The definition of total pumping head is the ability to work at the point of maximum pressure pump, so the pump is able to drain water from one place to another. Some parameters required to determine the total pump head such that the pipe friction loss, friction loss fittings & valves, pressure drop mechanical equipment, and geodetic head.
B.5.1. Pipe friction loss
Friction loss occurs because the pipe due to friction between the surface of the water in the pipe, causing friction and friction is what led to constraints on the pressure pump. The amount of friction loss depends on the type of pipe material, diameter, and length of the pipe.
By using the approach, the method of Hazen William formula to determine the amount of friction loss is as follows,
B.5.2 Friction fitting & valve
Friction loss fittings & valve that friction forces caused by the friction between the water and valve fittings (elbow, tee, check valve, butterfly valve, globe valve, etc.), and this friction causes the pump pressure barrier. The amount of friction loss depends on the diameter, type, and number of fittings & valves.
By using the approach, the method of Hazen William formula to determine the amount of friction loss is as follows,
Fitting hf = (x hf1 Counter fittings) + (x hf2 Counter fittings)
where:
Hf fittings: The total friction loss ... pipe. m
hf1: friction loss dg fitting him. (x) ... mm. m
hf2: friction loss dg fitting him. (y) ... mm. m
B.5.3 Pressure drop of mechanical equipment
Mechanical equipment commonly used in the pump and piping system is like Y strainers, water filters, air handling units (AHU), chiller, hot water tank, etc.. Each of the apparatus. predetermined pressure drop its value by the manufacturer which is between 1m s / d 15m.
B.5.4 Geodetic head (Hg)
Geodetic head is the vertical height of the highest point to the highest point of suction pipe discharge pipe. Geodetic head is an important parameter and its value must therefore should not be expected.
Friction loss fittings & valve that friction forces caused by the friction between the water and valve fittings (elbow, tee, check valve, butterfly valve, globe valve, etc.), and this friction causes the pump pressure barrier. The amount of friction loss depends on the diameter, type, and number of fittings & valves.
By using the approach, the method of Hazen William formula to determine the amount of friction loss is as follows,
Fitting hf = (x hf1 Counter fittings) + (x hf2 Counter fittings)
where:
Hf fittings: The total friction loss ... pipe. m
hf1: friction loss dg fitting him. (x) ... mm. m
hf2: friction loss dg fitting him. (y) ... mm. m
B.5.3 Pressure drop of mechanical equipment
Mechanical equipment commonly used in the pump and piping system is like Y strainers, water filters, air handling units (AHU), chiller, hot water tank, etc.. Each of the apparatus. predetermined pressure drop its value by the manufacturer which is between 1m s / d 15m.
B.5.4 Geodetic head (Hg)
Geodetic head is the vertical height of the highest point to the highest point of suction pipe discharge pipe. Geodetic head is an important parameter and its value must therefore should not be expected.
B.5.5. Suction head (Hs)
Suction pump suction head is the height of the water level to the highest point of suction pipe. Determined based on the height of the suction pump suction capability is the maximum height of a suction pump with a notice that there will be no cavitation at the pump TSB. Suction head there are 2 kinds of negative and positive suction suction.
Negative suction (Fig. B.5.5a.) That if the water level is below the pump, and a positive suction (Fig. B.5.5b.) That if the water level is above the pump.
Suction pump suction head is the height of the water level to the highest point of suction pipe. Determined based on the height of the suction pump suction capability is the maximum height of a suction pump with a notice that there will be no cavitation at the pump TSB. Suction head there are 2 kinds of negative and positive suction suction.
Negative suction (Fig. B.5.5a.) That if the water level is below the pump, and a positive suction (Fig. B.5.5b.) That if the water level is above the pump.
B.5.6. Pipe diameter and velocity
Pipe diameter and velocity are two integral parameters and the formulation can be written as follows:
Q = V x A = A (лd2) / 4
where:
Q: discharge pump ... .. m3 / h
V: velocity of water ...... m / s
A: cross sectional area of the pipe hole ... .. mm2
d: diameter of the pipe ... .. mm
л: 3.14
There is no definite limit to determine the velocity, but to get the optimal pump Total Head the ideal velocity constraints are 0,9m / s - 2m / s.
B.5.7. Determine the total head
Formulation total head are as follows:
Htot = Hf + Hf pipe fittings + HPD + HSF + Hg + Hs
where:
Hf pipe: pipe friction loss
Hf fittings: pipe & valve friction loss
Hpd: pressure drop equipment
HSF: safety factor
Hg: geodetic head
Hs: suction / riser head
B.6. High maximum suction, Cavitation and NPSH
Maximum height limit of a suction pump to note especially when planning stage, because if the pump is working above the pump suction height can not be able to suck up water or cavitation will occur so that the performance but the pump down. There are several important parameters related to the suction capability, NPSHR, NPSHa.
B.6.1. NPSHR
Or NPSHrequired NPSHR (Net Positive Suction Head required) is the pressure on the suction side of the pump, which is determined based on the design pump (suction inlet, impeller, etc.). NPSHR is positive so that is inhibiting the ability of the pump suction. If the pump with a small NPSHR value of the pump means having a good suction capability. NPSHR value can be obtained from the curve on the pump catalogs.
To determine NPSHR should not be determined at the point the pump working, but determined at the working point Qmax working point on the curve right, it is to provide a safety factor (suction capability) is sufficient.
Pipe diameter and velocity are two integral parameters and the formulation can be written as follows:
Q = V x A = A (лd2) / 4
where:
Q: discharge pump ... .. m3 / h
V: velocity of water ...... m / s
A: cross sectional area of the pipe hole ... .. mm2
d: diameter of the pipe ... .. mm
л: 3.14
There is no definite limit to determine the velocity, but to get the optimal pump Total Head the ideal velocity constraints are 0,9m / s - 2m / s.
B.5.7. Determine the total head
Formulation total head are as follows:
Htot = Hf + Hf pipe fittings + HPD + HSF + Hg + Hs
where:
Hf pipe: pipe friction loss
Hf fittings: pipe & valve friction loss
Hpd: pressure drop equipment
HSF: safety factor
Hg: geodetic head
Hs: suction / riser head
B.6. High maximum suction, Cavitation and NPSH
Maximum height limit of a suction pump to note especially when planning stage, because if the pump is working above the pump suction height can not be able to suck up water or cavitation will occur so that the performance but the pump down. There are several important parameters related to the suction capability, NPSHR, NPSHa.
B.6.1. NPSHR
Or NPSHrequired NPSHR (Net Positive Suction Head required) is the pressure on the suction side of the pump, which is determined based on the design pump (suction inlet, impeller, etc.). NPSHR is positive so that is inhibiting the ability of the pump suction. If the pump with a small NPSHR value of the pump means having a good suction capability. NPSHR value can be obtained from the curve on the pump catalogs.
To determine NPSHR should not be determined at the point the pump working, but determined at the working point Qmax working point on the curve right, it is to provide a safety factor (suction capability) is sufficient.
B.6.2 NPSHa
NPSHa or NPSHavailable (Net Positive Suction Head available) is the maximum pressure on the suction side are worth positive. NPSHa value determined from the results of calculations with the aim to compare the NPSHR so it can be known whether the pump cavitation will occur or not. NPSHa formula is as follows:
NPSHa = Hb - Hf - Hv - HSF - Hs
where:
Hb: 10.2 mtr head barometric
Hf: ... pipe friction loss. mtr
friction loss ... fitting & valve. mtr
pressure drop ... equipment. mtr
Hv: vapor head (from the table) .... mtr
HSF: safety factor of 0.5 mtr head
Hs: suction head / high suction .... mtr
NPSHa or NPSHavailable (Net Positive Suction Head available) is the maximum pressure on the suction side are worth positive. NPSHa value determined from the results of calculations with the aim to compare the NPSHR so it can be known whether the pump cavitation will occur or not. NPSHa formula is as follows:
NPSHa = Hb - Hf - Hv - HSF - Hs
where:
Hb: 10.2 mtr head barometric
Hf: ... pipe friction loss. mtr
friction loss ... fitting & valve. mtr
pressure drop ... equipment. mtr
Hv: vapor head (from the table) .... mtr
HSF: safety factor of 0.5 mtr head
Hs: suction head / high suction .... mtr
B.6.3. cavitation
Cavitation is the occurrence of air bubbles on the suction side of the pump due to several factors, namely the depth of suction is too high, the diameter of the suction pipe is too small, the water temperature is too hot, the use of pumps in the area that is too high (mountains).
Cavitation can cause damage to the pump impeller and pump housing primarily causing the pump performance (Q & H) has fallen dramatically.
Terms of cavitation so that the pump does not happen then it must meet the following requirements,
NPSHR <NPSHa
where:
NPSHR: NPSH value of the pump ... the data. mtr
NPSHa: results of the calculations ... NPSH value. mtr
So NPSHa value determined to provide restrictions / requirements NPSHR maximum value owned by a pump.
If the system pump cavitation occurs, then there are several methods to prevent cavitation is as follows:
- Suction height shortened or changed to positive suction.
- The diameter of the suction pipe is enlarged.
- Water temperature lowered.
- Using a small pump with NPSHR.
B.6.4. High maximum suction
High capability of a maximum suction pump can be determined, after the data NPSHR and other data known. To determine the maximum suction height must be considered not going to happen cavitation in pumps. Formulation to determine the maximum suction height is as follows:
Hs.max = Hb - Hf - Hv - HSF - NPSHa
NPSHa = NPSHR
where:
Hs.max: ... maximum suction height. mtr
Hb: 10.2 mtr head barometric
Hf: ... pipe friction loss. mtr
friction loss ... fitting & valve. mtr
pressure drop ... equipment. mtr
Hv: vapor head (from the table) .... mtr
HSF: safety factor of 0.5 mtr head
Hs: suct head / suction max ... high. mtr
Cavitation is the occurrence of air bubbles on the suction side of the pump due to several factors, namely the depth of suction is too high, the diameter of the suction pipe is too small, the water temperature is too hot, the use of pumps in the area that is too high (mountains).
Cavitation can cause damage to the pump impeller and pump housing primarily causing the pump performance (Q & H) has fallen dramatically.
Terms of cavitation so that the pump does not happen then it must meet the following requirements,
NPSHR <NPSHa
where:
NPSHR: NPSH value of the pump ... the data. mtr
NPSHa: results of the calculations ... NPSH value. mtr
So NPSHa value determined to provide restrictions / requirements NPSHR maximum value owned by a pump.
If the system pump cavitation occurs, then there are several methods to prevent cavitation is as follows:
- Suction height shortened or changed to positive suction.
- The diameter of the suction pipe is enlarged.
- Water temperature lowered.
- Using a small pump with NPSHR.
B.6.4. High maximum suction
High capability of a maximum suction pump can be determined, after the data NPSHR and other data known. To determine the maximum suction height must be considered not going to happen cavitation in pumps. Formulation to determine the maximum suction height is as follows:
Hs.max = Hb - Hf - Hv - HSF - NPSHa
NPSHa = NPSHR
where:
Hs.max: ... maximum suction height. mtr
Hb: 10.2 mtr head barometric
Hf: ... pipe friction loss. mtr
friction loss ... fitting & valve. mtr
pressure drop ... equipment. mtr
Hv: vapor head (from the table) .... mtr
HSF: safety factor of 0.5 mtr head
Hs: suct head / suction max ... high. mtr
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