THE “PUMPING SIDE” AND THE “POWER SIDE” OF A CENTRIFUGAL PUMP

It takes two to make a thing go right
It takes two to make it outta sight
It takes two to make a thing go right
It takes two to make it outta sight
Hit it!

("It Takes Two," by Rob Base and DJ EZ Rock, 1988)

THE TWO ESSENTIAL SIDES OF ANY CENTRIFUGAL PUMP

Every Centrifugal Pump has two conjoined functional areas that must work together if the PV Pressure is going to be injected into a liquid:

"The Pumping Side" and "The Power Side."

For example ...

PTOA Readers and Students just learned how Centrifugal Action infuses energy in the form of the PV Pressure into a liquid while it flows through a Centrifugal Pump ...

First, Centrifugal Force spins the liquid outward from the Eye of the Impeller ...

While spinning radially outward, the pumped liquid gains Velocity.

Next, Human-made technology takes over to swap the Velocity into the PV Pressure! How?

The specifically built Volute increases the flowing area available to the liquid.

Having a greater area to flow through causes the pumped liquid to slow down and lose Velocity.

So while flowing through the Volute, most of the decreased Velocity is swapped into an increase in the PV Pressure.

Voila!

The pumped-up liquid leaves the Pump Discharge with a greater amount of PV Pressure than it had at the Centrifugal Pump's Suction.

The Impeller and The Volute are two hardware components on The Pumping Side of the Centrifugal Pump.

This PTOA Segment defines the boundaries between The Pumping Side and The Power Side of a Centrifugal Pump.

The next few PTOA Segments will focus on the form and function of the hardware components found in the Pumping Side and Power Side of a Centrifugal Pump.

I hear ya out there in Reader World!

Kind of boring to memorize the name and use of hardware components.

Do it anyway!

Of all of the Process Technology subject matter, the content related to Rotating Equipment is vitally important to Plant Managers and Supervisors of Process Operations because Rotating Equipment is expensive and Rotating Equipment is vital to moving fluids between where they presently are and where they need to be.

A malfunctioning piece of Rotating Equipment is money down the drain!

For those good reasons ...

Modern Plant Managers and Process Operations Supervisors expect future Process Operators to be capable of identifying the form and function of Centrifugal Pump hardware.

Hey! Look on the bright side!

There's no theory of operation ... just simple memorization!

LIST OF "PUMPING SIDE" HARDWARE JARGON

"The Pumping Side" of the Centrifugal Pump is the side that is in direct contact with the liquid that is being pumped.

This cutaway photo features The Pumping Side of a Centrifugal Pump. The cone-shaped hardware on the backside of the pump is part of The Power Side of the Pump. The red stopper on the top side of the cone is where lubrication/seal oil would enter.

The liquid that is being pumped is often called "the process liquid" because it is the liquid that is being processed ... or moved ... through the pipes that connect to the pump Suction and Discharge.

The jargon that Process Operators are expected to know so that they can effectively communicate about the "Pumping Side" of a Centrifugal Pump includes:

Pump Suction Inlet Flange
Pump Casing ... with a way to drain and vent
Pump Casing Interior ... otherwise known as
The Volute
Impeller including The Eye of the Impeller
Wear Rings
Impeller Collar
Pump Discharge Flange
Minimum Flow Line from Pump Discharge to Pump Suction

LIST OF "POWER SIDE" HARDWARE JARGON

Thank you PumpFundamentals.com for the labelled Centrifugal Pump Diagram.

So how exactly is The Pumping Side of the Centrifugal Pump connected to The Power Side of the Centrifugal Pump?

PTOA Readers and Students who are reading the PTOA Segments in the intended sequential order learned in PTOA Segment #161 that a Driver of some type is what makes it possible for the Impeller to spin in the first place.

The Driver .. aka "Prime Mover" ... is the originating source of power on The Power Side of a Centrifugal Pump.

Far Left Side is The Pumping Side that contacts the processed liquid. The Power Side includes the Packing Box/Stuffing Box and cone-shaped Bearing Housing, the Coupling in the Center, and The Driver (aka Prime Mover) on the far Right Side.

Of course linking the power source to a spinning Impeller in an industrial grade machine is not as simple as it sounds.

PTOA Readers and Students also learned in PTOA Segment #161 that the rotary motion linkage of The Driver to the Pump via a Shaft demands that the Process Operator be alert and aware of the hardware components that perform the following essential duties:

Prevent the pumped liquid from leaking out of the pump.
Prevent metal-metal interfaces from contacting and overheating.
Prevent movement along the horizontal plane, aka Axial Thrust.
Prevent movement along the vertical plane, aka Radial Vibration.

Radial Vibration is Up and Down Action. Axial Thrust is Left to Right or Right to Left Action.

Remember ...

The Power Side of a Centrifugal Pump is not supposed to be processing the pumped liquid even though there is a Shaft piercing the Casing of the Pump!

Heck, that MUST MEAN that there has got to be hardware dedicated to sealing the process fluid into the pump as well as preventing leakage into the bearing support area.

Righteeo!

The list of Power Side hardware components includes:

Driver aka "Prime Mover"
Coupling
Shaft within a Shaft Sleeve which is supported by a
Sleeve Bearing
Bearing Housing
Axial Thrust Bearings
Radial Bearings
Slinger Ring
Pump Casing that can be 'easily' disassembled for needed repairs
Stuffing Box where the shaft penetrates the Pump Casing and which encloses the ...
Mechanical Seal with Stationary and Rotating Sealing Elements, O Rings, Compression Rings, Seal Oil Inlet and Outlet or ... for more old school pumps that are still allowed to vent fumes into the atmosphere ...
Packing Rings, Packing Gland, Packing/Gland Follower, Lantern Ring for gland sealing fluid.

Lubrication Oil Flow Diagram

All Centrifugal Pumps will have external Suction Line hardware like strainers or suction screens that remove debris from the flowing process liquid prior to its entry into the pump's Suction.

An important Auxiliary System external to the Centrifugal Pump is the Lubrication Oil supply sub-System.

The next several PTOA Segments are dedicated to exploring each of the Centrifugal Pump hardware components that have just been introduced.

First The Pumping Side hardware will be featured.

Then, the importance of lubrication will be emphasized.

And all this exciting information will be followed by covering the form and function of the hardware found within The Power Side of a Centrifugal Pump.

Stay tuned!

TAKE HOME MESSAGES: Infusing the PV Pressure into a liquid is accomplished via the two separate functional sides of a Centrifugal Pump.

The Pumping Side of the pump is the side that actually contacts the process liquid that is being pumped.

Important parts of the Pumping Side of a Centrifugal Pump include The Impeller and The Volute which PTOA Readers and Students already are familiar with.

The Power Side of the Pump includes the Driver and the interface of the Driver to the Pumping Side via a Shaft pierced through the Stuffing Box.

Besides the Driver supplying the motive force, the Power Side of the Pump includes hardware purposefully intended to seal the process fluid into the Pumping Side as well as provide lubrication to the bearings.

Creating the rotary motion that results in spinning the Impeller on the Pumping Side of the pump requires the Process Operator to be alert and aware of the form and function of Centrifugal Pump hardware so that s/he will be able to recognize operational problems which arise due to lack of seal or lube oil and /or daily wear and tear that causes excessive Axial Thrust or excessive Radial Vibration.

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