Desiccant Cartridges

Activ-Polymer® Technology
17. November 2018
Humidity Indicators
15. November 2018
Desiccant cartridges are required in order to effectively protect high-end equipment used for measuring and controlling optical and electronic devices against corrosion or moisture damage. The equipment needs to be protected against the penetration of dust and moisture and therefore perfectly sealed packaging is vital for the useful life of these products. The remaining moisture inside the equipment and the humidity penetrating through leaks in the packaging may condense by ambient temperature cooling and result in the formation of rust or mildew (glass). Deteriorated equipment becomes useless and involves serious consequential costs.


It is recommended to use the desiccant cartridges inside delicate equipment of measurement and control technology and other highly sensitive optical and electronic devices such as military equipment. The desiccant cartridges effectively protect the goods against moisture, corrosion and fungal contamination. They can be filled with a variety of desiccants, ranging from silica gel to molecular sieves with different pore sizes.


The desiccant cartridges are predominantly made from modern synthetic materials such as polystyrene . The cover is made of paper or other non-woven materials to achieve a diffusion of air humidity. The products are partly equipped with humidity indicators.

The Desiccant

Depending upon the application, the customer may request the appropriate desiccant, which is predominantly molecular sieve or silica gel (Silicon dioxide – SiO2).

Molecular Sieves

Molecular sieve is a round zeolite crystal with an adsorption capability of approx. 20% of its own weight subject to the relative humidity. The product regenerates at 400 °C. Molecular sieves have an especially high adsorption rate and are virtually dust free. They can be offered in different pore sizes: the standard pore size of molecular sieve used in desiccant cartridges is 4 ångström, but 3 ångström or 5 ångström molecular sieves can also be offered in individual cases.

How it Works

Please adhere to the following guidelines for optimal application and results: All components need to be hermetically closed, gaps need to be sealed. This is important because the drying process on the equipment interior leads to a slight pressure drop which may easily result in the intake of new humid air. All parts should be clean and dry and free from any residual moisture. Please note that plastic parts may contain a 3–5% level of residual moisture.


Desiccant cartridges are filled with active desiccants during the production process. In order for the desiccant to maintain their performance level during transport and storage, the product is delivered in hermetically sealed protective packaging. The standard form of packaging is a 0.2 mm polyethylene bag containing a humidity indicator. Another option is the use of water vapour resistant laminated aluminium barrier films in line with TL 8135-0003. The bags are non-transparent and the humidity indicators on the inside may only be inspected with the bag open. There is also an option to select from transparent laminated foil bags possessing a very high water vapour resistance in compliance with MIL-B22191, type I.

Protective Sleeves

The desiccant cartridges are additionally equipped with a protective sleeve according to VG-95239. One protective sleeve, made of transparent polystyrol, is screwed onto each desiccant cartridge. They may additionally be placed in an aluminium box (please refer to TL 4440-0007). We can only guarantee the proper condition and performance of the capsules and cartridges when all packaging remains intact and unopened during transportation. We would like to point out that all information with regard to military standards are based on their effective versions at the time this brochure was printed.
Tropack is developing and offering a wide selection of desiccant cartridges and capsules in various designs.

Product Range

Desiccant cartridges for fine-mechanical and optical devices according to VG 95 239 of black polystyrole with sight window and moisture indicator for 40 % rh in the head part of the desiccant cartridge

Article no. NATO Stock-No. Description Dimensions Installation length in mm
4440-12-158-5262 Rated size* 2,5 - 15 (transparent);
Thread: M16 x 1,5; Filling: 0,35 molecular sieves
4440-12-158-5263 Rated size* 5 - 25 (transparent);
Thread: M16 x 1,5; Filling: 0,7 g molecular sieves
4440-12-158-5264Rated size* 10 - 50 (transparent);
Thread: M16 x 1,5; Filling: 1,5 g molecular sieves
4440-12-175-4087 Rated size* 10 - 17 (transparent);
Thread: M 24 x 1,5 mm; Filling: 1,7 g molecular sieves
4440-12-175-4086 Rated size* 25 - 16 (transparent);
Thread: M 36 x 1,5 mm; Filling: 3,5 g molecular sieves
4440-12-158-5265 Rated size* 25 - 35 (transparent);
Thread: M 24 x 1,5 mm; Filling: 3,5 g molecular sieves
4440-12-158-5429 Rated size* 50 - 70 (transparent);
Thread: M 24 x 1,5 mm; Filling: 7g molecular sieves
4440-12-390-3594 Rated size* 100 - 45 (transparent);
Thread: M 36 x 1,5 mm; Filling: 14 g molecular sieves
* Rated size as 100 refers to the load capacity of a device with max. 100dm3.
The desiccant cartridges TL 4440-0007 are screwed tightly into the protective sleeves.
Cartridge head and sleeve are secured with red tape. The weights are at a tolerance of +/- 10%.

The filling weights of the cartridges can vary because of the different weight of the desiccants. If you should need other sizes and dimensions, please contact us - we are glad to help you. Technical details are subject to change, please contact us for the latest details.