| 摘要 |
A non-reversible plate having a depending tube structure with a discharge opening at the bottom in which there is a plate at the upper portion, rectangular in configuration, and which has an irregular anti-reversal collar beneath the plate portion is disclosed. Desirably the collar is elliptical in configuration and has a major axis at least seven millimeters longer than the minor axis. The longer axis is parallel with the length dimension. Another aspect of the invention is the utilization of a toggle actuated plate changing device which swings in and out of position and can only be actuated when the plate and tube intended for insertion presents the length for insertion into the valve structure. Suitable microswitch or related device is provided to permit actuation of the change actuator, but only when the plate is properly oriented for insertion. The method of the present invention includes the steps of pre-orienting and proportioning a tube or shroud having a plate at the upper portion for insertion into a plate changer assembly.
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