上密封 meaning in Chinese

back seat

Buyer refuse gawk delivery sealed sample survey report following
买主拒收货物，随后寄上密封样本与检验报告。
Back seal test
上密封试验
Reasonable design guarantees minimum maintenance . upper o - rings can be replaced without removing the valve from service
阀门结构设计合理，设有上密封装置，维修方便。
Cargo ex pacification extremely inferior now under survey we reserve right of claim airmail sealed sample
联合太平洋号上的货物质量极差，现正在检验之中。我们保留索赔的权力，今以航空寄上密封样本。
This connected burden receiving valve is lower sealing valve . this valve ' s structure is the same burden receiving valve , only diameter is differential
与料流调节阀连接的是下密封阀，下密的结构与上密封相同，只是口径不同。