VOGELSANG ADVANTAGES

WHY WOULD YOU COOSE VX-SERIES ROTARY LOBE PUMPS OVER PROGRESSING CAVITY PUMPS & OTHER ROTARY LOBE PUMPS

What municipal applications are appropriate for Rotary lobe pumps?

• FOG/ Septage
• Primary Sludge, Secondary Sludge, RAS, WAS, TWAS, Digested Sludge
• Dewatering Feed; centrifuge, belt thickener, etc.
• Digester Feed
• MBR Permeate

FOG

Sludge

Dewatering Feed

MBR

 

VOGELSANG AGAINST PROGRESSING CAVITY PUMPS

Progressing Cavity pumps are used for handling viscous and abrasive fluids with low shear. For Vogelsang and rotary lobe pumps, these types of pumps are what we compete against most often.

Basic Pump Components of a PC Pump:

1. Rotor
2. Stator
3. Pin Joint or Universal Joint

 

How the pump operates: Cavities are formed between stator and rotor. The rotor is shaped like a screw. As the rotor turns, the cavities are progressively moved through the pump to the discharge.

 

 

Basic components of Rotary Lobe Pumps

1. Gear Box
2. Housing
3. Shafts
4. Lobes

How the pump operates: During operation, the lobes mesh together, while rotating in the opposite directions. This rotation forms the cavities between the rotors and the casing. As the rotors spin, liquids and solids are drawn along the top and bottom housings and pumped out the discharge side of the pump.

 

 

Similarities in Vogelsang Rotary Lobe Pumps and Progressing Cavity Pumps

• Both were designed specifically to handle viscous materials with a high solids load.
• In fact, the more viscous the material, the more efficient the pump -- more than 90% hydraulic efficiency. As viscosity, and solids percentage, increases, the pump slip decreases. This results in an increase in hydraulic efficiency.
• Vogelsang pumps handle solids up to 17% by weight. Progressing Cavity pumps handle up to more than 25% solids by weight.

 

Comparing Pump Technology

• Dry Run
• Size/Footprint
• Maintenance and downtime
• Cost of spare parts

 

Run Dry

Vogelsang:

• Can run dry for 30 minutes without damage to the pump. This is vital if upstream equipment clogs or a valve does not get opened.

 

Progressing Cavity:

• Cannot run dry without immediate damage to the stator. Without lubrication provided by the
  liquid being pumped, a Progressing Cavity Pump will quickly heat up and swell.
  The swelling worsens with time and will result in melting of the stator, seizing the pump.
   

Example of stator with dry run (above).

 

Large Footprint/Size

Vogelsang:

• 40-50% Smaller footprint allows more design freedom and easier replacement.
• Spare parts take up less space in inventory.

Progressing Cavity:

• Large footprint not only affects floor space, more room is needed to pull the rotor for service.
• Spare parts are large (long) and difficult to stack.
   

Benefits:

When planning projects, rotary lobe pumps allow you to plan for smaller rooms, smaller facilities; requiring less construction and fewer resources. Even in cases of renovations and additions, smaller pumps such as Vogelsang rotary lobe pumps reduce excavation requirements, use smaller pads, and are more flexible in terms of configurations.

 

Maintenance, Repair & Downtime

Vogelsang:

• All equipment can be serviced or repaired, in line, in 1-3 hours, by one person.
   
• Easy access to entire wet-end.
   
• No need to disturb the flanges or connected piping.
   
• Wear parts can quickly be accessed, evaluated, removed and replaced.

 

 

Progressing Cavity:

• Must be removed from the line, then worked on in the shop or back to the factory and then reinstalled. This involves at least 3 people – an electrician, forklift driver and mechanic.
   
• Most wear parts on a PC pump are hidden from view and not easily accessed without disassembly.
   
• No good way to clean the pump or verify it has been completely cleaned out. This is problematic when pumping materials like paint.
   
• Maintenance is difficult and must be removed for repair. Progressing Cavity pumps are difficult to work on, requiring removal from the piping system to work on the stator and rotor in the shop.
   
• When the pump goes down, it typically takes a couple of days of work to get it back up and running.

 

 

 

 

Cost of Ownership

Vogelsang:

• Based upon the same size pump (over 20 GPM in flow), acquisition cost is roughly the same.
   
• The upfront cost varies based on a number of factors.
   
• Parts cost is typically 40-50% less than PC pump repair.
   
• Cost of maintenance is lower for us due to less time to repair.
   
• Life span is about the same.

 

Progressing Cavity:

• Cost of PC pump spares is 40-50% higher compared to RLPs.
   
• Maintenance is more difficult and time-consuming, so downtime is longer.
   

 

 

VOGELSANG VX SERIES ROTARY LOBE PUMPS AGAINST BORGER & OTHER LOBE PUMPS

 

 

Börger Pump vs Vogelsang (pictured in red) Wet-end

 

Component 1: Wet End - Front Wear Plate

Börger: The front wear plate is pressed between the cover and front edge of the wet end housing. The wear plate is reversible and is available in a variety of materials. The stated hardness of the standard wear plate is 550 brinell.

 

Vogelsang: The front wear plate is affixed on the inside of the front cover with two hex head bolts. The wear plate is reversible and is available in a variety of materials. The stated hardness of the standard wear plate is 700 brinell.

Benefit: Ours is harder without requiring special of the wear plate. Our wear plate is positively located by the door and the bolts. The Börger wear plate can move since it is not positively affixed to anything.

 

Component 2: Wet End – Housing & Radial Liners

Börger: The wet end housing is a one piece casting. To accommodate for normal wear, the use of radial wear liners is required. Changing wear liner brings the pump back into capacity provided that the lobe tips are also changed or the proper gap between the lobe tip and wear plate is maintained.

• Radial wear liners must be formed out of flat stock what limits the hardness of the material.
• The hardness of 327 is 52% softer than a standard Vogelsang housing segment.
• Radial wear liners are difficult to remove and install on a thoroughly used pump.
• Radial wear liners are an extra wear item.

 

Vogelsang: The wet end consists of three elements. The top and bottom housing segments and the ring flange. The ring flange has a series of adjustment holes to allow the segment to be placed in three locations. The total movement is up to 3mm.

• The wet end housing has two independent segments.
• They can be adjusted to compensate wear.
• They can have Tungsten Carbide Coating
• Easier to replace
• Radial liners are an option

 

1. Vogelsang’s the three-piece arrangement allows the pump to remain in in capacity longer without replacing any parts, through adjusting the housing segments to accommodate for wear.
    
2. Vogelsang housing segments are cast and are available in hardness up to 610 brinnel. Börger radial wear liners must be formed out of flat stock which limits the hardness of the material (52% softer than a standard Vogelsang housing)
    
3. Vogelsang design allows for commonality of wear parts throughout each series of pumps. While Vogelsang offers radial liners, they are not required due to the design of our housing segments. Börger requires radial liners can be viewed as and extra wear part that are often difficult to remove and install on a used pump.
    

 

Component 3: Lobes

Börger: The primary lobe configuration offered by Börger is a Bi-Lobe or twisted three wing lobe depending on the series. They also feature a design with removable elastomer coated tips mounted on a stainless steel core. There are a variety of elastomer options available.

 

HiFlo® Lobes

Vogelsang: The twisted HiFlo® lobe design in either a 4- or 6-wing version is what sets Vogelsang apart from other lobe pump designs.

Benefit: Vogelsang’s 4- and 6-wing lobes offer optimal hydraulic efficiency and are virtually pulsation free. Börger only offers 2- and 3-wing lobes which can't produce the same hydraulic efficiency. This is exaggerated at the pump wears. Börger’s 3-wing lobe is not pulsation-free and is not balanced in an even suction and discharge volume

This is often overcome by sizing the pump larger than it needs to be and then running the pump slower. Fewer tips result in shorter sealing lines in the pump. Any wear that takes place is magnified since each of their sealing lines is doing more.

 

Lobe Tips

Börger: Replaceable tips are often found to be difficult to remove and install on a pump that has been in use. It is common for grit to work its way into the track and mechanical fixtures making it difficult to work on parts. End users often report that tips can come loose during operation if not installed correctly.

Vogelsang: Vogelsang abandoned replaceable tips years ago, finding them inferior.

Benefit: Over time, Vogelsang HiFlo® lobes are easier to service. It is less expensive to purchase three sets of Vogelsang lobes versus three sets of Börger tips and a core. It is not possible to replace one tip as it will put the pump out of balance. In a Börger pump, the lobe core must be replaced for every three times the tips are replaced.

 

Component 5: Shaft Design

Börger shaft (above), shown with Scoring on the step-down design.

Börger: uses smaller diameter two-keyed shafts that are stepped down at the bearing, and threaded to accept the mechanical seal. This creates a series of stress points that cause the shaft to deflect, fatigue and break. These have a history of shaft failures in applications involving medium to high pressure with varying degrees of viscosity.

Reducing the shaft diameter, where it meets the bearings and then again where it meets the mechanical seals, reduces cost for the manufacturer, but the end user pays the price in the long run by buying replacement parts due to excessive wear to the lobes and seal caused by flexing at the weak points on the shaft. As shown to the right, a Börger shaft that has threads handles stress unevenly. Pressure is continuously changing from tensile to compressive. The continuously alternating load frequency is identical with the shaft RPM. Over time, cracks or fissures can develop at the step down which leads to seal and bearing failure, and ultimately, shaft failure.

Rotary Lobe Pumps are designed to have clearance between the lobe and housing. Deflection bends the shaft and forces the lobe tip into the housing unevenly throughout the pumping cycle. This creates wear and is inefficient pumping performance.

 

VIEW LARGER

The diagram above represents how shaft deflection leads to lobe wear-off; by which you see the lobe taking on a tapered shape resulting in poor performance and then failures of the lobe.

 

VIEW LARGER

In the diagram above, the arrows indicate the distance the shaft is deflecting and depicts how the deflection places the lobe tips in contact with the pump’s housing, resulting in unwanted wear and deterioration of the lobes tips.

 

Vogelsang: Vogelsang uses shafts that are consistent in diameter from back to front, and are larger in diameter than Börger pumps of the same capacity.

Benefits:

1. Utilizing a larger diameter shaft makes deflection nearly non-existent, which in turn reduces deflection, minimizes wear on the shafts, lobes, seals and bearings. This increases the life cycle of these parts, reducing maintenance and spare parts cost.
    
2. The Vogelsang shaft does not have step downs or threads so it takes stress evenly. Even stress prevents fissures and cracks from developing and ultimately prevents failure.

 

 

Component 5: Mechanical Seal vs. Component Seals

 

Börger: Börger’s seal is a three-part component system consisting of two seal faces and a threaded carrier that interlocks with the lobe. Common materials are Duronite/Duronite and SiC/SiC. The installer has to decide on how tight to make the seal -- too loose and the seal will leak; too tight and the faces will wear faster or even fail. Both faces must be free of fibers, dust or dirt. Installation time is increased as a result of the added preparation time. Since there is no shaft sleeve, if the seal fails, liquid will come in contact with the shaft.

Börger’s double lip seal is fitted into the casting of the pump and is capable of 150psi. The lip seal is not a part of the mechanical seal change out. It must be installed with special tools. Lip seal removal requires complete teardown of the pump and is not replaced during normal seal repair.

Vogelsang: The Block Ring Mechanical Seal is Vogelsang’s most advanced innovation in sealing technology. The seal has a shaft sleeve and lip seal combined into one simple cartridge seal design.

Benefit: Vogelsang’s hard Block Ring surface is wear resistant, especially against fibrous, abrasive and corrosive material. Any abrasion affects only the Block-Ring, not the seal itself. This design allows for excellent heat transfer due to the close contact between the lobe and shaft. Due to the greatly improved heat dissipation, the seal is also insensitive to dry running. It can handle pressures up to 232 psi.

NOTE: THIS ONLY APPLIES TO Börger BLUEline, their new ONIXline series has a different arrangement and can accommodate non-Börger seals.

 

Component 6: Buffer Chamber & Oil Bottle 

Vogelsang: A buffer chamber is molded into the case between the mechanical seal and bearing housing for protection of the gear case in the event of seal leakage or failure. An oil bottle is located on top of the pump to indicate pressure and oil color.

Börger: A plastic plug is located on top of the pump. It pops out to indicate a potential seal failure. There is no pressure to keep pumpage out of the seal chamber. Oil & sludge can spill out onto the floor during a seal failure, causing safety concerns and lost product. This is for their BLUEline pump, for the ONIXline I cannot see anything on top of the pump.

Benefit: Vogelsang pump users have advanced warning before a seal failure. As long as the oil in the canister atop the pump remains clean, the gear box and buffer chamber are clear of any foreign liquids. Should the oil become discolored, or pressure can’t be achieved, the pump can be serviced before damage occurs.

Adding pressure to the blocking chamber extends the life of the mechanical seals by offsetting the pressure in the wet-end. This keeps the buffer chamber close to the system pressure versus a low pressure zone like others.

Component 8: Injection Housing Design

Injection Housing

The InjectionSystem is a design solution based on modifications to the housing segments without purchasing a new pump. Extended, angled tips optimize the flow path of the pump to pass solids, while simultaneously protecting the lobe tips from being damaged by debris.

Background: Where did the idea come from?

This design solution came out of a CFD flow path study and findings related to pumping liquids with a high quantity of solids. It was discovered that the traditional “straight” inlets that are used in rotary lobe pumps currently create a vortex-effect that can temporarily trap material at the edge of the inlet (below). It was concluded that this vortex-effect and pattern of solids being trapped can lead to increased wear to the lobe tips as the solids can become trapped between the lobe tip and the side of the housing.

Why choose the InjectionSystem?

This design feature, unique to Vogelsang, extends the life of your lobes in high-solids applications. Note the housing segments have angled extensions on either the intake side of the pump or both the inlet and outlet sides, depending on flow and application requirements. These angles help optimize the flow path of the solids by diverting them directly into the throat of the lobes, avoiding damages to the tips.

 

 

Reasons to Choose Voeglsang over Börger:

• Vogelsang’s lobes improve your hydraulic pumping efficiency and lead to a longer last pump -- Borger’s 3-wing lobe is not pulsation-free and is not geometrically balanced. Any wear that takes place is magnified since each of their sealing lines is doing more. Only Vogelsang’s 4 and 6-wing lobes offer the highest efficiency and are virtually pulsation free.
  
  This means:
  • More balanced pumping action, with a less pulsation  better hydraulic pumping efficiency than Börger
  • Less wear on the lobes themselves
  • Longer service internals, equaling lower costs in replacement parts
     
• Vogelsang’s superior, larger shaft design will save you money – Vogelsang views the shaft as the backbone or the structural foundation of the pump. A weak backbone allows the rest of the system suffer. The smaller, step-down shaft design of Börger pump leads to higher shaft deflection. This deflection places strain the entire pump. This includes increased wear on the lobes, strain on seals, general decreased efficiency in terms or slip. Ultimately, the subsequent increased service hours/repair time, spare part costs, and downtime cost the end user money
   
• Seals* -- Vogelsang has a reliable seal that is far easier to work on and is less susceptible to improper replacement.
  • *For Blue Line pumps the installer has to decide on how tight to make the seal -- too loose and the seal will leak; too tight and the faces will wear faster or even fail. 
     
• Get Early Warning of Seal Failures - The Buffer Chamber and Pressurized Oil Bottle system on Vogelsang's pumps balances the pressure on either side of the seal and will act as warning devise, which allows for planned service and maintenance activities as opposed to emergency repairs.
   
• Easy, Cost-Friendly Börger Replacement -- need to replace a Börger pump? We regularly size against and replace their pumps easily, and we are aggressive on pricing when replacing Börger.

*Börger BLUEline and ONIXline are trademarks of Börger GmbH., Borken-Weseke, Germany. Vogelsang is not affiliated with Börger in any way. All included images of Börger equipment were taken and provided by employees of Vogelsang USA, and are property of Vogelsang USA. Disclaimer & Publishing Details