Pump Performance Tes;ng Goal: Measure te pump curve(s) Head versus flow rate: Efficiency versus flow rate: Maximum ead at = 0 Maximum flow rate at = 0 η η = 0 wen = 0 and = 0 Maximum efficiency Pump tes;ng in a nutsell Prep 1. Make sure te pump works: dry and wet tests. 2. Wire te circuit to measure voltage and current. 3. Configure tubing for te pump test. Data Collec;on Cange eigt of exit tube. Record mass flow rate, voltage and current. 1
Make sure te pump works: Dry and wet tests. SAFETY Keep water away from all electrical equipment except te pump, and do your best to keep te pump motor dry. Don t andle te power supply or mul;meter(s) wit wet ands or wet feet (or wen in contact wit water). Prevent water from splasing onto or near te power supply. Wipe up any water tat leaks onto te floor. Report any problems encountered to your instructor. 5 Dry Test: Make sure te impeller spins Power supply 12 VDC Pump Don t run your pump too long witout water. Te purpose of te dry test is to verify tat te motor works and tat te impeller can rotate freely. 2
Debugging te dry test If te impeller does not spin: Is te lid so ;gt tat impeller rubs? If so, loosen te screws olding te lid in place. Power supply 12 VDC Pump Is te motor misaligned? Try wiggling it. Are te electrical leads making good contact? Is te current limit on te power supply exceeded? Increase te current dial. Wet Test: Make sure te pump can move water. Power supply 12 VDC Pump Pail SAFETY Keep water away from all electrical equipment except te pump, and do your best to keep te pump motor dry. Don t andle te power supply or mul;meter(s) wit wet ands or wet feet (or wen in contact wit water). Prevent water from splasing onto or near te power supply. Wipe up any water tat leaks onto te floor. Report any problems encountered to your instructor. 9 3
Priming te pump Priming is te addi;on of water to te pump cavity so tat te impeller can create enoug suc;on to pull water from te supply reservoir. Use gravity feed from te supply pail to cause water to flow into te pump cavity. Gravity drives flow into te pump cavity Priming te pump 1. Connect te outlet tube first. Outlet tube Gravity drives flow into te pump cavity Priming te pump 1. Connect te outlet tube first. 2. Connect te inlet tube from te supply pail. Inlet tube Gravity drives flow into te pump cavity 4
Priming te pump 1. Connect te outlet tube first. 2. Connect te inlet tube from te supply pail. 3. Allow water to flow into te pump cavity. Gravity drives flow into te pump cavity Priming te pump 1. Connect te outlet tube first. 2. Connect te inlet tube from te supply pail. 3. Allow water to flow into te pump cavity. 4. Connect te power to te pump. Power supply 12 VDC Gravity drives flow into te pump cavity Debugging te wet test If water is not flowing: Are tere bubbles in te line between te pail and te pump? If so, tap te lines to move te bubbles. Is tere water in te pump cavity? If not, make sure te inlet is below te surface of te water in te supply pail, and prime te pump. Power supply 12 VDC Pump Pail 5
Set up te electrical circuit for measuring pump voltage and pump current. Do not start te test un;l you are also ready to measure V and I for te pump! Electrical circuit for pump power measurement Use your DMM to measure voltage Use te benc- top DMM to measure current DCV DCA Power supply 11.6 42.2 Pump motor Outlet Inlet Can you make te connec;ons? Use te DMM on top of te power supply to measure current. 6
11/21/12 To measure current, te current must flow troug te DMM: Te DMM is in series to measure current To measure current, te current must flow troug te DMM, and te sedngs must be correct. SAFETY Keep water away from all electrical equipment except te pump, and do your best to keep te pump motor dry. Don t andle te power supply or mul;meter(s) wit wet ands or wet feet (or wen in contact wit water). Prevent water from splasing onto or near te power supply. Wipe up any water tat leaks onto te floor. Report any problems encountered to your instructor. 21 7
Configure te tubing for measuring te pump curve. Configure te pump, tubing, meter s;ck, supply pail, and catc basin for te pump curve measurement DCV DCA Sample bucket Stopwatc Power supply 12 VDC 11.6 42.2 Catc basin Scale NOTE: is te distance from outlet of te ose (top) to te free surface in te pail (bogom). Preliminary Procedure 1. Fill te supply pail to about one- tird of full. 2. IMPORTANT: Align te bogom of ver;cal scale to te water level in te bucket. 3. IMPORTANT: Set te tare weigt of te small bucket. 4. Connect te pump to te supply pail and exit tube. All steps are important! 8
11/21/12 Align te ver;cal scale to te level of te water surface in te bucket Adjustment screws Look ere! Align te ver;cal scale to te level of te water surface in te bucket Use te tare func;on to cancel te dry weigt of te pitcer used to collect water samples. Empty pitcer on te scales Before clicking zero Amer clicking zero 9
Collec;ng Data: Basic Ideas 1. You coose, ten measure V, I, m and t 2. Allow t of at least 15 seconds. Use longer ;mes at low flow rates. 3. Use strategic selec;on of te order of First measure at te extremes: Find te maximum first. Fill in te middle of te range in random order 4. Use mul;meters to measure V and I. Do not trust te meters on te power supply Collec;ng Data: Basic Ideas (2) 5. Do not make pysical canges (e.g. canging impellers) during a single data set. If you make canges, start over, but keep your data. 6. Do not trow away data. Make notes about suspicious data. Discard measurements only at te analysis stage wen you are certain tat te data is not valid. Data Collec;on Procedure Note: Keep te pump running during tese measurements. 1. Empty te collec;on bucket. 2. Move te exit ose to a selected eigt Water jet sould exit te ose orizontally 3. Start te ;mer as te collec;on bucket is moved to capture te water 4. Collect enoug water 5. Record, m, t, V and I 6. Repeat for at least 10 sedngs (10 values). 10
11/21/12 Exit tube sould be orizontal Like tis: Not like tis: Data seet Label te seet wit team members, date, type of impeller (if more tan one is used) Make columns of data for, V, I, m, t. (inc) V (volts) I (amp) m (g) t (s) Tis is just a sample data seet. Make your own version on a full seet of paper. Be prepared to take more data tan you will eventually use. Strategic data collec;on: 11
Strategic Data Collec;on Take data were it magers. Tere is no reason to use te same t for eac flow rate measurement. Te scien;fically best procedure is to use longer t for lower flow rates. Wy? Tere is no reason to use even increments of. Te scien;fically best procedure is to use a random order of values. Wy? Naive data collec;on Tere is no need to use equal spacing of values. Te laws of Pysics don t care about equal! Don t do it! Tere is no need to collect data in order of increasing or decreasing. In fact, it s a bad idea 9 8 7 6 5 Don t do it! Take values in random and in strategic order. 4 3 2 1 Strategic data collec;on Te two most important data. First, establis te range of for your pump. Note tat te maximum may cange during te test. Your pump performance will cange as you run your pump. 12
Strategic data collec;on Te next important data. Te middle value of determines te curvature of te data set Strategic data collec;on Perform te remainder of te measurements by selec;ng a random order of values in te range between minimum and maximum. Strategic data collec;on If te data reduc;on spreadseet is created before taking measurements, you can see te pump curve emerge as data is collected. Oterwise, you will ave to visualize te data wit simple and sketces. 13
Sample results Head (m) 1.2 Measured data uadra;c fit 1 0.8 0.6 0.4 0.2 0 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 Flow rate (L/min) Efficiency (%) 1 Measured data 0.9 uadra;c Fit 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 Flow rate (L/min) Summary Study tese slides before coming to lab Create a data collec;on seet (or spreadseet) before star;ng te measurements. Use dry and wet tests to debug your pump before sedng up your measurements Set up te V and I measurements Take data strategically 14