Chapter 1
What problems arise when dew condensation occurs on metal products?
When moisture adheres to the surface of metal products, it can cause rust and corrosion. This is especially true for steel materials and metal parts during storage; not only the visual quality but also the impact on subsequent process must be considered.
Rust and corrosion of the product
When moisture adheres to a metal surface, corrosion can progress more easily depending on the material and environmental conditions. This can lead to cosmetic defects and a decline in quality.
Equipment corrosion
In piping, equipment, storage racks, and other similar structures, prolonged dew condensation can lead to corrosion and deterioration.
Impact on the work environment
When moisture accumulates on surfaces such as floors, it can lead to slippery conditions and other risks in the work environment.
Impact on packaging and storage items
dew condensation may affect moisture packaging materials and surrounding stored items.
dew condensation is not simply the phenomenon of "water droplets forming on a metal surface." It needs to be managed from multiple perspectives, including product quality, equipment maintenance, and the work environment.
Chapter 2
Why does dew condensation on metal products?
dew condensation is a phenomenon in which water vapor in the air cools and appears on the surface as water droplets.
For example, when warm, humid air comes into contact with a cold metal object, the temperature of the metal surface may fall below the dew point of the air. In this condition, moisture may form on the metal surface.
The important point is that dew condensation doesn't dew condensation simply because the air is humid, but rather because of the relationship between the temperature of the metal surface and the dew point temperature of the air.
Chapter 3
What is the dew point temperature? It is the temperature used to determine dew condensation will occur.
The dew point temperature is the temperature at which water droplets begin to form in air when the temperature is lowered while maintaining the same amount water vapor in the air.
By determining the dew point temperature from the air temperature and relative humidity, you can understand "at what temperature the air needs to cool before condensation is likely to dew condensation."
| Value to check | meaning | Relationship with dew condensation |
|---|---|---|
| air temperature | ambient air temperature | Used in combination with humidity to determine the dew point temperature. |
| Relative humidity | The ratio of the amount of water vapor that air at that temperature can contain. | The higher the value, the easier it is for the dew point to be reached with even a slight drop in air temperature. |
| Dew point temperature | The temperature at which water droplets begin to form | Used for comparison with metal surface temperature |
| metal surface temperature | Actual product surface temperature | The closer the temperature gets to the dew point, the higher the risk dew condensation. |
Rather than judging the risk of dew condensation based solely on relative humidity, a crucial point in dew condensation monitoring is comparing the dew point temperature with the metal surface temperature.
Chapter 4
How do you assess the risk dew condensation?
One way to assess the risk dew condensation is to look at the difference between the metal surface temperature and the dew point temperature.
| situation | Relationship between metal surface temperature and dew point temperature | Way of thinking |
|---|---|---|
| I have plenty of time. | The metal surface temperature is well above the dew point temperature. | Condition that is less prone to dew condensation |
| Note | The metal surface temperature is approaching the dew point temperature. | Continuously monitor temperature changes and humidity increases. |
| High risk | The metal surface temperature falls below the dew point temperature. | The likelihood of dew condensation occurring increases. |
In actual monitoring systems, one method is to set alarm conditions based on the difference between the metal surface temperature and the dew point temperature.
Alarm values cannot be determined uniformly for all sites. Please set management standards considering factors such as the type of metal, surface condition, surrounding environment, product requirements, and the time required for remediation.
Chapter 5
What are the difficulties with conventional dew condensation monitoring alone?
dew condensation prevention measures may include visual inspections by workers and periodic checks using temperature/humidity.
I only noticed it after dew condensation had occurred.
Visual inspection alone cannot capture changes during periods that were not observed.
Worker patrols are required.
Regularly checking multiple storage locations increases the burden of travel and record-keeping.
It is difficult to analyze the conditions under which it occurs after the fact.
Without a continuous record of temperature/humidity, and surface temperature, it becomes difficult to analyze the conditions under which dew condensation occurred.
I haven't looked at the condition of the metal surface.
Ambient temperature/humidity alone do not tell you how cold the surface of a metal product actually is.
By shifting dew condensation prevention measures from "visual inspection of results" to "continuous monitoring of conditions prone to dew condensation," preventative management becomes easier.
Chapter 6
Continuously monitor temperature/humidity to identify dew condensation risks.
By using a wireless temperature/humidity monitoring system, you can continuously collect temperature/humidity, and product temperature data from multiple measurement points and check the status on a monitoring screen.
Real-time monitoring
Check the current temperature, humidity, and metal surface temperature to determine if conditions dew condensation are approaching.
Calculation of dew point temperature
We calculate the dew point temperature from temperature and humidity data and check its relationship with the metal surface temperature.
dew condensation alarm
The system sets conditions according to management standards and triggers an alarm when the risk of dew condensation increases.
Check history and trends
We review past temperature/humidity, and metal surface temperatures to analyze seasonal changes and dew condensation conditions.
Chapter 7
System configuration Example | Monitoring dew condensation on Metal Products with MD8000 + CISAS
Chino offers configuration example where the MD8000 wireless logger with monitoring capabilities collects ambient temperature/humidity, as well as the temperature of metal products, and the CISAS monitoring application software is used to acquire, monitor, and notification the data.
What is this system looking at?
| data | Role |
|---|---|
| air temperature | To understand the surrounding environment and use it to calculate the dew point temperature. |
| Relative humidity | This data is used to understand moisture content in the air and to calculate the dew point temperature. |
| metal product temperature | Understanding the actual surface temperature of the product |
| Dew point temperature | The approximate temperature at which water vapor in the air begins to condense. |
| Metal product temperature - dew point temperature | Used as an indicator to understand the margin before dew condensation occurs. |
In this configuration, instead of simply looking at temperature/humidity to determine dew condensation, it monitors a combination of "how cold the metal product is currently" and "at what temperature the air begins to dew condensation."
Visualizing dew condensation risk with CISAS
In this configuration example, CISAS calculates the "dew point temperature," "metal product temperature - dew point temperature," and "dew condensation alarm rank" to monitor the risk of dew condensation.
data logging
- Wireless Data Logger with Monitoring Function MD8000
- temperature/humidity sensor
- Sensor for measuring the temperature of metal products
- Repeaters as needed
Monitoring and recording
- CISAS/V4
- Graphical display
- Real-time trends
- Alarm list / Alarm history
- memory function
View details of the MD8000 wireless logger with monitoring function.
Chapter 8
Key points for continuing dew condensation monitoring
Install the sensor in the appropriate location.
We will consider the placement of metal products, airflow, door opening and closing, and temperature differences with the outside air to determine a location that best represents the actual risk of dew condensation.
Measuring the surface temperature of a metal
It's important to know not only the ambient temperature/humidity, but also the actual temperature of the metal you don't want dew condensation.
Determine the alarm conditions.
The difference between the metal surface temperature and the dew point temperature is used to determine at what stage to alert the user to dew condensation.
Calibration regularly
When using temperature/humidity sensors or temperature sensors to manage data, consider calibration and inspection according to working conditions.
dew condensation monitoring is not complete simply by installing a system. It is crucial to design the operation to include sensor installation status, management standards, alarm response, calibration and inspection, and data review.
What is calibration? How to verify the reliability of measured values.
Chapter 9
Things to check before installing dew condensation monitoring system
| Check items | Confirm |
|---|---|
| Applicable products | What do you want to protect from dew condensation, such as steel materials, metal parts, or coils? |
| Storage location | Warehouse, indoor yard, storage facility, presence or absence of air conditioning, etc. |
| dew condensation causes | Seasonal changes, outside air inflow, opening and closing of doors, cooled products, etc. |
| Measurement items | Air temperature, relative humidity, metal product temperature, dew point temperature, etc. |
| Alarm | At what level of risk should an alert be issued, and to whom should it be notified? |
| Data Storage | How long should it be kept, and how should it be reviewed? |
| Sensor placement | Where to set up the representative point, where to measure the product temperature. |
| Calibration/maintenance | Calibration cycle, inspection, sensor replacement, and other operational procedures. |
FAQ
Frequently Asked Questions about dew condensation Prevention for Metal Products
At what humidity level does dew condensation?
It's not possible to determine the dew point solely based on humidity. dew condensation occurs due to the relationship between air temperature and humidity and the metal surface temperature, so it's important to determine the dew point temperature and compare it to the metal surface temperature.
Can dew condensation be monitored using only a temperature/humidity?
While it's possible to understand the surrounding dew condensation conditions, measuring the temperature of the metal product itself allows for a more direct confirmation of the relationship between the actual product surface and the dew point temperature.
What is the dew point temperature?
This is the temperature at which water droplets begin to form when air is cooled. It is an important indicator for determining the likelihood of dew condensation.
What are the advantages of wireless monitoring?
This makes it easier to distribute measurement points even in warehouses and storage locations where wiring work is difficult. It also allows for configuration where data from multiple locations can be viewed together in an office.
Can dew condensation be measured directly with the MD8000?
Instead of directly measuring the phenomenon of dew condensation itself, this configuration collects temperature/humidity, and metal product temperatures, and uses CISAS to calculate the dew point temperature and other parameters to monitor the risk dew condensation.
What temperature difference should I set dew condensation alarm to?
There isn't one single value that applies to all sites. You need to consider the product, the environment, the required response time, the impact of dew condensation, and other factors when setting management standards for each site.
Where should the sensors be installed?
You need to select a location that represents a high risk dew condensation. Check site conditions to determine the installation location, such as near air conditioning vents, doors, areas affected by outside air, and areas with large temperature differences for the product.
Summary
dew condensation prevention should shift from "checking humidity" to "checking the conditions under which dew condensation occurs."
When addressing dew condensation on metal products, it's important not only to monitor relative humidity, but also to examine the relationship between the dew point temperature (determined from air temperature and humidity) and the actual temperature of the metal product.
In particular, continuously monitoring the temperature-dew point temperature of metal products makes it easier to identify conditions prone to dew condensation before it occurs, rather than after.
In Chino's example system configuration, the MD8000 collects temperature/humidity, and metal product temperature, while CISAS calculates and monitors dew point temperature, temperature difference, and dew condensation alarm rank. This can be used not only for rust prevention of metal products but also for preventative monitoring to minimize the impact of dew condensation on equipment and the work environment.
I would like to consult about monitoring dew condensation on metal products.
You can consider configuration of dew condensation monitoring while checking the target product, storage location, temperature/humidity conditions, the temperature of metal products, and any necessary alarms.
I would like to consult about dew condensation monitoring.
