译文：

平衡阀在设计时的选择计算包括两部分内容，首先是流量特性的选择，其次是平衡阀口径选择。 １、流量特性的选择，在供热系统中，平衡阀一般装在干线的分支点，用户的热入口处，以极热源的分、集水器和热力站中的流量控制（包括调节阀和电动阀）。当热负荷变化时，常常需要依靠平衡阀的调节改变流量，配合供水温度的变化，使散热器的散热量适应热负荷的要求。换热器最理想的换热特性，　（包括热交换器、散热器）应对相对换热量与平衡阀相对开度成线性关系，亦即保证在调节过程中，平衡阀和换热器的综合放大系数维持不变，换热器（特别是散热器）的热特性在小流量时换热量变化大；在大流量时换热量变化小。也就是在小流量时放大系数大；大流量时放大系数小，为保持总放大系数不变，平衡阀的流量特性应该是小流量时放大系数小；大流量时放大系数大。 （1） 平衡阀的阻力应为系统总阻力的10%至30%之间，平衡阀应参照水压图进行； （2） 在选择平衡阀时，对于同口径的平衡阀，应该优先选用阻力较大的； （3） 在选择平衡阀时，为了增加平衡阀阻力占系统总阻力的百分比，可适当选择比管道直径较小口径的平衡阀。 在一般的供热系统中平衡阀前后压降在3KPa（未端用户）到300KPa（近端用户）之间，通过平衡阀厂家提供的不同口径的流量系数Kv用3KPa的最不利压降，△P代入公式即算出该口径平衡阀的最小可通流量（在全开时）若其值等于、大于设计流量，则该口径平衡阀选择合适。 ３、经验选型比管路的口径小1—2号。 为了提高平衡阀调节精度，节省投资，一般要求所选阀门的设计开度在60~90%之间。建议：根据Kv值在开度75%地方选定阀门 对于自力式流量控制阀：一般要求所选阀门流量为设计流量的105%以适应±5%的阀门误差。检查系统的{zd0}和最小压差是不是在阀门的压差控制范围内。通常自力式流量控制阀与管道尺寸相等。 对于自力式压差控制阀：一般要求所选阀门流量在自力式压差控制阀的范围内，保证自力式压差控制阀的最小启动压差就可以了。 对于限流止回阀：在系统设计和施工中水泵运行一定要通过调节泵出口阀，让其工作在额定范围内。在大多数水系统循环泵和水箱多数在一个水平面上，使用中循环泵的实际扬程只是循环管道和水泵水循环部分的流动阻力。一般小于水泵的额定扬程，从泵的曲线可看出这种情况泵就会处于过流量状态，使水泵和所配电机过负荷。对循环管道和水泵内水循环过度出刷，这样不仅功率消耗大而且影响循环管道和水泵的寿命。这样我们在水泵压出口装上限流止回阀保证水泵在高效区域运行。即安全又节约。空调的集中冷源，不论冷冻水还是冷却水系统常用多台泵并联。而在实际运行时，大部分时间为部分负荷运行，有时只需开一台水泵。这时系统摩阻大大下降，水量上涨常会导致泵的电动机过载。轻则跳闸，重则烧坏电机，影响制冷系统正常运行。例如：当两台泵并联工作时，如果一台泵停止运行，另一台泵流量会超过总流量的50%，有时可达80%。因此，建议在设计并联泵时应在每台泵的出水口上配备流量的限定装置，通常采用流量控制阀，可自动稳定流量。本超市提供限流止回阀，具备限流+止回功能。并能满足单台泵运行的需要。建议大家使用。 一般选型与泵的口径相同，而且此阀是可以调节的，配有止回功能。 　

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原文：

Valves in the design of the selection and calculation consists of two parts, the first thing is the choice of flow characteristics, followed by the balancing valve caliber choice. 1, flow characteristics of options in the heating system, the balance valve usually installed in the trunk of the branch point, the user's heat at the entrance to a very heat of the sub-catchment devices and thermal stations in the flow control (including regulating valves and Electric valves). When the heat load changes, often need to rely on balancing valve to change the regulation of traffic, with the water temperature changes, so that the radiator heat dissipation to adapt to the heat load requirements. The best heat transfer characteristics of heat (including heat exchangers, radiators) respond to the relative heat transfer and the relative balance valve opening into a linear relationship, that is, ensure that the adjustment process, the balance valve and an integrated heat exchanger amplification factor will remain unchanged, heat exchanger (especially radiator) and thermal characteristics of heat transfer in a small variation in flow; heat transfer in large flow fluctuations. That is, in a small flow amplification coefficient; large flow amplification factor is small, the total magnification factor in order to maintain constant flow balancing valve flow characteristics of a small amplification factor is small; large flow amplification coefficient. (1) balancing valve resistance to the total system resistance should be 10% to 30%, balance valve should refer to the hydraulic diagram; (2) In selecting balance valve, the balancing valve for the same caliber, priority should be given a greater choice of resistance; (3) In selecting balance valve, in order to increase the balance valve resistance accounted for the percentage of the total system resistance, may be appropriate to choose a smaller diameter than the pipe diameter balancing valve. Heating system in the general balance valve before and after the pressure drop in the 3KPa (not end user) to 300KPa (near-end users) between the manufacturers through the provision of various caliber balancing valve flow coefficient Kv of the most negative pressure drop with the 3KPa, △ P into the formula that calculates the minimum balance valve diameter can pass traffic (in the full-time) if its value is equal to, greater than the design flow, then the caliber choose the right balance valve. 3, experience, selection of a small diameter than the pipeline 1-2. In order to improve balance valve regulation accuracy, saving investments, general requirements for the selected design of the valve opening between 60 ~ 90%. Recommendation: According to Kv value in opening the selection valve 75% of the local For the self-operated flow control valve: general requirements for the selected flow valve at 105% of design flow to meet the ± 5% of the valve error. Check the system maximum and minimum pressure is not within the control valve differential pressure. Often self-operated flow control valves and pipe sizes are equal. For the Self-operated pressure control valve: general requirements for the selected valve flow control valve in the Self-operated pressure differential within the framework of self-operated pressure control valve to ensure minimum start pressure on it. For the current-limiting valve: In the system design and construction of pump operation must be by regulating the pump outlet valve, allowed to work in the rated range. In most water systems circulating pump and water tank most of them in a horizontal plane, using the actual head of circulation pump is only part of the cycle of pipelines and pump the flow resistance of the water cycle. Generally less than the rated pump head, pump curves can be seen from this situation would be in the off pump flow state, so that pumps and motors are equipped with overload. Inside the pipes and pumps for circulating the water cycle over a brush, so that power consumption is not only large but also affect the life cycle of pipelines and pumps. So that we exit the pump pressure valve installed to ensure maximum flow of water pumps to run at high efficiency region. That is safe and save. The concentration of air-conditioning cold source, regardless of chilled water or cooling water system used more than one pump in parallel. In actual operation, most of the time for part-load operation, and sometimes just to open a water pump. At this time the system friction declined significantly, rising water often leads to the pump motor overload. Ranging from tripping, heavy motor is burned, affecting normal operation of cooling system. For example: When the two pumps working in parallel, if one pump stops running, another pump flow rate will exceed 50% of the total flow, sometimes up to 80%. It is therefore recommended in the design of parallel pump should be at the outlet of each pump is equipped with traffic limited to devices, commonly used flow control valve that automatically stabilize flow. The supermarket provides current limiting valve, with current-limiting + non-return function. And can meet the needs of a single pump operation. Suggest that you use. Selection and pump diameter generally the same, but this valve is adjustable, with non-return function.

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