electric vs hydrualic pump 1

[kdashc]

I don't know much about pumps so please correct me if i am wrong. if i see a gear pump it is usually designated as a electric or hydrualic pump, and this is just how the pump is driven, electric pumps have an electric motor attached to the pump while a hydrualic pump has a shaft that needs to be rotated by some other means? And a hydrualic pump is basically an electric pump without the electric motor? is my understanding correct and is there anything else concerning this i should know (ie another means of driving pumps, any other differences bw hyd and ele pump)

thanks alot!

 

[JJPellin]

Your terminology is not consistent with my industry (oil refinery). Any pump can be driven by any driver. We have centrifugal and positive displacement pumps that are driven by air motors, electric motors, steam turbines, gas engines and diesel engines. We have pumps that are mechanically driven from other equipment by being coupled up to a gearbox, pump, compressor, motor or engine. We don't have any pumps that are driven by hydraulic motors, but we are considering hydraulic motor drivers for some of our decoking equipment. I would not describe any of our pumps as electric pumps or hydraulic pumps. I would describe them as a centrifugal pump, gear pump, screw pump, piston pump, diaphragm pump or progressive cavity pump.

If I mentioned a hydraulic pump, I would not be speaking about the driver or even the pump configuration. I would be describing the service. We have pumps that provide hydraulic pressure for pistons and actuators. These pumps might be called hydraulic pumps even though most of them are variable displacement piston pumps driven by electric motors. Some of them are gear pumps driven by electric motors or steam turbines.

If I ever referred to an electric pump it would just be because I was too lazy to say electric motor driven pump.

Other industries might use different terminology than what I am describing.


Johnny Pellin

 

[kdashc]

thanks johnny, i've just seen some gear pumps sold with an eletric motor attache to them and some gear pumps with no driver on them, i didn't know if there were any other fundemental difference to them. I guesse the gear pumps with an electric motor is sold just as a convinent packaging.

 

[MortenA]

I would assume that the "motorless" pumps are for replacement in application where the motors is still fine?

Best regards

Morten

 

[JJPellin]

The difference may be configuration. Some ANSI pumps are offered in a direct driven configuration with the impeller mounted on the end of the motor shaft. The pump has not bearings. It relies on the motor bearings to support the impeller. This is very compact but can have some reliability problems. As an alternative, the pump can be mounted to a base with a flexible coupling. In this configuration, the pump has its own bearings to support the shaft and impeller. But you still have to have a driver to couple it to. So the alternatives would be a direct drive model with the motor included as part of the pump or a coupled model with a motor, base-plate, pump and flexible coupling.

Johnny Pellin

 

[micalbrch]

kdashc,

You can drive a gear pump either by an electric motor or by a hydraulic motor (or by other drives as described already). The bare shaft pump is the same. To drive a gear pump by a hydraulic motor is not very common because a hydraulic motor needs to be driven by a hydraulic pump which is again driven by electric motor. And such a hydraulic pump is pretty often a gear pump, too. So, that makes no sense. But there is a technical difference between the various gear pumps. Gear pumps are used in the oil hydraulics up to high pressures of 4500 psi or in industrial applications for much lower pressures. Both are called gear pumps and have the same function principle but the gears and the materials are different.

 

[CH5OH]

strictly speaking all pumps are hydraulic pumps (hydraulic means liquid), however term is used for applications where oil pressure is used to create lineair or rotating motion.
jjpelin,
not much I can add to your comprehencive story
willing to learn every day, what is a progressive cavity pump? you mean a vane pump?

 

[JJPellin]

A progressive cavity pump uses a screw shaped rotor that rotates and translates in a parallel manner within a stator. Between the rotor and the stator, pockets (cavities) are created which move axially as the rotor rotates. Type it into a search engine and you should find some good diagrams and better descriptions.

Johnny Pellin