You're so vain
You probably think this song is about you
You're so vain (so vain)
I'll bet you think this song is about you
Don't you?
Don't you?
Don't you?

("You're So Vain," by Carly Simon, 1972)

 

VANE ROTARY-MOTION POSITIVE DISPLACMENT PUMPS

What if there were a type of Rotary-Motion PD Pump that could move a low-to-mid range viscosity liquid and yet was low maintenance because the rotating members did not wear down since they could "automatically compensate for wear?"

The low-to-mid range viscosity liquids include ammonia, solvents, alcohol, gasoline, refrigerants, and LPG (a mixture of propane and other gases that are in the liquid state when kept under pressure).

The Vane Rotary-Motion PD Pump is the pump described above!

The identifying characteristic of Vane Rotary-Motion PD Pumps is their capability to "automatically compensate for wear."

The unique design of the Vane Rotary-Motion PD Pump eliminates the metal-to-metal contact between their rotating members … Vanes.

What keeps the Vanes from contacting each other while moving liquid or fluid from Suction Port to Discharge Port?

The Vanes in the Vane Rotary-Motion PD Pump are held apart by the centrifugal force that is generated by the spinning Rotor.

 

Once the pump is up and running, the hydraulic PV Pressure within the pump also keeps the Vanes from touching.

 

Some models of Vane Rotary-Motion PD Pumps may even employ spring or push rod to help "compensate for wear."

Brilliant PTOA Readers and Students … meaning those who are reading the PTOA Segments in the intended, sequential order  … already know that an advantage of eliminating wear between moving metal parts is that peak pump performance can be maintained without the expense and maintenance of an auxiliary lubrication source.

Righteeo!

Besides their ability to  "compensate for wear," Vane Rotary-Motion PD Pumps have a positive reputation regarding:

• Easy maintenance.
• Maintaining good suction over the life of the pump.
• Ability to "dry prime" … aka prime without the need to add a liquid.

 

This PTOA Segment #213 will feature Sliding Vane Rotary-Motion PD Pumps and Flexible Vane Rotary-Motion PD Pumps.

The Vane Rotary-Motion PD Pump family also includes the Swinging Vane Rotary-Motion PD Pump, Rolling Vane Rotary-Motion PD Pumps, and External Vane Rotary-Motion PD Pumps.

Each Vane Rotary-Motion PD Pump family member has unique advantages which influence its selection for service over a different family member.

 

THE SLIDING VANE ROTARY-MOTION PD PUMP 

Benefits of the Sliding Vane Rotary-Motion PD Pump

Sliding Vane Rotary-Motion PD Pumps are selected when low rotational speeds and moderate Capacity/Flowrate will suffice for the pump's service  … and possibly for their Suction Lift capability.  PTOA Readers and Students learned all about Suction Lift in PTOA Segment #167.

Look closely at the nearby gif and note how the Blue Vanes slide down and back while they move the Golden Fluid from the Suction Port (on the left) to the Discharge Port (on the right).

The benefits of Sliding Vane Rotary-Motion PD Pumps include:

• Their high operating efficiency means that a less expensive motor (less Hp) can be used to drive the pump. A pump with less Hp also means that the electricity utility needed to drive the pump daily will also be lower than a pump that needs a driver with more power.
• The ability of the pump to dry run for awhile eliminates the need for monitoring/warning instrumentation.
• 

  These Sliding Vane Rotary-Motion PD Pumps are installed at a terminal.

  Easy maintenance because the Vanes can be replaced while the pump remains in the pumping system. That's right! The Sliding Vane Rotary-Motion Pump does not need to be taken to the mechanic shop to be repaired!  Otherwise stated, the pumps are renewable and repairable.

• The ability to move a moderate Capacity of small solids at a low Flowrate.
• The ability to move moderately viscous liquids without the need to install a fluid heating system.
• Their High Suction Lift capability means these pumps can lift liquid in excess of 25 feet (7.6 meters).

 

Sliding Vane Rotary-Motion PD Pump Hardware

Like the Internal Gear Rotary-Motion PD Pump featured in PTOA Segment #212, the Vanes in the Vane Rotary-Motion PD Pumps are not centered, but "eccentric."

In the nearby schematic, the Cam Ring could be mistaken for the interior wall of the pump's Casing. Focus on the outlined border of the Cam Ring which is clearly visible at the Suction Port and Discharge Port. The upcoming Blackmer You Tube more clearly shows a Cam Ring and the Cam Ring holes.

The holes in the Cam Ring allow liquid or fluid to be sucked into the pump from the Suction Port.

A disc-shaped Slotted Rotor holds both the Vanes and Cam Ring in place. The Slotted Rotor is sealed to the Cam Ring at two places. Locating the disc-shaped Slotted Rotor close to the upper wall of the Cam Ring is intentional. This positioning creates a crescent-shaped cavity in the bottom part of the pump as is shown in the nearby schematic.

 

How the Sliding Vane Rotary-Motion PD Pump Moves Liquids and Fluids

The disc-shaped Slotted Rotor turns with the Shaft.

While the Slotted Rotor is turning, the Vanes would fling outward radially were they not held in place by fitting into the slots on the Slotted Rotor.

As was mentioned above, liquid or fluid is sucked into the suction side of the crescent through holes on the suction side of the Cam Ring. The Cam Ring also has holes on the discharge side of the pump.

As the Vanes rotate past the Suction Port, they extend outward. A volume of liquid is "compartmentalized" between two neighboring Vanes, the Slotted Rotor, and the Cam Ring wall.

Thus "compartmentalized," the Vanes sweep the liquid or fluid to the opposite side of the crescent where Vanes are pushed back into the slots of the Slotted Rotor.

The volume of the "compartment" at the discharge side of the crescent is significantly decreased. The liquid or fluid being pumped is displaced through the holes of the Cam Ring on the discharge side of the pump and finally through the Discharge Port.

Hey, Fred ! Let's face it!

The operation of a Sliding Vane Rotary-Motion PD Pump is still hard to understand!

You Tube and Chill with Blackmer's 15 second Sliding Vane Pump You Tube!

The Blackmer Sliding Vane Pump You Tube can also be accessed HERE. Don't forget to give the Blackmer Sliding Vane Pump You Tube a Thumbs Up!

The rotation of the Slotted Rotor and the in and out movement of the Vanes from their slots reveals that the suction side of the Blackmer Sliding Vane Pump is to the right and the discharge side of the pump is above the pump body.

While chillin' with the You Tube, be sure to notice how the Vanes slide toward the Cam Ring wall at the suction side of the pump and then slide back into their slot on the Slotted Rotor on the discharge side of the pump.

The Cam Ring holes that are visible in the You Tube are on the discharge side of the pump.

 

Why Sliding Vane Rotary-Motion PD Pumps have Low Rotational Speeds

The Sliding Vane Rotary-Motion PD Pump would not function well if the Vanes did not contact the Cam Ring wall to form a tight seal. The factors that form the tight seal between the Vanes and Cam Ring are likewise responsible for making the pump famous for being able to "compensate for wear."

The tight seal results when centrifugal force is created by the rotation of the Slotted Rotor. Additionally, the force component of the hydraulic PV Pressure created within the pump helps with sealing. Some pump models have springs or other mechanical means of guiding the Vanes to contact the Cam Ring wall.

On the discharge side of the pump, the force component of hydraulic PV Pressure pushes the Vanes back into the slots on the Slotted Rotor.

The reason that Vane Rotary-Motion PD Pumps are suited for only low rotational speeds is because leakage across the Vanes increases at high rotational speeds. Leakage at the tips and sides of the Vanes can be decreased by increasing the number of Vanes.

Up to this point, the Sliding Vane Rotary Motion PD Pump described in this PTOA Segment have had a fixed output Capacity. Some models of Sliding Vane Rotary-Motion PD Pumps can be manufactured to vary the output Capacity by changing the degree of eccentricity between the Slotted Rotor and the Cam Ring.

Otherwise stated, some Sliding Vane Rotary-Motion PD Pumps can be designed to control a variable discharged Capacity at a constant rotational speed. Shazam! That's not at all the same as having a a variable speed Driver. However, the outcome of controlling a variable amount of discharged Capacity is the same outcome!

 

FLEXIBLE VANE ROTARY-MOTION PD PUMPS

Another member of the Vane Rotary-Motion PD Pump family is the Flexible Vane Rotary-Motion PD Pump.

A Flexible Vane Rotary-Motion PD Pump gif is shown nearby.

Like the Sliding Vane Rotary-Motion PD Pump described above, the Flexible Vane Rotary-Motion PD Pump must have eccentric motion generated between the rotating Rotor and the stationary Cam Ring to enable fluid to be moved from the Suction Port to the Discharge Port.

The design of the Flexible Vane Rotary Motion PD Pump does not rely on a Slotted Rotor and rigid Vanes to successfully operate.

Rather, the Flexible Vane Rotary-Motion Pump employs a single impeller which has several Flexible Vanes molded from flexible rubber material.

Note that the Flexible Vanes on the Flexible Vane Impeller extend outward after passing the pump's Suction Port and then get squashed up after passing the pump's Discharge Port.

As the Rotor and Flexible Vane Impeller rotate, the changing form of the Flexible Vanes creates a low PV Pressure area at the pump's Suction Port that sucks fluid into a cavity.

As the fluid is carried past the pump's Discharge Port, the Flexible Vanes get squashed up. The volume of compartmentalized fluid is greatly decreased and thence displaced from the pump via the Discharge Port.

 

Service of Flexible Vane Rotary-Motion Pumps

Flexible Vane Rotary Motion Pumps can easily move fluids with particles and solids because there is no place for the particles to lodge and gum up the rotation of the Flexible Vane Impeller.

Like the Lobe Rotary-Motion PD Pump featured in PTOA Segment #212, Flexible Vane Rotary-Motion PD Pumps are "low-shear pumps" which means the pump will not mechanically damage the fluid that is being pumped. Flexible Vane Rotary-Motion PD Pumps are the economical alternative for low-shear pumping.

Flexible Vane Rotary-Motion PD Pumps can produce low to moderate PV Pressures. The viscosity of the pumped fluid will determine the discharge PV Pressure.

Thus, Flexible Vane Rotary-Motion PD pump service includes industries involved with the manufacturing of foods, beverages, pharmaceuticals, cosmetics, and water-based glue.

The nearby colorful schematic of a marine seawater bilge pump is also a Flexible Vane Rotary-Motion PD Pump.

Due to their ability to self prime, Flexible Vane Rotary-Motion PD Pumps can handle tank stripping service without the need to install valving for manual priming.

Flexible Vane Rotary-Motion PD Pumps are also reversible, meaning the Suction and Discharge can be interchangeable. This feature makes it possible to clear process stream lines that service high-viscosity liquids.

Okay! That's a wrap on Sliding Vane Rotary-Motion PD Pumps and Flexible Vane Rotary-Motion PD Pumps.

 

 

Guess what?

Even the Process Technology and Operator Academy website needs to come down for a maintenance interval from time to time.

Once the new, more secure version is up and running, PTOA Readers and Students will learn about THE FINAL TYPE of  Rotary-Motion PD Pump that is to be featured in the PTOA … the Screw Pump!

Stay tuned!

 

TAKE HOME MESSAGES: Vane Rotary-Motion PD Pumps are known for:

• Dry priming.
• Great suction capability.
• Easy Maintenance

 

Neither pump would work well if a tight seal did not exist between the Cam Ring wall and Vanes. The tight seal is created by:

• Centrifugal force
• The force component of the hydraulic PV Pressure created within the pump
• Some pump models augment compensation with other hardware

 

The components that create the tight seal between the Vanes and Cam Ring wall also make it possible for these Vane Rotary-Motion PD pumps to "compensate for wear." The rotating members do not come in contact with each other so they do not generate friction that causes wear.  For this reason, no expensive lubrication system is needed for the Vane Rotary-Motion Pumps.

The Sliding Vane Rotary-Motion PD Pump features rigid Vanes on a Slotted Rotor eccentrically oriented to a stationary Cam Ring. Sliding Vane Rotary-Motion PD Pumps are used to move common industrial fluids, like LPG. At fast rotational speeds, leakage would occur across the Vanes in a Sliding Vane Rotary-Motion PD Pump. For this reason the Sliding Vane Rotary-Motion PD Pump is limited to low rotational speeds.

The Flexible Vane Rotary-Motion PD Pump features a Flexible Vane Impeller molded from plastic which deforms as it rotates with the Rotor. Flexible Vane Rotary-Motion PD Pumps are low shear pumps used in the production of food, beverages, pharmaceuticals, cosmetics, and water based glue.

Both pumps rely on eccentric motion between the rotating Rotor and stationary Cam wall to move liquid or fluid from the Suction Port to the Discharge Port. In both cases the fluid is "compartmentalized" as it moves from the suction side of the crescent to the discharge side of the crescent, where the fluid is displaced from an ever-decreasing volume.

©2020 PTOA Segment 0213

PTOA PV PRESSURE FOCUS STUDY AREA
PTOA ROTATING EQUIPMENT AREA - DYNAMIC AND POSITIVE DISPLACEMENT PUMPS

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