Where does one find polyurethane / PUR washers? Can NBRs be used instead? Is there another material which can be use in a location where PUR is called for?
Tuning Polyurethane washers
- Thread starter nvelkhunter
- Start date
McMaster carries several.
https://www.mcmaster.com/washers/material~polyurethane-rubber/
What is the application?
https://www.mcmaster.com/washers/material~polyurethane-rubber/
What is the application?
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FX Impact, A31, B23, C3, & B25.2.
A31, 2.9 x 1.78 PUR 90
B23, 2.84 x 2.62 PUR 90
B25.2, 2.84 x 2.62 PUR 90 (Power Plenum)
C3, 2.9 x 1.78 PUR 90
B25.2, 2.84 x 2.62 PUR 90
A31, 2.9 x 1.78 PUR 90
B23, 2.84 x 2.62 PUR 90
B25.2, 2.84 x 2.62 PUR 90 (Power Plenum)
C3, 2.9 x 1.78 PUR 90
B25.2, 2.84 x 2.62 PUR 90
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Sizing question, A31 for example, 2.9 x 1.78 PUR 90. What does the 2.9 and 1.78 represent? 2.9 mm is inside diameter? 1.78 mm is width?
| width |
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| inside dia |
| width |
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| inside dia |
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While I normally get my polyurethane 90 durometer o-rings from either the o-ring store or o-rings and more as their prices are good, FX uses a couple of oddball sizes that neither of those suppliers have in polyurethane 90 durometer… but as noted above, Mcmaster-Carr does. The price at Mcmaster is quite a bit more expensive, but they have them. Sometimes Amazon will have the 90 durometer polyurethane o-rings at a low price, but I’ve had mixed results with the quality of what actually arrives. Mcmaster has never let me down.
As far as sizes, FX lists all their o-ring sizes in the schematics in metric, the numbers are inner diameter and cross section. The majority of o-rings FX uses are metric, but any oddball size on the schematics (like 7.66 x 1.78) is actually an AS568 standard o-ring they’ve converted to metric… in this case 7.66 x 1.78mm converts to .301” x 0.070”, which is an -011 o-ring in AS568 sizing. The 2.9 x 1.78 o-ring you reference is actually a -006 AS568 standard o-ring.
As far as substituting an a buna-n o ring for a polyurethane... FX probably used a far more expensive polyurethane 90 o ring in those locations because a buna o ring won't last. Polyurethane o rings are much more abrasion and wear resistant when used on moving parts, which is why they're usually used on things like the fill valve piston, etc.
As far as sizes, FX lists all their o-ring sizes in the schematics in metric, the numbers are inner diameter and cross section. The majority of o-rings FX uses are metric, but any oddball size on the schematics (like 7.66 x 1.78) is actually an AS568 standard o-ring they’ve converted to metric… in this case 7.66 x 1.78mm converts to .301” x 0.070”, which is an -011 o-ring in AS568 sizing. The 2.9 x 1.78 o-ring you reference is actually a -006 AS568 standard o-ring.
As far as substituting an a buna-n o ring for a polyurethane... FX probably used a far more expensive polyurethane 90 o ring in those locations because a buna o ring won't last. Polyurethane o rings are much more abrasion and wear resistant when used on moving parts, which is why they're usually used on things like the fill valve piston, etc.
Upvote 0