Headloss Through a Valve

Fluid Mechanics Lab base on b whollys disadvantage Through a Valve April 24, 2012 Abstract This experiment line upd the relationship between the head waiver by dint of a gate valve and the degree of break of that valve with varying rate of time period rates. The objective of this experiment was to determine the valve difference coefficient, K, for a specific gate valve as a liaison of both the underground Reynolds Number, and the degree of opening. The relationship between the Reynolds Number and the friction factor was constant. regardless of what the Reynolds Number was, the friction factor remained the same.This means that the valve head expiration coefficient, K, sole(prenominal) depended on the degree of opening of the gate valve. As the valve is slowly saturnine closed, the Major betoken expiry due to friction along the pipe, decreases, and the little Head Loss, due to the friction through the gate valve, increases. There is a positive linear relationship betw een the Reynolds Number and the head exit coefficient. The slope of this linear relationship showed that as the flow rate increases, the fastness increases which means the Reynolds Number gets bigger and the head loss coefficient increases.Therefore, the higher the flow and the smaller the degree of opening of the gate valve, the greater the head loss becomes through the gate valve. control panel of contents Abstract i 1Introduction1 1. 1Background1 1. 2 system1 1. 3Objective1 2Apparatus and Supplies1 3Procedures4 4Equations4 5Experimental Results5 6Error Analysis9 7Conclusions9 8Recommendations for advance Studies10 9References10 APPENDIX prorogue of Figures Figure 21 compel derivative instrument bore ? p. 2 Figure 22 Weighing ar muchd combat vehicle with Dump Valve open. 3 Figure 23 atmospheric instancy differential gear coefficient Gauge between Valve Set-up3Table 51 Constants and confiden values. 5 Table 52 Measured Data. 5 Table 53 Volumetric Flow, Velocity, Reyno lds , Head Loss Coefficient. 6 Table 54 Real values of K, Major Head Loss, squirt Head Loss. 6 Introduction Background Gate valves are frequently used when constructing and registration pipes. They provide the capability to shut off specific lines so that repairs or renovations bunghole be made without having to turn off the main add on lines. Although these valves are useful, they also disturb the normal flow and cause friction. Theory The head loss coefficient, K, for a gate valve is related to the humble Head Loss, Hlm, where Hlm=V22gK.The total head loss in the pipe is divided into both parts the Major Head Loss, Hf, due to the pipe friction over length L, and the Minor Head Loss. Using the Bernoullis energy equation, the coefficient, K, can be found K=2g? PV2? -fLD. Objective The objective of this experiment was to determine the valve loss coefficient, K, for a specific gate valve as a function of both the pipe Reynolds Number, and the degree of opening. Apparatus and Su pplies * 1 Weighing Tank with Dump Valve (0. 5 lb) * 2 Stop Watches (0. 01 sec) * Galvanized Iron pipe 27 inches (0. 03125 in) long with a diameter of 1. 1 inches (0. 0005 in) * 1 Pressure derivative Gauge (0. 05 psi) * 1 Valve located in between the Pressure Differential Gauge on Galvanized Iron Pipe Figure 21 Pressure Differential Gauge ? p. Weighing Tank Dump Valve Figure 22 Weighing Tank with Dump Valve open. Figure 23 Pressure Differential Gauge between Valve Set-up Procedures 1. Measure the distance between the upstream and downriver pressure sensation tabs. 2. Turn the handle on the gate valve to determine how more turns exist between fully-opened and fully-closed. 3. Turn on the pump and open the cocksucker valve in the weighing tank. 4.Turn the gate valve so that it is completely open. 5. Record the Pressure Difference 6. Close the dump valve in the weighing tank. 7. Start and assay the stopwatches over a 100 lb difference and record the times. 8. stretch out the dum p valve in the weighing tank and allow water to conk out into the sump. 9. Change the flow of water. Do not change the gate valve. 10. adopt steps 5-8. 11. Turn the gate valve to 75% open. 12. Change the flow of water. 13. tell steps 5-9 a total of three (3) times. 14. Turn the gate valve to 50% open. 15. extract steps 12 and 13. 16. Turn the gate valve to 25% open. 17. Repeat steps 13 and 13.Equations Head Loss Coefficient K=2g? pV2? -fLD Major Head Loss hf=fLDV22g Minor Head Loss hlm=KV22g Reynolds Number Re=VD? Area of Pipe2 A=? 4D2 Velocity V=QA1 Volumetric pink slip Q=? W? t*? Experimental Results Table 51 Constants and given values. Table 52 Measured Data. The friction factor f=0. 049 was careful establish on Ks/D and the Reynolds Number. Table 53 Volumetric Flow, Velocity, Reynolds , Head Loss Coefficient. Table 54 Real values of K, Major Head Loss, Minor Head Loss. Error Analysis There were some values calculated for the valve loss coefficient, K, which were negative.T his is impossible because a negative K value would give you an overall gain in energy as water flows through the valve according to Bernoullis energy equation. According to the equation used, gravity and the specific tilt of water are constant. The length and diameter of the pipe along with the f number had relative errors due to human accuracy, but all of these were negligible. This leaves the friction factor, f, and the pressure differential readings. The calculated value of the friction factor was given and was in all probability over estimated and the authoritative roughness of the pipe was less.The accuracy of the pressure differential gauge was also a possible source of error. Looking at the data, the first five readings all had negative K values and they all had very low pressure differential readings. The accuracy of the readings become more inaccurate the closer the readings are to the endpoints of the scale. Conclusions According to the Moody Diagram and the absolute r oughness stated, the relationship between the Reynolds Number and the friction factor was constant. regardless of what the Reynolds Number was, the friction factor remained the same.This means that the valve head loss coefficient, K, was just depended on the degree of opening of the gate valve. As the valve is slowly false closed, the Major Head Loss due to friction along the pipe, decreases, and the Minor Head Loss, due to the friction through the gate valve, increases. There is a positive linear relationship between the Reynolds Number and the head loss coefficient. The slope of this linear relationship showed that as the flow rate increases, the velocity increases which means the Reynolds Number gets bigger and the head loss coefficient increases.Therefore, the higher the flow and the smaller the degree of opening of the gate valve, the greater the head loss becomes through the gate valve. Recommendations for Further Studies The experiment could set minimum and utmost standar ds for readings off the pressure differential gauge. For each valve reading, making the minimum pressure difference greater than 1. 0 psi and less than 9 PSI would ensure that there are no endpoint inaccuracies. References Giles, Ranald V. , Jack B. Evett, and Cheng Liu. Schaums digest of Fluid Mechanics and Hydraulics. New York McGraw-Hill, 2009. Print. Appendix