These valves have four or five pipe connections, commonly called ports.
这些阀门有四个或五个管道连接，通常称为端口。
The comparison of technical performances and economic cost have been made among five pipe materials of more representative to show the advantages and disadvantages of different materials.
针对可供选择的五种比较有代表性的管材，分别进行了技术特性、经济造价的比较，明确了参比管材的优缺点。
The comparison of technical performances and economic cost have been made among five pipe materials of more representative to show the advantages and disadvantages of different materials.
针对可供选择的五种比较有代表性的管材，分别进行了技术特性、经济造价的比较，明确了参比管材的优缺点。
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