VISI-FLO Sight Flow Indicators Allow Positive Flow Check
VII-FLO视线流量指示器允许正流量检查

任何流经工艺、水、燃料、废物或服务管线的产品，通常必须在管线上的特定位置进行测量。直视式流量指示器提供了一种简单、廉价的方法，可以定性地测量流量、方向、颜色和清晰度。这不仅是一种可靠的阅读方法，而且还允许观看者对产品进行个人解读。Any product flowing through a process, water, fuel, waste, or service line usually must be measured at certain points along the line. In-line sight flow indicators offer a simple, inexpensive means to qualitatively gage flow rate, direction, color, and clarity. Not only is this a reliable reading method, but it also allows personal interpretation by the viewer, who actually sees the product.

典型应用是在过滤器、润滑和冷却管线上，以积极验证流体流动。可视流量指示器也用于故障排除，或作为仪表、开关、过程指示器和其他控制设备的备份。Typical applications are on filter, lubrication, and cooing lines, to positively verify fluid flow. Sight flow indicators are also used for troubleshooting, or as backups for meters, switches, process indicators, and other control devices.

为了满足特定的需要，制定了许多不同的指标。A number of different indicators have been developed to serve specific needs.

螺旋桨指示器是显示不透明液体的- 佳方法，因为它的能见度很高。螺旋桨也是远距离观察的理想选择。但是如果流量太低，螺旋桨就不会转动。螺旋桨指示器的另一个可能缺点，取决于流量，是它们对管路的限制。例如，2英寸。流量为100 gpm的直径指示器将产生10 psi的压降。A propeller indicator is the best way to show opaque liquids because of its high visibility. The propeller is also ideal for observation at a distance. But if flow rate is too low, the propeller will not turn. Another possible drawback to propeller indicators, depending on flow, is the restriction they add to the line. For example, a 2 in. diameter indicator with 100 gpm flow will produce a 10 psi pressure drop.

双向挡板不仅指示流量，而且指向流向。此外，流量限制也很低。对于相同的2英寸。直径，200 gpm流量，一个挡板指示器只造成0.7 psi的下降。A bidirectional flapper not only indicates flow, but points in the flow direction. Also, flow restriction is low. For the same 2 in. diameter, 200 gpm flow, a flapper indicator causes only a 0.7 psi drop.

如果观察颜色和清晰度比验证流量更重要，则使用无挡板的普通双向可视流量指示器。这里的优势在于固有的简单性。A plain bidirectional sight flow indicator without a flapper is used where observing color and clarity are more important than verifying flow. Advantage here is inherent simplicity.

垂直线中使用滴水管。它是重力流和极低或间歇流的理想选择。滴液管通过保持液体滴到玻璃上来确保持续可见。A drip tube is used in vertical lines. It is ideal for gravity flow and for extremely low or intermittent flow. The drip tube ensures constant visibility by keeping the fluid form dripping onto the glass.

虽然选择- 好的指示器类型可能相当容易，但要区分流体相容性、压力和温度限制等因素则要复杂一些。可视流量指示器可以在许多不同的车身材料中指定，以满足流体相容性的需要。青铜是使用- 广泛的，而且通常成本- 低。球墨铸铁（与青铜具有成本竞争力）、碳钢和不锈钢（约为青铜成本的两倍）是其他标准车身材料。此外，还提供诸如蒙乃尔合金和哈氏合金等特殊材料。该表显示了人体材料与普通液体的相容性。While selecting the best type of indicator may be fairly easy, sorting out factors such as fluid compatibility, pressure, and temperature limitations is a bit more involved. Sight flow indicators can be specified in a number of different body materials to suit fluid compatibility needs. Bronze is the most widely used, and is generally lowest in cost. Ductile iron (which is cost competitive with bronze), carbon steel, and stainless steel (which is about twice the cost of bronze), are other standard body materials. In addition, special materials such as Monel and Hastelloy are available. The table shows the compatibility of body materials with common fluids.

密封件的选择也适合特定的化学应用。丁腈橡胶、碳氟化合物、三元乙丙橡胶、氯丁橡胶和聚四氟乙烯是常用的。指示器的温度限制取决于密封件的选择。Seals are also chosen to suit specific chemical applications. Buna, Fluorocarbon, EPDM, Neoprene, and PTFE are commonly used. Temperature limitation for the indicators is dictated by seal choice.

因为玻璃具有优异的耐化学性，在各种温度和压力下都表现良好，所以- 常用于观察镜片。指示器的- 大额定压力（通常为400 psi）由观察镜选择决定。碱石灰和硼硅酸盐是- 常用的两种玻璃。Because glass has excellent chemical resistance and performs well under a wide range of temperatures and pressures, it is used most often for viewing lenses. The maximum pressure rating for the indicators (generally 400 psi) is determined by viewing lens selection. Soda-lime and borosilicate are the two most common types of glass used.

模块化装置允许在标准主体内安装各种指示器，允许在不从工艺管线上拆除主体的情况下，方便检修或更换指示器。两侧的玻璃和密封件可以从所有装置的前部拆下，- 多2英寸。尺寸。选项还包括一系列尺寸和螺纹、法兰、承插或对焊端。Modular units allow the installation of various indicators within a standard body, permitting easy access for servicing or interchanging indicators without removing the body from the process line. The glass and seals from both sides can be removed from the front of all units up to 2 in. size. Options also include a range of sizes and threaded, flanged, socket, or butt-weld ends.

观察流量指示器应位于易于查看的位置。通常，许多行是通过一个“银行”的指标来定向的，因此可以同时查看几个关键行。对于危险品，应在玻璃上方放置一个可选的安全防护罩，以防意外损坏。Sight flow indicators should be located where they can be easily viewed. Often, a number of lines are directed though a “bank” of indicators, so several critical lines can be viewed simultaneously. With hazardous materials, an optional safety shield should be placed above the glass to prevent accidental breakage.

不需要对观察流量指示器进行常规维护。但是，长期使用后，可以更换玻璃和密封件。许多指标的工作寿命为20年或20年以上，很少或根本没有关注。Routine maintenance of sight flow indicators is not required. However, after long service the glass and seals can be replaced. Many indicators have a working life of 20 or more years with little or no attention.

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