Crosssection and schematic of a canned motor pump showing monitoring components of a radial monitoring system. The pump has a thrust balancing mechanism comprising of a rotating thrust disk and a stationary carbon ring. Standard pumps are produced with the pump and motor located separately and, because they must be coupled for use, the liquid they handle can leak outside the pump from the gaps in the casing through which the rotating axis passes. Centrifugal pumps are one of the worlds most widely used type of pump, having an extensive. The pump is not connected to the motor causing leakage. In the canned motor pump, the pump and motor form a single unit. The canned motor pump comprises a motor stator, a stator can disposed radially inwardly of the motor stator and in which a fluid passage of a main flow of a pumped fluid is defined, a rotatable shaft, a motor rotor fixedly supported on an end of the rotatable shaft and disposed. This element is also described as the containment cup or can. In use, the centrifugal canned motor pump implements flow rates up to 1,200 m. Failure of the existing pumps was caused by excessive bearing wear. Goulds vertical turbine pumps 3 goulds vertical turbine pumpsev v pump bowl assembly the bowl assembly is the heart of the vertical turbine pump. Canned motor pump is a centrifugal pump with pump and hermetically sealed electric motor mounted on single shaft thus eliminating the requirement of mechanical seal or other sealing device. Technical report canned motor pumps in compliance with api 685 a contribution to environmental protection dr. These problems, which include both mechanical and hydraulic problems.
Bearing monitor features mth bearing monitors take the guess work out of operating a canned motor pump. The pump basically has the same construction as that of the slurry handling type pump with mechanical seal, and it features a gas chamber between the pump and motor. Page 9 restarting the motor before ascertaining the nal pressure before attempting to disassemble cause can result in excessive heat leading to the pump. Canned motor pumps feature only two, maintenancefree bearings pedestal mounted mag drive pumps have a minimum of six bearings to support all rotating components. I took all the failure causes for each failure mode off the internet by doing a web. No newcomer to the field, teikoku has provided customers with proven canned motor pumps for 40 years. Pump bearings running dry check for minimum submergence, ensure min water level is above the centerline of first stage impeller 3. Nominal motor power must be greater or equal than pump motor. Improving reliability of canned motor pumps in refrigeration. The main unit includes a main pump, an auxiliary pump and motor means positioned between the main and the auxiliary pumps for driving the pumps. Added functions, such as a directionofrotation indicator, show whether the pump is running in the wrong. In a standard centrifugal pump, the drive shaft from the motor is connected, normally via a flexible coupling, to the impeller through the pump housing. Examine pump for friction between impeller and casing.
Nikkiso is now one of the largest manufacturers of canned motor pumps in the world. In all cases the motor components are shielded from the process fluidby nonmagnetic cans with the stator can providing the primary containment of the process fluid. Databased preventative maintenance based on actual bearing condition has never been this affordable. Nikkiso canned motor pump standard type with motor cooling jacket n type duration. Originally designed for the nuclear industry, canned motor pumps over the years have been developed and. Basic bearing number stainless steel fluororesin cage radial clearance 6315 t35d c3 lng pump bearings are employed as upper and lower support bearings on the mainshaft of a motor which drives the special pumps used for receiving and. Intelligent sealless pumps a unique evolution sciencedirect. Selfpriming, canned motor pump with very low npsh sihipcx side channel pumps pcx 3. Symptoms of bearing failure include flaking, pitting, unusual wear patters, rust, corrosion, etc. Teikoku canned motor pumps designed for zero leakage services in the cpi teikoku, the worlds largest supplier of canned motor pumps presents a stateoftheart, sealless pump. For hermetically sealed centrifugal pumps with canned motor of type of protection oil immersion, the same requirements as described in section 2. For the basic type, liquid from the impeller flows back to the pump chamber. There are main problems that afflict centrifugal pumps when in use.
One size bearing, shaft sleeve and thrust washer per motor frame support the entire nc series of pumps. Refrigerant was observed leaking from the motor conduit box, requiring an immediate shutdown of the pump. Us5692886a canned motor pump having concentric bearings. They are also well suited for high pressure operations. All these conditions can lead to reduced motor life. Canned sealless centrifugal pumps h series materials limitations mth h series sealless canned motor pumps are leak proof and explosion proof because the shaft is located completely inside the pump and there are no mechanical shaft seals that can degrade and leak during operation. Leakage from the pump goes through the gear box bearing drains to the bottom of the gear case which acts as the oil reservoir. Over a three year period a large number of bearings.
The pump and motor are integrated in the sealed leakproof structure of the centrifugal canned motor pump. Overview of pump problems typically found on centrifugal pumps. In contrast to the double mechanical seal which is sealed using a separate medium, the canned motor pump does not operate independently of the pumping medium. Expanding populations and rising standards of living in both the industrial and developing countries required innovative technologies to solve the demanding and progressively urgent problems of protecting the environment. No timeconsuming maintenance no motor and pedestal bearing lubrication levels to be continually monitored and maintained. The pump size, tank size, and other controls should be selected to keep the starts per day as low as practical for longest life.
Sep 01, 2008 canned motor pumps, therefore, are fully hermetic pump units. The pump is completely separated from the motor by a gas chamber, which ends concern over wear and corrosion of the mechanical seal caused by the pumped liquid and ensures a long. The rotor and impeller are mounted on a single shaft. Hti designed, manufactured and supplied canned motor type primary coolant pumps for nuclear reactor nr flowing water test loops at a us national laboratory. Each teikoku canned motor pump comes with the patented teikoku rotary guardian trg an electrical meter that continuously monitors both axial and radial wear. Selfpriming, canned motor pump with very low npsh sihipcx. This email address is being protected from spambots. Nikkiso company limited, a pioneer in canned motor pumps, began production in japan beginning in 1957. The pump has a secondary impeller which takes suction from main discharge. Failure analysis a guide to analyzing axial piston pump failures oilgear company milwaukee, usa 80776, rev. Innomag tbmag sealless thrustbalanced process pumps. The pump section can be of single or multistage design. A pair of axially spaced stationary thrust sliding surfaces is mounted on the bearing housing, and a pair of axially spaced rotating thrust sliding surfaces are mounted on the rotor in confronting relationship to.
Electrical explosion protection the canned motor is designed in type of protection oil immersion o according to en 600796. Why centrifugal pumps break shafts and how to prevent it. Hydraulic gear pump and motor failure analysis and repair. Try to get that from your current ansi sealed or mag drive pump supplier. If it wants couple a motor and a pump, bought separately, it must respect a following prescriptions. These bearings must be checked frequently for proper lubrication and critical tolerance dimensions. The cause and analysis of bearing and shaft failures in electric motors by austin h. Alfa laval solutions to specific centrifugal pump problems 31 how alfa laval can provide solutions to specific pump problems. Teikoku canned motor pumps playing a role in various situations around the globe teikoku electric, the worlds leading canned motor pump manufacturer pumpproduct linesteikoku electric mfg. High speed bearing wear rate measurements for spacecraft.
The loss of motor bearings in this continuous operation resulted in large unexpected maintenance and downtime costs. Lightning and power surge damage are major causes of submersible motor failures, so a threephase lightning arrestor is a must. Sealless pumps with leakproof construction with the pump and motor integrated into one housing. A closed or tightly throttled discharge valve may reduce the pump flow rate to an unsatisfactory operating point. Permanent magnets are located on the drive and pump shafts. Broken shaft or shaft enclosing tube disassemble pump. Styles include magnetic drive pumps and canned motor pumps as well as the peristalic hose or flexible tube pump. Useful information on magnetic drive pumps what are magnetic drive pumps. Figure 5 shows a lube oil pump mounted to an otherwise unused shaft of a 600 hp 450 kw speed reducer. Innomag is just a fraction of the cost and lead time of a metallic mag drive, canned motor pump, or high alloy pump with double seals and flush plan. The loops are designed to test reactor fuel and structural.
Over 400,000 units have been installed worldwide, covering every. Introduction bearing failures account for the majority 50% to 65% of all motor failures in industrial applications 6. Now you can get engineered, canned motor pumps at a price comparable to mechanical seal pumps. Canned motor pump is a centrifugal pump with pump and hermetically sealed electric motor mounted on single shaft thus eliminating the requirement. The trg indicates any serious malfunction of the pump before a failure occurs. This feature makes canned motor pumps the choice for lethal or extremely hazardous applications. The recirculation line is positioned external of the main unit, and is connected thereto between the pumps. It is impossible to say which will fail more often, it will depend on the installation. Standard api pump ra tios range from 35 to over 200. The impeller and diffuser type casing are designed to deliver the head and capacity that your system requires in the most efficient way possible. In the block design, the motor shaft carries the external magnet rotor, which transfers the magnet forces through the containment cup to the internal magnet rotor. Accessories several accessories are available to up grade canned motor pump installations.
Mechanical seal failure bushing and journal failure in magnetic drive and canned motor pumps see figure 2 sharp temperature rises in conductive containment shells no flowminimum flow. The pump and motor are connected by an adapter plate. You can bend the shaft until it breaks though not inside any centrifugal pump weve ever seen. Sealless pumps completely sealed rotary pumps are available from a number of manufacturers. Windmilling and thrust bearing performance analysis for multi pump nuclear test loop hayward tyler, inc. Nikkiso nonseal centrifugal canned motor pump lewa. Side channel pumps selfpriming, canned motor pump with very low npsh sihipcx side channel pumps pcx 3. Adequate precautions must be taken premature failure. The lists in the spreadsheet were put together by researching the web for centrifugal pump failure causes, including failure modes of components in the wetend, the bearing housing, the drive coupling, the electric drive motor and the base with foundations.
In our ebook 36 ways to kill your pump, we uncover several reasons why bearings fail prematurely. Windmilling and thrust bearing performance analysis for. Canned motor pump is a centrifugal pump with hermetically sealed electric motor mounted on single shaft thus eliminating the requirement of mechanical seal or other sealing device. Interchangeable bearings designed to withstand momentary cavitation or. Canned motor pumps in compliance with api 685 a contribution to environmental protection dr. A bearing device for use in a canned motor includes a bearing housing detachably mounted on a motor frame of the canned motor, and a radial bearing supported by. Entire rotating assembly is immersed in the liquid, and motor stator and rotor are isolated from the pumped liquid with corrosion resistant, nonmagnetic liner and. Sealless pumps, such as magneticdriven and canned motor pumps, are becoming more common in the petrochemical and power industries for their enhanced reliability and reduced leakage. Thermal motor protection a thermal cutout tco on the motor windings prevents motor damage due to excessive heat.
Traditionally, pump manufacturers used sic silicon carbide for bushings and bearings in these pumps because of its high hardness and ability to withstand. A canned motor pump has relative small size and low output power for use in, for example, circulating warm water. Bearings within the single containment shell of mag drive pumps cannot be monitored. Pump failures result in operational changes that reduce efficiency or result in a breakdown of the pump. Faulty seals can cause a process shutdown upon failure. The pump and motor are connected and sealed to prevent leakage. List of centifugal pump set failure modes, pump failure. One such device, which provides continuous monitoring of radial bearing wear in canned motor pumps is show in figure 1. All pump casing are adaptable to any size motor frame. Microsoft powerpoint cmp iom presentation 2009 teikoku author. Canned motor pumps are usually available in a range of configurations that are designed to for the process lubricated bearings. Kbl canned motor pumps are developed, based on the technical knowhow from nikkiso co.
A canned motor pump pressurized recirculation system which comprises a main unit and a recirculation line. By the 1960s, canned motor pumps had evolved to the point of standardization. A serious dc motor bearing failure problem in a paper manufacturing operation prompted us to begin research into this subject. Originally developed for the nuclear industry, the centrifu. Canned motor pumps nonseal sleeve tungsten carbide coated bearing carbon graphite silicon carbide lining thrust washer tungsten carbide coated shaft unit can be integrated in a process control system via a 4 to 20 ma signal. Because these units have no motor fans or ball bearings, and the shaft is completely enclosed, sealless canned motor pumps have a very low noise output below 60dba and very little vibration. The dynapump le even includes a built in bearing wear monitor standard. The pump impeller or impellers on multistage pumps is mounted at the overhung end of a shared pump and motor shaft. The difference between a standard pump and a canned motor pump.
Shaft bent due to damage through shipment, operation, or overhaul. Misalignment is the main reason for pump damage and trip as it can cause damage to stuffing box, failure of mechanical seal, bearing premature and pump over heat or seize. The pump meets the specification of the api685 standard. Nikkiso began with the production of centrifugal canned motor pumps in 1956, making it one of the first companies in the world to produce these pumps commercially, and it continues to do so today. If you use plastic pipe, the ground wire should also be connected to a stud on the motor to obtain. A failure investigation on this pump indicated that extreme wear of the. Teikoku dynapump le series instruction manual pdf download. The arrestor is mounted in the pump panel and grounded to both ground terminals onto pump panel and well head. Pump operating life never exceeded 1500 hours in spite of repeated attempts to identify the problems by both the manufacturer and the laboratory. Any static overload or severe impact can cause brinelling. Nikkiso nonseal, a regi s tered trade mark, is another commonly used term for canned motor pumps. Us5385454a bearing device for use in a canned motor. A bearing device for use in a canned motor includes a bearing housing detachably mounted on a motor frame of the canned motor, and a radial bearing supported by the bearing housing. Mckee, gareth forbes, ilyas mazhar, rodney entwistle and ian howard curtin university, western australia summary.
Electrical problems such as mentioned from vfds will cause motor failures, but could also cause pump bearing failures if the shaft current grounds through the pump instead. Canned motor pumps canned motors have a wide range of applications such as the primary driver for pumps, mixers and compressors. These complicating factors aligned in an unfortunate way on the international space station in 2010 and led to the premature failure of one of two active thermal control pumps used to maintain heat balance within the habitable volume. How to survive alone in the wilderness for 1 week eastern woodlands duration. Us4616980a canned motor pumps pressurized recirculation.
When you need them with justintime order fulfillment. Lower packaging and installation costs can also make innomag 20 30% less than even a more standard process pump. Sep 01, 2016 in contrast to canned motor pumps, a magnetically coupled pumps motor is not in the pumping medium. A resilient member such as an oring is interposed between the motor frame and the bearing housing for holding the bearing housing in radial position with respect to the motor frame. In the past few years with the wide use of pwm inverter drives, motor bearing failures have increased. True secondary containment design makes it virtually. Nikkiso canned motor pump function of axial thrust balance.