• 1 Subject to sections 2 to 4, every ship of a type set out in Column I of an item of the Table to this Schedule shall comply with the construction standards required of a ship by an organization set out in the heading to any of Columns II to XI of that item for the assignment of one of the classification symbols with notations shown in that column of that item.

• 2 The construction standards referred to in section 1 shall be those listed in the publication of the applicable organization as of December 31, 1976.

• 3 Where a ship does not comply with the construction standards referred to in section 1 respecting anchors and cables so that the applicable organization would assign a modified symbol, the anchors and cables need only meet the standards of that organization for the intended voyages to be made by that ship.

• 4 A non self-propelled ship need not meet the construction standards referred to in section 1 that are applicable to propulsion machinery.

TABLE

Interpretation

• 1 In this Schedule,

  aft perpendicular

  aft perpendicular means a perpendicular that coincides with the after side of the rudder post, or where no rudder post is fitted, with the centreline of the rudder stock; (perpendiculaire arrière)

  amidships

  amidships means the middle of length (L); (milieu du navire)

  bilge boundary line

  bilge boundary line means a line that in elevation is parallel to the line of the keel and coincident amidships with the boundary between the side of the hull and the upper turn of bilge; (ligne de démarcation du bouchain)

  breadth (B)

  breadth (B) means the greatest moulded breadth in metres; (largeur (B))

  forward perpendicular

  forward perpendicular means a perpendicular erected at the intersection of the fore side of the stem and the deepest operating load waterline; (perpendiculaire avant)

  length (L)

  length (L) means the distance in metres on the summer load waterline from the fore-side of the stem to

  • (a) the after side of the rudder post, or

  • (b) to the centre of the rudder stock, if there is no rudder post,

  which distance shall not be less than 96 per cent and need not be greater than 97 per cent of the extreme length on the summer load waterline; (longueur (L))

  ice breaker

  ice breaker means a ship specially designed and constructed for the purpose of assisting the passage of other ships through ice. (brise-glace)

Definitions

• • 2 (1) Subject to subsection (2), in every Arctic class ship, other than a Class 1 ship,

    • (a) the bow, forefoot, mid-body and stern are the parts of the ship, and

    • (b) the bow area, lower bow area, mid-body area, stern area, upper transition area and lower transition area are the areas of the shell

    shown in the figure to this section.

  • (2) In every Arctic class ship, other than a Class 1 ship,

    • (a) the forward extremity of the upper transition area is the forward extremity of the bow;

    • (b) the aft extremity of the upper transition area is the aft extremity of the stern;

    • (c) the forward extremity of the forefoot is the point at which the line of the keel is tangent to the stem contour;

    • (d) the bow area includes the bottom of the hull over the length of the forefoot;

    • (e) the lower bow area includes the bottom of the hull between the aft end of the forefoot and the aft end of the bow; and

    • (f) the lower boundary of that part of the lower transition area that is forward of amidships is the shortest line on the outside of the hull between

      • (i) the intersection of the bilge boundary line with the aft boundary of the lower bow area, and

      • (ii) the forward end of that part of the lower boundary of the lower transition area that is aft of amidships.

  • (3) In every Arctic class 1 ship the ice belt is that part of the shell that lies between

    • (a) a line that is 760 mm above and parallel to the deepest operating load waterline; and

    • (b) a line that is 610 mm below and parallel to the lightest operating waterline.

    

Dimensions

• • 3 (1) For an Arctic class ship set out in Column I of an item of Table I,

    • (a) the vertical height (D) of the forward extremity of the bow area above the deepest operating load waterline is set out in Column II of that item;

    • (b) the vertical height (AW) of the upper boundary of the mid-body area above the deepest operating load waterline is set out in Column III of that item;

    • (c) the vertical depth (BW) of the lower boundary of the mid-body area below the lightest operating waterline is set out in Column IV of that item;

    • (d) the vertical height (UT) of the upper boundary of the upper transition area above the upper boundaries of the bow area, mid-body area and the stern area is set out in Column V of that item;

    • (e) the vertical depth (BW + LT) of the lower boundary of

      • (i) the stern area, and

      • (ii) that part of the lower transition area that is aft of amidships,

      below the lightest operating waterline, is the value set out in Column VI of that item added to the value set out in Column IV of that item;

    • (f) the vertical height (C) of the aft extremity of the stern area above the deepest operating load waterline is set out in Column VII of that item;

    • (g) the length of the forefoot (E) is set out in Column VIII of that item;

    • (h) the horizontal distance (F) between the forward perpendicular and the aft end of the bow is set out in Column IX of that item; and

    • (i) the horizontal distance (S) between the aft perpendicular and the forward end of the stern is set out in Column X of that item.

  • (2) Notwithstanding paragraph (1)(h), the distance referred to in that paragraph need not be greater than the distance between the forward perpendicular and the point on the centreline that is 0.04L aft of the point at which, when proceeding aft from the stem, the breadth (B) is first reached.

• • 4 (1) The bow of every Arctic class ship shall be shaped so that it can break ice effectively.

  • (2) The stern of every Arctic class ship shall be shaped so that it can displace broken ice effectively.

Shell Plating and Framing

• • 5 (1) Subject to subsections (2) and (3), for each Arctic class ship set out in Column I of an item of Table II the shell plating and main framing in each area specified in the heading to each of Columns II to VII shall, without exceeding the yield stress of the materials from which they are made, be capable of withstanding the ice pressure shown in that Column of that item.

  • (2) Where waste is stowed in direct contact with the shell plating in the bow of a ship, other than an Arctic class 8 or 10 ship,

    • (a) the values shown in Columns II and III of an item of Table II, and

    • (b) with respect to the bow, the values shown in Column VI of an item of Table II

    do not apply and the values shown in those Columns of the next following item apply in substitution therefor.

  • (3) Where the total length of the mid-body of a ship, other than an Arctic class 1 ship, is fitted with side tanks that comply with section 6 of this Schedule

    • (a) the values shown in Column IV of an item of Table II, and

    • (b) with respect to the mid-body, the values shown in Columns V and VI of an item of Table II

    do not apply and the values shown in those Columns of the preceding item apply in substitution therefor.

  • (4) Subject to subsection (5), for each Arctic class ship in Column I of an item of Table III,

    • (a) the web frames supporting main longitudinal frames, and

    • (b) the stringers supporting main transverse frames

    in each area specified in the heading to each of Columns II to IV shall, without exceeding the yield stress of the materials from which they are made, be capable of withstanding the ice loading shown in that Column of that item.

  • (5) Where the flare of the side shell plating is less than eight degrees outboard from the vertical for a distance of five per cent or more of the length of the mid-body of an Arctic class ship between the lower boundary of the lower transition area and the lower boundary of the upper transition area, the ice loadings shown in Column III of an item of Table III do not apply and the ice loadings shown in Column II of that item apply in substitution therefor.

• 6 The side tanks referred to in subsection 5(3) of this Schedule and fitted in an Arctic class ship set out in Column I of an item of Table IV shall

  • (a) have a width measured from the outer shell of not less than that shown in Column II of that item;

  • (b) extend vertically from the outer bottom of the ship up to the deck at which the main watertight bulkheads of the ship terminate;

  • (c) be so constructed that, if the shell plating or turn of bilge plating is deformed or penetrated by ice, any internal stiffening structure will buckle before it penetrates the inner side of the tank; and

  • (d) contain no waste.

• • 7 (1) Subject to subsection (2), for an Arctic class ship set out in Column I of an item of Table II, the thickness of the shell plating in each area specified in the heading to each of Columns II to VII shall not be less than the spacing of the main frames multiplied by the factor obtained from the formula

    factor = 2 ÷ 3√P ÷ f

    where

    • (a) “p” is the pressure shown in each of Columns II to VII of that item;

    • (b) “f” is the yield stress of the shell plating material; and

    • (c) “p” and “f” are expressed in the same units.

  • (2) The thickness of the stem plate shall be not less than 1.3 times the thickness of the adjacent shell plating in the bow area determined in accordance with subsection (1).

• • 8 (1) For an Arctic class ship set out in Column I of an item of Table II, the section modulus of the main transverse frames with the adjacent shell plating in each area specified in the heading to each of Columns II, IV and VII shall not be less than the value given by the formula

    (ps (b-400)) ÷  8f cm³

     where

    • (a) “p” is the pressure in megapascals shown in each of Columns II, IV and VII of that item;

    • (b) “s” is the main transverse frame spacing in millimetres;

    • (c) “b” is the span of the main transverse frame in millimetres; and

    • (d) “f” is the yield stress of the main transverse frame material in megapascals.

  • (2) For an Arctic class ship set out in Column I of an item of Table II, the section modulus of the main longitudinal frames with the adjacent shell plating shall not be less than the value given by the formula

    ( b² spk) ÷ f cm³

     where

    • (a) “b” is the span of the main longitudinal frame in millimetres in the bow area, mid-body area or stern area, whichever area is applicable;

    • (b) “s” is the main longitudinal frame spacing in millimetres in the bow area, mid-body area or stern area, whichever area is applicable;

    • (c) “p” is, subject to subsection (3), the pressure in megapascals shown in Column II, IV or VII, of the item, whichever column is applicable with respect to the area specified in the heading to the column;

    • (d) “k” is,

      • (i) 1 ÷ 20300, in the case of framing in the bow area

      • (ii) 1 ÷ 18600, in the case of framing in the mid-body area

      or stern area; and

    • (e) “f” is the yield stress of the main longitudinal frame material in megapascals in the bow area, mid-body area or stern area, whichever area is applicable.

  • (3) Where longitudinal framing is used in the bow of a ship, the pressures shown in Columns II and III of an item of Table II shall be multiplied by the factor 1.2, except that in no case need the increased pressures so obtained exceed 10.34 MPa.

Subdivision and Stability

• • 9 (1) Every Arctic class ship that is used solely as an icebreaker shall, when at its worst operating condition with respect to stability and freeboard, be able to withstand the flooding of any one compartment and remain afloat in a satisfactory condition of equilibrium.

  • (2) Every Arctic class ship, other than a ship that is used solely as an icebreaker, shall, when loaded to its worst operating condition with respect to stability and freeboard, be able to withstand the flooding of any two adjacent fore and aft compartments and remain afloat in a satisfactory condition of equilibrium.

  • (3) The necessary calculations to ensure compliance with subsections (1) and (2), shall be based on the following assumptions of damage:

    • (a) the side damage

      • (i) in a longitudinal direction, extends within one compartment on a ship described in subsection (1) and within two adjacent compartments on a ship described in subsection (2),

      • (ii) in a transverse direction, extends outboard of the outermost longitudinal watertight bulkhead or for a distance of one-fifth of the breadth (B) where no such bulkhead is fitted, and

      • (iii) in a vertical direction, extends from the baseline to the underside of the main watertight bulkhead deck; and

    • (b) the bottom damage

      • (i) in a longitudinal direction, extends within one compartment on a ship described in subsection (1) and within two adjacent compartments on a ship described in subsection (2),

      • (ii) in a transverse direction, extends over any distance equal to one-sixth of the breadth (B) or for a distance of five metres, whichever is the lesser, and

      • (iii) in a vertical direction, extends from the level of the keel to the underside of the inner bottom or for a distance of six metres where no inner bottom is fitted.

  • (4) Notwithstanding subsection (3), where lesser extents of damage could have greater effect than the extents of damage described therein, the necessary calculations to ensure compliance with subsections (1) and (2) shall also be based on those lesser extents of damage.

  • (5) For every Arctic class ship, intermediate stages of flooding resulting from the damage referred to in subsections (3) and (4) shall be considered when making the calculations to ensure compliance with subsections (1) and (2).

• 10 Every Arctic class ship shall be constructed or equipped so that, when the ship is riding up or sliding off the ice,

  • (a) the ship has positive stability; and

  • (b) the deck edge of any part of the ship does not submerge.

Rudder and Steering Gear

• • 11 (1) The rudder, rudders posts, rudder stocks, pintles and steering gear of every Arctic class ship shall be strengthened as necessary to withstand the anticipated loading that a ship of that Arctic class may experience when navigating in those zones and at those times of year in which a ship of that Arctic class is permitted to operate.

  • (2) The main steering gear of every Arctic class ship shall be fitted with a shock absorbing device and shall be capable of moving the rudder from 35 degrees on one side to 30 degrees on the other in

    2.56 √L seconds

    where

    L

    is in metres

  • (3) Every Arctic class ship shall, in addition to the main steering gear, be fitted with

    • (a) an auxiliary steering gear capable of being readily connected to the tiller and, in the case of a ship of that category fitted with twin rudders operated by a single steering gear, an arrangement so that each rudder can be readily disconnected and secured; or

    • (b) an effective alternative means of steering the ship such as multiple propellers or side thrust arrangements.

  • (4) Every Arctic class ship shall be fitted with ice horns directly abaft each rudder in such a manner that

    • (a) the upper edge of the rudder is protected within two degrees port and starboard of mid-position when going astern; and

    • (b) ice is prevented from wedging between the top of the rudder and the ship’s hull.

TABLE V

[Repealed, SOR/78-180, s. 10]

Power Requirements

• • 1 (1) Subject to subsections (2), (3) and (7), the minimum continuous shaft power in kilowatts available from the propulsion machinery of every Arctic class ship shall not be less than the numerical value obtained from

    • (a) P_r × D_r ÷ D if D_r ÷ D ≥ 1, or

    • (b) P_r if D_r ÷ D ≤ 1,

      where

    • (c) “Pr” = (579.4-2.6 W^1/3) BA²,

    • (d) “B” = the maximum breadth of the ship at the operating waterline in metres,

    • (e) “W” = displacement of the ship in tonnes at the operating waterline,

    • (f) “Dr” = 0.05 √ Pr ÷ Z ,

    • (g) “D” = the diameter of the propellers in metres except that where the propellers are of different diameters,

      • D = √ (D₁² + D₂² + D₃²) ÷ Z ...,

    • (h) “Z” = the number of propellers, and

    • (i) “A” = for an Arctic Class ship set out in Column I of an item of the table to this section, the value shown in Column II of that item.

    	Column I	Column II
    Item	Arctic Class	Value of A in metres
    1	1	0.305
    2	1A	0.458
    3	2	0.610
    4	3	0.915
    5	4	1.220
    6	6	1.830
    7	7	2.135
    8	8	2.440
    9	10	3.050

  • (2) The minimum continuous shaft power available for the propulsion of every Arctic class ship shall not be less than that required to propel the ship in still water at a speed of 12 knots.

  • (3) A pollution prevention officer may accept a ship as an Arctic class ship where the shaft power is less than that required by subsection (1) for a ship of that Arctic class if the owner of the ship has demonstrated by physical model tests or by actual demonstration that the ship is suitable for navigation in those zones and at those times of year in which a ship of that Arctic class is permitted to operate.

  • (4) The shaft power that the propelling machinery of every Arctic class ship is able to develop when going astern shall not be less than 70 per cent of the power required for that ship in subsection (1) and the machinery shall be able to maintain that power for a period of not less than three hours.

  • (5) Every ship of Arctic class 10, 8 or 7 shall be

    • (a) powered by not less than two prime movers; and

    • (b) provided with not less than two propellers, each located at the stern.

  • (6) Every Arctic class ship that is propelled by steam driven machinery shall be provided with not less than two boilers that have an equal maximum evaporation rate.

  • (7) Every Arctic class ship that is propelled by diesel machinery other than

    • (a) diesel electric machinery, or

    • (b) diesel machinery that drives a controllable pitch propeller,

    shall be provided with machinery capable of developing 1.1 times the shaft power derived from the formula in subsection (1).

Machinery Protection

• • 2 (1) The propulsion machinery, gearing, shafting and propellers of every Arctic class 3, 4, 6, 7, 8 and 10 ship shall be designed so as to take into account the conditions that arise in the propulsion system when the propeller could be slowed or jammed by ice.

  • (2) Means shall be provided to prevent the prime movers of every Arctic class ship from overspeeding.

  • (3) Where an electric motor is used for the propulsion of any Arctic class ship, provision shall be made to automatically protect the motor from

    • (a) excess torque;

    • (b) overloading; and

    • (c) overheating.

Determination of Ice Torque

• • 3 (1) The calculations made to determine the dimensions of a propeller and screw shaft of every Arctic class ship shall include an ice torque factor.

  • (2) The ice torque factor described in subsection (1) shall be derived from the following formula

    M = mD²     kN.m

     where

    • (a) “D” = the propeller diameter in metres; and

    • (b) “m” = for an Arctic class ship set out in Column I of an item of the table to this section, the value shown in Column II of that item.

    	Column I	Column II
    Item	Arctic Class	Value of “m”
    1	1	12.0
    2	1A	15.7
    3	2	17.7
    4	3	21.1
    5	4	24.0
    6	6	28.5
    7	7	30.1
    8	8	32.2
    9	10	33.0

Testing of Materials

• 4 Materials used for propellers and shafting of every Arctic class ship shall be tested in accordance with

  • (a) the Marine Machinery Regulations; or

  • (b) in the case of a ship that is certificated by an exclusive surveyor of one of the classification societies described in paragraph 13(1)(b), the rules of that society.

Propellers

• • 5 (1) Propellers of every Arctic class ship shall be made of a material that has

    • (a) an elongation of not less than 19 per cent; and

    • (b) if made of carbon or low alloy steel, a Charpy V-notch test value of not less than 20.34 J at -10°C.

  • (2) The width and thickness of propeller blade sections shall not be less than that determined by the following formulae:

    • (a) for solid propellers at 25 per cent of the radius measured from the centre of the boss

    WT² = 2648 ÷ (S ( 0.65 + 0.7P )) ( 272H ÷ RN + 20.39M ) cm³,

    • (b) for controllable pitch propellers at 35 per cent of the radius measured from the centre of the boss

    WT² = 2108 ÷ (S ( 0.65 + 0.7P )) ( 272H ÷ RN + 23.45M ) cm³,

    • (c) for all propellers at 60 per cent of the radius measured from the centre of the boss

    WT² = 932 ÷ (S ( 0.65 + 0.7P )) ( 272H ÷ RN + 28.55M ) cm³,

    where

    • (d) “W” = expanded width of a cylindrical section of the propeller blade at the appropriate radius in centimetres;

    • (e) “T” = maximum thickness of the propeller blade at the appropriate radius in centimetres;

    • (f) “P” = in the case of a fixed pitch propeller, the propeller pitch in metres at the appropriate radius divided by the propeller diameter, or in the case of a controllable pitch propeller, 0.7 times the nominal pitch in metres divided by the propeller diameter;

    • (g) “H” = the maximum shaft power in kilowatts available for that propeller;

    • (h) “S” = the ultimate tensile stress of the material of the propeller blade in megapascals;

    • (i) “M” = the ice torque as determined in accordance with section 3 of this Schedule;

    • (j) “R” = propeller revolutions per minute at the maximum shaft power available for that propeller; and

    • (k) “N” = number of blades.

  • (3) The propeller blade thickness at 95 per cent of the radius measured from the centre of the boss shall not be less than that determined from the following formulae for a ship of the appropriate Arctic class:

    • (a) for an Arctic class 10, 8, 7, 6, 4, 3 or 2 ship

    t = ( 20 + 2D )  √ 490/S mm, and

    • (b) for an Arctic class 1A or 1 ship

    t = ( 15 + 2D )  √ 490/S mm,

     where

    • (c) “t” = thickness of blade in millimetres;

    • (d) “D” = diameter of propeller in metres; and

    • (e) “S” = ultimate tensile stress of the material of the propeller blade in megapascals.

  • (4) The strength of the mechanism in the boss of a controllable pitch propeller shall be 1 1/2 times the strength of one of the blades when a load is applied at 9/10 of the radius from the centre of the boss in the weakest direction of the blade.

Shafting

• • 6 (1) Subject to subsection (2) and section 9 of this Schedule, the diameter of a screw shaft of every Arctic class ship shall not be less than that derived from the following formulae:

    • (a) if the diameter of the propeller boss is one-quarter of the diameter of the propeller or less,

      Screw Shaft Diameter

      

    • (b) if the diameter of the propeller boss is greater than one-quarter of the diameter of the propeller,

      Screw Shaft Diameter

      

       where

      • (c) “Su” = the ultimate tensile stress of the material of the propeller blade in megapascals;

      • (d) “Sy” = the yield stress of the material of the screw shaft in megapascals; and

      • (e) “WT²”, = in the case of the formula in paragraph (a) the value derived from the formulae in paragraph 5(2)(a) of this Schedule and in the case of the formula in paragraph (b) the value derived from the formulae in paragraph 5(2)(b) of this Schedule.

  • (2) Where the diameter of a screw shaft when calculated by the appropriate formulae in subsection (1) is less than that of a screw shaft required by the appropriate formulae in the Marine Machinery Regulations, the diameter of the screw shaft shall not be less than that required by those Regulations.

  • (3) When calculations are made to determine the diameter of the intermediate shaft in order to determine the diameter of the screw shaft for the purposes of subsection (2), the diameter of the intermediate shaft need not be increased as required in section 7 of this Schedule.

  • (4) Where carbon or low alloy steel is used for the construction of a screw shaft, the material shall

    • (a) be subjected to a Charpy V-notch test at -10°C; and

    • (b) have an average energy value of not less than 20.34 j.

• • 7 (1) Subject to subsection (2) and section 9 of this Schedule, the diameter of the intermediate and thrust shafts for an Arctic class ship set out in Column I of an item of the table to this section, shall be determined by the appropriate formula in the Marine Machinery Regulations, and the diameter determined by that formula shall be increased by the amount shown in Column II of that item.

    	Column I	Column II
    Item	Arctic Class	Percentage of Increase in Diameter
    1	1	No Increase
    2	1A	4
    3	2	8
    4	3	12
    5	4	15
    6	6 and 7	20
    7	8 and 10	20

  • (2) Notwithstanding the requirements of subsection (1), the diameter of the intermediate and thrust shafts need not exceed 0.85 times the diameter of the screw shaft determined by section 6 of this Schedule.

Gearing

• • 8 (1) Subject to section 9 of this Schedule, where gearing is fitted between the engine and the propeller shafting of an Arctic class ship set out in Column I of an item of the table to this section, the gearing shall be designed and constructed to transmit, in addition to the maximum torque that the engine is able to develop, the percentage increase in torque that is set out in Column II of that item.

    	Column I	Column II
    Item	Arctic Class	Percentage of Increase in Torque
    1	1	15
    2	1A	15
    3	2	30
    4	3	50
    5	4	60
    6	6 and 7	70
    7	8 and 10	100

Deep Submerged Propellers

• 9 Notwithstanding the requirements of sections 5 to 8 of this Schedule, where, in the case of an Arctic class ship set out in Column I of an item of the table to this section, the propeller tips at their highest point are not less than the distance set out in Column II of that item below the lightest operating waterline of the ship, the construction of the propellers, shafts and gears need not be stronger than that required for an Arctic class 3 ship.

  	Column I	Column II
  Item	Arctic Class	Minimum Distance in metres
  1	4	3.05
  2	6	4.57
  3	7	5.34
  4	8	6.10
  5	10	7.63

Cooling Water Arrangements

• • 10 (1) Every Arctic class ship shall be provided with at least one sea bay or tank from which cooling water for machinery that is essential for the propulsion of the ship may be drawn.

  • (2) The sea bays or tanks described in subsection (1) shall be

    • (a) located as close to the keel as practicable; and

    • (b) be supplied with water from more than one sea inlet box.

  • (3) The sea inlet boxes described in paragraph (2)(b) shall

    • (a) be fitted on each side of the ship;

    • (b) each have an area open to the sea of at least six times the total area of the pump suctions served by the sea bay; and

    • (c) be connected to the sea by pipes, valves and a strainer so that the strainer may be shut off from the sea and from the sea bay and the cross sectional area of such pipes, valves and strainer shall be not less than the total area of the pump suctions served by the sea bay.

• • 11 (1) Every sea water pump in an Arctic class ship that provides sea water to machinery essential for the propulsion of the ship shall be able to draw sea water directly from the sea bay or tank described in subsection 10(1) of this Schedule.

  • (2) The design flow velocity of sea water through the suction pipe to any pump described in subsection (1) shall not be more than 2.03 m/s.

  • (3) Cross connections shall be provided from the overboard discharge pipes from the machinery referred to in subsection (1) and such cross connections shall be

    • (a) connected to the pipe between the valve on the sea inlet box and the strainer;

    • (b) of the same bore as the overboard discharge pipe; and

    • (c) provided with a suitable system of valves so that the water may be re-circulated.

Air Starting Systems

• • 12 (1) Every Arctic class ship that is propelled with engines that are started by compressed air shall be provided with not less than two air receivers and the total capacity of the air receivers shall be sufficient to provide, without replenishment, air for

    • (a) 12 starts in the case of a ship with reversible engines; or

    • (b) six starts in the case of a ship with non-reversible engines.

  • (2) The compressed air required in subsection (1) shall be provided by more than one independently driven air compressor and the air compressors shall have sufficient capacity to charge the air receivers from empty to maximum pressure in not more than 30 minutes.

  • (3) The capacity of the smallest air compressor required by subsection (2) shall not be less than two-thirds of the capacity of the largest air compressor.