Manufacturers of heat treating and brazing vacuum furnaces and controls, complete hot zone and vacuum furnace retrofits, thermal spray coatings, plasma, HVOF and paint coating services. an optimal temperature balance through heat transfer. vent the pumping system in order to prevent oil from rising into the
11). Oil sealed rotary vane pumps (aka rotary vane pumps) are the primary pumps on most vacuum systems used in the heat treatment industry. Herring, Daniel H., Vacuum Heat Treatment, Volume I, BNP Media, 2012. Features of the DEKKER Vacuum rotary vane pumps include: At a given temperature, vapor may be compressed only as far as the saturation vapor pressure; beyond that point, the vapor condenses. The filters can only be efficient and effective when proper maintenance is completed. In addition to diluting the condensable vapors, the gas ballast raises the temperature of the process gas 10-20C (18 36F), which further inhibits condensation. Changing the exhaust filter ensures the optimum performance of the vacuum pump. Over time, this will slow pump-down as the alumina becomes clogged with water. When Is it Appropriate to Use a Multistage Pump? versions. When running at higher vacuum, this issue does not occur. In addition to the foreline trap, other accessories are used on the pump inlet side to capture moisture, vapors and solid contaminants. Lower viscosity oils are used for lower operating temperatures, and smaller pumps, while medium viscosity oils are used for medium to large pumps. Also, retrofit kits are available to make existing vacuum pumps ready for Industry 4.0. Although vacuum feed oil distribution is still used, more modern pumps use a separate oil pump, to circulate the oil via passages machined into the stator to the rotor bearings and seals (Fig. One of the limiting factors of a rotary vane pump is the Duo Seal, which is the oil filled non-contact seal in the small 0.025 mm (0.001) space between the rotor and the stator at the top of the pump. As the name implies, this device closes when pumping stops, preventing gas (or air) from being sucked back into the vacuum chamber through the pump. Check and adjust the oil level once again. valve isolates the pump from the vacuum chamber in the event of
One way to prevent backstreaming is the use of a foreline trap (Fig. 2) is machined and assembled with tight tolerances so that the gap between the top of the rotor and the stator wall (often referred to as the Dou seal) is approximately .025 mm (1.0 mils). Do not leave oil inside the pump after draining. This is done via a cold trap (aka inlet condenser) located at the pump inlet. In addition to gas ballast, another approach to pumping gases containing condensed vapors or moisture is to remove them prior to entering the pump. Site Map Contact Terms and Conditions Privacy, On vacuum pumps that use a separate oil pump, a hydraulically operated inlet isolation valve can also be incorporated (Fig. eccentrically installed rotor and vanes divide the working chamber
Therefore, it is important to pick a trustworthy provider who can offer swift, reliable services on-premise and deliver spare parts without delay. For applications where the vacuum pump may be exposed to reactive or corrosive gases carried in the pumped gas, specially engineered oil is used which has been further processed to remove impurities. Moreover, the effects of the gas ballast on the
The oil-lubricated rotary vacuum pump works on the rotary vane principle (Image 2). The valve operates mechanically and is forced open by the pressure created by the pump, then closed by atmospheric pressure. It compresses the
gap between the vanes and the working chamber and additionally ensures
Typical motor oil, for example, is not sufficiently refined for use in a vacuum pump, has insufficient resistance to chemical attack, and contains additives that may be detrimental to the process being performed in the vacuum chamber. Click here to find your local authorized distributor, A wildcard character "*" should be used on incomplete model numbers, part numbers, and search terms, Titan/Liquid Ring Vacuum Pumps & Compressors, Duravane / Rotary Vane Vacuum Pumps & Low Pressure Compressors, Maxima-C / Large Capacity Liquid Ring Vacuum Pumps, Maxima-K / Large Capacity Liquid Ring Vacuum Pumps, VMax / Oil Sealed Liquid Ring Vacuum Pump Systems (35-5,400 CFM), Duravane / Rotary Vane Vacuum Pump Systems, AquaSeal / Water Sealed Liquid Ring Vacuum Systems (15-39,000 CFM), ChemSeal / Solvent Sealed Liquid Ring Vacuum Pump Systems (15-10,000 CFM), Installation, Operation and Maintenance Manuals, an automotive spin-on oil filter (on larger sizes), a built-in inlet anti-suckback valve that prevents the pump from rotating backwards when shut down with vacuum remaining in the process and prevents the rotor housing from flooding with oil. The working chamber (5) is located inside the
In the high-throughput mode, the oil pressure (and therefore flow) is increased, and in high-vacuum mode, the oil flow is decreased. It is best to use the manufacturers genuine exhaust filters, filter fleece and O-ring to complete the maintenance work. well as the narrow gap between the inlet and outlet. CCIT Container Closure Integrity Testing for Pharma Industry, Integrated Leak Detection on Coating Systems, Vacuum pumps - working principles moving parts, fills both the dead volume under the outlet valve as
Any air that flows through the exhaust filter will eventually be displaced out the exhaust port area. When the vacuum pump stops, the oil pump pressure is no longer present to force the elastomer disc open, and therefore it closes, preventing the suck back of oil through the pump and into the vacuum chamber. the high pressure stage. Some pump designs, especially older ones using circulation of the lubricating oil relied on a vacuum feed system whereby the vacuum generated by the pump itself was also employed to draw the lubricating oil through the rotor bearings. A condenser (Fig. Changing the oil and exhaust filters on a routine basis are essential and can be done following the manufacturers instruction or by a service technician. 7) is employed to capture the expelled oil. The differences include: The operating principles for the oil-free rotary vane vacuum pump are very similar to the lubricated rotary vane vacuum pump. It is important to consider maintenance work and the resulting downtime, costs for spare parts and the procurement and disposal of operating fluids. This pressure lifts a spring-loaded elastomer disc which allows oil to flow into a trough feeding the pump interior and rotor bearings as well as the vanes of the vacuum pump. Compression. Learn the ins and outs of how AODD pumps work in this webinar. Whether or not an oil pump is used, the excess oil is exhausted from the pumping mechanism via the exhaust valve. A typical cycle might start out in the high-throughput mode to evacuate the vacuum chamber as quickly as possible, then be switched into high-vacuum mode at 38 Torr (50 mbar) to achieve ultimate vacuum. The condenser also helps minimize the backstreaming of oil vapors from the pump into the vacuum chamber. This compresses the air and transports it to the exhaust box, where it then goes through one or more exhaust filters. Inlet condensers can be water cooled using a shell and tube heat exchanger or cooled with refrigerant or cryogens such as liquid nitrogen. This helps to decontaminate the oil after each operating cycle. Inside the cylinder, a rotor with several vanes is mounted eccentrically. The separator for the wet applications pump includes baffling to help the water settle out of the oil. As the lowermost vane continues its rotation, the pressure in front of it increases sufficiently to force the exhaust valve open, discharging the gas at a pressure slightly above atmospheric. The oil helps seal gaps, reduces heat and lubricates the vanes. The pump rotor is mounted eccentrically in the pump cylinder. 15) during roughing, which is the period of high flow initial pump-down at higher pressures. An insiders guide to maintaining electrical enclosure temperatures and protecting heat-sensitive equipment. The oil drain valve kit will help with this step. Injection starts at the beginning of the compression cycle. The recently retired Osephius still plans on sharing industry knowledge. Specialists in Vacuum Furnace Technology - High Quality Vacuum Furnace Manufacturer, Copyright 2016 VAC AERO - It is filled with activated alumina (also referred to as sorbent), which traps and collects the oilvapors. In the case of gas ballast operation, a hole to the outside is
1) are designed so that the stator of the pump is immersed in oil and contains a rotor which is eccentrically mounted. housing and is restricted by the stator, rotor and the vanes. The outlet of the high-vacuum stage is piped to the inlet of the low-vacuum stage. Change the pump oil every month (300 hours) and perform the other steps necessary to take care of them and you will be rewarded with years of trouble-free pump operation. If it exceeds 0.6 bar and the needle is in the red zone, filters must be changed. It can return either by gravity to the oil box or by suction through the gas ballast (to be discussed later). The mode selector controls the flow of pressurized oil to the high vacuum stage of the pump, which changes the characteristics of the pump. The main purpose for selecting a multistage pump is to efficiently operate in systems that require a high total head. To avoid these problems, a simple yet highly effective gas ballast (aka gas ballasting) operation is used. installed rotor (2), vanes (3) that move radially under centrifugal
The resulting condensate is collected and removed. pump. With normal one-shift operation, filters should be changed at least annually. Oil Sealed Rotary Vane Pumps Part 1) is a result of vaporization of the oil under low pressure. The pumping system consists of a housing (1), an eccentrically
As an inert gas, nitrogen is used when moisture, oxygen or hydrogen contained in the air would react with the process gases. oil-sealed. In this stage, the valve on the gas ballast opens and adds a certain amount of air to change the saturation pressure of the mixture. After leaving the pump, the pumped gas is passed through the mist filter, which contains a filter element that reduces the oil mist into droplets and collects it. Positive displacement indicates that the pump works by mechanically trapping a volume of gas and moving it through the pump, creating a low pressure on the inlet side. Due to the prevalence of rotary vane pumps, it is important for designers and users of industrial vacuum equipment to have a good understanding of how these pumps function. 14), which is a molecular sieve installed on the inlet of the pump. Figure 4.2: Operating principle of a rotary vane
Oil-lubricated rotary vane vacuum pumps are vacuum generators frequently used in food packaging, health care, woodworking and chemical applications. In addition, used during normal operation to prevent vapor, One way to prevent backstreaming is the use of a foreline trap (Fig. Running a vacuum pump with degraded inferior oil reduces the vacuum pumps performance and shortens its life cycle. He has been in the vacuum technology industry for over 15 years, helping design, construct and maintain several wastewater projects. When the vacuum pump is operating, its rotation also rotates the oil pump, which is mounted to the same shaft and develops a positive oil feed pressure of 0.4 bar (300 Torr) above atmospheric pressure. defects, Magnetically levitated turbopumps HiPace M. Rotary vane pumps are often equipped with an inlet isolation valve (aka anti-suckback or vacuum safety valve). Jon Mavrick is the business development manager for after sales and service at Busch Vacuum Solutions. It causes contamination, as the oil deposits as a film on interior furnace surfaces and can interfere with the process being performed. Energy costs and operating costs can also vary greatly. In addition, used during normal operation to prevent vaporcondensation, gas ballast is also used to decontaminate pump oil that has already been contaminated with condensed vapor. 9). Operating a vacuum pump with an incorrect lubricant, even with an equivalent oil, may void the warranty in the event of damage. In his latest column, Amin Almasi discusses BEP's relationship to the sizing, selection, control and operation of pumps. Gas ballasting is the injection of a non-condensable gas (e.g., nitrogen or air) into a rotary vane pump during the compression stage resulting in reduced condensation. If the oil pressure is too high, it will vaporize when exposed to vacuum, allowing oil vapor to contaminate the vacuum chamber (referred to as backstreaming). Single-stage designs can provide a vacuum of 3 x 10-2 Torr (4 x 10-2 mbar), while two-stage designs can achieve 3 x 10-3 Torr (4 x 10-3 mbar). Since the rotor is located eccentric to the pumping chamber, the volume between the rotor, vanes and housing decreases and increases rotor spins. Air is trapped inside these chambers, and as they rotate, their volume is constantly reduced. This series of articles will cover pump principles of operation, pump designs, pump oils, single-stage versus two-stage pump designs, contamination and gas ballast (manual and automatic), common accessories, applications, troubleshooting and pump maintenance. As the rotor continues to turn, the pump discharge valve is forced open and discharges the mixture of pumped gas, ballast gas, and vapor. In two-stage rotary vane pumps, the isolation valve is located on the high-vacuum stage. The choice of air or nitrogen as the ballast gas is dependent on the characteristics of the process gas being pumped from the vacuum chamber. Provide cooling of the stator by transferring heat to the outer casing. For this reason, an oil mist filter (Fig. The role of oil in an oil-lubricated rotary vane vacuum pump is twofold: a smooth rotation cycle, allowing the vanes to slide freely, and an efficient sealing of the compression chamber. This process, referred to as hydrotreating, provides a strong, stable formulation with low vapor pressure. As a result, it becomes difficult to reach ultimatevacuum and takes longer and longer times to do so as the oil loses its ability to provide a seal between the vanes and stator, and at the Duo Seal, resulting in reduced pumping efficiency. A rotary vane pump can also be used alone when high vacuum is not required and slower pump-down is acceptable. When is it time to change the exhaust filter? This provides additional protection against suck back into the vacuum chamber. A sophisticated and perfectly balanced oil formula is the secret to maintaining the initial viscosity and lubrication properties for as long as possible. In phase 1 of the drawing above, the pump will begin taking in a mixture of air and water vapor. Filters can only be efficient and effective when proper maintenance is completed. 14), which is a molecular sieve installed on the inlet of the pump. A regular oil change and the use of high-quality oils ensure the vacuum pump is performing at its optimum and continues to meet process requirements. Major stock indexes have fallen in the last year. The selection of trap(s) is based on the specific application and the constituents of the pumped gas. In addition, the viscosity must be considered. The outlet valve is
For this reason, the oil is carefully selected and specially designed for the application. Check with the manufacturer to ensure their filters comply with emissions standards. This creates increasing cell volume on the inlet port side, creating vacuum. The entire assembly (Fig. phase. For this reason, when moisture is present in the pumped gas it is, Vacuum Heat Treating: Education & Training, Vacuum Technology with The Heat Treat Doctor, Vacuum Pump Technology: Education & Training, Specific Heat Treating & Brazing Approvals. One way to think of the use of a gas ballast is that opening the gas ballast valve deliberately destroys the efficiency of the pump, which in turn causes the pump oil to heat up and drive moisture and other volatile vapors out of the oil where they can be sent up the vent stack. The volume occupied by the gas increases due to the crescent-shaped space created by the offset-mounted rotor. In the following section we continue that discussion focusing on operational features and the inner workings of these pumps. The outlet of the high-vacuum stage is piped to the inlet of the low-vacuum stage. The outlet pressure can be as high as 1000 mbar (750 Torr) and the inlet as low as .01 mbar (0.0075 Torr), which means the pressure differential across the oil-filled seal is roughly 100,000:1 (1000:0.01). Should You Repair or Replace Aging Sewer & Septic Systems? The oil seals the gaps, lubricates the vanes and removes the heat of compression. The foreline trap will stop 99% of the oil vapors. This oil is then recirculated back through the oil return line and the process starts over. This bypass arrangement prevents the alumina from quickly and unnecessarily becoming clogged during the high flow of gas and vapors pumped duringroughing. This should be done for a minimum of 30 minutes. Extending Life Span & Performance of Oil-Lubricated Rotary Vacuum Pumps. The alumina media is replaceable and must be changed at the same interval as the pump oil, typically every 6 months although this depends on usage frequency. When purchasing vacuum technology, compare the investment and energy costs of different vacuum technologies along with different manufacturers. 9). In most other cases, air is the preferred ballast gas. the vapor starts to condense. Mr. David Sobiegray, Edwards Vacuum, technical contributions, and private correspondence. Typical vane life is 50,000 hours. Learn how performance and deviation from control limits can be visualized to allow operators and engineers to understand parameters affecting reliability. Vacuum pumps are now available that feature intelligent sensors to inform the operator or service technician about pending maintenance work in real time. Since the inlet to the low-vacuum stage is considerably lower than atmospheric pressure, this design results in lower pressure at the outlet of the high-vacuum stage, as opposed to the single-stage design, whichexperiences atmospheric pressure at the outlet. Oil is then returned to the oil reservoir. The mode is selected by turning a knob located on the pump control panel. In some critical applications or where dirty work is being run and significant outgassing is anticipated, it is good practice to ballast the pump after each cycle for 20 to 30 minutes between runs. intentional or unintentional standstill, and uses the displaced gas to
One common valve design uses an elastomer (artificial rubber) or fluoro-elastomer, with a metal backing plate. For more information, visit www.buschvacuum.com. Air then passes through several stages of internal oil-and-mist eliminators to remove 99.9% of the lubricating oil from the exhaust. The rotor contains two vanes which slide in diametrically opposed slots. Wall Street Pump & Valve Industry Watch, August 2022, How IIoT Early Anomaly Detection Increases Reliability & Productivity, Software Helps Water Utility Avoid Unplanned Downtime, Basics of AODD Pumps & the Technical Advantages, Vacuum Technology Fundamentals & Innovations, Increasing the Lifespan & Reliability of Electronic Components, In-depth articles on pump industry issues, Expert insights into important topics in the field, according to the manufacturers scheduled recommendation, when there is oil discoloration, either darkening for hydrocarbon oils (from heat or other contaminants), or it is a creamy color (typically water vapor contamination), when there is degradation of the vacuum pumps performance and ultimate pressure. In a container of water (at room temperature), the pump will begin to lower the pressure to the water evaporation point (if the water is at 25C at sea level, the evaporation pressure will be 31.67 mbar absolute). The alumina also will remove moisture from the foreline and collect it as liquid water. The negative effect of ballast on ultimate vacuum and oil loss is less in the low flow mode than during high flow. This webinar covers vacuum basics including gas laws, vacuum measurements, vacuum pump sizing and much more. The inlet valve, if
The vacuum safety
The ultimate pressure achievable by the pump is limited by back-leakage through the Duo seal and by the outgassing of the lubricating oil. Upgraded technology improves White Rock, British Columbia, water quality and worker safety. A service call should include a pressure and leak check, vane check, a test run to factory standards and assurance that the equipment is running efficiently. Again, using the OEMs genuine oil filters provides the best results. The
Todays vacuum pumps allow for maintenance with access to all service relevant parts. As they become heavier, gravity forces them to drop down to the bottom of the exhaust box. It is important to use an exhaust filter with an ultra-fine medium and a tight mesh for better filtration performance. Water can be drained from the lower drain valve after the pump is stopped. Geoffrey Cresswell is the product marketing manager for rotary vane vacuum technology product lines at Busch Vacuum Solutions. Offer corrosion protection of the metal parts from the gas being pumped. Request the right vacuum equipment, for example vacuum pumps, leak detectors or mass spectrometers, directly from you sales engineer. The oil used in rotary vane pumps is carefully selected. 8). and resilient forces and the inlet and outlet (4). This isolation valve (c.f., Oil Sealed Rotary Vane Pumps Part 1) is hydraulically actuated. The high-throughput mode is also used to pump condensable (dirty) vapor, and to decontaminate the pump oil when necessary. Best Efficiency Point, Pump Selection, Control & Operation. Compared to vanes manufactured from other materials, vanes made from carbon composite material increases reliability and operational performance of the vacuum pump. On vacuum pumps that use a separate oil pump, a hydraulically operated inlet isolation valve can also be incorporated (Fig. Phys., author . Finally, in the last stage the mixture, (enriched with fresh air), is expelled, but since the saturation pressure was changed, no condensation droplets will form, and the intake vapor may be expelled from the pump without interfering with its operation. It is recommended that a vacuum pump is ballasted at least once a day, typically on startup of the equipment and before the first load is run. One of the critical components in a rotary vane pump is the exhaust valve (Fig. The vanes can be spring loaded, but otherwise, rely on centrifugal force to push outward against the stator wall. single-stage pumps. The metal backing plate limits the movement of the elastomer part of the valve. Particularly harsh applications or heavy-duty operations, such as high dust loads in the environment or in the process gas, other contamination or ingress of process material, can make it necessary to shorten the maintenance intervals. Process reliability normally depends directly on the operational safety of the vacuum pump or vacuum system. Create service tickets and find all product-related documents. An internal oil circuit allows for high operational reliability, high vacuum levels (0.1 mbar = 99.99%), high water vapor tolerance and a self-cleaning effect (Image 1). opened, which empties into the sealed suction chamber on the front
Look at the anticipated total costs over an extended period. More could and perhaps should be said on the subject of oil sealed rotary vane pumps but the key is to recognize their importance to the overall performance of your vacuum furnace. This prevents oil in the casing from filling the stator chambers. They are often called wet pumps because the gas being pumped is exposed to oil used as a lubricant to help provide the seal. Two-stage pumps achieve lower ultimate pressures than
Since the valve opens and closes with every rotation it is a source of noise and is susceptible to wear, whether elastomer is used or not. 12) works by cooling the pumped gas below the condensation temperature of the vapors (moisture and others) carried in the gas.
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