Pump stations or units are sophisticated high-tech systems supplying water to industrial plants, fire trucks, houses or entire communities, evacuating waste waters and delivering them to waste treatment plants. Pump stations are capable of handling the following media:
Principle of operation of any pump station is quite simple: water is pumped into the accumulation tank and is refilled as it is running out. Level sensor monitoring the tank level switches the pump on and off.
Water supply pump station is a monoblock unit where a pump is connected to a hydraulic accumulator via a switch, which automatically initiates cycle repetition by the pump, if water pressure drops to a certain critical threshold. Pump stations are necessary to supply water from deep wells or other independent sources. They may also be used for pumping water from water networks with insufficient pressure and to fill emergency storage tanks. The system does not need to be submerged and is installed on the surface without any special safety control, since all the processes including hydraulic shock elimination are performed either in automatic or semi-automatic mode. For sewage systems special sewage pumping stations are produced equipped with an additional tank to capture solids. For this application cutter pumps are no less efficient. Before buying a pump station it is recommended to know exactly your water consumption to select a hydraulic accumulator best suited for your requirements. Only then long-term and reliable operation of the entire system is guaranteed. Deep-well pump stations are equipped with special injectors connected to a jet centrifugal pump. Stations with outboard ejectors are equipped with the same type of pumps, but the outboard design lets the ejector be submerged to the bottom and pump water from wells fifty or more meters deep. The main pumping unit remains on the surface. Such stations are quite convenient, when the well is remote from the customer. They have low efficiency and are quite sensitive to water contamination with suspended solids.
Thus, the operation principle of a pump station, which seems to be quite simple, includes quite a sophisticated water supply system.
A pump station as a hydraulic engineering complex is designed for water intake from irrigation or drainage sources with water lifting and movement towards the point of consumption or storage tank.
Pump stations (PS) may be classified according to different properties as follows:
Pump stations may have a different flow rate irrespective of the scope of application and pump head: low flow rate – up to 1 m³/s; medium flow rate – 1 - 10 m³/s, high flow rate – 10-100 m³/s and unique stations with flow rate exceeding 100 m³/s.
According to the energy source pump stations are classified into electric and thermal stations. The latter are driven by an internal combustion engine. Pump stations may either be operated seasonally or throughout the year. A distinction is made between pump stations with surface and underground water intake. Stationary pump stations are installed indoors, in rooms or buildings designed for core and auxiliary hydromechanical, electrical and mechanical equipment, pipeline valves, etc. According to their design features they may be split into above-ground, chamber and modular pumping stations. Stationary pump stations may have either manual or automatic control. The choice of a stationary pump station is determined by several factors as well as technical and economic calculations.
Mobile pump stations as compared to the stationary type are more mobile, manoeuvrable and 20-25% less expensive. They are used to feed water into the open or closed type irrigation systems, sprinklers and water supply systems. Mobile pump stations are easily transportable, which makes them flexible for different irrigation areas during the entire irrigation season. Their expedient use in irrigation of floodplains, with significant fluctuations in the water level in the source, does not require the construction of expensive water intake devices, and the depth of water source at the site of water intake should not be <0.6-0.8 meters. If the depth is less, a most simple retaining structure or a pit should be used. When choosing a location for the installation of a mobile pumping station, one should look at the water access and the site for the pumping station, which should provide a suction height of max. 1.5 to 3 meters. Mobile pumping stations can be land and floating, they can have their own internal combustion engine and an electric motor driven by a shaft with power take-off from a tractor that transports the pumping station to all water intake points. Land pump stations, in turn, may be classified into suspended or trailer design. Considering their wide range of applications in land improvement, mobile pump stations are mass-produced, easy to install and move in case of changing water level in the source and service several sites.
Power-driven mobile pumping stations are classified according to their capacity: 25 - 750 liters per second, head: 5 - 100 meters, design of the running gear: skids or wheels.
Pump stations are usually installed within a short period using high technologies, advanced unified equipment and innovative construction practices. Pump stations or units include a pump room, water intake systems, intake chambers, diversion chambers and water tanks. Any pump station includes electrical components and a transformer substation which may also be installed in the pump room. Some of the above equipment may be dispensed with or functionally integrated with other equipment. For example, a pump room and a water intake chamber may be combined into the same engineering structure, which is typical for the first stage pumping stations. Water disposal pump stations may have a pump room combined with a receiving tank. Pumping equipment of a pump station may differ depending on its application: there are stations with horizontal and vertical arrangement of pumps, axial and centrifugal pumps, which may be installed with a positive suction height or with flooded suction.
There are the following types of pump stations according to pump room arrangement with respect to the ground level:
Land pump stations are characterized by pump room floor flush with surrounding land surface. Truck access may be available.
In semi-recessed pump stations the floor is recessed relative to the land surface and there is no floor structure between the pump room and the first floor which is typical for recessed pump stations. If the recession is quite deep, additional underground floors for auxiliary equipment may be constructed. Such stations are called shaft-type pump stations.
Underground pump stations are characterized by entirely underground arrangement, compact design and automatic control. They may have a rectangular (easier installation of unified components of equipment), round, elliptical (improved take-up of hydrostatic pressure) or complex shape. According to the type of control pump stations are divided into: - manual control stations, where operators control the station’s operation; - automatic control stations, when the station operates automatically and control is performed based on water level in the tank or water pressure in the line, etc.; - semi-automatic control stations, when the station is switched on and off by the operator while all the other operations are performed automatically; - remote control stations operated from remote pulpit. When selecting a pump station, it is common to compare all the technical characteristics and economic indicators of several types of stations, depending on the purpose and future application of the equipment, waste waters are analyzed (for the presence or absence of solid inclusions, viscosity, density, aggressiveness of media and temperature conditions). It is also important to determine the scope of application: whether it is a household or industrial pump unit.
Taking about types of pump stations they may also be subdivided into:
Sewage pump stations are designed for waste water disposal: storm, sewage, industrial waste waters. They are noted for the following advantages:
A sewage pump station is installed inside a housing and includes pumps (main and auxiliary), sensors, pipeline and connection piping. The main distinctive feature of a sewage pump station is the availability of a special container for removing large particles contained in the waste water. The container is regularly removed and emptied, then cleaned. Sewage pump stations may function in almost all atmospheric conditions, which is also a positive aspect.
In today's independent water supply system, the most important component is a pumping unit, which is either purchased ready-made or is assembled by the user, if it is a compact installation for a private house. In order to avoid any problems with the operation of the pumping unit, one should understand the principle of its operation. To select a pump station according to your needs, one should bear in mind two factors: technical parameters of the pump station and specifics of the well. Among the technical specifications delivery rate is of primary importance. It means that the station should lift the volume of water sufficient to cover all the household and related needs. Among the characteristics of the well an important role is played by its capacity, depth, static water level (pump out of operation), dynamic water level (pump in operation), filter type and pipe diameter. Standard pump stations efficiently lift water from wells up to 9 meters deep. They may be equipped either by a self-priming centrifugal pump or a self-priming vortex pump. With respect to the station’s flow rate the practice shows that: for a residential building housing a family of four a pump station of low or medium flow rate (2-4 m³/h) and head of 45-55 m may be sufficient.
Pump stations with an accumulation tank are considered obsolete, but they still exist. Accumulation tank is very bulky, its water level and pressure are controlled by a float, the data are displayed on a sensor which signals for water make up. It has always been a popular water supply system, however it had a lot of drawbacks:
State-of-the-art pump stations are equipped with a hydraulic accumulator. The idea is that a pressure switch is installed at the station. The stations that are equipped with a hydraulic accumulator are considered advanced and have less drawbacks. The switch controls the upper pressure limit of the ambient air, which is compressed in the hydraulic accumulator under water pressure. After the required pressure is achieved, the pump switches off to switch on only upon receiving a signal from the pressure switch on the lower pressure threshold.
Irrespective of whether the pump station has an accumulation tank or a hydraulic accumulator, it is equipped with a pumping unit, diaphragm pressure vessel, pressure switch, pressure gage, cabling and connectors. The main pump of a pump station may either be equipped with an ejector or not. In case of an inbuilt ejector water is lifted by negative pressure. Such pump stations are quite costly, however this price is justified, because they can lift water from 20 to 45 meters deep. These stations are highly efficient, quite compact, but very noisy in operation, so it is better to install them in utility rooms.
There are also pumps for pump stations with an outboard ejector, which is submerged with two pipes into a well or a downhole. Water enters the ejector via one of the pipes generating a suction flow. The system should be free of any air or sand, the efficiency of these pumps is much lower than that of standard pump stations. Such a station may be installed at home, it operates noiselessly.
In fact there is an enormous number of different pumps used in pump stations.
Recently there have been some advance developments in fire truck industry, where the quality of a pumping unit is of critical importance, since it is virtually the core element of a fire truck. Pumping units used in fire extinguishing are a combination of engineering communication systems capable of ensuring the safety of people in a building at the time of the onset of a fire. The main purpose of such units are elimination of the spreading fire, rapid and efficient fire extinguishing and removal of smoke and carbon dioxide from the building.
Previously fire trucks were equipped with a regular fire pump. Fires may be different and, accordingly, their extinguishing also has a number of distinctive features due to various requirements to the operation of pumping units. To eliminate fire on the upper floors, a high-pressure pumping unit is required. To extinguish large-scale forest fires, a fire truck with a high-performance pumping unit (70 - 100 l/s) is needed. In this case one truck will be sufficient instead of two 40 l/s each.
State-of-the-art fire-extinguishing pumping units manufactured by global leaders in this field are equipped with innovative control and remote control systems, automatic pressure regulation, automatic water filling and dosing of foaming agent, an LCD for data output. However, it is difficult to use such equipment in our conditions when it comes to global fires, for example, in the Siberian climate. How can an LCD survive in such a fire?
One of the important elements of a fire truck pumping unit is a vacuum water filling system operating from an open reservoir. Vacuum method of water filling can be manual and automatic; piston, diaphragm, slide gate, water ring and gas jet pumps can be used as a vacuum pump of the unit. Each of these systems of a pumping station for fire trucks is suitable for certain operating conditions.
Operation of vacuum water filling system, in particular, level and rate of pumping, is directly related to the functioning of the motor drive, or the rpms of the motor. This involves certain inconveniences in the maintenance of fire equipment, a daily check for "dry vacuum" is necessary. The pumps of the vacuum pump station are a stand-alone vacuum system and were developed recently by the order of the Ministry of Emergency Situations of Russia. They are equipped with a single motorized drive receiving power from the fire truck’s battery. Electric signals controlling the pumps make almost all the processes of fire-fighting operations automatic, and such stations are today the most promising ones for water filling. This has already been noted by all reputable manufacturers of fire trucks in Russia.
The following components are available for a standard pumping unit in a fire-extinguishing system (optional equipment is also available):
For fire-extinguishing systems, fire-fighting pumping units of modular type have been developed and are widely used, which are designed for supplying fire extinguishing agent to a fire-extinguishing water supply system. They are used for indoor and outdoor fire fighting in buildings and structures, on process equipment in workshops, warehouses, etc. A modular fire water pumping unit includes a pumping equipment module and a control system module.
Modular pumping station may include the following equipment:
It should also be noted that modular fire water pumping units are equipped with control cabinets with LCDs, individually selected for each unit and displaying operating and control settings, pump operating parameters, fault messages, etc., which demonstrates a number of advantages of the modular system:
However, as it was said above, such equipment is difficult to operate in our conditions when it comes to global fires.
Pumping stations are widely used in oil and gas industries, for example, in the development of oil fields. Here, booster pump stations are used that transport water-gas-oil mixture from the well to oil collection and processing points, to the locations of collection and storage of processed oil. Booster pump stations are often equipped with separators to collect formation water or separate associated petroleum gas or equipment for pumping water into the injection well. Besides, booster pump stations are used for transportation of commercial oil over long distances, they can be equipped with tanks for temporary storage of oil in the event of emergency or a scheduled break in oil pumping. Pump stations used in petroleum product handling are indispensable, since without such equipment it is just impossible both to transport and pump through pipelines installed at oil plants, oil storages and terminals for pumping oil and crude oil products. Pumping is carried out from tanker cars, trucks, oil tankers. There are two types of pump stations: mobile and stationary. The latter are especially widely used and are subdivided, in turn, into stations of open and closed types. The most common pump stations are of modular type, which include centrifugal pumps, in particular, spiral casing screw pumps. These pumps are excellent for handling different media. They are used for pumping gasoline, kerosene, diesel and aviation fuel, i.e. light petroleum products, as well as fuel oil, oil, water contaminated with quartz sand, fibrous and mechanical impurities, i.e. dark oil products, as well as gaseous media with a large volume of gas. A modular-type pump station includes a pumping unit with branches for connection to pipelines, power supplies for the unit and instrumentation. For the transfer of high-viscosity petroleum products, for example, with high paraffin content, stations equipped with screw-type pumps are used, and the pumping units themselves are manufactured in explosion-proof design, the main difference being that pumps and electric motors are installed together without any intermediate shafts. Pump stations are installed as a rule in low areas of tank farms to pressurize and to improve the suction process. In petroleum industry, pump stations called floating stations are used for the bunkering of fuel oil, unloading of oil products from a barge or a tanker, if this cannot be done using shore pumping equipment and where there is a b fluctuation in the water level. Floating pump stations are usually installed on a pontoon or a ship that is moored to the side of an oil tanker, and water level in the reservoir is irrelevant. Mobile pump stations installed on trailers or car frames allow, for example, to collect spilled petroleum products, to clean tanks, water basins and water contaminated with sand. Mobile pump stations are widely used in the oil industry, emergency services, shipping industries for the bunkering of ship fuel, pumping of petroleum products in the warehouse, replacement of temporarily out-of-service stationary pump stations, as well as filling of railroad and truck tanks.
Recently, floating pumping units have been gaining popularity, which are holding the station on the surface of water and serve as a supporting structure for the pump casing. The pump includes an inlet and an outlet, as well as an injection device submerged into the fluid. The injection device is inserted into the fluid flow between the inlet and outlet and has an elongated shaft. During operation and start of the pump unit, the outlet is arranged horizontally in the preset position. The power motor supported by a floating structure is connected to the fluid injection device and is capable of driving it. The preset position of the outlet, and accordingly, the direction of water outflow, stabilizes the position and ensures stability of the floating structure of the pump station. The pump has a constant flow rate, high capacity, is supported by a floating structure and may be partially immersed in water (in a predetermined position). Floating pumping units have been known for many years and are used for numerous applications: in drying and irrigation systems, in pumping facilities, for water level control during excavation and dredging, etc. Often floating pumping stations find their application in water treatment plants, such as mixers for downflows, as well as in water aeration devices. The shortcomings of floating pumping stations include rather complicated operation in ice-bound conditions or when water waves exceed three points; limited head pressure; unsuitability at a water depth of <1.5 - 2 m and a flow rate of > 3 m/s.
A cluster pump station is also a widely known pumping facility designed to maintain reservoir pressure in oilfields. Cluster pump stations include several pumping units with parallel connection, valves or slide gates at the inlet and outlet of each pumping unit and a single manifold at the outlet. Water channels lead from the manifold to injection wells. The disadvantage of cluster pump stations is often the fact that pumping units of the same type operating in parallel usually have different hydraulic parameters typical for operating at different capacities and efficiencies. During the analysis of hydraulic indicators of these pumping units it was found that the actual capacity of an individual pumping unit, which is connected in parallel to other similar units and operating in parallel with them, can in some cases equal zero. By changing the hydraulic circuit of a cluster pump station, its capacity and efficiency can be increased.
There are some pump station models developed specifically for country houses. They include a metallic or plastic storage tank for accumulating a certain water reserve, plus the pump itself. If water level in the well drops, the hydraulic accumulator is connected to the domestic water supply.
The main advantages of pump stations for country houses are that they are installed at the ground level and only a thin hose with a check valve is lowered into the well. Such a pump station provides max. 1.5 bar pressure in the domestic water supply system, which is enough to supply the required water volume for a two-story house. The shortcomings of such pump stations are that they must be installed in a warm room and require regular maintenance with constant control of pressure and automation system operation; it is necessary to clean the storage tank and check valve on a regular basis.
For the operation of such a station, a well minimum 8 meters deep is necessary. If the depth of the well is max. 30 meters, it is possible to use pumps with an injector capable of pumping water at such depth.
The main purpose of such a pump station is to provide continuous water supply to residential houses and buildings in case of an accident in water supply network. Today in emergency situations, drinking water is brought in containers, which is clearly not enough for full water supply. The innovative pump station developed for emergency water supply systems provides for high-quality water supply during repairs, power outages and emergency situations.
In order not to be disappointed in a pump station you buy for your country house or for industrial needs, you should take into account a number of important points and parameters when ordering a station:
Owners of country houses and cottages are often faced with the problem of water supply caused by their remoteness from the centralized water supply system. For this reason many acquire modern high-power pump stations, which are highly efficient. With such a unit available, an independent water supply system can maintain the required level of pressure, continuously supplying water to intake points. A household pumping station is equipped with protective systems that prevent overheating of the unit and its failure. A check valve ensures water retention in the station’s tank preventing its backflow to the natural reservoir, when the electric pump is turned off.
The principle of operation of this equipment is to pump water into the station’s storage tank until a certain pressure level is reached. After that the pump of the station is automatically switched off. When pressure level drops to a critical value, a special relay sends a signal to switch the pump unit back on. If water consumption is low, the pump station motor remains in the off mode.
The purchase of a pump station or unit is justified if you have a well or a downhole. Quite often downhole submersible pumps are used for water intake, but if water level in the source drops, such equipment will simply not be able to function. Therefore, the optimal solution is to purchase a pumping station that includes not only the pump itself, but also a storage tank for accumulating a water reserve. If it is impossible to supply water to the water supply line from the primary source, the station switches to the storage tank.
In addition, pump stations and units are usually equipped not with submersible pumps, but with surface pumps. These units are ideally suited for servicing standard small diameter water reservoirs in suburban areas. At the same time, a household pump station can be used not only for domestic water supply, but also for watering vegetable patches. For both purposes, a driven well or a shallow sand hole will be sufficient that is not suitable for submersible pumps, while a hose with a check valve and a cross section of about 1 inch will perfectly cope with water intake.
Another advantage of household pump stations is their ability to create and stabilize pressure in a self-contained water supply system. At the same time, they provide good pressure not only at the lower floors of a private house, but also at the upper floors. This type of equipment is compact enough, easy to operate, quickly mounted / dismantled, and also has a relatively low cost compared to submersible pumps.
The design of modern pump systems includes a pump connected to a storage tank. This tank, including a check valve, requires regular cleaning, and the accumulator of the station - constant monitoring and control of the pressure level and correct functioning of the automation system. Besides, a number of restrictions are imposed on the depth of the well used for water intake by the pump station, for example, the total vertical and horizontal distance from the pump to the water should not exceed 8 meters. However, today’s manufacturers offer pump units equipped with a special ejector enabling them to pump water from a 30-meter depth.
Other disadvantages of pump stations include their noise, the need to fill the water hose when the pump is started and increased power consumption. These stations have a shorter lifetime than submersible pumps, and their performance is directly related to the purity of the pumped water. It is recommended to install this equipment only in heated rooms, which can also be considered a disadvantage for private houses with heating issues.
Types of pump stations
Since pump stations are extremely versatile, they are widely used in a great variety of industries. In general, they are divided into household and industrial stations, with the latter having higher power, as well as improved strength and performance.
Industrial high-pressure pumping equipment is used for fire extinguishing. Collection and pumping of waste waters is carried out using modular pump stations, which are usually sold as ready-to-use assemblies, which greatly facilitates their installation and provides additional quality assurance.
Filtering pump stations are used to supply drinking water to populated areas. State-of-the-art technologies used in their production provide for ultraviolet cleaning of water, as well as effective elimination of bacterial microorganisms and various harmful impurities without any chemicals. Thus, pump stations maintain optimal water-salt balance and environmental purity of pumped water, which has a positive effect on its quality.
A hydraulic station is usually used to supply water to hydraulic equipment, whereas a booster station is necessary to maintain or increase pressure in the hydraulic system.
Household pump stations are ideal for water supply of cottages, country houses and farms, as well as for watering gardens, greenhouses and vegetable patches. Sewer household stations collect and dispose of waste waters delivering them to local treatment facilities, and a specific type of equipment depends directly on the depth of the pipeline, volume and contamination of wastes, composition of the pumped liquid and the type of pump used. So pump stations are usually equipped with horizontal, vertical, diagonal, axial and centrifugal pumps.
How to choose a pump station
When choosing a pumping station/ unit, first of all, it is necessary to take into account its power, water intake height, flow rate and storage tank capacity. These are the main parameters, but in addition to these, other characteristics play an important role in the choice of equipment, such as the maximum level of water lifting, the presence / absence of protection from overheating and dry running, the materials of the accumulator and the pump, and control method (manual, automatic or remote).
The basic indicator for a household station is power, which usually ranges from 600 to 1500 watts. It is also recommended to take into account the number of water intake points, as well as the distance from the unit to the well and the volume of fluid that the well can provide per time unit. In order to consistently supply water to a private house using a pump station, a station model with a flow rate of 3000 to 6000 l/h should be preferred, whereas for a country house this figure should be between 0.6 and 1 m3/h.
You should choose the storage tank capacity based on accurate calculation of the exact water reserve required for stable water supply to the house in case of disruptions in water lifting from the well or emergency power outages. It is also better to give preference to a hydraulic accumulator made of stainless steel - it is optimal in both price and quality. Cast-iron hydraulic accumulators are more expensive and more reliable, while plastic models are inexpensive, but their service life is much shorter as compared to cast-iron and steel tanks.
With increased water intake in a private house, it is recommended to purchase a pump station protected against dry running and overheating. Such models are more expensive, but their equipment will prevent any additional repair costs in the event of failures, which often occur when the pump is running at high speed, there is no fluid in the supply system and the motor is overheated.
Such protection will significantly increase the service life of a household pump station connected to an autonomous water supply system.
Also an excellent choice for a private house is an automated station that switches the unit on, when the accumulation tank is empty, and stops the pump after filling the tank.
In addition, if the well is deep, one should choose a unit with an ejector, which will pump water from the depth of 30 meters.
Finally, each pumping station used for both domestic and industrial application can be equipped with a special basket recovering solid inclusions from the pumped liquid.
In this case, the ideal choice will be a pump equipped with an integrated cutting mechanism, or a pump originally designed for fluids containing solid impurities. If explosive substances are present in the handled liquid, a pumping station with an explosion-proof motor is required.