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G. Spelsberg GmbH & Co. KG Installation distribution board series AK III with accessories

DLG-APPROVED: "Resistance to ammonia"

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The Approval

A test mark “DLG-APPROVED for individual criteria” is awarded for agricultural products which have successfully fulfilled a scope-reduced usability testing conducted by DLG according to independent and recognised evaluation criteria. The test is intended to highlight particular innovations and key criteria of the test object. The test may contain criteria from the DLG test scope for overall tests, or focus on other value-determining characteristics and properties of the test subject. The minimum requirements, test conditions and procedures as well as the evaluation bases of the test results will be specified in consultation with an expert group of DLG. They correspond to the recognised rules of technology, as well as scientific and agricultural knowledge and requirements. The successful testing is concluded with the publication of a test report, as well as the awarding of the test mark which is valid for five years from the date of awarding.

The DLG-APPROVED test “Ammonia resistance” includes technical examinations in the laboratory and in the NH3 test chamber of the DLG Test Center Technology and Farm Inputs in Gross-Umstadt. Brand-new samples of all materials used were tested. The testing was based on the DLG test specification for the study of ammonia resistance, version 2.4/2021. Other criteria were not tested.

Assessment in brief

The brand-new materials are tested regarding their ammonia resistance according to DLG-APPROVED test methods. The tested materials have met the requirements regarding the examined criteria.

Table 1: Overview of results

Dlg Quality profileTest result   
Single Criteria
Resistance to Ammonia
 – AK IIIinstallation distribution boardresistant+ + + +
 – AK PEN-SLterminal stripresistant+ + + +
 – AK AScover stripresistant+ + + +
 – SNIstepped nippleresistant+ + + +
 – ASTattachment spoutresistant+ + + +
 – BSTventilation spoutresistant+ + + +
 – DMSdouble membrane spoutresistant+ + + +
 – DMS/swdouble membrane spoutresistant+ + + +
  insulating plugresistant+ + + +

* The DLG test framework provides the following options in its evaluation schemes:
+++ or better = meets, exceeds or clearly exceeds the specified DLG standard,
++ meets the legal requirements for marketability,
- = failed 

The product

Description and specifications

The materials tested here are components of the installation distribution board from the series AK III. The switching cabinet case is also used in animal houses and  an thus be exposed to elevated levels of ammonia in the housing environment.

Table 2: Specifications (manufacturer information)

Installation distribution board series AK III  
Rated voltage 400 V
Rated current 63 A (125A)
Length 300 - 1.050 mm
Width 315 mm
Height 155 mm
Partitioning units 14 - 70
Accessories  Dimensions (L x W x H)
AK PEN-SLterminal strip285 mm x 40 mm x 30 mm
AK AScovering strip107 mm x 52 mm x 5 mm
SNIstepped nippleØ 30 mm x 20 mm
ASTattachment spoutØ 30 mm x 23 mm
BSTventilation spoutØ 25,5 mm x 13 mm
DMSdouble membrane spoutØ 25,5 mm x 14 mm
DMS/swdouble membrane spoutØ 30 mm x 15 mm
 insulating plugØ 14 mm x 5 mm

The Method

Ammonia resistance

The ammonia resistance of the materials was determined by a laboratory testing according to the DLG test standard for agricultural use. With the DLG laboratory test for NH3 resistance, it is possible to determine the ability of the test sample to withstand the effects of animal house air over a usage period of about 10 years. The test was carried out in a gassing chamber under the following climate conditions:

Test duration 1500 h
Air temperature 70 °C
Relative humidity 70 %
Ammonia concentration 750 ppm

For assessing the NH3 resistance, the test samples were examined visually, gravimetrically and through a measurement of the material thickness before and after the climate testing. The measurement of shore hardness only yielded relevant and tangible results for the accessory parts. The materials were tested on the basis of at least two samples.

Detailed account of the test results

Ammonia resistance

During the test, all tested components and materials were resistant. No visual or functional properties of the materials were restricted after the fumigation in the ammonia-containing environment. All deviations of the measured parameters were within the measurement uncertainty or the evaluation thresholds. Thus, it can be assumed that the materials are able to sufficiently withstand a NH3-containing atmosphere, as it would be the case for exhaust air in pig houses for example.

Table 3: Change through the NH3 exposure – distribution board

Component Visual assessment Weight Thickness Evaluation
Box no change 0.2 % resistant
Hinged window, hinge, grip no change 0.2 % 0.9 % resistant
Upper part no change 0.1 % 7.7 % resistant
Cover screw 1 no change 2.3 % 3.8 % resistant
Cover screw 2 no change 1.5 % 0.0 % resistant
Double membrane spout no change -0.8 % 0.0 % resistant
Installation distribution board series AK III       resistant

Table 4: Change through the NH3 exposure – accessories

Accessories Visual assessment Weight Shore hardness Evaluation  
AK PEN-SL terminal strip no change < 3.0 % + 8.6 % resistant
AK AS cover strip no change < 3.0 % < 5.0 % resistant
SNI stepped nipple no change < 3.0 % < 5.0 % resistant
AST attachment spout no change < 3.0 % < 5.0 % resistant
BST ventilation spout no change < 3.0 % < 5.0 % resistant
DMS double membrane spout no change < 3.0 % < 5.0 % resistant
DMS/sw double membrane spout no change < 3.0 % + 6.5 % resistant
  insulating plug no change < 3.0 % < 5.0 % resistant


The brand-new materials were tested regarding their ammonia resistance in the laboratory and in the NH3 test chamber of the DLG Test Center  Technology and Farm Inputs in Gross-Umstadt according to DLG-APPROVED test methods. All tested materials have met the requirements 
regarding the examined criteria. Thus, the entire component is to be classified as resistant to ammonia-containing air.

Manufacturer and applicant

Günther Spelsberg GmbH & Co. KG
Im Gewerbepark 1
D-58579 Schalksmühle

Telephone+49 (0)2355 892-0
Telefax +49 (0)2355 892-299

Test implementation

DLG TestService GmbH, Gross-Umstadt location
The tests are conducted on behalf of DLG e.V.


Division head
Dr. Ulrich Rubenschuh

DLG test specification 
“Ammonia resistance”, for light systems and 
stable equipments (version 2.4/2021)

Test engineer
Tommy Pfeifer *

*    Author


DLG TestService GmbH - Groß-Umstadt location • Max-Eyth-Weg 1 64823 Groß-Umstadt Germany • Tel.: +49(0)69 24 788-611 •