Hi In a pump (which operates in normal condition: steady state), pump torque is positive and fluid torque is of equal magnitude and of opposite direction so that the sum of both is zero. ''P. 66 of 'Water Hammer: An Analysis of Plumbing Systems, Intrusion, and Pump Operation' by: Dr. Loganathan and ... I need so explanation about opposite sign of pump torque and fluid torque? Both rotate in a same direction, then why one of positive and the other is negative?