Difference between revisions of "Scroll pump"

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*"it seems like you can get them in a mix of bronze, carbon, and MoS2"
 
*"it seems like you can get them in a mix of bronze, carbon, and MoS2"
  
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Anything quick to try?
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* https://www.mcmaster.com/o-ring-cord-stock/cross-section-shape~square/
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** Roughly the right size but too high friction
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===Commercial===
 
===Commercial===
 
Sample commercial pricing. Keep distributors anonymous unless they explicitly list pricing  
 
Sample commercial pricing. Keep distributors anonymous unless they explicitly list pricing  

Revision as of 09:26, 21 May 2021

Tip seal

One of the biggest issue of owning a scroll pump is tip seals wear out fairly quickly and can be expensive to replace. Many scroll pumps are essentially totaled if kits can't be found readily. This section is about evaluating the merits of making DIY tip seals

Understand wear profile of different materials. Ex: for hobby use a lower grade material may be good enough for low duty cycle

How to know when tip seal is running low without opening / hearing grinding? What it be helpful to install hour counter?


Comments:

  • We have made our own tip seals before
  • Stopped since they seemed to last a little under half as long as the proper ones
  • https://www.mcmaster.com/86375K162/
    • Resilient Polyurethane Foam Sheet
    • with Adhesive-Back, Medium, 12" x 12" x 1/16"
  • https://www.mcmaster.com/1441T21/
    • Slippery UHMW Polyethylene Film
    • Adhesive-Back, 12" x 12" x 3/64"
  • then it's just held in the frame pictured above and waterjet
  • the little bit we have left says UH-9, PORON
  • I mean we also run 24/7
  • so tip seal replacements after about a year of runtime instead of 2-3
  • also the DIY ones definitely produced more "dust"


Made-in-China

  • Tip Seal PTFE Filled Bronzed Wear Strips Special Designed for Scroll Compressor
  • PTFE + Bronze
  • Also used in hydraulic cylinders
  • "it seems like you can get them in a mix of bronze, carbon, and MoS2"


Anything quick to try?

Commercial

Sample commercial pricing. Keep distributors anonymous unless they explicitly list pricing

Vendor Pump Kit Price Notes
Busch FO 0018 C OHO Tip seal $545.00

2021-04

Busch FO 0018 C OHO Full $3928.00

2021-04

How much does a pump cost..
Edwards nXDS6i nXDS10i nXDS15i & nXDS20i Tip seal

73501801

$220

2021-05-19

Compatibility between these? Could we match one of the less expensive kits to one of the more expensive pump rebuilds?

Manufacturing gaskets

Some suggested that these can only be injection molded

Suspect these can be (waterjet?) cut from sheets or simply applied as strips

Laser cutting probably isn't precise enough and would produce nasty fluorinated fumes

Milling might work (with enough support) but will waste a lot of expensive material

Material (black)

Busch black gasket material analysis

  • Suspected to be bronze filled PTFE
  • FTIR has confirmed PTFE is primary organic
  • EDS analysis pending

Busch gasket dimensions

  • Maybe 2.5 mm => 0.0098" square
  • Height
    • Channel: maybe 0.075"
    • Gasket (worn): around 0.080"
  • Width
    • Channel: maybe 0.095" wide
    • Gasket: maybe 0.096" wide
  • Scroll area: around 7"
  • Length needed: around 276" (23')
    • Gasket length: around 69"
    • Gaskets: 4

McMaster-Carr has bronze filled PTFE sheets

Material (yellow)

Scrolls [walls] are anodized aluminum

[gasket] likely Class 3 PTFE filled

that 1045 is even more likely


Rulon J can be made in thin film form

Looking at some rebuild kits

  • official kit has green viton orings not brown [for general gaskets]

Other option could be use something like PTFE bronze that could wear off easier but it's 10X cheaper so you would endup changing the seal more frequently but without custom built orders


Yellow gasket

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