GMW GMW16163 PDF

This specification covers fluoroelastomers used in static sealing of Crankcase Ventilation Systems for gas (flex fuel) and diesel engines using B20.

Material Description. Materials are divided into the following types:

Type A: Fluoroelastomer (FKM/FPM) gasket or o-ring for use as sealings for +150 °C permanent and +175 °C peak temperatures.

Type B: All Type 1 or 2 fluorocarbon (FKM/FPM) gasket or o-ring compounds with a functional temperature range of -15 °C to 175 °C are defined by ASTM D1329 TR₁₀ and SAE J2236 respectively. 

Type C. All Type 3 fluorocarbon (FKM/FPM) compound(s) with a functional temperature range of -25 °C to 175 °C are defined by ASTM D1329 TR₁₀ and SAE J2236 respectively.

Type only (no subscript grade) specification descriptions indicate the approved compound met all the requirements in Table 1 Material and Performance Properties.

Grade Description. Compound approvals that require special designations by engine fluid resistance are designated with a subscript letter. These compounds met the requirements differing only by the select fuel in which they were tested. This permits a gas or diesel only approval.

Ag, Bg, Cg. These symbols identify material types with resistance to gas only.

Ad, Bd, Cd. These symbols identify material types with resistance to diesel only. 

Symbols. Identify the elastomer nomenclature using ASTM D1418 or ISO 1629.

Typical Applications. The ventilation system transfers combustion (blow-by) gases, water and fuel vapor out of the engine crankcase. This standard covers the use of fluorocarbon elastomer whose function is to seal the vent system (plenum, air/oil separator, flow control devices - valves or orifices, quick-connect o-rings, fittings or caps). Hose and tubing is covered by other standards.

Remarks. 

Fluorocarbons, when immersed in static (non-aerated) test fluids, often have higher property loss changes than in aerated fluids. These test conditions may not give direct correlation with service performance, but serve as comparative data for decision making.

Some prints/drawings identify "D" or racetrack shapes as o-rings. To avoid confusion, testing and table data only apply to the ASTM D1414 definition of an o-ring.

Recent studies by DuPont Polymers recommend no metal oxide peroxide cure FKM/FPM compounds for maximum protection against biodiesel containing water.

Elastomers used in crankcase vent system purchased assemblies are selected by supplier specific criteria and often remain unspecified or unidentified on end user prints and drawings. As the original equipment manufacturer (OEM) end user we reserve the right to define common rather than source specific requirements. Use this document in the appropriate Statement of Requirements and corporate prints and drawings as designated in Section 8 Coding.