paraphrase lab report
shosho12Problem Statement
Objective of this lab is to achieve a better understanding of the head loss across the system of 4 different styles of electrical pumps. Generating a pump curve relating our head loss to flow rate at a high and low power setting. This will allow us to find our most efficient operating rate for each of the different pumps. We then look at how friction factor interacts with the flow rate by controlling the gate valve increases the Reynolds number which contains a reducing velocity leading to greater head loss through the valve because of the increased pressure change through the pump.
Experimental System and Procedures
The system involved with this lab consists of a bucket acting as a tank containing our water supply which we attach a line to the intake end of our electric pump to in order to move the our fluid through the discharge tube through both the regulation valve and rotameters back into the main tank as shown in Appendix A, Figure 1. Using the isolation valve we can isolate the pump for changing them out by closing it and prime the pump when it’s opened. There are two pressure gauges for this system, one before and after the pump. The regulation valve after the pump is used to control flow and evaluated for friction factor during the experiment.
Calibration of the rotameters must be done before effectively evaluating the pressure gradient over different flow rates. By taking the time it takes to fill up a portion of 2,000 mL graduated cylinder we can relate an actual flow rate to a prediction curve from the calibration process. Being able to relate the rotameter reading to our trend line allows us to accurately make flow readings throughout the experiment.
Using the calibrated rotameters we can record the relation of head pressure to flow rate through the gate valve at different flow settings. The flows interaction with pressure is what generates our pump curves. Completing this for the Gear, Vane, Peristaltic, and Centrifugal pumps at both a high and low energy setting we can evaluate the curves to figure out the most efficient operating conditions for each.
For generating the friction factor we used the centrifugal pump since it doesn’t use positive displacement to move the water which will allow for us to fully close the gate valve and get a pressure reading. Recording the pressures and flow rates for when the valve is fully open, 75%, 50%, or 25% of the way open as well as when the valve is completely closed. From the flow rate we can generate a Reynolds number for each stage of the gate valve.
Experimental Data Collection
Calibration curves are generated by adjusting the regulator valve so we have an accurate reading on the rotameter to go by. Once all of the bubbles are out of the system we know we’ve achieved a steady-state to take our flow reading. Using a stopwatch we can time the amount of time and then relate that with the measured flow rate we get from time of how long it takes to fill a portion graduated cylinder. Repeating this for all 3 of the rotameters will allow us to relate the instruments reading to an actual flow rate with greater precision then the instrumentation reading alone. The recorded data for each of the different rotameters is located in Appendix B. in the Tables A1-A3, this data is then used to generate our figures A1-A3. From the figures we generate our calibration equations A1-3 listed in Appendix B.
After calibration of the rotameters we can efficiently get our flow readings when adjusting the regulator valve. This grants us better accuracy while collecting data for our pump curves. Setting the regulator valve to different flow rates we record the head pressure for each from the head pressure gauge. Doing this at a high and low power setting for each of the four pumps gives us a greater idea of the pumps operating potential at different operating levels/stroke rates. Our data points for each of the pumps is located in Appendix B with its own alphabetical prefix ranging from Table B-E with our high energy level labeled with a suffix of 1 and the lower energy level having the suffix of 2. Each pump has its own generated pump curve plot with both energy levels recorded on it located in Appendix B ranging from Figure B-E.
Before unhooking the Centrifugal pump we took readings of head pressures to get a calculated head loss from equation 2 of Appendix C and comparing them with the flow rates of the different stages we set the regulating gate valve to at 100, 75, 50, 25 and 0% open which all have their unique friction loss factor constant Leq listed in Table G in appendix C to help us generate the friction factor through the valve using equation 4 from Appendix C. We then relate this to our Reynolds number which is generated using equation 3 from Appendix C. The data is noted in Appendix B Table F1 and plotted on Figure F.
Conclusions and Recommendations
From this lab we’re hoping to be able to learn how to size different styles of pumps for moving water through a smooth pipe. We would be able to generate our most efficient operating conditions for each of these pumps from the data we came up with. We wouldn’t be able to upscale our data since we don’t know the pressure relationship with a pump of greater size. Our data is only good for moving water, using a different fluid would change the viscosity of what’s going through the system and would vary our pressures due to the different interaction that it has with the pipe walls.
We did figure out some universal data that would be consistent for all forms of pump usage finding out that our greatest pressure drop comes when we change rates at the greater end of the flow rate spectrum. From our graphs we found out the Gear pump operates at similar efficiency for both power levels when moving water. The vane pump was the most powerful of all the pumps, with the fastest flow rates and most linear trend line. The more linear the trend line is means that the pumps more efficient than the ones with more curve to them and has more resistance to pressure loss throughout the higher range of flow rates with the two energy levels approaching each other as the rate increases. Where the peristaltic and centrifugal pumps both start closer and have rapidly decaying head pressure at the faster flow rates. The two power levels grow further apart from each other as the flow rate is increased indicating that the faster you want to move the material you’re going to want to operate at the higher power setting, or maybe you have a valve that limits your acceptable pressure head so you want to operate at a lower power setting.
Make sure to fit the correct rotameter for each of the pumps, the CF 50500 requires a high flow rate, Cal Q Flow is the next highest flow, and the Key instruments has the acceptable lowest flow rate. Also when calibrating the rotameters it’s possible to record the pressures and plot the points on the pump curves saving time and increasing efficiency.
For improving the experiment safety we would recommend relocating the system onto a cart which has locking wheels so that it doesn’t move around when you bump into or lean on the cart. For our purposes of measurements we only used the head pressure gauge, the vacuum pressure gauge didn’t see any variation with any of the pumps.