BLACKMER IOM E Series, Инструкция по установке, эксплуатации и обслуживанию, Страница: 11 / 52

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RELIEF VALVE PERFORMANCE
Optional integral relief valves provide pump protection from over-pressure conditions. While not intended for continuous use, internal
relief valves protect the pump from closed discharge valves or other intermittent over-pressurization of the system.
Depending on the size of the pump, you will get one of two relief valve designs, a non-externally adjustable or an externally adjustable
relief valve. The design of the E1-2 thru E1-82 are spring-loaded and contain only three (3) parts. This design addresses the problem
of over-pressurization by “cracking” (where the poppet lifts off the seat) at the nominal pressure-relief setting, allowing pumped fluid
to recirculate internally from the discharge side back to the suction side.
RELIEF VALVE – E1-2 THRU E1-82 MODELS
In order to maintain the integrity of the relief valve setting, the E1-2 thru E1-82 relief valves are not adjusted by means of an external
jack screw. Rather, seven (7) relief valve settings are fixed at the factory and adjusted by changing the poppet and spring
combinations. See the pump designation system section for details on available E1-2 thru E1-82 relief valve settings.
The design of E1-133 and E1-222 is spring-loaded and externally adjustable. It addresses the problem of over-pressurization by
initially cracking, and eventually full-bypassing at the nominal pressure-relief setting, allowing pump fluid to recirculate internally from
the discharge side back to the suction side.
RELIEF VALVE – E1-133 AND E1-222 MODELS
To properly size the integral relief valve, it is important to understand the difference between crack pressure and full bypass
pressure .
Crack pressure is the pressure at which the poppet just begins to lift off the seat. This pressure is not affected by variations in fluid
viscosity or pump speed. The pump will provide full flow rate at all pressures below the cracking pressure. E1-2 through E-82 pressure
relief valves are sized based on cracking pressure.
Full bypass pressure is the pressure that occurs when 100% of the pump’s flow rate is bypassing internally through the valve and
no flow is exiting the pump. E1-133 and E-222 pressure relief valves are sized based a full bypass pressure.