泵试验的目的和采 用的标准
一、试验目的
    泵的性能及性能曲线迄今为止还不能用数学方法来精确推算出来，只能通过泵的试验来确定。对于新设计的泵或泵的某项目的科研，通过泵的试验来验证是否达到了预期的要求，得出正确的性能参数，做出性能曲线图，一般都是在实验室内进行，必要时须现场进行测试。而对于老产品通过试验来保证泵的质量(即出厂试验)或验证合同中用户提出的要求( 即验收试验)，验收试验的内容、方法、精度、地点等由双方签订的合同或协议中明确进行规定，试验地点可在制造厂的实验室内，也可在需方使用现场或在第三方实验室内进行。
二、目前泵试验采用的标准
    试验采用的标准是随技术的发展是经常变更的，下面列举出目前离心泵试验所采用的主要试验标准。
    (1)《回转动力泵水力性能验收试验1级和2级》(CB/T 3216- 2005)

(2)《水泵流量的测定方法》(GB/T 3214- -2007)

(3)《泵的振动测量与评价方法》(JB/T 8097- 1999)

(4)《泵的噪声测量与评价方法》(B/T 8098- 1999)

第二节泵试验种类和方法

泵的试验按试验内容可分为运行试验、性能试验、汽蚀试验、 四象限试验、水泵模型及装置模型试验等。
一、 泵的运行试验
    泵的运行试验一般分为磨合性运行试验和可靠性模拟运行试验。

1. 磨合性运行试验

泵在规定点(设计点)运行工况下，检查泵的振动和噪声是否符合要求;检查泵的轴承及轴封处的温升是否符合要求;检查轴封泄漏量;停泵后检查泵的密封环、轴承、轴套、平衡装置等的磨损情况。磨合运行试验要求有一定持续运行时间后 再进行检查，如表8 - 1所示。

2.可靠性模拟运行试验

根据用户现场的使用条件，在制造厂的试验台上进行较长时间的运行试验。可靠性模拟运行试验一般是用于使用工况非常特殊:试验内容超出常规的试验要求(可能遇到的危险因素)；试验介质的性质、 试验温度及压力有特殊要求的场合下的就验，需在供货合同或协议议中进行明确的规定。
二、泵的性能试验
    泵的性能试验是通过试验方法测得泵的主要性能参数值，如流量Q、 扬程H、泵的输入功率P (轴功率)、转速n和通过计算得到的泵的输出功率Pu(有效功率)和泵的效率η等值，以及他们之间的关系曲线Q - H曲线、Q-P曲线、Q-”曲线。
1.性能试验方法
    泵的性能试验前，先要进行泵的磨合性试验，并还要进行稳定性检查。稳定性检查包括读数波动性检查和重复检查，波动幅度应符合表8 -2所规定的范围，重复性应符合表8-3的规定范围。
    所谓读数波动是指在一次读数的时间内， 读数相对于平均值的变动，波动值的计算公式:
                       最大读数值-平均读数值/平均读数值x100%
                         最小读数值一平均读数值/平均读数值x 100%
     所谓重复性是同一量(除只有转速和温度允许进行调整外。其余如节流阀、水位、填料函、平衡水等所有调节位置应完全保持不交的情况下的同量)相邻两次茂数尚(对排一试验点应以随机的时间间隔不少于10s的相邻两次读数)的变化。对每一个试验工况点，最低限度应取3组读数，并应记录每一个独立读数的值和由每组读数导出的效率值。每一量的最大值与最小值的百分率差不得大于表8 -3给出的值。需要注意，如果读数增加，则允许有较大的相差。
重复性值计算公式为:
                            最大值-最小值/最大值x100%

上述检查完后，可以进行性能试验，试验时，可以通过调节出口调节阀来得到不同的流量点，一般要求从关死点 (Q=0) 到最大流量点(0=1.40)之间包括规定点(设计点)在内的13个以上的流量点进行测试，每一个流量点记录下相关的数值，例如流量、压力、真空度、转速、功率等数值，然后计算出泵的流量、扬程、 转速、输出功率、输入功率、效率等。最后按式(2-39)、式(2-40)、式(2-41)比例定律换算到规定转速下的性能参数，并将性能参数绘成泵的性能曲线。
2.试验液体

对输送非清洁冷水液体的泵，可以用清洁冷水来进行泵的性能试验，然后换算到相应液体的性能。
3.试验转速

因受试验条件限制，试验转速可能与规定转速不一致，可以通过比例定律，将试验性能换算到规定转速的性能。但不能相差太大，否则会带来较大的误差。标准规定，在流量和扬程的测量时，对试验精度为1级和2级时，试验转速在规定转速的50%到120%的范围内进行，对试验精度为精密级时，试验转速在规定转速的80% ~ 120%的范围内进行。在泵的输人功率测量时，不论是1级、2级还是精密级，都规定试验转速在规定转速的80% ~ 120%的范围内进行。

4.试验精度

泵的试验精度分为精密级(A级)、 1级(B级)、2级(C级)三种。不同的精度要求，泵各性能参数测量的不确定度容许值是不同的。表8-4表示了深各个性能参数总的测最不确定度答许值，表8 -5表示了泵的效率总的不确定度导出值的容许值。

从表8-5中可以看出，精密级精度最高，测量仪表常需要原位标定，试验较难达到，所以只有在特殊要求下采用。1级精度较高，可用于检测中心、重要新产品、重大科研项目测试鉴定等的试验。2级精度较低，可用于泵生产厂常规的出厂试验。
5.容差系数
    由于泵在制造过程中，必定会产生偏差，渣浆泵所以每台泵产品都可能会发生几何形状和尺寸不符合图样的可能，故在对试验结果与保证值(工作点)进行比较时，应允许有一定的容差值存在，泵的这些容差，只与实际的泵有关，并不涉及试验条件和测量不确定度。
    容差系数士tq，  土ty，土In分别为流量、扬程和效率的容差系数值，如表8-6所示，用于保证点Qc、He保证点Qc、H。由合同或协议中规定，如无规定，通常情况下即为泵的规定点(设计点)。
6.保证的证实
    试验所得到的结果是否达到了供货合同或协议书中规定的保证值(包括它们的容差)，也即判别泵是否达到了性能的要求，这就是保证的证实。
(1)泵流量、扬程保证的证实:
    将测量得到的结果换算到规定转速，然后绘制出Q -H的关系曲线( 与各测量点拟合成最佳的曲线代表泵的性能曲线)，如图8-1所示。

通过保证点(lc、 He)作水平线段士t0 .Q。和作垂直线段土1日. He的容差“+”字线。

如果Q-H曲线与“+”字线相交或至少相切，则认为泵的流量和扬程已得到了保证，泵的流量和扬程判别为合格。
(2)泵效率保证的证实:
    泵试验的效率值是由通过规定的保证点Qc、He和坐标轴原点所作的连线，与实际试验测得的Q-H曲线相交的交点，作的一条垂线 与实际测得的Q一η曲线相交的交点的效率值为此泵的效率值。如果该效率值高于或至少等于ne.(1 -t,)的值，则认为泵的效率是在容差范围内，认为泵的效率合格。如图8-1所示。

如果测得的流量Q、扬程H值大于保证值Qc，Hc: 但仍在容差范围内，且效率也在容差范围内，泵虽然是合格的，但要注意此时实际的输人功率可能要大些，要注意原动机功率的配备情况是否够大。
    如果泵的流量、扬程测得的比规定的高，已超出了上容差范围时，可通过车削叶轮直径来进行修正，对型式数K≤1. 5的泵，直径车削不超过5%，车削后的性能可用下式来计算(车削后不需要重新做实验):

式中下标r代表切削后的，1代表试验的，D2、D.、D:如图8-2所示。型式数K:

对型式数K≤1.0的泵，叶轮直径车削不大于3%时，可认为车削后工作点的效率不变。

Purpose and standard of pump test

I. test purpose

So far, the performance and performance curve of the pump can not be accurately calculated by mathematical method, but can only be determined by the pump test. For the scientific research of a newly designed pump or a certain project of the pump, the test of the pump is used to verify whether the expected requirements have been met, the correct performance parameters are obtained, and the performance curve is drawn, which is generally carried out in the laboratory. If necessary, the field test is required. For the old products, the quality of the pump (i.e. delivery test) can be guaranteed by test or the requirements of the user in the verification contract (i.e. acceptance test). The content, method, accuracy and location of the acceptance test shall be clearly specified in the contract or agreement signed by both parties. The test location can be in the laboratory of the manufacturer, the user's site or the third party's laboratory.

II. Current pump test standards

The standards used in the test are often changed with the development of technology. The main test standards used in the current centrifugal pump test are listed below.

(1) level 1 and level 2 hydraulic performance acceptance test of rotary power pump (CB / T 3216-2005)

(2) measurement method of water pump flow (GB / T 3214-2007)

(3) vibration measurement and evaluation method of pump (JB / T 8097-1999)

(4) measurement and evaluation method of pump noise (B / T 8098-1999)

Section II type and method of pump test

According to the test contents, the pump test can be divided into operation test, performance test, cavitation test, four quadrant test, pump model and device model test, etc.

I. operation test of pump

The running test of pump is generally divided into running in test and reliability simulation test.

1. Running in test

Under the operating condition of the pump at the specified point (design point), check whether the vibration and noise of the pump meet the requirements; check whether the temperature rise of the bearing and shaft seal of the pump meet the requirements; check the leakage of the shaft seal; check the wear of the sealing ring, bearing, shaft sleeve, balance device, etc. of the pump after stopping the pump. Running in operation test requires a certain duration of operation before inspection, as shown in table 8-1.

2. Reliability simulation operation test

According to the use conditions of the user's site, a long-term operation test is carried out on the test bench of the manufacturer. Reliability simulation operation test is generally used for very special working conditions: the test content exceeds the conventional test requirements (possible risk factors); the test shall be carried out when the nature of test medium, test temperature and pressure have special requirements, which shall be clearly specified in the supply contract or agreement.

II. Pump performance test

The performance test of the pump is to measure the main performance parameters of the pump through the test method, such as flow Q, head h, input power P (shaft power), rotation speed n of the pump, the equivalent value of output power Pu (effective power) and pump efficiency η obtained through calculation, as well as the relationship curve Q-H curve, Q-P curve and Q - "curve between them.

1. Performance test method

Before the performance test of the pump, the running in test of the pump shall be carried out first, and the stability inspection shall also be carried out. The stability inspection includes reading fluctuation inspection and repeated inspection. The fluctuation amplitude shall meet the range specified in table 8-2, and the repeatability shall meet the range specified in table 8-3.

The so-called reading fluctuation refers to the change of the reading relative to the average value in the time of a reading, and the calculation formula of the fluctuation value:

Maximum reading value - average reading value / average reading value X100%

Minimum reading value - average reading value / average reading value x 100%

The so-called repeatability is the same amount (except that only the speed and temperature can be adjusted). Other adjustment positions such as throttle valve, water level, stuffing box, balance water, etc. shall be kept in the same amount when they are not intersected completely) the change of the adjacent two times of Mao number (the adjacent two readings of the first row of test points shall be no less than 10s at random time interval). For each test condition point, at least 3 groups of readings shall be taken, and the value of each independent reading and the efficiency value derived from each group of readings shall be recorded. The percentage difference between the maximum value and the minimum value of each quantity shall not be greater than the value given in table 8-3. It should be noted that a large difference is allowed if the reading increases.

The calculation formula of repeatability value is:

Max min / max X100%

After the above inspection, the performance test can be carried out. During the test, different flow points can be obtained by adjusting the outlet regulating valve. Generally, more than 13 flow points, including the specified point (design point), are required to be tested from the dead point (q = 0) to the maximum flow point (0 = 1.40). Each flow point records the relevant values, such as flow, pressure, vacuum degree, speed Then calculate the flow, head, speed, output power, input power and efficiency of the pump. Finally, according to the law of proportion of formula (2-39), formula (2-40) and formula (2-41), the performance parameters are converted to the performance parameters at the specified speed, and the performance parameters are drawn into the performance curve of the pump.

2. Test liquid

For the pump conveying non clean cold water liquid, clean cold water can be used for performance test of the pump, and then converted to the performance of the corresponding liquid.

3. Test speed

Due to the limitation of the test conditions, the test speed may be inconsistent with the specified speed. The test performance can be converted to the performance of the specified speed through the law of proportion. However, the difference should not be too large, otherwise it will bring a large error. According to the standard, when measuring the flow and head, when the test accuracy is level 1 and level 2, the test speed shall be within the range of 50% to 120% of the specified speed, and when the test accuracy is precision level, the test speed shall be within the range of