闸阀应用建议
Service Recommendations for Gate Valves

1. 闸阀通常应用于开启-关闭场合，不推荐用于节流应用。
   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，阀杆垂直向上。也可以安装在垂直管道或者阀杆不是垂直向上的水平管道上，但是根据阀门的通径大小、应用环境和材料的具体情况，可能要求特殊的结构。如果购买的阀门准备采用特殊的安装方式，则在订购时，应该说明阀门的朝向。
   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. 对于温度超过260^oC的应用环境，建议采用柔性或拼合式楔形闸板，避免楔形闸板由于热膨胀而被卡住。这种情况在阀门冷关闭而后热开启状态下可能发生。
   Flexible or split wedges are recommended for service above 500^oF to avoid wedge binding due to thermal expansion. This may occur if the valve is closed when cold, and then heated to operating temperature.
4. 当用于高速流体(湍流)或热循环应用时，为了避免松开，螺纹阀座环应该锁焊在阀体上。请在订购时加以指定说明。
   Threaded seat rings should be lock welded to the body when used in high velocity (turbulent) or thermal cycling services to avoid loosening. Please specify.
5. 在以足够的力量关闭闸阀后，阀杆应该稍微回转(1/8至1/4圈)，以释放阀杆负载。这使得阀杆能够稍微膨胀，不会卡住或损坏阀门，也不会影响关闭效果。
   After closing a gate valve with sufficient force to develop shutoff, the stem should be backed off slightly (1/8 to 1/4 turn) to relieve stem load. This will enable the stem to expand slightly without binding or damaging the valve and will not affect shutoff.
6. 如果拆卸掉阀座环安装耳柄，则高度整体性关闭闸阀可以用在热水出口或采用软铁的管道系统中。在订购时请加以指定说明。
   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.

截止阀应用建议
Service Recommendations for Globe Valves

1. 通常在安装截止阀时，要让流体流进和压力位于阀瓣的下方。如果流体流进是在另一个方向，那么在安装之前，要与制造商进行确认。在某些特定的应用条件下，或者阀门配置缸体或电动马达执行机构，那么设计和安装阀门，让流体从阀瓣上方流进，就可能具有成本低的优点。如果执行机构是根据这些条件进行选型，则必须小心谨慎，确保阀门安装正确。
   Globe valves are normally installed with flow and pressure under the disc. Always check with the manufacturer 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. 当用于高速流体(湍流)或热循环应用时，为了避免松开，螺纹阀座环应该锁焊在阀体上。请在订购时加以指定说明。
   Threaded seat rings in valves in services with high velocity (turbulent) flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.
3. 通常截止阀适用于大多数节流应用，并且当管线流速(英尺/秒)不超过240(v是流体介质的特定流量英尺³/磅)时，使用寿命也是最长的。不建议截止阀长期在开启度小于10%状态下用于节流应用，因为可能产生剧烈的振动、噪音，并且损坏阀瓣和阀座。采用流量较小的更小通径的阀门或V型端口阀内件，可以增加阀门开启度，从而避免造成损坏。连续严酷的节流应用可能要求采用控制阀。
   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.

截流止回阀的应用建议和局限性
Service Recommendations and Limitations of Stop Check Valves

1. 截流止回阀最适用于低流速或中流速应用环境。截流止回阀的通径正确计算选择非常重要。管线流速太低或太高都可能损坏阀内件，缩短阀门的使用寿命。
   Stop-check valves are best suited for low to moderate velocity applications. Correct sizing of stop-check valves is important. Either too low a line velocity or too high a velocity can damage valve internals and shorten valve life.
2. 应该避免应用在频繁出现流体倒流和间断的应用系统中。截流止回阀应该安装在离泵和压缩机尽可能远的地方。如果怀疑系统可能有问题，则在选型和订购截流止回阀之前，应该与美国太平洋阀门公司一起重新审核管道系统。
   Service in systems involving frequent flow reversals and pulsation should be avoided. Stop-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 before selecting and purchasing stop-check valves.
3. 当用于高速流体(湍流)或热循环应用时，为了避免松开，螺纹阀座环应该锁焊在阀体上。请在订购时加以指定说明。
   Threaded seat rings in 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

1. 截止阀类型的节流止回阀可以用在水平管道上，阀杆垂直向上。
   Globe pattern stop-check valves can be used in horizontal piperuns with the stem straight up.

旋启式止回阀应用建议
Service Recommendations for Swing Check Valves

1. 旋启式止回阀最适用于中流速应用环境。旋启式止回阀通径的正确计算和选择非常重要。管线流速太低或太高都可能损坏阀内件，缩短阀门的使用寿命。请参阅第22页里的通径建议。
   Swing check valves are best suited for moderate velocity applications. Correct sizing of swing check valves is important. Either too low a line velocity or too high a velocity can damage valve internals and shorten valve life. See sizing recommendations on page 22.
2. 应该避免应用在高流速，频繁倒流，间断或剧烈湍流的应用系统中。旋启式止回阀应该安装应该远离弯头等其它设备，这样通常可以减少或消除这些设备可能产生的问题。如果怀疑系统可能有问题，则在选型和订购旋启式止回阀之前，应该与美国太平洋阀门公司一起重新审核管道系统。
   Service in systems involving rapid and frequent flow reversals, pulsation or excessively turbulent flow should be avoided. Locating swing check valves away from elbows, equipment, etc., within the piping system can often minimize or eliminate problems caused by this type of application. Suspected problem systems should be reviewed with Pacific Valves before selecting and purchasing swing check valves.
3. 旋启式止回阀通常适用于安装在水平管道上。如果阀瓣止回结构能够利用流体轻微的支撑住阀瓣，则这种阀门也可以应用在垂直管道上(仅限于流向朝上)。如果阀门准备用在垂直管道上，在订购时应该明确指定说明。
   Swing check valves are normally designed for installation in horizontal pipe runs. When disc stops are designed to hold the disc slightly into the flow stream, the valves may also be used in vertical pipe runs (with flow up only). When valves are to be used in vertical pipe runs, this should be clearly specified.
4. 一般来说，外置杠杆和压铁对于通径大于DN160的旋启式止回阀，并无法有效防止阀门的拍击现象。
   Generally, outside lever and weights are not effective in preventing slamming of swing check valves in sizes above 6".
5. 当用于高速流体(湍流)或热循环应用时，为了避免松开，螺纹阀座环应该锁焊在阀体上。请在订购时加以指定说明。
   Threaded seat rings in valves in services with high velocity (turbulent) flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.