30 CFR 7.48: Acid resistance test.

(a) Test procedures. (1) Prepare one sample each of the insulated surfaces of the battery box and of the cover that measure at least 4 inches by 8 inches, by the thickness of the sample which includes the insulation plus the battery cover or box material. The insulation thickness shall be representative of that used on the battery box and cover. If the insulation material and thickness of material are identical for the battery box and cover, only one sample need be prepared and tested.

(2) Prepare a 30 percent solution of sulfuric acid (H2 SO4) by mixing 853 ml of water with 199 ml of sulfuric acid (H2 SO4) with a specific gravity of 1.84. Completely cover the samples with the acid solution at the test temperature range of 65 °F−80 °F (18.3 °C−26.7 °C) and maintain these conditions for 7 days.

(3) After 7 days, record the condition of the samples.

(b) Acceptable performance. At the end of the test, the insulation shall not exhibit any blistering, discoloration, cracking, swelling, tackiness, rubberiness, or loss of bond.