| 摘要 |
<p>The pump is provided with a by pass (3) parallel to the suction intake pipe (2). In order to provide an automatic by pass control at certain working ranges, a one way valve is fitted which will only open in the direction of the hydraulic flow. The valve is a simple flap which will fall by its own weight if fitted to a vertical section of the by pass or may consist of spring loaded flap. The spring may be adjusted so that the flap closes by slight or no pressure. The unit can be used in a heating circuit and a boiler inlet pipe.</p> |
