Vacuum
5 articles
Apiezon Vacuum Grease Comparison Chart
Grease AP101 AP100 M N Main Application General use Lubricating High vacuum General vacuum Melting Point ASTM.D 566 >200°C 42-52°C 40-60°C 42-52°C Working temp. range -40 to180°C 10 to 30°C 10 to 30°C -269 to 30°C Vapor Pressure (@20°C) <1.0x10 -5 Torr 7.0x10 -11 Torr 1.7x10 -9 Torr 6x10 -10 Torr Relative Density (@20°C) 0.981 1.042 0.894 0.911 Radiation Resistance No No Yes No Outgassing Characteristics TML ASTMS .E 595-90 - <1.0% - <1.0% Lubricity 4 Ball Test ASTM .D 2763 (IP 239) 450kg 450kg 140kg 150kg Viscosity of molten grease (@ 50°C / @ 100°C) - - 413cp - - - 29.8cp - Coefficient of expansion per °C over 20°C-30°C 0.00066 - 0.00075 0.00072 Thermal conductivity - - 0.194w/m°C 0.194w/m°C - - - 0.095w/m°C Latent heat of fusion - - 18.7cal/g 15cal/g Fusion Peak - - 34°C 31°C Vol. resistivity - - 2.6x1016cm 2.0x1016cm Permittivity - - 2.1 2.3 Loss tangent - - <0.0001 <0.0001 Surface breakdown at flash over - - 28kV 27kV Electric strength - - 850V 820V Grease H L T PFPE 501 Main Application Cryogenic High temps Medium temps High temps/lubricating Melting Point ASTM.D 566 does not melt 42-52°C 112-137°C Working temp. range -10 to 240°C 10 to30°C 10 to 120°C -15 to 250°C Vapor Pressure (@20°C) 1.7x10 -9 Torr 7x10 -11 Torr 4.6x10 -9 Torr 1.3x10 -12 Torr Relative Density (@20°C) 0.918 0.896 0.912 2.003 Radiation Resistance No Yes No Outgassing Characteristics TML ASTMS .E 595-90 <1.0% <1.0% - <1.0% Lubricity 4 Ball Test ASTM .D 2763 (IP 239) 250kg 150kg - 800kg Viscosity of molten grease (@ 50°C / @ 100°C) - 766cp - - 62.3cp - Coefficient of expansion per °C over 20°C-30°C - 0.00076 0.00073 Thermal conductivity - 0.216w/m°C - - - - Latent heat of fusion - 15.1cal/g - Fusion Peak 25°C 32°C * Vol. resistivity - 1.2x1016cm 3.3x1012cm Permittivity - 2.3 2.3 Loss tangent - <0.0001 <0.0001 Surface breakdown at flash over - 24kV 24kV Electric strength - 730V 730V
Apiezon Vacuum Grease Vapour Pressure
Vapour Pressure of Apiezon H Grease Over Working Temperature Range Vapour Pressure of Apiezon L, M, N and AP100 Greases Over Working Temperature Range Vapour Pressure of Apiezon T Grease Over Working Temperature Range Vapour Pressure of Apiezon AP101 Grease Over Working Temperature Range Vapour Pressure of Apiezon PFPE 501 Grease Over Working Temperature Range
Low Vacuum Pumping
Low vacuum pump applications and selection: Two-stage rotary vane pumps and the even higher (oil diffusion, turbo molecular, ion getter) vacuum pumps are selected considering pumping speed and ultimate vacuum in terms of removing some of the remaining very small fraction of gas molecules from a space. The weight of the earth atmosphere exerts a pressure of 1.033kg/cm². So a negative pressure of that would be a perfect vacuum. The difference between a mediocre vacuum pump (all diaphragm pumps give a relatively poor vacuum, but they are certainly not useless) and the very highest vacua is small in terms of kg/cm². High vacuum pumps remove a fraction of one percent of the remaining molecules. That no longer represents any real change in the weight of the atmosphere. So a vacuum of 0.8kg/cm² is good for lifting and filtering, but not sufficient to even back a turbo molecular pump. To obtain faster filtering or to lift objects it is best to compare vacua expressed in kg/cm². Any vacuum will exert some suction and so get some flow. Here is a conversion of our three diaphragm pumps - giving capacity in kg/cm² which gives you a practical comparison of three diaphragm pumps suction power. VFV-30 Diaphragm Vacuum Pump, 300mmHg 0.408kg/cm² VFV-60 Diaphragm Vacuum Pump, 600mmHg 0.816kg/cm² VF3-220 Oil-less Diaphragm Vacuum/Pressure Pump 0.881kg/cm² The biggest pump gives little more negative pressure, but that pump has a much greater pumping speed (litres/min or m3/hour) than the other two pumps. So that pump would offer little advantage when filtering and only excel if lifting involves much leakage. Obviously the larger pump is much better for pumping on larger volumes - like a vacuum oven. However, if the application is vacuum infiltration and involves low boiling point and particularly hot materials (resins), then a small pump more easily avoids boiling. Troubleshooting Guide Possible Reason Pressure Vacuum Excessive Noise Overheating Won't Start Low High Low High Dirty filter X X X X Dirty muffler X X X X Dirty valves X X X X X Bent valves X X X Low voltage X X X X X Wrong voltage X X Regulators set too high X X X Regulators set too low X X
Manual Shaping Carbon Rods
Indicator on thumb screw indicates approximately 1mm diameter. Break carbon rod about 50mm - 75mm long. Insert flat end into the hole in the base of the carbon rod sharpener. Gently push the rod up into the cutter while rotating it in a clockwise direction. Hold the carbon rod sharpener so that any carbon dust falls into a waste container. The formed tip should range from 0.4mm to 2mm in length to give the approximate film thickness shown in the table below. It is often helpful to use a paper or porcelain indicator near the specimen. Approximate grey scale is indicated in the last column of the table. IF: M = mass evaporated W = mass per unit area W= M 4o D2 D = distance to specimen W= and t t p M t = thickness (of carbon) p = density (of carbon) =V= 4o D2p or 2l r = radius of carbon rod l = length of carbon rod v = volume of carbon evaporated M= Vp and M = or 2 1p t= or 2.1 = r 2.1 4 or 2 1 Using the carbon rod sharpener as set, r = 0.5mm. For convenience, D = 100mm (with added block or platform) and the following table can be used directly. 1 t (approximate) Indication 0.4mm 2.5nm Very light 0.6mm 3.8nm Light 0.8mm 5nm Medium 1.0mm 6.2nm Medium-dark 1.5mm 9.5nm Dark 2.0mm 12.5nm Very dark (Refer to electron microscopy textbooks by Hall, Kay, Pease and others.)
Vacuum Flange Types and Sizes
General Information: No, NW, KF (from Klein Flansche) and QF are the same types of vacuum flange systems. KF is the more popular European term, while NW is more popular in North American. QF in reference to Quick Flange, is descriptive of the type flange system. Most standard NW/KF style quick release vacuum connections are made from a high quality grade 304 stainless steel. Stainless steel is a cleaner, stronger and more durable alternative to aluminium. For specific applications, some vacuum components are also available in aluminium. The NW/KF system refers to the bore dimensions. NW/KF Size External Diameter (A) Internal Diameter, Metric (B) Internal Diameter, Imperial (B) NW/KF10 30mm 14mm 12.7mm (½") NW/KF16 30mm 20mm 19.05mm (¾") NW/KF25 40mm 28mm 25.4mm (1") NW/KF40 55mm 45mm 38.1mm (1½") NW/KF50 75mm 57mm 50.8mm (2") C = length of flange can vary Vacuum Connection Parts and Fittings Vacuum clamps, O‐rings, centring rings, blanking plates, hose adapters are widely used in vacuum systems and low‐voltage pipe systems, such as electronic, food machinery, the petrochemical industry, and medicine machinery. Most vacuum fittings come with plastic protective caps which help protect the NW/KF flanges from scratches and dust. A typical KF or NW assembly consists of two identical flanges, a centre-ring and a clamp with a fastener that allows for frequent connection and disconnection without tools. A vacuum seal is created by uniform application of pressure by the clamp on 15° surface of the flange. When the clamp is tightened the flange surfaces compress the o-ring (held in place by the centre-ring) to generate a seal. Hinged clamp assemblies like the one above are most commonly used for making KF-flange vacuum seal connections. Assembly is simplified by the 360° rotatable flanges ad self-centring feature of the centring-ring. Applications for vacuum systems are as varied as the imagination and include use for: Roughing and foreline plumbing for vacuum systems Small systems Systems demanding frequents changes or cleaning Experimental systems in research laboratories Teaching laboratories ISO fittings (ISO‐K / ISO LF) ISO fittings are joined by a centring ring and an elastomer o‐ring. "The ISO large flanges come in two varieties. The ISO‐K (or ISO LF) flanges are joined with double claw clamps which clamp to a circular groove on the tubing side of the flange. The ISO‐F (or ISO LFB) flanges have holes for attaching the two flanges with bolts. Two tubes with ISO‐K and ISO‐F flanges can be joined together by clamping the ISO‐K side with single claw clamps which are then bolted to the holes on the ISO‐F side." ‐ Wikipedia ISO large flanges are available in sizes from 63 to 500mm nominal tube diameter. ISO standard size Tube Diameter DN63LF 63.5mm DN100LF 102mm DN160LF 160mm DN200LF 200mm DN250LF 254mm DN320LF 316mm DN400LF 400mm DN500LF 500mm Conflat fittings (CF / ISO‐F) Conflat (CF) fittings use a copper gasket and knife‐edge flange to achieve an ultrahigh vacuum seal. "Each face of the two mating CF flanges has a knife edge which cuts into the softer metal gasket, providing an extremely leak‐tight, metal‐to‐metal seal. Deformation of the metal gasket fills small defects in the flange..." ‐ Wikipedia