The pressure chamber is a volute body pump, the radial force in the deviated from the design conditions is calculated as follows: 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 traffic. When the pump is running under design conditions, according to the above formula to find the radial force coefficient is equal to zero, zero flow when the radial force coefficient is the largest, that is, K = 0.36 The size of the coefficient 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, and K may reach 0.6 at zero flow rate.