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§ 7.48 (7) Repeat steps 2 through 8 for the other sample.

(b) Acceptable performance, Neither sample shall have a deflection greater than .010 inch at 180 °F (82 °C).

(Approved by the Office of Management and Budget under control number 1219-D100)

[53 PR 23600, June 22, 1988; 53 FR 25569, July 7, 1988]

§ 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 (H2SO4) by mixing 853 ml of water with 199 ml of sulfuric acid (H2SO4,) 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.

(Approved by the Office of Management and Budget under control number 1219-9100)

§ 7.49 Approval marking.
Each approved battery assembly shall be identified by a legible and permanent approval plate inscribed with the assigned MSHA approval number and securely attached to the battery box.

§ 7.50 Post-approval product audit.
Upon request by MSHA, but no more than once a year except for cause, the approval-holder shall make an approved battery assembly available for audit at no cost to MSHA.

§ 7.51 Approval checklist.
Each battery assembly bearing an MSHA approval plate shall be accompanied by a description of what is necessary to maintain the battery assembly as approved.

(Approved by the Office of Management and Budget under control number 1219-6200)

§ 7.52 New technology.
MSHA may approve a battery assembly that incorporates technology for which the requirements of this subpart are not applicable, if the Agency determines that the battery assembly is as safe as those which meet the requirements of this subpart.

Subpart D—Multiple-Shot Blasting Units
SOURCE: 54 FR. 48210, Nov. 21, 1989, unless otherwise noted.

§ 7.61 Purpose and effective date.
This subpart establishes the specific requirements for MSHA approval of multiple-shot blasting units. It is effective January 22, 1990. Applications for approval or extensions of approval submitted after January 22, 1991 shall meet the requirements of this subpart.

§ 7.62 Definitions.
The following definitions apply in this subpart:

Blasting circuit. A circuit that includes one or more electric detonators connected in a single series and the firing cable used to connect the detonators to the blasting unit.

Blasting unit. An electric device used to initiate electric detonators.

Normal operation. Operation of the unit according to the manufacturer's instructions with fully-charged batteries, with electric components at any value within their specified tolerances, and with adjustable electric components set to any value within their range.

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