لماذا يتم غلق محبس الطرد عند بدا تشغيل؟ centrifugal pump ويتم فتحه عند بدا تشغيل axial pump بالرغم من ثبات معادلة الباور

centrifugal pump theory is that ths fluid takes its energy from impeller and casing thus we must open discharge valve partialy or closed it until the fluid take its discharge energy but  in another pumps like reciprocating pump the fluid takes its energy from piston moving and we have discharge valve not open until fluid takes its energy