🔍 Key Concepts

• Material compatibility of O-rings with different lubricants in pneumatic systems • Effects of oil-based vs silicone-based lubricants on rubber and on small control ports/passages • Manufacturer/common practice for diaphragm-operated relay valves in clean, dry air systems

💭 Think About

• Look at how many small ports and passages are in the relay valve body—what kind of lubricant could migrate and clog or swell components? • Which lubricant type is typically recommended for rubber seals that must stay flexible, seal low pressures, and not react with dry air or system materials? • Would a completely dry O-ring be more or less likely to wear, stick, or tear in a sliding pneumatic application like the one shown?

✅ Before You Answer

• Eliminate any option that could attack, swell, or soften rubber or leave a varnish/residue in small air passages • Focus on options that are chemically inert to rubber, stable over time, and suited for dry, compressed air systems • Consider standard maintenance practice: relay valves and control valves usually specify a very light film of the chosen lubricant, not a heavy coating