50 Hz and 60 Hz

Hertz is the unit of frequency in the International System of Units. In the electrical grid this value could be 50 Hz (Europe, Asia, Africa and Australia) or 60 Hz (North and South America). It is named after the German physicist Heinrich Rudolf Hertz who studied electromagnetic waves in the mid 1800's. The electric motors are designed to operate at a given frequency. Some of our pumps engines are designed to operate independently of 50 Hz or 60 Hz. Here you can find every detail about our products.

Absorbed power

Absorbed power is the power that the pump absorbs from the motor, to give to the liquid the deliver power. Not all the absorbed power becomes delivered power, as some power is lost through friction and to the function of the pump itself. The delivered power is always less than the absorbed power, and the ration between the two is a number always lower than 1. This number is known as the efficiency.


Official DAB pumps delegate who manages the sales of our products. Here you can find the list.


It is an acronym for American Iron and Steel Institute (AISI), an association of the North American steel producers. Nowadays used throughout the world, AISI is followed by a four-digit that identifies the properties of the steel alloy in use in that product.

Alternate current (AC)

The alternate current (AC) is a form of distribution of electrical power. In the AC the electric current periodically reverses direction. In Europe the AC power is at 400 volt at 50 Hz.

Axial pumps\Inline pumps

Depending on the direction of liquid passing through a pump, the pump can be called axial (or inline) if the delivery and suction are on the same axis.

Backward impeller

Type of impeller mainly used in pumps suitable for drainage of sewage. It is called "backward" because it is far from the bottom of the pump, making it more suitable for pumping water with solid bodies in suspension or particularly dense liquids.


Pressure measurement unit. The official measure for the International System is the Pascal “Pa” (the unit is named after Blaise Pascal, mathematician, physicist and French philosopher). Commonly are used the bar (all written down):


1 bar = 100 kPa



It is a perforated bucket-shaped container that in the pumps allows to filter solid bodies.


The blow is a hydraulic phenomenon that occurs when a valve is suddenly opened or the flow of fluid moving inside the pipes is abruptly blocked. It is a negative phenomenon because it can damage the pipes and the mechanical part of the pump if the liquid strikes the walls violently.

Bottom valve

It has the same function as the retention valve but is located inside the tank from which the pump draws the suction water.


It is synonymous with bearings. They consist of two different parts, where the first is housed in the body of the support and the other one is stuffed on the pivot of the body to be supported.


The acronym that is used to indicate our Technical Assistance Centers in Italy. They are our authorized service centers, divided by geographic area. The list for the Italian market is here.


Electrical component that allows the operation of single-phase motors. It is necessary to ensure the starting of single-phase motors, It is not present in three-phase motors.


Referring to pumps, cavitation is the phenomenon that occurs when the pressure in an inner point of the pump decreases by turning the liquid into gaseous state (bubbles, hence cavitations). The bubbles are unstable and when they come out of the low pressure zone they implode creating vibrations that in the long run will damage the material or the components of the pump. Usually the most exposed structure to this negative phenomenon is the impeller.

Centrifugal pump

The centrifugal pump uses a impeller to move the liquid, aspirating and moving it by the centrifugal force determined by the mechanical movement of the impeller. All of our pumps are centrifugal.


It is a pump for moving the water in the heating system, a pump that runs water in a closed circuit, often with glycols.

Clean Water/Dirty Water

It is necessary to know if the water is clean or dirty to use the correct pump. For clean water we refer to drinkable water, for dirty water we refer at water who have some chemical in it. Here you can find the technical sheet of our products.

Clear contact

A clear contact is a contact where there isn’t electrical tension.

Closed impeller

A type of impeller not suitable for pumping liquids with suspended solid bodies, compared to open ones, they have a higher efficiency.

Delivered power

The delivered power is the power delivered by the pump to the liquid. The value of this delivered power depends in three factors: flow, head, and specific weight of the pumped liquid. The higher these three factors, the higher is the power delivered by the pump. In order to pump a liquid a pump must be driven by a motor. The power that the pump needs in order to operate is called absorbed power.

Delta connection

Type of electrical connection in the three-phase motors, the symbol for the delta connection is ∆. This type of connection bring to the wildings the same voltage of the line.

Differential pressure (prevalence)

It is the power of a pump (the ability to lift water from one level to another). The capacity of a pump to elevate a certain number of cubic meters of water to a certain height, the maximum lift height, usually expressed in m3 (water column meters).

10 mca = 1 bar


Prevalence is given by several variables, such as the geodetic aspiration height and the geodetic height of the mandate.

Dip switch

Electronic component used in electronic devices. It is a group of switches who are manually switchable without the use of tools.

Discharge tank/Storage tank

A tank that is installed between the water inlet pipe and the domestic plant and it is used to have more liquid available to keep the plant under pressure. It also provides a water reserve to meet requests when the user's demand is higher than that available from the aqueduct.

DNA - DAB Navigator Application

DNA (Dab Navigator Application) is DAB software that allows to find in just a few seconds the pump model that best suit your needs.
DNA uses two different logical selection criteria, for hydraulic performance or for pump model. DNA makes available to the user the entire spare parts list as well as all the technical documentation available. Frequent updating and easy to use. DNA is the perfect support tool for engineers, installers and retailers, even for the end users.

Dry run

"Dry run” is when the pump works without having liquid inside. A pump should never "dry run" because if it is not adequately cooled by the liquid some parts of the pump will overheat and breaks. The pumps have a device that prevents them from running in the absence of liquid.


The efficiency is obtained by dividing the delivered power by the absorbed power and is normally expressed as a percentage. For example, an efficiency of the 75% of a pump indicates that only 75% of the absorbed power is converted into delivered power, with the remaining 25% being lost due to friction. Therefore, the higher the efficiency of a pump, the smaller the portion of absorbed power being lost. The efficiency of a pump expresses better than any other parameter the quality of the pump the related savings in terms of operating costs.

Electrical terminal

Motor connection point with electric line. In three-phase motors, the connection can be delta or star. You can change them by changing the position of the connector.

Engine Backing

Engine lower part/end part (where for example our MCE/C inverter is installed).

Ethernet/Ethernet cable

A family of computer networking technologies. Nowadays the Ethernet cable should at least be category 5e. The Ethernet cable has a connector called RJ-45.

Expansion Tank

Container that avoids the blows and ramps in the delivery on a hydraulic system. It also allows to deliver pressurized water in case of small demands.

Exploded view drawing

Type of graphic representation of an object. In our DNA software an exploded product drawing is always present and serves to identify the exact code of the spare parts.


Frequently Asked Questions. This section of the website, where you can find the most asked questions about our products.


Circular plate for coupling tubes with screws or bolts.

Geodesic high

It is measured in meters and represents the difference in level between the position where the pump is located and the surface of the liquid to be lifted.


Glycol is a chemical compound used as antifreeze in closed hydraulic circuit.

HP - horse power

The international System uses the Watt, but commonly the horse power is also measurement of power. There are many different standards and types of horsepower. The mechanical horse power (imperial horsepower) is:


1 hp = 1,014 CV or 745,69 W
Hydraulic power

Hydraulic power is the hydraulic capacity of a pump, that is, the volume of liquid that is shifted to the unit of time. It is measured in cubic meters per hour (m3 / h) for very large pumps or liters per minute (l / m) for small and medium sized ones. There is a formula for converting values:

1 m3/h = 16,66 l/m



The impeller is a disk with blades that makes a liquid flow by aspirating it from a pipe and pushing it into another pipe through the centrifugal force. The impeller is a rotating component that is moved by the axis of the motor and increases the prevalence, pressure and flow of the liquid (depending on the characteristics of the impeller, such as thickness or diameter). The impellers can be made of different material, metal (cast iron, bronze, steel) or technopolymer (eg Noryl or Ultem); the impeller differ for uses (low / high temperatures, corrosion resistance, different pH, etc.). The presence of several impellers increases the prevalence and pressure.


"Inrush" means that when starting a pump it will turn the impeller for a few moments faster then usual. It is a normal function, this function reduce the probability that any solid particles deposited during the stop will prevent proper movement.


A plumber or electrician who performs the installation of the product; He should be the reference person between the end user and the DAB Pumps customer service. He is the first person to contact in the event of a problems with our product.

Installer menu

It is called "installer menu" because changing the parameters in this menu affects the operation of the pump and must be performed by experienced personnel (as the installer). The procedures to enter in the installer menu is different for every products. All of our manuals are available on our site or here in our DNA software.

Intake duct

The intake duct is the pipe in which the liquid arrives to the pump.

International System of Measurement

It is the world's most widely-used unit of measurement (essentially used anywhere except in the U.S.), also known as a decimal metric system. It was founded in 1889 from the need to standardize the units of measure (among the proponent countries there was also the then Kingdom of Italy). It is called International System since 1961.


A device that changes the voltage and frequency of the alternating current at the output, allowing also to modify the operating speed of an electric motor (in our case the one in the pumps). This type of function save energy since instead of working at maximum speed the motor can work at variable speeds depending on the workload. An inverter is not indispensable for the operation of the pump. Here you can find our inverter.


Acronym of "International Protection" i.e. the degree of "international protection" (standard protection). It is indicated by two digits after the IP letters, the first one vary from a scale from 0 to 6 and indicates the protection at the entry of small solid bodies (sand or dust), 0 no protection, 6 maximum protection. The second number vary from a scale from 0 to 9 and indicates the protection from liquid entry, where 0 indicates the absence of protection, 9 the maximum protection.


Local Area Network, a network of interconnected computer. This type of network means that the computers can communicate with each other, but not necessary they can communicate with the Internet.

Mechanical Seal

It is used to isolate the chamber where the liquid circulates from the outside. The mechanical seal is the part of the pump which is suitable for isolating two environments, among which there is a component with circular motion. For example, the mechanical seal serves to isolate the electrical part from the chamber where the liquid circulates. It is said that the seal is "mechanical" because it is the set of components pushed by a spring to prevent the liquid from reaching the electric part of the engine.

Meters of water column

meters of water column is the unit of measure of the prevalence, 10 mwc corresponds to 1 bar of pressure (100 KPa)


The monophase alternating current system in Italy is 230 volts and 50 Hz (normally available for domestic users).

Motor rotation direction

The direction of rotation of an engine is invertible only in the case of three-phase motors (the single-phase motor always rotates in the right direction independently of the terminals connection). It is one of the features that must be checked when installing a three-phase pump, the rotation direction must always be the correct one to ensure the right operation. Each manual of our products tell you how to verify the correct direction of rotation, when the pump is already installed and before installation. If the direction of rotation is incorrect, remove the current and reverse two of the three phase conductors. Refer to the specific product manual here on our site or in our DNA software.


It means that the pump has two or more impellers (more impellers provide more prevalence and pressure).

Non return/non return valve (ball valve or gate valve)

Closure device that can be automatic or manual, allows only one direction of the flow; in the pumps is used to prevent the flow of the liquid to exit the pipes after the pump is switched off. A ball valve is commonly used in pipes (for gas or liquids), it works by rotating a ball inside the pipe that allows the opening, the closing or the reduction of the flow. Gate valve, unlike balls valve, use a shutter as a closing / opening pipe.


We need to know it to know where and when the cavitation can occur: NPSH (NPSHa)  is a measure of how close the fluid at a given point is to flashing, and so to cavitation. The Required NPSH (NPSHr): the head value at a specific point (e.g. the inlet of a pump) required to keep the fluid from cavitating.



NPSH stands for Net Positive Suction Head.
The physical meaning of this expression is the absolute pressure that must exist at the suction port of the pump in order to pump the liquid without
causing cavitation.
This can occur when the absolute pressure falls to values likely to allow the formation of vapour bubbles within the fluid, causing the pump to work with
reduced head.
Therefore, NPSH can also be seen as the pressure required to compensate load losses in the path between the suction port and the point with the lowest
pressure of the impeller.
All this demonstrates the importance of checking that the pump is not producing cavitation, as in addition to creating high noise similar to metal
hammering, cavitation will also quickly damage the impeller.
A special formula associates the NPSH value required by the pump with the conditions of the system and with the type of liquid, allowing to calculate the
minimum pressure required at the suction, and consequently to determine the position in which to locate the pump in relation to the free surface of the
liquid to be pumped.
The general NPSH formula is:

NPSH formula


Z1 = the difference in level (in m) between the axis of the pump and the free surface of the liquid to be pumped.
p1 = the possible pressure (in kg/cm2) on the surface of the liquid in the tank from which it is collected. If the liquid is collected from an open tank and
the surface of the liquid is in contact with the atmosphere, p1 will be equal to 0.
pb = atmospheric pressure (in kg/cm2) at the site of installation.
pv = the vapour tension (in kg/cm2) of the liquid at pumping temperature.
γ = the specific weight (in kg/dm2) of the liquid at pumping temperature.
10 = conversion factor of the units of measure used.
Hr = head loss (in m) in the suction pipework.


Circular rubber ring that serves as a gasket. It is also called O (letter of the alphabet) erre (O-R).

Oil bath engine/Water bath engine

Type of lubrication of the motor. The two types of engines at the technical and performance levels are the same; in the first the maintenance is simpler; in the second the maintenance is more difficult and costly.


It refers to the position of a pump. Overhead means that the pump is at a higher level than the liquid to be aspirated. Underhead means that the pump is at a lower level than the liquid to be aspirated.

Packing rings

Wire group together used for mechanical seal or as gasket.


In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. The scale is from 1 to 14. One is extremely acid, 14 extremely basic. 7 in neutral.


Pressure means weight per unit of area (e.g. Kg/cm2). In case of liquids the pressure that the liquid exerts on a surface is given buy the product of the head of the liquid, multiplied by its specific weight. A Column of water of 10 m high is equivalent to approximately 1 Kg/cm2.

Pressure drop

The pressure drops are the loss of energy caused by the rubbing of the liquid along the pipe walls (viscous friction) and the localized pressure drop due to the presence of shrinkage, curves, valves etc.

Pressure switch

A device that allows to activate / deactivate a machine / engine when a given pressure value is reached.


Priming of a pump is defined as the phase during which the machine is filled with water through the intake duct. If the operation is successful, the machine can work smoothly and define as “primed". The priming must always be done manually following the procedure described in the manual. The manuals of all of our products can be found here on our website or in our DNA software.


In our case a pump is a machine that can convert electricity into hydraulic energy transmitted to a liquid. The transmitted energy causes the liquid to move. All pumps are made of two basic components: electric motor and hydraulic part. Circulators are particular types of pumps.


Polyvinyl chloride is the vinyl chloride polymer, a plastic material with many uses, such as water pipes, electrical wiring, floors and window structures.

Qualified personnel

Qualified personnel mean the persons who, by virtue of their training, experience and education, as well as the knowledge of the relevant regulations can perform any necessary activity and is being able to know and avoid any danger (definition for technical staff IEC 364).

Raziometric sensor

Analog sensor with 0-5 volt signal.


Electric device controlled by current variations.

Residual-current device

Safety device that interrupts electrical current in case of electric dissipation or ground-to-ground link. It comes into operation when it detects anomalies between the electric currents detected at input and output from the electrical system.

Roman well

The roman wells are those with circular base with pulleys and buckets to draw the water from the bottom.


In electric motors is the moving part (rotating) while the stator is the fixed part.


Literally, "setting point", i.e. value to set, it is found in some of our products and can always be set manually or by the initial wizard.

Specific weight of a liquid or a fluid

The specific weigh of a liquid or a fluid is the weight per unit volume of the liquid. Specific weight is usually measured in Kg/dm3 or Kg/l (one L is 1 dm3).

Star connection

Type of electrical connection in the three-phase motors, the symbol for the star connection is Y. This connection decreases the voltage from the 400 V of the line to the 230 V on the windings. In a 230 V line it can also be used to further reduce the operating voltage and reduce the power consumption: a voltage across the windings will be equal to 155 V.

Star-delta starting

It is used in three-phase motors to allow the engine to start with less power at start-up (to reduce the electric absorption), passing from star to delta link after a few moments. In high power engines, to avoid excessive current at the starting point, the "star-delta" starter is used; it consists in starting the star engine for a few seconds, then making it work normally in a triangle. There are special timers for this delicate maneuver, usually lasting half a second, just enough to make the contacts of the command remote control switches. Starting with a star, we have a starting current reduced by 1/3, when the motor is then stopped, it does not perform this exchange.


In electric motors the stator is the fixed part, while the rotor is the moving part.

Stuffing box

A type of mechanical seal.

Technical Sheet

The document that contains the technical details of a product, such as prevalence, flow rate, type of liquid supported, building material of the impeller and other technical information. You can find every tecnichal sheet in our DNA software.

Three phase

It is a combined system of three AC circuits in Italy (and in Europe) at 400 volts at 50 Hz. Three-phase connections can take place at star or delta.


There is troubleshooting in each of our manuals and it is helpful to consult it in case of problems before calling for technical assistance.

All of our manual are here on the website or here in our DNA Software. Also, you can find the troubleshooting here in the F.A.Q. pages.

If you wish to speak to technical support please contact us on 0333 777 5010 option 2


A valve is an organ or mechanism that serves to regulate the flow of fluids or gases into the pipes.

Venturi nozzle

The Venturi nozzle is a particular conformation of a pipe that utilize the Venturi (or hydrodynamic paradox) effect, the physical phenomenon discovered and studied by the Italian physicist Giovanni Battista Venturi. When a velocity increases, a fluid stream decreases in pressure . At a practical level this is a reduction in the pipe section (or in the increase of the same, in this case the pressure increases and the speed decreases). It is a component in self-priming pumps (e.g. our JET pumps).


The volt is the unit of measurement of the International System. The volt is the electrical potential difference. It is called “Volt” in honor of the Italian physicist of the end of 1700, Alessandro Volta.

Volumetric Pump

The volumetric pump works by utilizing the volume variation of a chamber to cause the suction of a liquid.


In the case of pumps, the component that collects the liquid leaving the pump.


Measurement of the International System for power. It is named after James Watt (1736 - 1819) for his contribution to the development of the steam engine. This value is always present in the technical sheet of our product, here in the DNA software.

Wet rotor circulator

It is a circulator in which the rotor is cooled by the liquid itself.


Under the Wi-Fi name there are different technologies for wireless connection of devices to the Internet or LAN.


Intersection point between the plant curve and the hydraulic pump curve (can be calculated via our DNA software, it is where the pump stabilizes to ensure a certain performance).

50 Hz and 60 Hz

Glossary content

Hertz is the unit of frequency in the International System of Units. In the electrical grid this value could be 50 Hz (Europe, Asia, Africa and Australia) or 60 Hz (North and South America). It is named after the German physicist Heinrich Rudolf Hertz who studied electromagnetic waves in the mid 1800's. The electric motors are designed to operate at a given frequency. Some of our pumps engines are designed to operate independently of 50 Hz or 60 Hz. Here you can find every detail about our products.