centrifugal pump mechanical seal leaking

0000007625 00000 n 0000001288 00000 n Insufficient Net Positive Suction Head (NPSH): If you don’t have enough suction head to your pump, the rotating assembly can become unstable, cause cavitation, and result in a seal failure. The leak was not severe and only a drop a second was seen leaking. Mechanical packing, a fibrous material usually impregnated with a lubricant such as graphite, was cut into sections and stuffed down what was called a “stuffing box.” A packing gland was then added to the backside in order to pack everything down. Check rings for the following: Embedded Solids See if the solids are embedded in all the rings. These devices preserve the integrity of the pump systems by preventing fluid leaks and keeping contaminants out. The centrifugal pump spins a shaft at high speed which rotates an impeller, creating a vacuum through centrifugal force that pulls the water. All seals leak—they have to in order to maintain a fluid film over the entire mechanical seal face. 0000001649 00000 n ALLOWING THE PUMP TO RUN DRY Allowing your pump to run dry can be very damaging to a mechanical seal. Mechanical Seals primarily prevent leakage around the Shaft of a pump by mating the flat face of a ring-shaped Rotating Seal to the flat face of a ring-shaped Stationary Seal. This article will explain what a mechanical seal is and the key design features that make them work. It reduces leakage between the pump and the surroundings to an absolute minimum. If the pump has a motor, on the backside of the motor the shaft has either a screwdriver slot or double flats for holding the shaft during impeller removal. A mechanical seal or compressed packing is used to prevent liquid under pressure inside the pump from leaking out of the pump to atmosphere. Read on for a basic understanding of mechanical seals, and how they differ from packing. Last, keep an eye out for face distortions from pressure or heat, since a mechanical seal under great pressure will actually bow, and the skewed profile can cause a leak. You need to take the Length of Straight Pipe at Suction into account—some older pump systems that often came as a packaged skid include a 90º elbow at suction right before the flow enters the impeller eye. 2. This pump minimizes leakage with a Mechanical Seal. As mentioned the mechanical seals will not block the leakage completely, thus the pump will always have a leakage. Here are a few tips for How to install the mechanical seal in a centrifugal pump. We have pumps for every industry and application, and the experience to help you make the best decision. Experts say that several types of damages can occur. The obvious function of our Centrifugal Pump Mechanical Seals is that of a check valve to prevent liquid under pressure from leaking out of the pump, or from drawing air into the pump when under vacuum conditions. Mechanical seals are usually end-face seals or rotating-face seals, but in some designs they can be circumferential or even a hybrid of lip-type seals. For example, auxiliary systems are sometimes required to provide an acceptable operating environment for a mechanical seal. Pumps are specially designed and manufactured to cater for a whole range of different applications. Do you have a good tribological (the study of friction) pair? Therefore, the test machine mechanical seal leakage, in the exclusion of the shaft and the end of the seal after the entry into force, are basically due to moving and static ring friction caused by damage. Performance Issues? Mechanical seal systems are used on various seal designs to detect leakage, control the seal environment and lubricate secondary seals. ����JgUr�z+�d�ڷ�M7�1�����L��T�é�[`;%�O�Ґ�)Aя}�!�"Qk{�i`�.B����lޚ����K�*6X�P�H�E�)p(aC�����&1u�l�[�('��&,N �. 2 If a mechanical seal is stored installed in a centrifugal pump, the preparation and storage conditions for both components must be considered together. A seal with defects in the face or other components will typically leak at startup. I recently attended the Turbomachinery and Pump Symposium, produced by the Texas A&M Turbomachinery Lab. Mechanical seal After a static test, high-speed rotation during operation to produce centrifugal force, will inhibit the fluid leakage. A centrifugal pump uses the principle of centrifugal force to move water through plumbing systems and hoses. The obvious function is that of a check valve to prevent liquid under pressure from leaking out of the pump, or from drawing air into the pump when under vacuum conditions. You need a proper seal flush arrangement, along with sufficient cooling. It could take several rounds of investigation to identify the true root cause of a packing issue. hެX�nE��W�2A�vW�{I����J,�,��΃k��$��眪��IH����~��ԩ�{>�}{!����Ɖ�'ݵ��r���Ŀ��j�iz3�{���D7s��rZ�\O?����~���*������WS��&��F1_\���ֳ;\Og��-�X����Vsw��L�"��ɇ�w�ӓ{�/��n^.ώ����]bx���;h6���q��X��}\��_�=�t/o܏��Օ��/���U��֦wƐ|���P����}�����i��䛤��訡;?T��p��S�|���au����)5/��G|��՚���A�m�����U��!�U=5ׇ)�V ���ߋ�p�w�+��'�=vO���g C�ʳt�����uA|�6�R|���X3� ����A}��|a!�V�EÜdۗ]�})��Z���t=�}+����8�>^=��}����������r��������ww��\܃��rܚ@�Kj��'k�R.v಺V���3C|���;��d7��C��n�f����3���3@Uݟӌtj�Qp_��ϥ����g��Z���f����p���:���� They assist in sealing the rotating component of the shaft alongside the stationary component/part of centrifugal pump housing. And last, check the bearings. Since our subject is dealing with pumps, let’s first explore a basic understanding of the need to seal a process liquid in a centrifugal pump. Bearings have short life 15. Priming – Casing and suction line not completely filled with liquid. They’re responsible for leaks and failures of the system, but they also indicate problems that would eventually cause serious damage down the road. The flow that goes into the pump has to go out of the pump. mechanical seal, this thin liquid film, of necessity, leaks to the low pressure side of the seal, usually outside the pump. A mechanical seal is a device that is used to control leakage between a rotating shaft and a liquid- or gas-filled vessel. Mechanical Seals and Packed Shaft Seals. 0000001761 00000 n Dirt or contamination in between the mechanical seals. Mechanical seals vs. pump packing? That water, necessary to lubricate and cool the shaft, will leak either into the process or into the atmosphere. Mechanical seals play a critical role in the centrifugal pump. Due to the rotation of the impeller, centrifugal force generates, and vacuum is created. The pump imparts head (or pressure), which means it increases the energy of the pump fluid. 0000000991 00000 n Anyone who works with pump sales and engineering knows that when any kind of anomaly occurs anywhere in the system, it’s got to be the pumps fault. The rotating part is axially pressed against the stationary part. Mechanical seal After a static test, high-speed rotation during operation to produce centrifugal force, will inhibit the fluid leakage. x�b```e``z�����������b�@̱P@��9g R'"���L�����"�q"DΠf���4 ���fIcc��n b`�6��A,�d�c�2 :ā���-� K+�2�; �����|�@�c`�l�L@l�RL� >#�0 %f#� endstream endobj 28 0 obj <> endobj 29 0 obj <> endobj 30 0 obj <>/Font<>/ProcSet[/PDF/Text]/Properties<>/ExtGState<>>> endobj 31 0 obj <> endobj 32 0 obj [/ICCBased 40 0 R] endobj 33 0 obj <> endobj 34 0 obj <> endobj 35 0 obj <>stream 610 and 682) Presented By Prakash Kumar ME(NSPL) CONTENTS OF PRESENTATION BRIEF ABOUT CENTRIFUGAL PUMPS AS PER Std .API 610 . Depending on the pump type and the process variables, … Magnatex 3596 Series pumps and spare parts come with a 5-year unconditional warranty on materials and workmanship. Shaft misalignment, coupling imbalance, and impeller imbalance can all contribute to mechanical seal failures. direct the flush water away from the process to avoid contamination. thanks The more common end- or rotating-face mechanical seal designs feature mating faces as the primary sealing elements. The pump and seals must be dried before storage. A centrifugal pump with a mechanical seal cartridge is disclosed. The pump has a pump casing, a rotatable drive shaft extending into the casing from the rear side, and an open impeller mounted on the drive shaft, this impeller having radially extending vanes with leading and trailing edges. Certain component failures of a centrifugal pump, such as coupling, hydraulic, static joints, and bearings, will cause the whole system to fail, but approximately sixty-nine percent of all pump failures result from the sealing device malfunctioning. As the flow enters through the impeller eye of the pump and up the impeller vanes, the fluid is at a lower pressure and low velocity. Dual systems have barrier fluids; the auxiliary seal pot needs to be in the right location, with the correct instrumentation and piping. It has two basic components: A stationery ring that is secured in the seal gland. Though it is a rare occurrence, the eventualities are critical if it happens. (2) When the sealing end face is installed, not clean it up and contain granular impurities. Suitable for many different fluids in a variety of in-dustries and processes, it is capable of handling low, medium and high flow volumes. However, at times, they cause problems due to leakage. So we have a centrifugal pump mechanical seal failure the other day. Mechanical Seals primarily prevent leakage around the Shaft of a pump by mating the flat face of a ring-shaped Rotating Seal to the flat face of a ring-shaped Stationary Seal. Learn the basics of mechanical seal application and how they perform compared to traditional packing. 0000004933 00000 n Its main responsibility is to control leakage. The mechanical seal will soon fail if the pump continues to run in this condition. Here are a few tips for How to install the mechanical seal in a centrifugal pump. © © 2020 Highlands Publications, Inc. All Rights Reserved. Mechanical seals are used in most oilfield centrifugal pumps. A thin layer of the pumped liquid is always between the two faces to lubricate and cool the seal. The elbow causes a turbulent flow that creates instabilities in the rotating assembly. Shaft or sleeve wear Pump overheats, seizes, or both 18. Your pump seal is probably to blame. If a mechanical seal is stored installed in a centrifugal pump, the preparation and storage conditions for both components must be considered together. CP’s ceramic lined double mechanical seal centrifugal pump is engineered to meet the most stringent quality standards and ensure reliability and utmost safety in production opera-tions. Other miscellaneous factors account for only about 8 percent of all failures. You also need to avoid a bad base: Is the base secure? Operating Dead-Headed: If you set the control valve too low to throttle the pump, you can choke the flow. All the suction/discharge and bypass piping needs to be engineered correctly as well, especially if some pipes have been repaired at some point over the years. 0000007815 00000 n Mechanical seals vs. pump packing? Expellers can also be more cost-effective than mechanical seals and, since repairing mechanical seals can cost up to 60% of the installation, price is a factor for many. MECHANICAL SHAFT SEAL A mechanical shaft seal … ____________________________________________MODERN PUMPING TODAY, July 2016Did you enjoy this article?Subscribe to the FREE Digital Edition of Modern Pumping Today Magazine! WHY DO PUMPS NEED TO BE SEALED? Seals and Sealing Handbook, Fifth Edition. Choked flow causes recirculation within the pump, which generates heat and promotes a seal failure. Speed too … A seal leak that develops after some period of use is normally caused by an application related factor. However, for most users, addressing one of the first four categories will hold the solution they need. Centrifugal Pump Mechanical Seal and Bearing Reliability Optimization @inproceedings{Makarachi2014CentrifugalPM, title={Centrifugal Pump Mechanical Seal and Bearing Reliability Optimization}, author={P. Makarachi and Mohammad Pourgol-Mohammad}, year={2014} } TIPS TO PREVENT MECHANICAL SEAL LEAKAGE IN A CENTRIFUGAL PUMP • Mechanical seals play a critical role in the centrifugal pump. In order to understand centrifugal pump leakage, it’s important to first understand the basic operation of a centrifugal pump. The flow then exits through the discharge, at which point the pressure is high but the velocity slows. Application Data Sheet Pipeline Leak Detection Description: Flow and liquid level detection in drain line systems. The mechanical seal is the shaft seal device of the centrifugal pump, which has the advantages of small leakage and long life. It has a shaft that spins at great speed and rotates an impeller. prevent the flush water from collecting on the floor (overspray), which is both an OSHA concern and a housekeeping concern. Fluid enters a centrifugal pump through the suction nozzle at the center of a rotating impeller. A mechanical seal is a device that is used to control leakage between a rotating shaft and a liquid- or gas-filled vessel. 1. Process Pump & Seal, Inc. is your local distributor of Centrifugal Pumps. A mechanical seal is a device that uses the centrifugal force to push water through the hoses and plumbing system. This article teaches you how to replace the mechanical seal. 1.Mechanical seal failure phenomenon and analysis Pump mechanical seals are available in a wide variety of models, there are five main leak points: (1) Seal between bushing and shaft. Scot Pump replacement parts, seal kits and repair kits keep your Scot Pump in prime condition. Mechanical seals are used in centrifugal pumps to keep water or any liquid from making contact with the delicate parts of the machine. No Water Delivered. While mechanical seals can range in price from $6,000 to $40,000, stuffing boxes range from $500 to $3,000, depending on shaft size. Lubrication selection guidelines Most pumps are lubricated with rust and oxidation inhibited oils (R&O) that also have small amounts of antifoam and demulsifier additives. Magnatex expeller/repeller design pumps are used in applications where there is a possibility of dry run conditions, liquid slurries up to 40% or crystallizing liquids, all of which are damaging to mechanical seals or packing. All Single Mechanical Seals leak—they have to in order to maintain a fluid film over the entire mechanical seal face. The leakage that comes out the atmospheric side is VERY low. Seal Failure Is Usually An Indication of Problems Other Than The Mechanical Seal. Contact Centritec Seals for more information on our centrifugal seal manufacturer services, or … Slide the mechanical seal along the shaft but be careful … Due to the rotation of the impeller, centrifugal force generates, and vacuum is created. The pump was started again to see if the seal leaks during running but it did not. Depending on your application, you may need to: As with every pump, you’ll want to test your pump to discover the annual costs it requires to run. Mechanical seal has short life 13. An off-design operation within the mechanical seals. Every centrifugal pump must accommodate a spinning shaft while mechanically maintaining fluid or gas contained in the “wet end” of the pump. … Problem: Pumps require a form of mechanical seal, these seals will eventually break down and leak. 0000003871 00000 n 0000004412 00000 n They eliminate the need for gland water that stuffing boxes require, minimizing water consumption and offering significant savings as some don’t require flush water. An eroded, worn, or fretted dynamic o-ring (or gasket) as the mechanical seal moves. Introduction The mechanical seal acts as a check valve and a slider bearing. Mechanical seal systems are used on various seal designs to detect leakage, control the seal environment and lubricate secondary seals. Call us today ! Seals are ubiquitous, in industry, the home, transport and many other places. Double mechanical seals Back-to-Back are generally selected where pumped liquid is absolutely not allowed to leak from the pump. Determining the point of failure is achieved by routine monitoring of the seal. Corpus ID: 34398568. They are situated on the shaft of the motor. Description. Fluid enters a centrifugal pump through the suction nozzle at the center of a rotating impeller. Have you chosen the correct facing combinations? need to be stored separately from the pump. The causes of centrifugal pump mechanical seal leakage are analyzed as follows: 1.Leakage during static pressure test (1) The sealing end face is damaged, deformed or damaged during installation. It has two basic components: A stationery ring that is secured in the seal … The leak was not severe and only a drop a second was seen leaking. Seal reliability is greatly affected by the seal design and the operating environment. I’ve been attending this conference off and on for 25 years and always sit in on the discussion groups for pump users and mechanical seal users. Due to the rotation of the impeller, centrifugal force generates, and vacuum is created. The mechanical seal leaked when the pump was stopped (Not immediately after stopping but after 1/2 an hours time. Know about Mechanical Seal in a Centrifugal Pump. Choose a replacement seal or contact us for help finding the right part for your pump. The atmospheric side must not enter into the seal chamber. This video will show you how to safely and properly replace a pump seal. Centritec Seals' operations result is significantly lower operating temperatures of the lubricating fluid, the bearings, and the components within the contained mechanical shaft seal housing. Mechanical seals are a major factor in rotating equipment reliability. During the test run, the pump is not filled with water or the external water supply is not opened to the machine to start the pump operation, or the water is running during use; the pump is checked. These lapped faces run against each other, one rotating with the shaft and the other stationary with the equipment housing. The same topics come up year after year. Regular maintenance of these seals is needed to ensure there are no leaks. In this case, the mechanical seals should be stored in accordance with Storage of Mechanical Seals in Their Original Packaging. This may indicate the following: 1. Frank Rotello is mechanical seal reliability engineer for Cummins-Wagner. Mechanical Seals and Packed Shaft Seals. Before mechanical seals were developed, engineers typically sealed a pump with mechanical packing. If the tolerance of the bearings wears thin, the shafts will move and cause vibrations in the pump. Rings of ceramic, carbide, carbon or composites of these materials are lapped flat in the range of less than 1 micron on an axial end face. If you have improper venting, air can get trapped around the seal and won’t be able to evacuate the stuffing box. Place a new mechanical seal onto the shaft. Other times, failure is a result of poor selection or installation errors. Tips to prevent Mechanical Seal Leakage in a Centrifugal Pump. It has a shaft that spins at great speed and rotates an impeller. Is it grouted properly? The leakage that comes out the atmospheric side is fairly low; the leakage in a Hydrocarbon, for example, is measured by a VOC meter in parts/million.Before mechani… In many cases, the centrifugal pumps are perfor-mance tested or hydrostatic tested on water prior to storage. %PDF-1.4 %���� There simply isn't sufficient space between the two flat surfaces to leak … This pump minimizes leakage with a Mechanical Seal. Mechanical seals are critical components in centrifugal pump systems. All seals leak—they have to in order to maintain a fluid film over the entire mechanical seal face. 27 0 obj <> endobj xref 27 18 0000000016 00000 n A mechanical shaft seal is made up of a stationary face and a rotating face. Loud blow is heard each time pump is started or stopped 20. Low Vapor Margin: These are flashing fluids; hot hydrocarbons will flash once exposed to atmospheric conditions. Mechanical Seals in Centrifugal Pumps. Tag the removal order of each ring and bag up each packing sample, noting the date and MTBF. A mechanical seal pump could potentially save you a lot of annual costs. protect the bearing box from flush water, which can contaminate the oil and eventually lead to a bearing failure. 0000001121 00000 n Which is the best and most effective sealing technology for your pump or agitator application? Leak during test run. What about the seal face material quality? Seal leak can be In addition, after the pump is installed, if you have misaligned pipes bolted to it, you will impart a lot of strain on the pump. 0000000910 00000 n CASE STUDY ON MECHANICAL SEAL DURING COMMISSIONING OF NSPL PUMP AFTER MOH. The pumping fluid is hot water. Your springs should not be clogged or your bellows corroded. When you operate the pump outside that region, you create problems with the flow that cause the system to fail. The leakage that comes out the atmospheric side is fairly low; the leakage in a Hydrocarbon, for example, is measured by a VOC meter in parts/million. As you remove the rings from the stuffing box, try to keep the rings in removal order to best determine the failure mode. Causes and solutions for leakage of mechanical seals: 1. Basics of fluid pump sealing. The reliability of any centrifugal pump in a critical application is strongly influenced by the performance of the mechanical seals. As the fluid film passes across the mechanical seal, it can flash at the atmospheric side and cause a failure. Double mechanical seals in Series are chosen where the pumped liquid may escape the pump toward the pump exterior but it is controlled and contained in the closed seal loop but never to escape to the atmosphere. 0000004223 00000 n A mechanical seal is a device that uses the centrifugal force to push water through the hoses and plumbing system. A mechanical seal is simply a method of containing fluid within a vessel (typically pumps, mixers, etc.) Leak during test run. Packing seals are removed and replaced much more often than mechanical seals, which causes considerable wear and tear to the pumps as they are disassembled and reassembled.

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