字幕对照译文
Calculation of discharge head in the system
---How to calculate
---example of a calculation
系统排放压头计算
---计算方法
---举例说明
I would like to show you how to calculatethe required head in the waste water system in the commercial building. In theEN standard 12056-2, we will find the formula to be used for that.
本课程讲述，商业建筑污水系统压头计算。在EN 12056-2标准中，可以查询到计算公式。
The formula shows that the total head issum of the geo head in the system; the friction loss in the valves and fittingsin the system; and the linear friction loss in the pipes.
该公式指出，总压头包括：系统高度差、阀门附件局部损失，以及管路沿程损失，三者之和。
The geo head is independent of the flowrate in the system, it’s a constant. Where there is the friction loss in the fittingsand valves and in the linear pipe is a dynamic value, it depends on the flow inthe system.
高度差压头独立于流速，是常量。阀门附件摩擦损失以及沿程阻力损失是动态变化的，随流量改变。
So we have a static value, and we have adynamic value here. Now we will take a look at how to find the geo head in thesystem.
所以，这里既有常量，又有变量。先看高度差压头计算方法。
Now we will find out what is static head orthe geo head in this system. The static head is difference between theintermediate value between the start and stop level and to the highest point inthe discharge system. If there is the back flow level like here, water loop,that will be the highest point in the system. So, intermediate value, betweenstart and stop and to the highest point, is here, so for this system, this willbe the geo head.
来看静压头也就是高度差压头计算方法。它是污水泵启动和停止液位的中间值，与最高提升点之差。这里水回流的位置，就是系统提升最高点。图示这段高度，就是系统高度差压头hgeo。
And if we want to show that on the curve chart,we put the value of the geo head here, and that will be the high which the pumpwill have to lift the water, independent of the flow rate.
如果在图上表示，这段就是高程差。这个高度，就是水泵必须把水提升的高度，该值是独立的，与流速无关。
And now we will again to the dynamic flowrate in the linear pipe, and that will give us together with the friction lossof the head required in the valves and fittings, we will give the slop of thesystem curve. That is the dynamic friction loss in the system.
考虑线性管道内沿程损失，以及阀门附件局部损失，这条斜上抛物线，表示系统流动摩擦总损失。
Now we have the formula for the frictionloss in the linear pipe system here, it is the multiplication of the press loss,depended on the flow rate, that’s value we can find in the chart, multiply bythe length of the pipe. And it is important that we only choose the length ofthe upward going pipe, because downward going pipe will be the flow of thewaste water will be moved by means of the gravitation in the system.
来看线性管道内摩擦损失公式，是乘积关系，和流速相关；这个系数可以从图表中查到，系数乘以管道长度，就是损失值。计算管道长度时候，只考虑向上的部分即可；而向下的部分，是通过重力作用自然流动，不予考虑。
For the calculation of the friction loss inthe linear pipe, we need to use a diagram which is shown here, this is anexample of a system where we have a flow rate of 3.76 liter per second(l/s)，we have a pipe size of DN 70, andwe have a water velocity of 0.96 meter per second(m/s).And in the diagram, wecan read the value of the press loss depending on the flow rate, to be 0.02.Sowith the pipe length of the 75 meters，we can calculate the friction loss to be 0.02 times 75 meters, whichis 1.5 meters.
计算线性管道内摩擦阻力损失，需要一张查询图表。举例来看，流速3.76l/s，管径DN70，污水流速0.96m/s。根据这三个值，查到系数是0.02.管道长度是75米，沿程阻力损失就是，0.02乘以75，等于1.5米。
So, the friction loss in the linear pipesystem for this system of the 75 meters will be 1.5 meters.
该线性管道系统中，75米长管道沿程阻力损失是1.5米。
The diagram we showed here was representinga rough mush in the pipes of 0.25, and of course you need to use the rightdiagram depending on the pipe material used.
该图指的是管子粗糙系数为0.25的情况，实际计算时候，应该根据管子制造材料不同，选取恰当的图表查询系数。
The last factor we need to calculate tofind the total head in the system is the friction loss in the valves andfittings. This is the formula for calculating that value.
最后计算阀门和附件摩擦阻力损失。这个就是计算公式。
We must count the valves and fittings inthe system, and for each of this valves and fittings as a set value and in thetable show here. You can find the individual set values for the bends and forthe different valves of types. We multiply the value with the velocity in squaredivided by two times the gravitation of constant.
先数出来系统中阀门和附件的个数，每种阀门附件的压头损失系数如表格所示。不同弯头和阀门压头损失系数都可以找到。该值乘以水流速度的平方，除以2倍重力加速度常数，就是局部损失。
Now we will make an example of the calculationof the friction loss in the valves and fittings.
通过举例计算说明阀门附件摩擦损失。
And for this example, the sum of the setvalues will be 6.7, and we multiply that with the velocity we had before 0.96,divided by 2 times 9.82, that gives us friction loss of 0.33 meters.
该例子中，所有系数之和是6.7，乘以前面提到的速度0.96的平方（忘了平方），除以2倍g-9.82，得到压头损失0.33米。
So now we can calculate the total headrequired in the system, by adding the three heads together. We have the statichead, the geo head as said that two, 5 meters, we calculate the friction lossin the linear pipe system to be 1.5 meters; and the head loss in the valves andfittings to be 0.33, and that gives us total head of 6.83 meters.
上述三项相加，得到系统总压头。其中:静压头也就是高程差5米，沿程损失1.5米，阀门附件局部损失0.33米，故总压头6.83米。
That means we need to find the pump that isable provide the head of maximum of this value or above.
这意味着，选泵扬程要等于或大于这个压头值。
So now I have shown you how to calculatethe total head required in the system, and I hope that you have understandingof what factors influence the total head, that you need to think about what is statichead, what different valves and fittings kinds in the system, and what size ofpipe is there.
前面讲述了系统总压头的计算，希望大家了解总压头的影响因素，需要考虑静压头、阀门附件种类以及管子尺寸等。
So if you have any questions, please callme.
如果有问题进一步咨询，请联系我。
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