1. 闸阀通常用于启闭应用场合，不建议用于节流应用。
   Gate valves are normally used for on-off service and are not recommended for throttling service.
2. 闸阀通常安装在水平管道上，阀杆垂直朝上。也可安装在垂直管道上；或者安装在水平管道上，但是阀杆并不是垂直朝上，但是可能根据阀门通径、应用环境和材料的不同而要求特殊的结构。如果订购的闸阀将要采用非常规安装方式，则在订购时应该指明阀门的朝向。
   Gate valves are normally installed in horizontal pipe runs with the stem vertical. They can also be installed in vertical or horizontal pipe runs with the stem other than vertical, but may require special construction depending on valve size, service conditions and materials. WHEN PURCHASING VALVES FOR OTHER THAN NORMAL INSTALLATION, THE VALVE ORIENTATION SHOULD BE SPECIFIED.

3. 高度完全关闭闸阀可以用在热水龙头，或拆卸阀座环安装吊耳后，用在采用软铁块的管路中。请在订购时加以指定说明。
   High Integrity Shutoff gate valves can be used for hot tapping or in pipeline services where a soft pig is used if the seat ring installation lugs are removed. Please specify.

1. 一般情况下，安装的截止阀总是使得流体流进和压力位于阀瓣的下方。如果截止阀要安装在其他方向，则在安装前，请与美国太平洋阀门公司确认是否可行。在某种应用条件下，或者当阀门配置缸体或电动马达执行机构，则安装截止阀使得流体从阀瓣上方流进，则可能会有成本低廉的优点。如果是根据这种考虑选择执行机构，则必须小心谨慎，以确保阀门能够正确安装。
   Globe valves are normally installed with flow and pressure under the disc. Always check with Pacific Valves before installing valves with flow in the other direction.
   Under certain service conditions or when valves are equipped with cylinders or electric motor actuators, there may be a cost advantage in the designing and installing the valves with flow over the disc. If actuators are sized for these conditions, care must be taken to assure valves are installed correctly.
2. 如果阀门用在高速流体(湍流)或热循环应用环境中，则螺纹阀座环应该锁焊到阀体上，避免松落。请在订购时加以指定说明。
   Threaded seat rings for valves in services with high velocity (turbulent) flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.

3. 普通截止阀适用于大多数节流应用，而且当管路流速(英尺/秒)不超过240(v是指流体介质的流量，英尺³/磅)时，则使用寿命最长。不建议长时间应用在开启度不足10%的节流应用场合，因为可能会产生剧烈振动和噪音，对阀瓣和阀座造成损坏。采用具有更小流量的通径更小的截止阀或V形阀内件截止阀，可能使得阀门能够具有更大的开启度，因此可以避免损坏。持续严酷的节流应用场合可能需要配置控制阀。
   Conventional globe valves are suitable for most throttling applications and will provide the greatest service life where pipe line velocity in FT/SEC does not exceed 240. (v is a specific volume of flowing medium, ft.³/lb.) Prolonged throttling at less than 10% open is not recommended due to the possibility of excessive vibration, noise and damage to disc and seats. Use of smaller valves or V-Port trim with lower flow capacity may permit the valve to be open at a greater percentage, thus avoiding damage. Continuous severe throttling applications may require a control valve.

　　止回阀最适用于低速或中速流体应用场合。正确选择止回阀的通径很重要。管路流速太低或太高都可能损坏阀门内部构件，缩短阀门使用寿命。
　　Check valves are best suited for low to moderate velocity applications. Correct sizing of check valves is important. Either too low a line velocity or too high a velocity can damage valve internals and shorten valve life.
　　应该避免应用在会频繁出现倒流和间断的应用场合。止回阀应该安装在距离其他设备，如泵和压缩机等，尽可能远的地方。对于可能存在问题的系统，在选择和订购止回阀之前，应该与美国太平洋阀门公司的工程技术人员一起审核。
　　Service in systems involving frequent flow reversals and pulsation should be avoided. Check valves should be located as far away from equipment such as pumps and compressors as possible. Suspected problem systems should be reviewed with Pacific Valves Engineers before selecting and purchasing check valves.

　　如果阀门用在高速流体(湍流)或热循环应用环境中，则螺纹阀座环应该锁焊到阀体上，避免松落。请在订购时加以指定说明。
　　Threaded seat rings for valves in services with high velocity (turbulent flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.

局限性
Limitations:

　　截止阀结构的止回阀应该用于水平管道，阀杆垂直朝上。
　　Globe pattern check valves should be used in horizontal pipe runs with the stem straight up.