# O-Ring Design for low pressure applications

I'm trying to figure out how to create a seal for a very low pressure gravity feed system. Essentially its a low pressure solenoid valve. Is there any equations to estimate the amount of force you would need on a o-ring to seal it from any leaks of pressure $$p$$ its placed in a spring solenoid combination so I need to have this as low pressure as possible. Any ideas on what force I would need from the spring to seal a liquid the pressure is due to a height of about 40mm with a liquid like water. So if my math is right that's $$\rho g h = 997 kg/m^3 * 0.04m * 9.81m/s^2 = 391.22\ pascals$$ at the o-ring so pretty small amount of pressure.

Also what material would you suggest for the O-ring I have considered, I have used 50 Durometer with no success and am thinking about moving to a silicone based O-Ring. I can't increase the force of the spring because a solenoid will need to overcome it and i'm limited on space.

• If you don’t create enough force between o-ring and solenoid it will leak... if the o-ring is a tight fit around the solenoid then control the fit of the o-ring in the bore. It will add to the load for the solenoid - is this a valve of some type - what about a collapsible pipe section being crushed as the pressures are low... – Solar Mike Sep 7 '19 at 3:28
• O-ring manufacturer's websites have lots of great information on how to design with O-rings. For instance applerubber.com. You can also call them and they are very likely to help you with your application. – Eric S Mar 1 at 0:09