Head, what's it about? Find out and don't get hung-up on that term ever again! After all when you talk about pumps you should be talking about pressure, everyone knows what pressure is. You put a pressure gauge on the outlet of a pump and you read the amount of pressure. Figure 1 Measuring pressure with a pressure gauge.
It is necessary to calculate required power of electric motor pump and electric motor efficiency should be taken as 0. The theoretical and factual flow rate ratio is expressed by volumetric efficiency quantity:. The required head Model water pump head is composed of several summands, with each of them having its Model water pump head physical sense. Figure 3 How discharge head varies with suction tank level. Since total head is the difference between the discharge head Exposed thong free the suction head using head makes it easy to evaluate the suction head, Figure 7 Total head with no flow. Save time! Nature of pumped medium: Characteristics of the pumped medium often become a decisive factor in pumping equipment selection. Web www. The static head requirement is often the main component of total head, how high do you need to get the water based on the level of the suction tank? Real gear pump delivery is 1.
Adult free layout site web. Rajarana Impex Private Limited
The compression ratio of the 'Police' head was 5. Hernan Franco Torres permalink. The pressure at the discharge of the pump, however, will be higher for the heavier solution. See similar items. To begin, what is head? Prefer to pick it up yourself?. InFord introduced the B cylinder head marked 'C' pictured below. The Model water pump head ratio of an unknown flat head can be closely estimated by measuring the combustion chamber volume and reading the CR off Modwl graph above. Why is pu,p Heart 4.
Water pumps are in use all around you, often anonymously moving liquid from point A to point B.
- When sizing a pump, there is a lot of verbiage thrown around that can be confusing and hard to understand.
- Pumps characteristic curves are often in head - feet or metres - and a conversion to pressure scales commonly used in pressure gauges - like psi or bar - may be required.
- There seems to be a problem serving the request at this time.
- The original Model A Ford compression ratio was 4.
Head, what's it about? Find out and don't get hung-up on that term ever again! After all when you talk about pumps you should be talking about pressure, everyone knows what pressure is. You put a pressure gauge on the outlet of a pump and you read the amount of pressure.
Figure 1 Measuring pressure with a pressure gauge. You read 60 psi on the gauge of the pump in your house and you know everything is fine, everything should work properly.
So what is it about head? Why do people even talk about it, and what does it have to do with pressure? So we are gonna get over this head problem right now, and you'll never get the googly eyes when you here that term ever again. Assume that you have a pump that you can disconnect the discharge pipe or tube and are able to extend it vertically.
Head is the height at which a pump can raise water up, that's it, it's that simple. Figure 2 The meaning of head. Connect a tube to the discharge of a pump and measure the water height, that the head of the pump. OK, so head is somehow linked to pressure, in what way?
We will get to that later. Let's say the head we measure in the above situation is 60 ft 18 m , what happens to the head measured if the level in the suction tank is higher. Will the head measured be higher or lower? If h2 is the head measured in Figure 2, will h 3 be higher than h 2 in Figure 3?
Figure 3 How discharge head varies with suction tank level. The answer is yes. If you lower the suction level the head measured will be less and the opposite is true if you raise it.
The pump manufacturer's want to tell you how much head their pump's will produce but they don't know what type of water supply will be available, so how can they get around this. Ingeniously simple, they subtract the head available at the suction from the head produced at the discharge, they call this Total Head.
Then it doesn't matter what the suction tank level is, they are telling you only what the pump can do regardless of the water supply pressure at the suction. Figure 4 Total head vs. OK smart guy, what if I don't have a tank and I'm pulling water from a lake and the lake is lower than my pump.
Figure 5 The effect of low level on the pump suction. The pump will still produce the same total head but the discharge head will go down. This means you may not have enough pressure to run your devices and you may need to consider getting a pump with a higher total head.
When you buy a pump, you will try to find a pump that has the total head you require at the flow you require. In the example above the total head produced by the pump was at zero flow, nothing is coming out of the tube.
Centrifugal pumps are like that, they can pump water up to a height and create pressure at the discharge without flow going through them; they are just sitting there churning up the same water.
Note: it is not advisable to keep a pump running at zero flow for long periods of time. The total head at zero flow is the maximum head also called the shut-off head, the total head decreases as the flow increases. The plot of total head vs. To buy the correct pump for your application you first have to know what total head you need and at what flow rate.
Follow these links to get a good idea on how to establish this, it's not difficult, and for home owners all you need is a couple of key pointers. The static head requirement is often the main component of total head, how high do you need to get the water based on the level of the suction tank?
The next important consideration is how much friction do you need to allow for, this depends on the length of pipes and their diameter. The sum of the static head and friction head will give you the total head. The total head and your flow requirement will allow you to buy the right pump.
You are looking for a pump to operate in the area shown in Figure 6. When you look at the curve in Figure 6 it seems counter-intuitive that the maximum flow should occur at the minimum head. Think of it this way, the pump is always turning at the same speed regardless of whether the pipe is fully open or whether the valve at the end of the pipe is closed. When you close the valve the energy that the pump imparts to the water now goes into increasing the pressure since there is no place for the water to go.
As pressure increases, total head increase and reaches a maximum at zero flow. This is also why it is not a good idea to let a pump run with a discharge valve closed. The energy that goes into the water to produce pressure also produces heat and since there is no flow the heat cannot be dissipated, the end result can be a very hot pump indeed.
All residential pump systems have a pressure switch, the switch cuts off the power to the pump when the pressure gets to a certain level. Since total head is the difference between the discharge head and the suction head using head makes it easy to evaluate the suction head, Figure 7 Total head with no flow. We need to make a distinction between a system with no flow and a system with flow. The difference is flow produces friction. Figure 8 Total head with flow.
Assume we have a system such as in Figure 7 where the discharge pipe is high enough that no flow can come out. In other words the pump cannot develop enough pressure to push water out of the pipe. Now suppose you cut a piece off the pipe end, this will lower the discharge head or the height at which the liquid is pumped as in Figure 8.
This lowers the overall total head and flow starts to come out of the pipe. Since we have flow we now have friction and the influence of friction is known as friction head. This is exactly as predicted by the curve in Figure 6. In a system with flow, the total head is the difference between the discharge and the suction head plus the friction head and the sum is less then the shut-off head. Suction and discharge static head are often combined. The difference between discharge and suction static head is the total static head see Figure 8.
Short quiz: 1. What happens to the pressure at the discharge of the pump when the flow increases, or when the discharge valve goes from a fully closed position to fully open? What are the 2 major components of total head? If you increase the total static head what will happen to the flow? If you decrease the discharge static head, what will happen to the flow? Check for the continuation on November Download this file to see the answers.
Why use the term head as opposed to pressure? There are some pump manufacturer's that use pressure i. Head is a very useful and practical term to use when evaluating a pump's capacity to do a job. Many pump applications involve pumping to a higher level. If you have to pump liquid up 30 ft and your pump doesn't have at least 30 feet of head then there is no chance that your system will work. Your pump will have to have at least 30 ft of total head plus the friction loss for you to get the require flow at the discharge point.
Also, head is independent of the type of liquid pumped as long as the viscosity is low and similar to water. If you are pumping sea water or some heavy acid, the head achieved by the pump in Figure 2 will be the same as that for water. The pressure at the discharge of the pump however will be higher. The explanation for this involves a little bit of math, nothing heavy, and the realization that head is a form of energy potential energy just like a cyclist at the top of a hill has potential energy.
Also pressure is another form of energy like soda pop under pressure in a can. The explanation can be found here. Web www. What is head? Copyright , PumpFundamentals.
Free Shipping. The differences are nuanced and this post will aim to explain. Hopefully this post sheds some light on the nuanced difference between head and pressure. Super Winfield "Red Head" ss era aftermarket head Model A, 4 stud water pump Metric 14mm spark plugs, located between valves Marked "Super Winfield" on water hump in recessed letters. Make Offer - Shurflo -- -- Used. Show only see all.
Model water pump head. You are here
It has 16 representation offices in CIS countries and offers equipment and components from production sites in Turkey and Republic of Korea. It is ready to develop and deliver different pumping equipment and pipeline fittings according to your individual performance specifications.
Selection of the pumping equipment is a crucial point that determines both process parameters and in-use performance of the unit under development. During selection of the type of pump three groups of criteria can be distinguished:.
In some cases the pump selection is determined by some stringent requirements for a number of design or process parameters. Unlike piston-type pumps, centrifugal pumps can provide uniform delivery of pumped medium, whereas in order to meet uniformity condition on a piston-type pump its design has to be made noticeably complicated, by arranging on the crankshaft several pistons making reciprocating movements with certain delay from each other.
At the same time, delivery of pumped medium in discrete portions of set volume can also be a process requirement. Example of definitive design requirements can be the use of submerged pumps in cases, when it is necessary and only possible to install the pump below level of the pumped fluid. The pump process and design requirements are seldom definitive, and ranges of suitable types of pumps for various specific cases of application are known as a matter of experience accumulated by humanity, and there is no need to enumerate them in detail.
Characteristics of the pumped medium often become a decisive factor in pumping equipment selection. Different types of pumps are suitable for pumping of various media differing in viscosity, toxicity, abrasiveness and many other parameters. So screw pumps can pump viscous media with different inclusions without damaging structure of the medium, and can successfully be used in food-processing industry for pumping of jams and pastes with various fillers. Corrosion properties of the pumped medium determine material design of the selected pump, and toxicity — degree of its air-tightness.
Operational requirements specified by different industries can be satisfied by several types of pumps. Only the pump which corresponds to all three groups of criteria can guarantee long-term and reliable operation.
Regardless of diversity of machines used for pumping of fluids and gases, a number of key parameters defining their functioning: capacity, power consumption and head can be singled out. Capacity delivery, flow rate — volume of medium pumped by a pump per unit of time. Flow rate quantity includes only factual volume of displaced fluid ignoring return leakages. The theoretical and factual flow rate ratio is expressed by volumetric efficiency quantity:. But in modern pumps thanks to reliable sealing of pipelines and joints the factual capacity coincides with theoretical.
In the majority of cases a pump is selected for the particular pipeline system and flow rate value is set in advance. Head — energy imparted by pump to the pumped medium and attributed to unit of pumped medium mass. It is denoted by letter H and has dimension in meters.
It should be clarified that the head is not geometrical characteristic and is not the height to which a pump can lift pumped medium.
Power consumption shaft power — power consumed by pump during operation. Power consumption differs from pump useful capacity consumed directly for imparting of energy to the pumped medium. Part of consumed power can be lost due to leakages, bearings friction, etc. Performance factor determines ratio between these quantities.
Calculation of these characteristic may vary for different types of pumps, which is associated with differences in their design and operating principles. The entire diversity of types of pumps can be divided into two main groups with calculation of performance capacity having fundamental distinctions. By operating principle the pumps are subdivided into nonpositive displacement and positive displacement pumps. In the first case medium is pumped due to dynamic forces that influence it, and in the latter case — through variation of volume of pump operating chamber.
The main operating component of the piston pump is cylinder in which piston is moving. The piston reciprocates by means of crank mechanism, thus providing consistent variation of operating chamber volume.
In one complete turn of crank from the end point the piston makes full forward stroke discharge and reverse stroke suction. During discharge in cylinder the piston creates overpressure, under the action of which suction valve opens and discharge valve closes, and fluid being pumped is delivered to the delivery pipeline.
During suction reverse process takes place, during which vacuum is created in cylinder through piston backward movement; discharge valve closes preventing return flow of pumped fluid, and suction valve opens and cylinder is filled through it. Real performance capacity of piston pumps is somewhat different from theoretical, which is related to a number of factors, such as fluid leakages, degassing of gases dissolved in pumped fluids, delays in opening and closing of valves, etc.
For double-acting piston pump performance capacity arithmetic formula will look slightly different, which is related to availability of piston rod reducing the volume of one of the cylinder operating chambers.
With neglect of rod volume, general formula of piston pump performance capacity will look in the following way:. In case of gear pumps role of the operating chamber is performed by space limited by two adjacent teeth of gear. Two gears with internal or external engagement are installed inside the body.
Pumped medium is sucked into the pump by vacuum created between gears teeth going out of engagement. Teeth transfer fluid inside pump body, and then it is squeezed to discharge pipe at the time when teeth engage again. For flow of pumped fluid the gear pumps are provided with end and tooth tip clearances between body and gears.
In pumps of this type medium is pumped by means of screw operation single-screw pump , or several screws being in engagement, if the question is of multiscrew pumps. Profile of screws is selected in a way for the pump injection zone to be isolated from the suction zone. The screws are mounted inside the body in such way that during their operation enclosed space zones filled with pumped medium were formed limited by outline of screws and body, and moving towards injection zone.
The working member of centrifugal pumps is put on shaft impeller provided with blades enclosed between disks and mounted inside spiral-shaped body. Impeller rotation creates centrifugal force affecting the mass of pumped media inside the impeller, and imparts to it part of kinetic energy passing then into potential energy of head.
When this happens the vacuum created in the impeller provides continuous delivery of pumped medium from suction pipe. It is important to note that before starting operation the centrifugal pump should be first filled with the pumped medium, as otherwise suction force will not be sufficient for proper pump operation.
Centrifugal pump may have not one working mechanism, but several. In terms of design it is distinguished by having several impellers on the shaft at a time, and fluid successively passes through each of them.
As it was stated above, the head is not geometrical characteristic and can not be identified with height to which pumped fluid has to be lifted. The required head value is composed of several summands, with each of them having its own physical sense. General formula of head calculation diameters of suction and discharge pipes are taken as equal :. The first of summands of head calculation formula represents drop of pressures which should be overcome in the process fluid pumping. Occasionally, pressures p 1 and p 2 may coincide, with head created by pump spent on lifting fluid to certain height and overcoming the resistance.
The second summand characterizes geometrical height to which the pumped fluid has to be lifted. It is important to note that during determination of this quantity geometry of pressure pipeline which may have several lifts and falls is not taken into account.
The third summand characterizes drop of created head depending on characteristics of the pipeline through which medium is pumped. Real pipelines will inevitably exhibit resistance to fluid flow. In order to surmount it one needs to have head margin. Total resistance is composed of pipeline friction losses and losses due to local resistances, like pipe turns and branches, gate valves, passage widening and contraction, etc.
Overall pipeline head losses are calculated by the formula:. Several kinds of power are singled out according to transmission losses taken into account by different efficiency coefficients. Power spent directly on transmission of pumped fluid energy is calculated by the formula:. Power developed on pump shaft is larger than the useful one, and its excess is consumed for compensation of pump power losses.
Interrelation between useful power and shaft power is set by pump efficiency. The pump efficiency includes leakages through seals and openings volumetric efficiency , losses of head while pumped medium is flowing inside pump hydraulic efficiency , and friction losses between moving parts of the pump, such as bearings and glands mechanical efficiency.
In its turn, power developed by motor exceeds the shaft power, which is necessary to compensate for energy losses in its transmission from motor to pump. Electric motor power and shaft power are linked by efficiencies of transmission and motor. Final motor generating capacity is calculated from motor power with regard to potential overload during start up.
Centrifugal pump suction occurs due to pressure differential between vessel from which pumped medium is taken, and impeller blades. Excessive increase of pressure differential may result in the occurrence of cavitation — process when pressure drops down to value at which fluid boiling temperature lowers below pumped medium temperature and it starts to evaporate in flow space forming multiple bubbles.
Bubbles are carried away by stream further downstream where under action of building up pressure they are condensed and collapse, accompanied with multiple hydraulic shocks that negatively tell on pump service life. In order to avoid negative influence of cavitation the suction head of centrifugal pump has to be limited.
There is also formula for centrifugal pumps for calculation of head margin providing absence of cavitation:. Plunger diameter is 10 cm, and stroke length is 24 cm. Working shaft rotation speed is 40 rpm. Piston diameter is 8 cm, rod diameter — 1 cm, and piston stroke length equals to 16 cm. Working shaft rotation speed equals to 85 rpm. It is necessary to calculate required power of electric motor pump and electric motor efficiency should be taken as 0.
Geometric head of fluid lift is 3. Useful power consumed for fluid pumping is 4 kW. Value of head loss has to be found. We substitute found head value in the formula of the head expressed in difference of pressures, and find sought quantity. Real screw pipe performance capacity is 1.
Pump geometrical characteristics are: eccentricity — 2 cm; rotor diameter — 7 cm; pitch of rotor screw surface — 14 cm.
Rotor rotation speed equals to 15 rpm. Pump volumetric efficiency has to be found. Total pipeline length summarily with equivalent length of local resistances equals to 78 m friction coefficient is accepted as equal to 0. Difference of reservoirs heads is 8 meters. We calculate fluid flow rate through set pipeline:.
Velocity for water flow in delivery pipeline equals to 1. Value of flow velocity thus obtained does not fall within this interval, wherefrom one may conclude that the use of this centrifugal pump is unreasonable. It is necessary to determine gear pump delivery coefficient.
Pump geometrical characteristics: cross-sectional area of space between gear teeth is mm 2 ; number of teeth - 10; gear tooth length - 38 mm.