I just installed spring brakes on drive axle of a bobtail, and don't know what to do with the balance port of the relay valve. Leaving the port open, the spring brake will set and release as it should with no loss of air through the balance port. If I plug the port, the relay will not exhaust the air to set the brakes. I know there are all kinds of relay valves that work differently, but this one seems to be just a single function valve .I am using the original relay valve(quick release)for the service brake, so the new valve only controls spring brake. Can I just leave the balance port vented to atmosphere, or will dirt getting in it be a problem? This relay has a supply, exhaust, balance and two ports for the brake hoses.

I can't seem to find any place to balance the valve to the rest of the system. TIA