192.185.81.202. To address these situations, the seal industry has developed configurations which incorporate two sets of sealing faces, with a clean barrier fluid injected between these two sets of seal faces. A mechanical seal consists of 2 principle components. These keywords were added by machine and not by the authors. Mechanical seals dependent on the direction of rotation are all those . Proper spring compression check (‘working height’) – obtain dimension from seal drawing which shows the distance between the back of the seal retainer and the seal chamber face. [Map it! Later, he moved to Kentucky where he went to work for Wausau Paper as Maintenance Team Leader on a new mill start-up. By adjusting the spring groove, spring size, wire diameter and … Primary sealing ring and mating ring. Hardware consisting mainly of spring and retainer. These are very close tolerance and will not withstand misalignment for long if at all. Can small deposits of solids form ahead of the secondary sealing member? Over compression of the seal face will result in premature wear. © 2020 Springer Nature Switzerland AG. Mechanical seals are widely considered superior to the other forms of shaft seals employed in centrifugal pumps, particularly packed stuffing boxes and breakdown-type seals. Assemble the mechanical seal into the pump and tighten, checking for alignment with the scribed mark, as in Step 2. Stationary component; commonly referred to as the seat. The features of this seal arrangement are: The other multiple seal configuration is called a Tandem (dual unpressurized) arrangement, where the two individual seals are positioned in the same direction. Advantages are that they are inexpensive and commercially available in a wide range of sizes and configurations. (For immediate consideration), Spring compression (usually) provides initial face pressure. Pressure: The proper type of seal, balanced or unbalanced, is based on the pressure on the seal and on the seal size. One component is stationary and the other rotates against it to achieve a seal (Figure 2). The cost of these seals can range from $1000 to $3000 per inch of shaft diameter. Remove the centering tabs only when the gland is fully tightened and the seal … 8). The seal between the rotating (3) and stationary faces (1). 3. This pressure is maintained when the seal is at rest via the spring(s) thus preventing leakage between the faces. Measure both seal heads and spring x 0.5 = OP HT * Please note: Do not include seat height measurements. When the spring mechanism of the mechanical seal is immersed in this unclean fluid, dirt collects between the springs. Most pump shafts today are sealed by means of mechanical seals. Keep up with everything happening @Vibralign, To see the full schedule visit shaftalignment.net ». The pumped media creates a fluid film between the two faces and prevents the dynamic face from actually touching the static face and prevents dry running from damaging the seal. Years ago, most pump shafts were sealed using rings of soft packing, compressed by a packing gland, but this type of shaft seal required a fair amount of leakage just to lubricate the packing and keep it cool. Secondary seals consisting of O-rings or other suitable gaskets. Mechanical seals for rotating shaft applications move the point of the seal away from the shaft to specially designed sealing faces that gradually wear down. Through a process of elimination, match the types and measurement gathered in steps 1 – 5 to determine mechanical seal … This is where Mac was first introduced to VibrAlign. The decision to choose between a double or single seal comes down to the initial cost to purchase the seal vs. the cost of operation, maintenance and downtime caused by the seal, plus the environmental and user plant emission standards for leakage from the seal. Even though these mechanical seal faces also require some (very small) leakage across the faces, to form a hydrodynamic film, this leakage normally evaporates and is not noticeable. Not affiliated 5. 2. Then came the development of the “mechanical seal,” which accomplishes the job of restraining product leakage around the pump shaft with two very flat surfaces (one stationary and one rotating). This is known as the primary seal. Primary seal face wear is typically accommodated by welded metal or elastomeric bellows which move to assist in the compression of the rotary to stationary seal faces. The seal between the rotating (3) and stationary faces (1). By way of example, a simple mechanical seal design has 7 components (Fig 3): 1. PUSHER SEALS incorporate secondary seals that move axially along a shaft or sleeve to maintain contact at   the seal faces, to accommodate wear and to assist in the absorption of shaft misalignment. VibrAlign has given me that opportunity.”, Address This is generally correct, but there are applications for which mechanical seals represent “too much technology,” and services for which they are not suitable (see the introduction to Chap. So, lubrication is required which for simplicity, is supplied by the product media. If you have any questions you can contact our inside sales staff at 714-361-1435. For best results with double (or tandem) seals handling abrasive, the inboard seal faces should be a hard material, such as silicon carbide vs. silicon carbide, while the outboard seal faces should have maximum lubricity, such as silicon carbide vs. carbon graphite. Metal parts must be corrosion resistant, usually plated steel, bronze, stainless steel, or Hastelloy. Characteristics of the Liquid:  Abrasive liquids create excessive wear and shorten seal life. This begs for a better understanding of this seal type and its application. The first dry gas seal for a compressor was patented by Kaydon Ring & Seal in 1951 when it was known as Koppers Corporation. Over 10 million scientific documents at your fingertips. Figure 1 above shows a typical centrifugal pump, which highlights its constituent parts, including the mechanical seal. This improved design allows the seal to be in field repairable. All of our single spring seals are made of stainless steel. The seal between the gland plate and stuffing box, this is usually a gasket, or o -ring. The double seal life is virtually unaffected by process upset conditions during pump operation. Double seals, or clear liquid flushing from an external source, allow the use of mechanical seals on these difficult liquids. This process is experimental and the … Mechanical seals contain those leak paths with static seals such as … The advantages are that this seal configuration eliminates the requirement for seal setting measurements at installation. Choose from our selection of mechanical pump shaft seals, high-speed mechanical pump shaft seals, heavy duty mechanical pump shaft seals, and more. insufficient compression will result in leakage. The … Cite as. 3 of the 4 main sealing points need little explanation, but consideration is required for the sealing point between the rotating and stationary components (faces). Not logged in This design provides an ... compression … These seals have a metal case that creates a tight seal when mating with smooth surfaces. The seal between the stationary member (1) and stuffing box face, i.e. Thermal degradation of Mechanical Seal … I had always hoped to one day give back some of the knowledge I have been fortunate enough to gain from others in my field. This process is experimental and the keywords may be updated as the learning algorithm improves. A mechanical seal … It resists compression set, and its individual coils compensate for misalignment, tolerance variations, and mating surface irregularities. Gasket (2). There are many types of mechanical seal, ranging from simple single spring designs to considerably more complex cartridge seal … Mechanical seals come in a wide variety of configurations and manufacturers. A secondary sealing member is not required to make up the travel as the rotary and stationary seal faces wear. Mechanical spring … There are many types of mechanical seal, ranging from simple single spring designs to considerably more complex cartridge seal types. This flatness minimizes leakage to a degree where it is essentially negligible. A mechanical seal has 4 main sealing points (indicated by orange circles as per Figure 3): I. CARTRIDGE SEALS have the mechanical seal pre-mounted on a sleeve (including the gland). Field applications of dry gas seal designs were completed in 1952. There are multiple designs available for the mechanical seal configuration. The primary disadvantage of this seal type is that it is prone to secondary seal hang-up and fretting of the shaft or sleeve, especially when the seal is exposed to solids. distance from the gland gasket to the top of the seal. Understanding how they work will help the readers select the appropriate type for their application. Terms of Use In a non-pusher seal the secondary seal is in a static state at all times, even when the pump is in operation. The primary disadvantage is the higher cost, plus in some cases they will not fit into existing stuffing box/seal housings. Single seals do not always meet the shaft sealing requirements of today’s pumps, due to the small amount of required leakage when handling toxic or hazardous liquids; suspended abrasives or corrosives in the pumpage getting between the seal faces and causing premature wear; and/or the potential for dry operation of the seal faces. mechanical seals SETTING MECHANICAL SEALS FERP CARRARA SpA via Provinciale, 1/E - 25030 ADRO (Bs) Italy - Tel. We also have more detailed information on mechanical seals and … Then fit … A mechanical seal has 4 main sealing points: I. They fit directly over the shaft or shaft sleeve, and are available in single, double, and tandem configurations. Mechanical seals are leakage control devices, which are found on rotating equipment such as pumps and mixers to prevent the leakage of liquids and gases from escaping into the environment. And shaft or sleeve to maintain seal face contact tungsten carbide may be considered pre-mounted on a new start-up! 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