Vacuum Technology and Vacuum Design Handbook for Accelerator ...

More documents

Recommendations

Info

ISO-F flanges are more of a traditional bolted flange type joint like Dependex. ISO-F and ISO-K can be joined together using a half clamp which fits onto a standard ISO-F flange. The half clamps then attach to the ISO-K flange. Available in sizes from 63 mm nominal bore to 500 mm NB. 8.7 Conflat CF Conflat is designed as an all metal vacuum seal for ultra high vacuum applications. A copper gasket is sandwiched between two thick stainless steel flanges that have a knife edge machined into the sealing face. As the flanges are tightened together the knife edges “bite” into the copper to produce an all metal seal with very low outgassing. The term "ConFlat" is a registered trademark of Varian, Inc., so "CF" is commonly used by other flange manufacturers. Conflat sealed systems can reach vacuums as high as 1 x 10 -11 Pa. The copper gasket locates into a partially recessed in a groove in each flange to provide alignment prior to tightening. It also stops the gasket from moving during bake out. Conflat can be baked up to 450°C. - 30 - One half of an ISO-K assembly – clamp style Note the slot for locating the jaw of the clamp ISO-K adapter flange that allows ISO-K to become an ISO-F. Note that the retaining ring slots into the outer groove on the ISO-K flange ISO-F flange Bolt style Centring ring Fig 4. ISO family of Flanges Note for each flange drawing: Seal Side Air Side
Most Conflat flanges have imperial sized bolts. The original style of bolt had a multi-face head that a ring spanner would fit over. This is to allow more purchase on the head from many angles. It is not uncommon now to find hexagon and socket head screws in use. Be aware that the steel must be a high tensile grade to ensure optimum force can be used to crush the gasket. It is essential that the flange faces are parallel during and on final tightening. A torque wrench may be used to facilitate uniform tightening. It is highly recommended that a molybdenum grease or graphite loaded grease is used on the threads. Conflat flanges are available in sizes from 10 mm nominal bore to 250 mm NB. Sometimes nominal bore is written DN in front of the size, eg DN63. Square section Viton ‘o’ rings may be used with Conflat flanges however this compromises the ultra high vacuum design and ultra high vacuums may not be reached. Problems • Copper gasket not aligned in groove and edge is partially clamped on the bolt hole face of the flange. This lead to partial seal and most likely, a leak. Most Conflat flanges have two small grooves a little more than a millimetre wide machined into the bolt face. These are for locating special clips that hold the gasket in place while the flanges are brought into place. Just prior to tightening they clips are removed. They are sometimes mistakenly called pressure relieving grooves. • Copper gaskets must only be used once. Unless the copper hasn’t been fully compressed after the first use there will not be enough material for the knife edge to reform a seal. • Due to the forces required for a knife edge to indent a copper gasket the flanges are made of stainless steel and quite thick. Large flanges are quite heavy and care must be taken not to drop them. • Where Conflat flange bolts have been used more than once the threads in the flange and screws may have stretched. In this case, it is recommended that the same screws are reused in the stretched threads (with a little molybdenum grease) as they will have the same profile. Sometimes using new screws in a stretched thread will cause binding. Re-tap the flange if necessary. • Stretched threads are possible where nuts and bolts are used through open holes so ensure the nuts go onto the bolt the same way they were removed. Alternatively replace the nuts and bolts outright. • For ultra high vacuum ensure the gaskets are handled with gloves. Copper reacts well with the sweat in a fingerprint leading to a long outgassing process. 9. Bellows Bellows consist of two styles, edge welded for ease of extension or compression and corrugated style which is has minimal movement. Each style is made from a thin stainless steel that has been electron beam welded. The ends are usually finished in a standard flange to suit the application. 9.1 Corrugated style These are typically used for two purposes. Firstly, to allow sections of beam lines or equipment to be compressed to allow easy removal of sections without dragging the sealing surfaces against each other. Secondly, as bellows can distort and still maintain their structural integrity they are ideal to - 31 -
Page 1 and 2: Vacuum Technology and Vacuum Design
Page 3 and 4: Contents Page Chapter 1 - Vacuum de
Page 5 and 6: 3.5 Reynolds Number (Re) 3.6 Viscou
Page 7 and 8: • Top and bottom flanges to have
Page 9 and 10: • STAR utilises many of the major
Page 11 and 12: • For all other vacuum equipment
Page 13 and 14: 1. Terminology ANTARES - Australian
Page 15 and 16: Non-cylindrical chambers must be ca
Page 17 and 18: 3.9 Design by numbers This is a mat
Page 19 and 20: The ultimate vacuum is improved by
Page 21 and 22: pump. Slowly open the pump out valv
Page 23 and 24: Precautions • Before venting a va
Page 25 and 26: • Changing faulty seals - cleanin
Page 27 and 28: can be used on stainless steel with
Page 29: • Some steps for inner rings have
Page 33 and 34: on the location of the valve. See t
Page 35 and 36: The third type is magnetically coup
Page 37 and 38: 13. Pumping 13.1 General It is not
Page 39 and 40: • On ANTARES the Pfeiffer brand i
Page 41 and 42: The pressure exerted from a vacuum
Page 43 and 44: as Avogadro's number. The mass of t
Page 45 and 46: pumped at the highest flow rate ach
Page 47 and 48: Gas Formula Molecular weight - 47 -
Page 49 and 50: It is normally specified in Pa.l.s
Page 51 and 52: 4. Limitations The most fundamental
Page 53 and 54: connection. Even some metals (Cd, Z
Page 55 and 56: adequately tight if the equilibrium
Page 57 and 58: Appendix 1 - Structural Calculation
Page 59 and 60: Factor tables for thickness calcula
Page 61 and 62: Factor A table for Stainless Steels
Page 63 and 64: PCTFE exhibits high chemical resist
Page 65 and 66: ass has good corrosion resistance t
Page 67 and 68: Glass is similar to ceramics in thi
Page 69 and 70: Appendix 4 - Surface finishing In m
Page 71 and 72: Appendix 5 - Vapour Pressures conti
Page 73 and 74: Aluminium 6061-T4 Aluminium 6061-T4
Page 75 and 76: SS H2 glow discharge - 150°C SS Ar
Page 77 and 78: Araldite (moulded) Araldite D Arald
Page 79 and 80: fittings and equipment protruding f
Page 81 and 82:
References • Berman, Vacuum Engin
Page 83 and 84:
Vacuum Technology and Vacuum Design
Page 85 and 86:
5.3 Fumes form exhausts 5.4 Earthin
Page 87 and 88:
Chapter 1 Vacuum design standards a
Page 89 and 90:
• Electric arc with rods is not r
Page 91 and 92:
8. Lubricants, vacuum greases and e
Page 93 and 94:
Chapter 2 Design Criteria, Informat
Page 95 and 96:
mostly imperial. Typically, UNC and
Page 97 and 98:
3.5 Flexible design It is prudent t
Page 99 and 100:
option. This is where add on vacuum
Page 101 and 102:
The accelerator beam lines are divi
Page 103 and 104:
Water vapour and residual solvents
Page 105 and 106:
• Cryopumps must not be operated
Page 107 and 108:
Final clean. It is recommended that
Page 109 and 110:
8.3 Edwards This is no longer a pre
Page 111 and 112:
ISO-F flanges are more of a traditi
Page 113 and 114:
join sections of beam line or equip
Page 115 and 116:
• Feedthroughs can be purchased i
Page 117 and 118:
12. Internal Devices There are many
Page 119 and 120:
services, can be regenerated withou
Page 121 and 122:
Chapter 3 Overview of Basic Vacuum
Page 123 and 124:
2. Pressure Fundamentals 2.1 Genera
Page 125 and 126:
Pressure (Pa) Molecules / cm 3 Mole
Page 127 and 128:
By evaluating the Knudsen (Kn) and
Page 129 and 130:
table in “Conductivities” below
Page 131 and 132:
Where: qpV = Throughput flow rate p
Page 133 and 134:
Diffusion Permeation Desorption Lea
Page 135 and 136:
4.4 Diffusion with desorption At op
Page 137 and 138:
4.7 Bake-out The following prerequi
Page 139 and 140:
For Hemispherical End (h2): R ≤ 8
Page 141 and 142:
Example 3: For comparison, calculat
Page 143 and 144:
Appendix 2 - Low Outgassing Special
Page 145 and 146:
Appendix 3 - Materials for use in V
Page 147 and 148:
• Polyvinyl Chloride (PVC) is acc
Page 149 and 150:
o Apiezon Sealing Compound Q • Va
Page 151 and 152:
- 70 - Appendix 5 - Critical Vapour
Page 153 and 154:
Appendix 6 - Outgassing tables for
Page 155 and 156:
Stainless steel Stainless steel 304
Page 157 and 158:
PVC 24h @ 95% relative humidity PTF
Page 159 and 160:
Appendix 7 - Local Plant and Safety
Page 161 and 162:
Regular maintenance applied via Acc
Page 163 and 164:
Page 165 and 166:
Contents Page Chapter 1 - Vacuum de
Page 167 and 168:
3.5 Reynolds Number (Re) 3.6 Viscou
Page 169 and 170:
• Top and bottom flanges to have
Page 171 and 172:
• STAR utilises many of the major
Page 173 and 174:
• For all other vacuum equipment
Page 175 and 176:
1. Terminology ANTARES - Australian
Page 177 and 178:
Non-cylindrical chambers must be ca
Page 179 and 180:
3.9 Design by numbers This is a mat
Page 181 and 182:
The ultimate vacuum is improved by
Page 183 and 184:
pump. Slowly open the pump out valv
Page 185 and 186:
Precautions • Before venting a va
Page 187 and 188:
• Changing faulty seals - cleanin
Page 189 and 190:
can be used on stainless steel with
Page 191 and 192:
• Some steps for inner rings have
Page 193 and 194:
Most Conflat flanges have imperial
Page 195 and 196:
on the location of the valve. See t
Page 197 and 198:
The third type is magnetically coup
Page 199 and 200:
13. Pumping 13.1 General It is not
Page 201 and 202:
• On ANTARES the Pfeiffer brand i
Page 203 and 204:
The pressure exerted from a vacuum
Page 205 and 206:
as Avogadro's number. The mass of t
Page 207 and 208:
pumped at the highest flow rate ach
Page 209 and 210:
Gas Formula Molecular weight - 47 -
Page 211 and 212:
It is normally specified in Pa.l.s
Page 213 and 214:
4. Limitations The most fundamental
Page 215 and 216:
connection. Even some metals (Cd, Z
Page 217 and 218:
adequately tight if the equilibrium
Page 219 and 220:
Appendix 1 - Structural Calculation
Page 221 and 222:
Factor tables for thickness calcula
Page 223 and 224:
Factor A table for Stainless Steels
Page 225 and 226:
PCTFE exhibits high chemical resist
Page 227 and 228:
ass has good corrosion resistance t
Page 229 and 230:
Glass is similar to ceramics in thi
Page 231 and 232:
Appendix 4 - Surface finishing In m
Page 233 and 234:
Appendix 5 - Vapour Pressures conti
Page 235 and 236:
Aluminium 6061-T4 Aluminium 6061-T4
Page 237 and 238:
SS H2 glow discharge - 150°C SS Ar
Page 239 and 240:
Araldite (moulded) Araldite D Arald
Page 241 and 242:
fittings and equipment protruding f
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
The pressure exerted from a vacuum
Page 367 and 368:
as Avogadro's number. The mass of t
Page 369 and 370:
pumped at the highest flow rate ach
Page 371 and 372:
Gas Formula Molecular weight - 47 -
Page 373 and 374:
It is normally specified in Pa.l.s
Page 375 and 376:
4. Limitations The most fundamental
Page 377 and 378:
connection. Even some metals (Cd, Z
Page 379 and 380:
adequately tight if the equilibrium
Page 381 and 382:
Appendix 1 - Structural Calculation
Page 383 and 384:
Factor tables for thickness calcula
Page 385 and 386:
Factor A table for Stainless Steels
Page 387 and 388:
PCTFE exhibits high chemical resist
Page 389 and 390:
ass has good corrosion resistance t
Page 391 and 392:
Glass is similar to ceramics in thi
Page 393 and 394:
Appendix 4 - Surface finishing In m
Page 395 and 396:
Appendix 5 - Vapour Pressures conti
Page 397 and 398:
Aluminium 6061-T4 Aluminium 6061-T4
Page 399 and 400:
SS H2 glow discharge - 150°C SS Ar
Page 401 and 402:
Araldite (moulded) Araldite D Arald
Page 403 and 404:
fittings and equipment protruding f
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419 and 420:
Page 421 and 422:
Page 423 and 424:
Page 425 and 426:
Page 427 and 428:
Page 429 and 430:
Page 431 and 432:
Page 433 and 434:
Page 435 and 436:
Page 437 and 438:
Page 439 and 440:
Page 441 and 442:
Page 443 and 444:
Page 445 and 446:
Page 447 and 448:
Page 449 and 450:
Page 451 and 452:
Page 453 and 454:
Page 455 and 456:
Page 457 and 458:
Page 459 and 460:
Page 461 and 462:
Page 463 and 464:
Page 465 and 466:
Page 467 and 468:
Page 469 and 470:
Page 471 and 472:
Page 473 and 474:
Page 475 and 476:
Page 477 and 478:
Page 479 and 480:
Page 481 and 482:
Page 483 and 484:
Page 485 and 486:
Page 487 and 488:
Page 489 and 490:
Page 491 and 492:
Page 493 and 494:
Page 495 and 496:
Page 497 and 498:
Page 499 and 500:
Page 501 and 502:
Page 503 and 504:
Page 505 and 506:
Page 507 and 508:
Page 509 and 510:
Page 511 and 512:
Page 513 and 514:
Page 515 and 516:
Page 517 and 518:
Page 519 and 520:
Page 521 and 522:
Page 523 and 524:
Page 525 and 526:
Page 527:
ERROR: stackunderflow OFFENDING COM
show all

Vacuum Technology and Vacuum Design Handbook for Accelerator ...

Create successful ePaper yourself

Delete template?

Save as template?