Pressure chamber is a snail-shaped pump, radial force at design conditions deviation from the formula, FR = 1000KHD2B2 Where FR-radial force, N; H-head, m; D2- impeller outlet diameter, m; B2- impeller outlet width (including the thickness of the two covers), m; K-radial force coefficient, can be obtained by the following formula: K = 0.36 [1- (Q '/ Q) 2] Where Q- design flow; Q '- Actual Flow When the pump is running under design conditions, the radial force coefficient is calculated as above and the radial force coefficient at zero flow is the largest, ie K = 0.36. The factor K is also related to the pump type , In some cases, the actual value of K is greater than that obtained from the above formula, K may reach 0.6 at zero flow rate