This situation eventually impacts the spring’s ability to respond to movements and vibrations, and the ability to keep the seal faces closed. Double seals and double gas barrier seals are becoming the seals of choice. The answer? However, because of the delicate components used for this new sealing method, mechanical seal failures are the greatest cause of pump down time. 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. 2. All of our single spring seals are made of stainless steel. This will determine the seal size diameter - which is either the shaft size or the sleeve size that the seal fits over. While researching several mechanical seal manufacturers to gain some insight as to what their tolerances were (they are specific to configuration and are provided with the mechanical seal), I ran across the following very good article on mechanical seal basics. The first dry gas seal for a compressor was patented by Kaydon Ring & Seal in 1951 when it was known as Koppers Corporation. There are many types of mechanical seal, ranging from simple single spring designs to considerably more complex cartridge seal … If you have any questions please contact us at: E-mail about your mechanical seals … Hardware consisting mainly of spring and retainer. (For immediate consideration), Spring compression (usually) provides initial face pressure. The primary disadvantage is the higher cost, plus in some cases they will not fit into existing stuffing box/seal housings. Assemble the mechanical seal into the pump and tighten, checking for alignment with the scribed mark, as in Step 2. Spring-Loaded Rotary Shaft Seals Also known as oil seals, use these to retain oil on rotating shafts in … Richmond, VA 23236 Temperature: Can determine the use of the sealing members as materials must be selected to handle liquid temperature. By adjusting the spring groove, spring size, wire diameter and … 530-G Southlake Blvd. The metal inner seal parts are never exposed to the liquid product being pumped, which means no need for expensive metallurgy; especially good for viscous, abrasive, or thermosetting liquids. This pressure is maintained when the seal is at rest via the spring(s) thus preventing leakage between the faces. Single spring mechanical seals for centrifugal pumps consist of two very flat faces, one rotating (dynamic) and one stationary (static), that slide against each other to form a seal; these faces are pressed together by a spring. 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. This improved design allows the seal to be in field repairable. This field is for validation purposes and should be left unchanged. The seal type and arrangement selected must meet the desired reliability, life cycle costs, and emission standards for the pump application. They fit directly over the shaft or shaft sleeve, and are available in single, double, and tandem configurations. A mechanical seal consists of 2 principle components. 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. Rather than a dynamic o-ring which can cause wear on a pump shaft, this seals … Finally, it should be noted that there are special single seal housing designs that greatly minimize the abrasives reaching the seal faces, even without an external water flush, but this is a subject for another column. Thermal degradation of Mechanical Seal … The rotating component (3) and stationary component (1) are pressed against each other, usually by means of spring force… Part of Springer Nature. 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). This begs for a better understanding of this seal type and its application. The cost of these seals can range from $1000 to $3000 per inch of shaft diameter. A mechanical seal … VibrAlign has given me that opportunity.”, Address So, lubrication is required which for simplicity, is supplied by the product media. This is a preview of subscription content, https://doi.org/10.1007/978-1-4615-6604-5_9. Pressure: The proper type of seal, balanced or unbalanced, is based on the pressure on the seal and on the seal size. 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. The advantages of this seal type are the ability to handle high and low temperature applications (metal bellows), and that it does not require a rotating secondary seal, which means it is not prone to secondary seal hang-up or shaft/sleeve fretting. Stationary component; commonly referred to as the seat. Identification of the exact liquid to be handled is the first step in seal selection. The seal between the rotating (3) and stationary faces (1). Unable to display preview. mechanical seals SETTING MECHANICAL SEALS FERP CARRARA SpA via Provinciale, 1/E - 25030 ADRO (Bs) Italy - Tel. Solids in the stuffing box, gasket protrusion or other foreign material restrict the motion of the dynamic seal ring. 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. In a non-pusher seal the secondary seal is in a static state at all times, even when the pump is in operation. Distributor of O-rings, Minnesota Quad Rings®, Hydraulic Seals, U-cups, Piston Cups, Vee Packings, Wipers, Lathe Cuts, Teflon?products, Teflon Spring Loaded & Teflon?Oil Seals, Mechanical Shaft Seals… Many early mechanical seal designs placed the spring inside the process fluid. These keywords were added by machine and not by the authors. Mating faces must also resist corrosion and wear. Then fit … Carbon, ceramic, silicon carbide or tungsten carbide may be considered. This is known as the primary seal. 8). Most pump shafts today are sealed by means of mechanical seals. A pusher seal type should not be selected if the secondary seal is likely to hang-up. Double seals, or clear liquid flushing from an external source, allow the use of mechanical seals on these difficult liquids. 192.185.81.202. 1. Metal parts must be corrosion resistant, usually plated steel, bronze, stainless steel, or Hastelloy. Because mechanical shaft seal failures are the number one cause of pump downtime, we decided to dedicate this column to mechanical seal basics. The typical features of this seal arrangement are: The proper selection of a mechanical seal can be made only if the full operating conditions are known. The rotating component (3) and stationary component (1) are pressed against each other, usually by means of spring force.The mating faces of both components are precision machined (lapped) to be extremely flat within 2 light bands, which is an optical method of measuring flatness). 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