary to measure surface temperature in hard to reach spots with a dewmeter? Should a separate probe be helpful?

Dewcheck dewpointmeters (dpm) are mainly used during the painting of large structures. Most of the times larger area's are being coated. The surface temperatures are being taken at specific spots which are considered to be representative for the whole area that will be coated at that moment. These specific spots are usually not chosen in hard to reach area's. Often inspectors need to climb ladders or scaffolding, a one handed dewmeter therefore comes in more handy than dewmeters having a separate probes. When not in use the Dewcheck dew point meter can be safely stored in its special holster-case complete with belt-clip. Beside this a probe cable is sensitive and get easily damaged. Probe cables often get stuck.

What makes Dewcheck dew point meter the best choice for use in the protective coating industry?

First of all the idea of developing a combination dewmeter to measure all specific climate parameters including Delta T specifically for the surface treatment industry was originated by our company. In 1992 TQC started comprehensive research after the needs of the specific customers group such as coating inspectors which lead to the first generation of Dewcheck climate gauges. The experience of producing and servicing dewmeters for such a long time has generated a wealth of experience and information that was used to create the latest model of Dewcheck gauges. - The gauge is a truly "one hand" operated gauge. No cables that can get stuck or damaged. - The instrument has been specifically developed for use in harsh environments. Electronics, sensors and housing are all extremely robust. - Due to the integrated filter at the RH-probe and its excellent recovery characteristics (100% recovery) after condensation of the RH-probe (or in rainy weather) the dewmeter is ideal for outdoor use. The Dewcheck is designed for use outdoors. - Large rubber keys and the ergonomically shaped housing makes is possible to use the dewmeter wearing gloves. - Illuminated display and the build-in flash light makes the dew point meter (dpm) ideal in poorly lit situations. - The special designed holster case made of genuine leather protects the dewmeter when not in use.

Why is humidity so important?

Each coating manufacturer will specify the humidity conditions that are required to perform a proper application of the coating. Some coatings (eg. Epoxies) may not be applied when the humidity is higher than eg. 70% or 80% while other coatings (moisture cure coatings) do require a humidity over a certain minimum level in order to achieve a perfect cure.

Do I need to measure climate when using waterborne coating?

Yes! Especially with waterborne coatings the humidity and temperature are very important. A low humidity will dry the coating too fast which makes a proper application impossible. A high humidity will cause the coating to stay wet and is will not cure. Too low temperatures , especially below freezing point, will destroy waterborne coatings.

Can I measure other surfaces than steel with my Dewcheck dew point meter?

Yes! The Dewcheck surface probe can be used on any type of surface. Although the major field of application is within the steel protection industry such as the painting of ships, bridges, tanks and other steel constructions the dew point meter is also used for during painting works on concrete, brick, wood, plastic, non Ferro metals etc..

Why is there a flash-light integrated in the Dewcheck dewpointmeter?

Dewcheck's are often used in confined spaces such as (ballast)tanks and cargo holds since climate conditions are unpredictable in the locations. An extra light can be a great help if the inspectors flash-light fails.

A Dewcheck requires an investment which is higher than the relatively low-cost sling psychrometers and mechanical thermometer. Why should I pay this extra money?

There are various reasons: - Timesaving/Faster - while these devices take several minutes each to stabilize per measurement, the Dewcheck Dew Point Meter displays all 5 values (a Dataset) in a few seconds. Ta - Air Temperature Ts - Surface Temperature RH - Relative Humidity Td - Dew Point Temperature Ä - the difference between surface and dew point temperatures
- Easier to use There is no need for counting revolutions per second in a timed interval using de-ionized water ,reading a "hard to read" glass thermometer (impossible in poorly lit situations), using a slide-rule calculator ,waiting minutes for a surface thermometer to stabilize and finally looking up values in a cross reference table.
- Easier to handle Truly one handed design with large back lighted display.
- More accurate Tighter tolerances on all values, less chance on human-errors and no miscalculations.
- Robust No fragile glass thermometers, sensitive bi-metallic thermometers but a robust piece of electronics in a strong compact package.
- Versatile Unlike a sling psychrometer, the Dewcheck Dew Point Meter (DPM) works well in cold environments and hot. The logging options increases its versatility even more.

I have seen there are hygrometer instruments on the market that show delta T values and relative humidity only . Wouldn't that be just enough to check if my climatic conditions are suitable to apply a coating?

Although these parameters are important you need the full picture to be sure about the climatic conditions. A very low air-temperature combined with a moderate or low relative humidity will lead to very low dewpoint temperatures and if they are below 0°C they are actually called frost point rather than dewpoint. The delta T will show a satisfying number but it could very well be that you are applying your paint over ice when your air temperature is below 0°C. Therefore in cold situations you always need to know your air temperature.

Warm (sun heated)surfaces could also generate problems. High surface temperatures often lead to dry-spray effect with it linked chemical problems. A dewmeter like DewCheck that provides you all necessary parameters is not only option to be absolutely safe in each type of application.

Will a DewCheck humidity sensor condensates when it is brought from a (very) cold environment to a warm environment?

The DewCheck humidity sensor is extremely thin and lightweight. Its body temperature will follow temperature changes very fast thus avoiding condensation in fast climate changes in 99% of the situations. Some other dewmeters are using humidity sensor that is directly positioned on a printed circuit board. This increases the mass of the sensor and will slow down the acclimatize of the sensor's body which often will lead to condensation of the humidity sensor

Will condensation of the humidity sensor lead to malfunctioning of the DewCheck?

No, in the rare occasion a DewCheck sensor condensates the moisture evaporates within seconds and the instrument is ready to use. No influence of accuracy.

Some other sensors used in the industry need quite some time to recover after condensation and often have some form of hysteresis. In order to achieve correct measurements those sensors need to be put into a very dry environment (below 20%RH) for a considerable time to regain their accuracy.

Are DewCheck dewmeters sensors sensitive for dust particles and pollution?

Like any other sensitive instrument it is advised to keep the instrument as clean as possible. The dew point meter's humidity sensor, which is typically the most sensitive part, however is protected by a thin white membrane. This is unique to DewCheck. Other gauges have open sensors which means dust particles will adhere directly of the sensing element. In combination with regularly condensation of the sensor the dust will "bake" onto the sensor which on a longer term leads to drifting values. Even when an instrument is "Dustproof" its sensor will need to have contact with the air in order to take measurments.

What is new about the DewCheck4 Series 2?

DewCheck 4 Series 2 is now standard supplied with a USB communication cable and the TQC Dewlog Analysis software. The hardware and firmware of the series 2 Dewmeter are renewed to even further enhance long term stability and accuracy.

Are there different versions of DewCheck dewmeters?

No, one Dewcheck dewmeter does it all. Each Dewcheck measure ALL climatic parameters necessary for painting and has full memory on board with USB connection. The only extra is the magnetic holder to use the instrument on site as a permanent dewpoint data logger.

Is a DewCheck waterproof?

No the DewCheck dew point meter (DPM) is not waterproof. A DewCheck dewmeter is typically used in situations where dry circumstances are required. When is rains there is no need to use an instrument. Some instrument claim they are equivalent to a certain IP class. Note that equivalent is not the same as compliant and usually there is a reason to state matters in this way...