pump calculations 3D

static suction head when the source of the liquid being pumped is above the pump the head pressure caused by this column acts to push the liquid into the pump this situation is called static suction head static suction head is the distance in meters from the centerline of the pump suction up to the liquid level being pumped in the pump suction situation to the right the liquid source level is three meters above the pump suction so the static suction head is three meters static discharge head when the pump is discharging to a tank located above the pump the pump is required to overcome the head created by the height of the liquid in the vertical discharge line the height the destination is above the pump centerline is called the static discharge head static discharge head is the vertical distance from the centerline of the pump to the free discharge of the liquid into the discharge tank in metres free discharge refers to the open end of the pipe discharge line or the tank level into which the pump is discharging which ever is highest in the included diagram the end of the discharge pipe is higher than the tank level therefore static discharge head is measured from the end of the discharge pipe to the centerline of the pump in the pumping situation to the right the pump discharges into the tank below the tank level so static discharge head is from the top of the tank level to the centerline of the pump in the pumping situation to the right static discharge head is measured from the centerline of the pump discharge up to the bottom of the downspout this is because the downspout acts as a siphon to pull liquid order the discharge line and less than the effect of discharge head total static head total static head is the net effect that the suction and discharge static heads have on a pump performance it is a measure of how hard a pump has to work to pump the liquid against the study can this net effect depends on whether we are pumping from a static lift or a suction head situation because the pump has to work to overcome static head in both a static suction lift and a static discharge head then in a static suction lift scenario total static head equals static suction lift plus static discharge head in this situation here we have a pump in a static suction lift situation and we can see that the total static head is the sum of the static suction lift plus the static discharge here example 1 what is the total static head in the pumping scheme shown so since it is a static lift situation total static head equals static discharge head plus static suction lift static suction head is the vertical distance from the pump suction line to the end of the discharge line so here's the end of our discharge line here here's the center line of the pop so the static discharge head is 5 meters static suction lift is the vertical distance from the level in the source tank up to the centerline of the pump suction so static suction lift equals 4.5 meters total static head equals static discharge head plus static suction lift total static head equals 5.0 meters plus 4.5 meters total static head equals nine point five meters total static head with suction head static suction head acts to push liquid into the pump and improve its performance static discharge head acts to resist flow since total static head is a measure of how hard a pump works to overcome static pressure then in a static suction head situation total static head equals static discharge head - static suction head so when your diagram here we see static suction head helping to push liquid into the pump suction static discharge head resisting flow from the pump pushing down into the pump again so the total static head is the difference between the two example two what is the total static head in the pumping situation shown and as we can see from the diagram it's a static suction head situation since it is a static head situation total static head equals static discharge head - static suction head looking at their diagram we know that static suction head is the distance from the centerline of the pump suction to the top of the level in the source tank so in this case we have four metres from the pump suction up to the bottom of the tank plus two meters to the level in the top of the tank so static suction head would be 6 meters on the discharge side to get static discharge head it is again from the centerline of the pop up to the top of the liquid in the destination tank and that is 12 meters so our total study care would be static discharge head - static suction head which would be 12 meters minus 6 meters which would give us a total static head of 6 meters sometimes we have to convert the pressure in kPa generated by the weight of a column of liquid to static head in meters we can use the formula static head in meters equals equivalent pressure in kPa divided by the product of G times the relative density example 3 a standby pump has the suction valve shut and a pressure reading on the pump pump discharge is a hundred and seventy kPa if the relative density of the liquid is one point four what is the static discharge head ignore vessel pressure okay here's our question a standby pump has the suction valve shut and a pressure reading on the pump discharge of a hundred and seventy kPa if the relative density of the liquid is one point four what is the static discharge head assuming the pressure on the pump discharge is due to static discharge head only we can say static discharge head equals static pressure and kPa divided by the product of G times the relative density static discharge head he puts a hundred and seventy kPa divided by the product of 9.81 m/s^2 times one point four static discharge head is twelve point four meters so the pressure showing on the pressure gauge and the discharge of the pump of a hundred and seventy kPa would be attributed to twelve point four meters of vertical height of liquid we can use the above formula to convert static head to equivalent static pressure in kPa example for a liquid having a relative density of two point four has the level in the our stank of 3.5 meters above the pump suction what is the pressure at the pump suction in kPa due to the static suction head so example for liquid having relative density of 2.4 has a level in the source tank 3.5 meters above the pump suction what is the pressure at the pump suction in kPa due to the static suction head static suction pressure and kPa equals static suction head and meters times the relative density times G static suction pressure and kPa equals a head of 3.5 meters times the relative density of 2.4 times G which is 9.81 m/s^2 so the static suction pressure is 82 point 4 kPa which means our gauge on the suction side of the pump which show eighty two point four kPa due to the height of the liquid above the pump suction earlier we saw how atmospheric pressure acting on the surface of the source tank can help push liquid into the pump especially in the suction lift situation in some cases pumps have to remove liquids from or push liquids to vessels pressurized at a pressure greater or less than atmospheric in the case of pressurized vessels the pressure acting on the liquid in the vessel is changed from kPa to equivalent head pressure the pressure in the source vessel assists a pump in moving liquid the pressure in the destination vessel resists the pump in moving liquid the pressure in the destination vessel minus the pressure in the source vessel is the total pressure head the pump has to pump against if both the source and destination tanks are on or above atmospheric pressure we can use gauge or absolute pressure to calculate the net pressure head as long as we use both for the source and the destination tanks later when calculating net positive suction head we will be dealing with the suction side of the pump only an absolute pressures will be used because I'm aspheric pressure assists in pushing the liquid into the pump changing vessel pressure in kPa to equivalent head in meters we're going to look at three possible scenarios and three equations for each one case one if the liquid being pumped is water at four degrees C then pressure head in meters equals vessel pressure in KP KP a divided by G or 9.81 m/s^2 so example five water at four degrees c is pumped from a tank having a pressure of 450 kPa what is the equivalent pressure head pressure head equals ka PA divided by G pressure head will equal 450 kPa divided by 9.81 m/s^2 so the pressure head would be forty five point nine meters k-stew if the liquid has a relative density other than one the pressure hidden meters equals the vessel pressure in kPa divided by the relative density times G our 9.81 m/s^2 example six what is the total equivalent pressure head in meters and the pumping system to the right if the liquid being pump has a density of 750 kilograms per cubic meter example 6 what is the total equivalent pressure head in meters in the pumping system to the right if the liquid being pumped has a density of 750 kilograms per cubic meter step 1 changing density to relative density relative density equals the density which is 750 kilograms per cubic meter divided by the density of water which is a thousand kilograms per cubic meter so the relative density of the liquid is 0.75 step 2 finding the net pressure on the discharge and suction vessels since the discharge vessel pressure acts to resist pumping and the source vessel pressure acts to assist pumping net equivalent pressure equals discharge vessel pressure - suction vessel pressure that equivalent pressure will equal 200 kPa - 125 kPa so the net equivalent pressure is 75 kPa step 3 finding the total pressure head total pressure head equals net equivalent pressure divided by the product of the relative density times G total pressure head equals 70 K 75 kPa / 0.75 times 9.81 m/s^2 total pressure head is ten point two meters case three if the liquid being pumped is water at a temperature greater than four degrees C then the pressure head in meek meters equals the vessel pressure in kPa divided by the relative density of the water times 9.81 m/s^2 where the relative density of the water is 1 / VF + VF is the specific volume for the given temperature example 7 what is the nut pressure head in meters in the pumping system in the diagram to the right if the liquid being pumped is 60 degrees C water example 7 what is the nut pressure head in meters in the pumping system in the diagram if the liquid being pumped is water a 60 degrees C step 1 finding a net pressure in the system the net pressure acting on the system is the 200 kPa in the destination tank mine is the hundred and 25 kPa in the source tank which gives us 75 kPa since this nut pressure is in the direction of the destination tank it is pressure the pump has to overcome to push liquid to the destination step to finding the relative density of the water from steam table 2 at 60 degrees C V F equals one point zero one seven two relative density equals one divided by V F relative density equals one divided by one point zero one seven two therefore the relative up the water at 60 degrees C 0.98 3-0 step 3 finding the equivalent pressure head in metres equivalent pressure head in meters equals the kPa due to the head pressure the net head pressure divided by the relative density times G equivalent head pressure meters equals 75 kPa divided by 0.98 three times nine eight point nine point eight one meters per second squared equivalent pressure head in meters equals seven point seven eight meters

Channel: Terry Hagell

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Id: 5KSNvZnGuBs

Length: 20min 3sec (1203 seconds)

Published: Mon Mar 13 2017