Q-2, r. 9.01 - Design code of a storm water management system eligible for a declaration of compliance

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98. The sizing of a flow control device of a non- submerged thin-walled weir type is established using equation 4-3, in the case of a trapezoidal weir.
A thin-walled weir is a weir made of a thin plate less than 5 mm thick.
A trapezoidal weir consists of 1 rectangular weir and 2 triangular weirs.
Equation 4-3: Qns = Cd × (L – 0.1 × i × H) × H3/2 + Cc × Ø × H5/2
where:
Qns=Flow discharge by a non-submerged thin-walled trapezoidal weir (m3/s);
Cd=Flow coefficient for the rectangular central part of the weir, with Cd= 1.81 + (0.22 x H/P), where P= height of the crest above the channel bottom or invest or the discharge channel (m1/2/s); if H/P < 0.3, Cd = 1.84;
L=Length of the weir (m); for a triangle weir L = 0 m;
i=Number of contractions: 0, 1 or 2;
H=Height of the runoff curve above the crest (m);
Cc=Flow coefficient for each triangle of the weir; a value of 1.38 must be used where tg-1(Ø) is between 10° and 50°(m1,5/s);
Ø=Ratio of the horizontal distance and the vertical distance of each of the lateral walls; for a rectangular weir Ø = 0.
O.C. 871-2020, s. 98.
In force: 2020-12-31
98. The sizing of a flow control device of a non- submerged thin-walled weir type is established using equation 4-3, in the case of a trapezoidal weir.
A thin-walled weir is a weir made of a thin plate less than 5 mm thick.
A trapezoidal weir consists of 1 rectangular weir and 2 triangular weirs.
Equation 4-3: Qns = Cd × (L – 0.1 × i × H) × H3/2 + Cc × Ø × H5/2
where:
Qns=Flow discharge by a non-submerged thin-walled trapezoidal weir (m3/s);
Cd=Flow coefficient for the rectangular central part of the weir, with Cd= 1.81 + (0.22 x H/P), where P= height of the crest above the channel bottom or invest or the discharge channel (m1/2/s); if H/P < 0.3, Cd = 1.84;
L=Length of the weir (m); for a triangle weir L = 0 m;
i=Number of contractions: 0, 1 or 2;
H=Height of the runoff curve above the crest (m);
Cc=Flow coefficient for each triangle of the weir; a value of 1.38 must be used where tg-1(Ø) is between 10° and 50°(m1,5/s);
Ø=Ratio of the horizontal distance and the vertical distance of each of the lateral walls; for a rectangular weir Ø = 0.
O.C. 871-2020, s. 98.