mud pump cavitation for sale

A well-placed suction stabilizer can also prevent pump chatter. Pump chatter occurs when energy is exchanged between the quick opening and closing of the reciprocating pump’s valves and the hammer effect from the centrifugal pump. Pump isolation with suction stabilizers is achieved when the charge pumps are isolated from reciprocating pumps and vice versa. The results are a smooth flow of pumped media devoid of agitating energies present in the pumped fluid.

Heavty duty mud pump with 22 kW power and 380V voltage. 150 mm caliber and 10-16m of head can better help work in bog, farm and sewage treatment plant.

Pump body thick. The pump body is made of high quality pig iron, durable and equipped with a thickened base. Thickened impeller, wear-resistant and dry rotating.

(Place the vertical mud pump upright or tilted in the liquid. Make sure the pump case is completely submerged in water. In addition, the motor part can not be immersed in water.)

The pump vibrates. Pump shaft and diesel engine (or motor) different center, impeller unbalance, bearing damage. Solution: adjust the concentricity, the impeller for balance test, replace the bearing.

Quick wear of pump. Poor construction environment, long conveying distance and long water inlet pipe. Solution: replace the sand field, add the afterburner unit, shorten the length of the inlet pipe to reduce cavitation.

The pump cannot absorb water. The perfusion water is not enough, the air in the pump can not be discharged, the suction pipe leakage, the front lining plate and the impeller gap is large. Solution: continue to pour water, check whether the pipeline leaks, adjust the clearance between the impeller and the front lining plate.

After trying multiple pump types, and 6 pump failures due to cavitation, Paul Michalski of 212 Environmental was desperate and determined to find the right pump for his Vapor Liquid Knockout Tank.

Upon asking around, and scouring the internet, Paul found a reference to Carver Pump on an engineering forum and called Carver Pump. Paul explained the issues he’d had with other centrifugal pumps, and carefully explained how the system worked to Derek King, Carver’s Central Region Sales Manager (563) 203-0037 derekking@carverpump.com. Before hanging up the phone on the initial call, Carver Pump sized and selected a Carver Model 850 Horizontal Filtrate Pump perfectly suited for this type of low NPSH pumping.

Skeptical of Carver’s claims, Derek scheduled a trip to the site to help the team at 212 Environmental set up their controls and come up with a parts list necessary for the install. Carver Pump made recommendations, and when the pump was delivered, the installation went off without a hitch.

The pump issues that Paul was seeing were taking place at the knockout tank. The knockout tank is designed for a flowrate of approximately 2,900 scfm at 160 in-H2O vacuum.  The extracted vapors, groundwater, and rainwater infiltrate enter the knockout tank through a 16-inch diameter inlet located near the bottom of the tank.  Vapors are diverted upward and pass through a wire mesh demister filter which removes the liquid droplets. With a much higher gas-liquid ratio, the vapor leaves the separation equipment through a 16-inch diameter outlet.

Meanwhile, the separated liquid (groundwater and rainwater infiltrate) accumulates at the bottom of the knockout tank and are transferred to an oil-water separator. This transfer is where the model 850 pump comes in. The issue with using a standard centrifugal pump is that the vacuum being pulled on the tank makes for a low Net Positive Suction Head available; or NPSHa. The other issue is that a typical centrifugal pump has to be sized perfectly and continuously tweaked to accommodate varying flows. A standard centrifugal pump cannot lose prime or run dry.

Cavitation happens when the static pressure of a liquid is below that of its vapor pressure. This causes the water to boil, creating steam bubbles inside the pump. Once these air bubbles implode, this causes vibration. Though one implosion may be small, thousands can chip away at the pump metal – this is how cavitation damages the pump, and how cavitation affects pump operations.

Cavitation can occur anywhere in the pump line. There is suction cavitation, where the pressure at the suction of the pump is too low, and there is discharge cavitation, where a high discharge pressure causes the fluid to circulate rather than exit the line.

In typical applications with a centrifugal pump, there is a consistent flow rate. This is why after performing several calculations, the correct pump size can be found to let the pump function properly and avoid cavitation. Once the priming liquids fill a correct-sized pump, it can run without a high risk of cavitation.

However, in the vapor liquid separator, the vacuum created a very low pressure at the pump impeller. Plus, since the flow is inconsistent, sizing the pump properly is extremely difficult.

These are the reasons why cavitation already caused 6 pump failures. Because even if a positive displacement priming pump was used to help with the low NPSHa, the inconsistent flow rate may still cause cavitation.

The model 850 and its sister series, the 855 are rugged in design, dependable in nature, and have been proven in some of the earth’s harshest environments. Capable of operating in vacuum conditions up to 26” Hg (353 in-H2O), these pumps are well suited for use on vapor liquid separators or liquid knockout tanks. A vent port allows pumping to resume even after short periods of interrupted flow. Meaning, the pump can empty the tank, continue to run until the tank begins to fill again, and then re-prime itself and continue pumping, all without hurting the pump. This assures continuous pumping, from a trickle to full capacity. This capability is well suited for liquid knockout tanks where the incoming fluid can vary in amount.  Horizontal Vacuum Filtrate Pump | 850 | Carver Pump

The 850 is available as either a close coupled or frame-mounted unit with an option for side-mounted motor with belt drive. The front and back pull-out design allows for easy maintenance. And the pump is available with a number of shaft sealing options.

After Paul and the 212 Environmental Team had the pumps installed, and after the pumps had ran for 9-10 months, Derek took another trip down to the site to take some photos, and make sure everything was still operating as it should with the pump and get some more information about the system for this article.

During that visit Paul Michalski of 212 Environmental said, “When you write about this project, talk about Carver’s customer service, because we’ve never had this type of service from a pump manufacturer.” he continued, “I was skeptical, after 6 other pump failures, I needed this one to work, but I was skeptical. (Carver Pump)… coming down here to the site and conferencing in Carver’s Inside Sales Manager to help  create a parts list for install and discuss the controls portion of the project was invaluable.”

It was clear that Paul and the 212 Environmental Team had found their solution. By trusting Carver Pump, they were finally able to find a pump that worked perfectly for their application and not, as had happened so many times before, see yet another pump fail.

Cavitation is an undesirable condition that reduces pump efficiency and leads to excessive wear and damage to pump components. Factors that can contribute to cavitation, such as fluid velocity and pressure, can sometimes be attributed to an inadequate mud system design and/or the diminishing performance of the mud pump’s feed system.

Although cavitation is avoidable, without proper inspection of the feed system, it can accelerate the wear of fluid end parts. Over time, cavitation can also lead to expensive maintenance issues and a potentially catastrophic failure.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump “knocking,” which typically sounds like marbles and stones being thrown around inside the equipment. However, the process of cavitation starts long before audible signs reveal themselves – hence the name “the silent killer.”

Mild cavitation begins to occur when the mud pump is starved for fluid. While the pump itself may not be making noise, damage is still being done to the internal components of the fluid end. In the early stages, cavitation can damage a pump’s module, piston and valve assembly.

The imperceptible but intense shock waves generated by cavitation travel directly from the fluid end to the pump’s power end, causing premature vibrational damage to the crosshead slides. The vibrations are then passed onto the shaft, bull gear and into the main bearings.

If not corrected, the vibrations caused by cavitation will work their way directly to critical power end components, which will result in the premature failure of the mud pump. A busted mud pump means expensive downtime and repair costs.

As illustrated in Figures 1 and 2, cavitation causes numerous pits to form on the module’s internal surface. Typically, cavitation pits create a stress concentration, which can reduce the module’s fatigue life.

To stop cavitation before it starts, install and tune high-speed pressure sensors on the mud suction line set to sound an alarm if the pressure falls below 30 psi.

Accelerometers can also be used to detect slight changes in module performance and can be an effective early warning system for cavitation prevention.

Although the pump may not be knocking loudly when cavitation first presents, regular inspections by a properly trained field technician may be able to detect moderate vibrations and slight knocking sounds.

Gardner Denver offers Pump University, a mobile classroom that travels to facilities and/or drilling rigs and trains rig crews on best practices for pumping equipment maintenance.

Severe cavitation will drastically decrease module life and will eventually lead to catastrophic pump failure. Along with downtime and repair costs, the failure of the drilling pump can also cause damage to the suction and discharge piping.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump ‘knocking’… However, the process of cavitation starts long before audible signs reveal themselves – hence the name ‘the silent killer.’In 2017, a leading North American drilling contractor was encountering chronic mud system issues on multiple rigs. The contractor engaged in more than 25 premature module washes in one year and suffered a major power-end failure.

Gardner Denver’s engineering team spent time on the contractor’s rigs, observing the pumps during operation and surveying the mud system’s design and configuration.

The engineering team discovered that the suction systems were undersized, feed lines were too small and there was no dampening on the suction side of the pump.

Following the implementation of these recommendations, the contractor saw significant performance improvements from the drilling pumps. Consumables life was extended significantly, and module washes were reduced by nearly 85%.

Although pump age does not affect its susceptibility to cavitation, the age of the rig can. An older rig’s mud systems may not be equipped for the way pumps are run today – at maximum horsepower.

The positive displacement mud pump is a key component of the drilling process and its lifespan and reliability are critical to a successful operation.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

Due to the nature of its operation, pistons, liners, and valve assemblies will wear and are considered expendable components. There will be some corrosion and metallurgy imperfections, but the majority of pump failures can be traced back to poor maintenance, errors during the repair process, and pumping drilling fluid with excessive solids content.

A few signs include cut piston rubber, discoloration, pistons that are hard to remove, scored liners, valve and seat pitting or cracks, valve inserts severely worn, cracked, or completely missing, and even drilling fluids making their way to the power end of the pump.

The fluid end of a positive displacement triplex pump presents many opportunities for issues. The results of these issues in such a high-pressure system can mean expensive downtime on the pump itself and, possibly, the entire rig — not to mention the costly repair or replacement of the pump. To reduce severe vibration caused by the pumping process, many pumps incorporate both a suction and discharge pulsation dampener; these are connected to the suction and discharge manifolds of the fluid end. These dampeners reduce the cavitation effect on the entire pump which increases the life of everything within the pump.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

Additionally, the throat (inside diameter) can begin to wash out from extended usage hours or rather quickly when the fluid solids content is excessive. When this happens it can cut all the way through the seat and into the fluid end module/seat deck. This causes excessive expense not only from a parts standpoint but also extended downtime for parts delivery and labor hours to remove and replace the fluid module. With that said, a properly operated and maintained mud recycling system is vital to not only the pump but everything the drilling fluid comes in contact with downstream.

Mud pump cavitation: Routineinspections, maintenance canprevent ‘silent killer’ from reducingrig efficiency, equipment reliabilityWith pumps being run at max horsepower at today’s well sites, best practicescan help contractors to avoid premature damage, extend consumables life

CAVITATION IS AN UNDESIR ABLE will see the equipment shaking and hear the a sealing surface. These unexpected failurescondition that causes a reduction in pump pump “knocking,” which typically sounds are expensive and lead to a minimum ofefficiency and excessive wear/damage to like marbles and stones being thrown around eight hours of rig downtime for modulepump components. Factors that can contrib- inside the equipment. However, the process replacement.ute to cavitation, such as fluid velocity and of cavitation starts long before audible signspressure, can sometimes be attributed to an reveal themselves – hence the name, “the PREVENTING CAVITATIONinadequate mud system design and/or the silent killer.” Stopping cavitation before it starts is adiminishing performance of the mud pump’s Mild cavitation begins to occur when matter of routine inspection and mainte-feed system. the mud pump is “starved” for fluid. While nance. For starters, install and tune high- Other factors contributing to cavitation the pump itself may not be making noise, speed pressure sensors on the mud suctioninclude: damage is still being done to the internal line to alarm if the pressure falls below • Improper sizing of charge pump; components of the fluid end. Mild cavita- 30 psi. Accelerometers can also be used to • Improper maintenance of charge pump tion damages the module, piston and valve detect slight changes in module performanceimpellers – worn impellers cause a reduction assembly. These hidden and intense shock and can be a good early warning systemof fluid pressure; waves generated by cavitation travel directly for cavitation prevention. Routinely conduct • Dirty or clogged charge pump feed and from the fluid end to the pump’s power end, visual inspections on the pump. While thedischarge lines; causing premature damage (vibration) to knocking may not be loud, if inspections are • Improper size of plumbing from charge the crosshead slides, thus passing onto the conducted on a regular basis, a field techni-pump to mud pump; shaft, bull gear and into the main bearings. cian will be able to detect moderate vibra- • Elevation changes and excessive elbows If not corrected, the vibrations caused by tions or knocking sounds. Finally, maintainin plumbing from mud tank to mud pump; cavitation will work their way directly to the gear end of the pump and check oil on aand these critical power end components, caus- regular basis. • Lack of/or inadequate suction and dis- ing premature failure, expensive downtime Gardner Denver offers Pump Universitycharge dampening. and repair costs. (PumpU), a mobile classroom that travels to Cavitation is an avoidable issue, but with- As referenced in Figures 1 and 2, the customers’ facilities and/or drilling rigs andout proper inspection of the feed system it process of cavitation causes numerous pits trains rig crews on how to properly maintaincan accelerate the wear of fluid end parts. Tis to form on the module’s internal surface. pumping equipment. Participants in thecan lead to expensive maintenance issues and Typically, cavitation pits result in a stress program have found that their improveda potentially catastrophic failure. concentration that results in a reduced maintenance skills have extended the life fatigue life of the module. Washouts are one of fluid end expendables on their sites, inMILD VS SEVERE CAVITATION of the leading causes of module failure and addition to lowering repair costs, decreasing When a mud pump has entered full cavita- take place when the high-pressure fluid cuts production costs and reducing workplacetion, rig crews and field service technicians through the module’s surface and damages hazards.

FIGURES 1 (LEFT) AND 2: Long-term, severe cavitation can cause surface pitting on a module crossbore and reduce the module’s fatigue life. Overtime, cavitation can lead to expensive maintenance issues and a potentially catastrophic failure.

RESULTS OF CAVITATION formance. Consumables life has been extend- The best way to prevent pump cavitation At the onset of cavitation, there will be ed significantly, and module washes have is to check the system’s feed lines and equip-reduced life in expendables and gradual wear been reduced by nearly 85%. This improved ment daily for any signs of abnormal noise oron the modules and power end. Severe cavi- performance has drastically reduced rig vibrations. Although it’s impractical to flushtation will drastically decrease module life downtime and has increased the operational system piping during drilling operations,and will eventually lead to catastrophic pump efficiency and customer satisfaction for the strainer screens should be checked daily tofailure, causing unwanted and costly down- drilling contractor. remove any debris or other flow restrictions.time. In addition, failure of the drilling pump Additionally pre-charge (centrifugal) pumpscan also cause damage to the suction and THE IMPACT OF TODAY’S DRILLING should be inspected regularly to ensure out-discharge piping. RIGS put flow and pressure is adequate. Following While pump age does not affect its sus- these simple steps will allow you to achieveCAVITATION IN THE FIELD ceptibility to cavitation, the rig’s age can. maximum performance from your pumping A leading North American drilling con- Oftentimes, a rig’s mud systems aren’t equipment and reduce unplanned equipmenttractor encountered chronic mud system equipped for the way pumps are run today – outages. DCissues on multiple rigs. The company expe- at maximum horsepower.rienced more than 25 premature modulewashes in one year and a major power-endfailure. Gardner Denver’s engineering teamwas called and spent time on the contractor’s When a mud pump has entered fullrigs observing the pumps during operation

technicians will see the equipment shakingtems were undersized, feed lines were toosmall and there was no dampening on thesuction side of the pump. There were also

and hear the pump ‘knocking’... However,issues with the feed line maintenance – linesweren’t cleaned out on a regular basis andsolids from the fluid had formed a thick cake

the process of cavitation starts long beforeon the bottom of the pipe, further reducingits diameter. The engineering team recom-mended increasing the diameter of the feed

audible signs reveal themselves – hence thelines and routine cleanings to improve flowand reduce the risk of cavitation. Following the implementation of these

Cavitation is a common problem for centrifugal pumps. If you hear strange noises coming from your pump there’s a good chance cavitation is the issue. But what exactly is cavitation? And how can you go about preventing it? Read on to find out.

To understand how to prevent pump cavitation, it’s important to have a good understanding of what the problem is and how it arises. There are several types of cavitation which we’ll discuss below, but the process is similar.

Cavitation Defined: Cavitation is the formation and accumulation of bubbles around a pump impeller. This tends to form in liquids of any viscosity as they are being transported through and around a pump system. When each of these tiny bubbles collapses or bursts, it creates a high energy shock wave inside the liquid. Imagine throwing a stone into a pond. The circular ripples which are created in this process are similar to cavitation bubbles exploding. The difference here is that due to the sheer number of bubbles creating these shock waves, the impeller and other pump components can be eroded over time.

1. Vaporisation: Also known as inadequate NPSHa cavitation or ‘classic cavitation’, this is the most common form. It occurs when a centrifugal pump imparts velocity on a liquid as it passes through the eye of the impeller. If the impeller isn’t functioning correctly, some of the liquid may be boiled quickly (vaporised), creating those tiny shock waves we discussed above.

2. Turbulence: If parts of the system - pipes, valves, filters, elbows etc. - are inadequate for the amount or type of liquid you are pumping, this can create vortexes in said liquid. In essence, this leads to the liquid becoming turbulent and experiencing pressure differences throughout. These differences can erode solid materials over time, in the same way that a river erodes the ground.

3. Vane Syndrome: Also known as ‘vane passing syndrome’, this type of cavitation occurs when either the impeller used has too large a diameter, or the housing has too thick a coating. Either or both of these creates less space within the housing itself. When this happens, the small amount of free space creates increased velocity in the liquid, which in turn leads to lower pressure. This lower pressure heats the liquid, creating cavitation bubbles.

4. Internal Re-circulation: In this instance, the pump cannot discharge at the proper rate and so the liquid is re-circulated around the impeller. The liquid travels through low and high pressure zones resulting in heat and high velocity. The end result? Vaporised bubbles. Common cause for this, is when a discharge valve has been close while the pump is running.

5. Air Aspiration Cavitation: Another common form. Air can sometimes be sucked into a pump through failing valves or other weak points such as joint rings. Once inside, the air has nowhere to go but along for the ride. As the liquid is swished around, the air forms bubbles which then gets popped under pressure by the impeller.

As with any structural or mechanical issue, it’s important to have a reliable maintenance process. Checking on components and the performance of your pump is a great way to identify early warning signs of cavitation.

Decreased Flow or Pressure: If your pump is not producing the amount of flow as stated by the manufacturer, this could mean that cavitation is occurring.

Erratic Power Consumption: If bubbles are forming around the impeller, or the impeller itself has already started to fail, you may notice that your pump requires more power than usual to transport its media. You may also notice fluctuations of power use as suction rises and falls depending on how the impeller is performing.

Noise: If there’s one sign of cavitation, it’s noise. When the bubbles implode they can make a series of bubbling, cracking, sounds. Alternatively, it might sound like tiny marbles or ball bearings rattling around inside the impeller housing.

In addition to the above, operating a centrifugal pump to the far right of the BEP (or off the end of curve) can cause cavitation. When the flow increases, Net Positive Suction Head required (NPSHr) also increases and when the NPSHr exceeds the Net Positive Suction Head available (NPSHa), cavitation occurs.

Now that you know what to look for, and understand the different types of cavitation you might encounter, you can formulate a plan to prevent cavitation, saving large amounts in maintenance and replacement parts.

Ensure you are not exceeding your pump’s manufacturer performance guidelines. A pump system which is pushed too hard will inevitably fail. Such as running the pump off the end of the performance curve. It is best to increase

Preventing vane passing or vane syndrome cavitation is relatively easy. Ensure that the free space between your impeller and its housing is 4% of your impeller’s diameter or more. Any less and cavitation will begin.

This can be a tricky one to prevent. Even the smallest amount of air being sucked into the system could over time cause cavitation. Going over your installation with a fine tooth comb to make sure all joints and connections are sealed properly, is the best approach.

By preventing cavitation, you will significantly increase the efficiency and lifespan of your pump. Remember, prevention is worth a thousand cures, so take the time to carry out a thorough maintenance program and it will save you in the long run.

If you need any help identifying which components you need for your system, don’t hesitate to contact one of our pump experts, be assured with the best advice from Global Pumps, Australia"s Most Trusted Industrial Pump Provider.

Detect a failing pump before it becomes a major problem: Learn about Condition Monitoring for Pumps and other Rotating Equipment. Global Pumps provide the latest remote condition monitoring technology available in Australia.

With the NPSHr rating supplied with the pump, engineers only need to calculate the NPSHa on their own. Anyone can do this with the formula shown below:

HA is the atmospheric pressure affecting the surface of the liquid while it’s in the supply tank. Unless the system involves a closed tank, this is likely the local absolute pressure based on altitude. HZ measures the amount of vertical distance the slurry travels between the supply tank and the pump’s center line. Work from the lowest point the liquid can reach in the tank since draining the volume changes the NPSHa. HF accounts for friction caused by the piping between the tank and pump. Friction coefficients are recorded for most standard piping materials. HV reflects the velocity of the head found at the suction port. Many engineers leave this measurement out since it’s often very small. Finally, insert the HVP into the formula by measuring the vapor pressure of the liquid, which is based on its pumping temperature. Temperature fluctuates in many slurry pumping operations, so use the highest temperature since that will reflect the highest vapor pressure as well.

By using a simple formula to properly size slurry pumps with NPSH, users can keep them running for years with minimal maintenance and repairs. Preventing cavitation may take a little extra work in the beginning, but it will pay off for the entire lifespan of the slurry pump.

Through different hydrodynamic principles, EDDY Pump technology overcomes obstacles including cavitation/NPSH loss, seal failure and clogging. Cavitation, which affects a pump’s ability to deliver high percent solids while maintaining high production rates, is a constant problem in mining and other slurry pumping applications. Through different hydrodynamic principles, EDDY Pump technology can overcome cavitation, so the pump does not suffer from loss of suction or performance.

This phenomenon is accomplished through the synchronized eddy effect generated by the geometrically shaped rotor acting in sync with the hydrodynamic pattern of the volute. Tests show that there is no evidence of cavitation at speeds up to 2,000-rpm. The cumulative effect of this energy gives this pump a greater head than many pumps and the ability to pump more concentrated material over longer distances.

Instead of operating with an impeller, the EDDY Pump uses a patented rotor design, which can avoid wear and tear much longer than many traditional impellers commonly found in centrifugal and other pumps. Due to the shape of the rotor and larger tolerance between the volute, the pump ensures less abusive contact with the pumping material. Wearing plates and wear rings are also not needed to regulate efficiency, which eliminates the problem of wear rings coming into contact. When wear rings contact, it generates a high amount of friction, which produces heat that causes the rings to gall (friction weld). When galling occurs, the pump can seize.