Minimum continuous flow provision will safeguard centrifugal pumps against the following two major consequences. 1) Mechanical integrity:- A pump in block condition will result in high differential pressure which will lead to, · Excessive noise & vibration · Overheated casing internals · Probability of seal failures. · Shaft misalignment or damage. 2) Thermal Impact:- Due to block condition, overheating of fluid due to churning action inside the casing will result in, · Temperature rise · Seal failure · Cavitation · Pump impeller damage (Note:- Fluid leak in any of the above cases may lead to fire or toxic hazard)
As per good engineering practice, in absence minimum continuous flow requirement of pump from vendor, minimum circulation loop is designed with 25% flow of design capacity.