Dehumidifying Sheet "DryKeeper"

1.

less degree. Air circulation sometimes permits entry ofmoisture causing inside-dew condensation.

INTRODUCTION

Many engineers are supposedly being annoyed by thedew condensation phenomenon inside the cabinet forelectrical facilities installed outdoors. Inside-dew condensation can occur in tightly sealed cabinets. For example, if
the door of a cabinet is sealed in an ambient atmosphereof 25°C, 60 % RH, the dew point is reached when thetemperature drops by 8.3°C to 16.7°C, and dew condensation occurs below this temperature. Thus, however
effectively a cabinet may be sealed, inside-dew condensation can not be prevented if the temperature and humidityof the atmosphere are high at the time of door closing.
Moreover, cabinets usually have led-in cables and thelike making it difficult to completely seal their feedthroughs, and thus leaving air circulation in a greater or2.

WHAT IS DRYKEEPER?

DryKeeper is a dehumidifying sheet that absorbs moistureand prevents occurrence of inside-dew condensation for along period, thereby suppressing rusting. It has the following features:
1) It efficiently absorbs moisture and reduces atmospheric humidity, suppressing inside-dew condensation.
2) It absorbs moisture in a high-humidity atmosphereand discharges moisture in a low-humidity atmosphere in a reversible manner. See Figure 1.
3) Because of its reversibility, it can be used continuously for a long time.

80

Absorbance (%)

703.

60
50

SPECIFICATIONS OF DRYKEEPER

Table 1 shows the specifications of DryKeeper.

403020Absorption

10Discharge

Absorption

Discharge

Absorption

00100200300400500Time (h)Figure 1

Moisture absorbing and discharging characteristics
of DryKeeper.

Table 1

Specifications of DryKeeper.

Product No.

KS-A4Size

A4 size, 2-mm thickness

Maximum absorption

About 100 cc per sheet

DryKeeper(about 70 % of own weight)
Dehumidifying sheet

Structure

Nonwoven cloth envelope

Polyethylene film

Photo 1

Field test of DryKeeper in a cabinet for high-voltageuse.

1

Humidity (%) / Ambient temperature (°C)

After installation

Before installation
10080

Humidity

6040Temperature

20012345Elapsed time (week)

Figure 2
Photo 2Transition of cabinet humidity before and after installation of DryKeeper.

Dew condensation before installation of DryKeeper.

2) The cabinet's inside after the application ofDryKeeper
Inside-dew condensation was eliminated and thehumidity dropped to around 60 %. See Photo 3 andFigure 2.
3) Long-term sustainability
Tests have been continuing since October 2000,
demonstrating the long-term sustainability of the product.
More than one year has passed since DryKeeper wasinstalled in the cabinet, and yet no dew condensation canbe seen, achieving satisfactory results.
Photo 3Dew condensation eliminated after installation of
DryKeeper.

5.
4.

APPLICATION EXAMPLE OF DRYKEEPER

We have been carrying out, in collaboration with Tokyo
Electric Power Co., field tests to see how far DryKeeper iseffective in actual cabinets installed outdoors. Figure 1
shows the cabinet used for the field tests and the test
results are summarized as follows:
1) The cabinet's inside before the application of
DryKeeper
Inside-dew condensation was seen and the humidity
was nearly 100 %. See Photo 2 and Figure 2.

2

IN CONCLUSION

It has been demonstrated that, as a new type of dehumidifying sheet, DryKeeper is effective in suppressing theinside-dew condensation in electrical facilities installed
outdoors having a high degree of sealing. We would liketo recommend the product to those who are annoyed byinside-dew condensation.
For more information, please contact:
Functional Products Development Group, Insulated
Wire Production Department, Power Cables Division
TEL: +81-463-21-8289
FAX: +81-463-21-8292

Furukawa Review, No. 222002