O ring groove design

[Mo_gad]

I’ve been searching for the standard used for the designing of the screw plug o ring groove in the pcp guns blocks (like the valve plug in raw hm1000 and fx crown for example) and i found some standard explaining the groove design but for hydraulic systems and i noticed that they are different from the ones used in pcp blocks, in the hydraulic standard i notice that the cavity always has an angle (from12-15 degree)but the pcp ones it’s straight as shown in the photos attached so could anyone please help me understand this point?! I compare many fluid standards and I couldn’t found a matching one

[rsterne]

Here are two sites that I use....

https://www.ponnmachine.com/engineering-tools/o-ring-groove-design

https://www.marcorubber.com/o-ring-groove-design-directory.htm

I have never seen tapers used.... I make my grooves with a simple tool like a parting tool, of the appropriate width for the cross section of the O-ring.... The depth of the groove to give the correct compression is measured from the opposite sealing face....

The O-ring gets forced into the low pressure corner, like this.... Ignore the arrow, that was for another reason (avoid sliding in that direction, the O-ring will tend to bind)....



If the clearance is too great for the hardness of the O-ring, it will extrude into the gap.... When old O-rings are removed, they are often flattened and/or squared off from continuous pressure, but as long as the two contact surfaces in the diagram are smooth, they should remain sealed.... O-ring lube allows them to migrate into that corner without abrasion or tearing....

Bob

[OTmachine]

The style of oring seal that the OP posted a picture of is usually referred to as a Boss O-ring Seal which is typically used for Hydraulics.  There is a Mil-Spec for it also, (I believe MS-3906?).