HNBR vs Silicone for Motor Oil

[thescreensavers]

I am looking at a pressure sensor to install on my G37 ,

I can purchase the Silicone option for just under $60 where as the HNBR option will be $96 shipped.

The data sheet says I should get the HNBR material but, we talk about Silicone ADBVs all the time.


Can I save a buck here and go with the Silicone option?

 

[brianl703]

Seems to me that if the data sheet says to use HNBR material with oil it's because they know that the silicone material won't hold up.

What's the consequence of a seal failure on one of these? Large quantities of oil spewing out of the sensor? Potential fire if it hits a hot exhaust manifold or engine locking up if enough oil leaks out? All to save $30?

If you really want to save money, see if a GM oil pressure sensor like 12674782 will do what you want. They run about $30 or less and use the same 3-pin connector as the sensors you're looking at, and a little Google research will tell you what thread size they use and what the voltage output/PSI relationship is.

 

[JHZR2]

Silicone vs HNBR | Articles | Jehbco Silicones

Silicone and HNBR are commonly used for o-rings, gaskets, seals, and tubing. Their physical properties vary such as temperature and abrasion resistance, chemical compatibility and tensile strength. Jehbco Silicones can help you find the right rubber for your application.

jehbco.com.au

 

[Boomer]

Hydrogenated nitrile butadiene rubber (HNBR) is a very robust, oil resistant polymer. The hydrogenation removes any remaining carbon-carbon double bonds which would be the reactive sites in regular NBR rubber and that would cause oxidative breakdown. Use what the manufacturer says.

 

[thescreensavers]

Seems to me that if the data sheet says to use HNBR material with oil it's because they know that the silicone material won't hold up.

What's the consequence of a seal failure on one of these? Large quantities of oil spewing out of the sensor? Potential fire if it hits a hot exhaust manifold or engine locking up if enough oil leaks out? All to save $30?

If you really want to save money, see if a GM oil pressure sensor like 12674782 will do what you want. They run about $30 or less and use the same 3-pin connector as the sensors you're looking at, and a little Google research will tell you what thread size they use and what the voltage output/PSI relationship is.

Why wouldn't silicone O-Ring hold up? Oil Filters use it and its considered an upgrade over NBR. Usually sensors will seep if they fail nicely .

Thanks for the GM recommendation, my car sees >100 PSI at cold start so I'd need a 150 psi gauge for reliability hence the PX3 sensor I am looking at. No issue with spending the difference in cost just thought I would ask the question. Obviously I see what the spec sheet says but my time here reading about oil filters is what's having me second guess.

Silicone vs HNBR | Articles | Jehbco Silicones

Silicone and HNBR are commonly used for o-rings, gaskets, seals, and tubing. Their physical properties vary such as temperature and abrasion resistance, chemical compatibility and tensile strength. Jehbco Silicones can help you find the right rubber for your application.

jehbco.com.au

Yea I googled the differences before posting , Both say Oils hence my post.

Hydrogenated nitrile butadiene rubber (HNBR) is a very robust, oil resistant polymer. The hydrogenation removes any remaining carbon-carbon double bonds which would be the reactive sites in regular NBR rubber and that would cause oxidative breakdown. Use what the manufacturer says.

Seems like I am leaning that way now anyhow, HNBR and be done.

 

[JHZR2]

Yea I googled the differences before posting , Both say Oils hence my post.

That’s great, but did you review the link I posted?

“However, HNBR is resistant to most forms of fuels and oils, whereas silicone is not compatible with a lot of hydrocarbon fuels. With this in mind, HNBR would be the superior choice for the automotive industry, although fluorosilicone compounds can be a good fuel-resistant alternative if a silicone-based material is required.”

Other clues include that while silicone does say it is compatible with oils, it also says it has issues with fuels and aromatic hydrocarbons. Guess what’s in fuel? And guess what gets loaded into oil when fuel dilutes it? You have no idea if the silicone unit has a fluorosilicone seal or not. It could be the cheapest silicone o ring from China, or something better.

It’s true we talk about silicone ADBVs and whatnot, but they’re purpose made for that environment. Unless we really know something about the item in your situation, it would make sense to use the better seal…. Unless replacement is super easy and the part is readily seen, then the gamble is yours.

 

[brianl703]

Why wouldn't silicone O-Ring hold up? Oil Filters use it and its considered an upgrade over NBR. Usually sensors will seep if they fail nicely

In an oil filter, it's more of a flap, not an o-ring (so it's probably a bit thicker than an o-ring) and it doesn't have to seal against the high pressure you'd find in an oil pressure sensor, only the pressure of whatever oil is in the engine above it.

And I have a car with an oil pressure sender that's leaking badly. So badly I don't want to even start it to move it to my driveway where I can jack it up to fix it. (It's currently parked on grass). It was actually squirting oil out the side! I'll see if my riding mower in conjunction with a tow strap will pull it off the grass and onto my driveway. Said oil pressure sender is 38 years old, though. And a friend of mine has confirmed that he's had them fail that way too, leaking so bad that they'd empty the crankcase in 20 minutes or less.

Thanks for the GM recommendation, my car sees >100 PSI at cold start so I'd need a 150 psi gauge for reliability hence the PX3 sensor I am looking at.

The GM sensor may well be capable of 150 PSI readings, especially if, as I suspect, it's the same as a GM high side AC pressure sensor, just with a different thread.

 

[brianl703]

It’s true we talk about silicone ADBVs and whatnot, but they’re purpose made for that environment.

Also a silicone ADBV is not expected to seal for 100,000 miles of use, unlike an oil pressure sender/sensor. Maybe 20K at most and the consequences of failure are minor.