Rubber Gaskets

That would depend on the various specifications that controlled the materials.

Do you understand Durometer? Do you understand molding? Gumstock? Extrusion?

Your question suggests that you know nothing about the subject.

That was the message I was trying to relay Lyn. My experience in this field is next to none and I feel it is the same with the engineers who sent us prints that post a nominal durometer, giving no tolerance. I admit there was some ignorance on our part for not pursuing this with the OEM. So what I'm trying to find out is, how critical the hardness is....is the various type generally held to plus or minus 1 durometer point or more like 5 points?

Still not enough information for any informed answer. And comparing the automotive and nuclear material requirements is virtually impossible.

There must be a specification called out somewhere. That will give you the tolerance range. I can't believe there isn't a tolerance call-out somewhere on the drawings, or BOM, or somewhere.

So, let's assume you are building a door gasket. It's not solid, so Durometer measurement is useless. You'll need to measure the compression of the material. There are ASTM specifications that control all this, with tolerances.

If it's solid, there will be some tolerance. + - 5 points is typical for Shore A materials.

If you'd just tell us what you are REALLY trying to accomplish there may be help here.

Thank you Lyn...trying to get information out of people who work in the nuclear industry is like pulling teeth. I found out the material in question was Neoprene made in accordance to MIL-G-1149 type 2 class 5 having a durometer of 65....After checking with vendors who sell this material I found on the majority they tolerance their material at ± 5 durometer points. What I'm trying to discern is a Shore A gage that was used to measure durometer and later failed calibration. Without getting into the pro's and con's your help along with another persons direction gave me the information to come to a conclusion. Thank you again.

inspectorK

For presure cooker applications in India, compression molded nitrile gaskets are used. Generally hardness is 70 +5/-5, 75 +5/-5 and 80 +5/-5 Durometer depending on diameter.

bioramani

Some information can be found here, here, and even here. Hope it's helpfull :)

RVZ717 the information you sent me is very helpful....thank you so much!

InspectorK

It really makes no difference which market or application.

The general rule is +/- 5.

From one gage to another you may have different results.

You may have two sample each coming in at 60 duro.

However one can feel stiffer than the other.

So in some application you need a full ASTM D2000 call out to insure you get the right

properties.

Hope this helps.

OK,K, There are standard industry accepted tolerances for Rubber products. They are published in the RMA Handbook for Rubber Products. The standard tolerance for Shore-A Hardness is usually +/- 5 points when measured IAW ASTM-D-2240. Not all rubber materials are the same. They can be custom compounded to meet certian performance requirements. When clamped in a static gasket application with sufficient loading my concern wouldn't be with the calibration date on the Durometer. I would be more concerned with the amount of leachable chlorides from the Chloroprene (Neoprene tm) in high radiation environments which cause stress corrosion and pipe fractures. We lost a couple of Navy Submarines back in the day prompting a program called Sub-Safe. The Navy eventually eliminated Neoprene in nuclear applications.